Forest Management Guidelines for the Protection of the Physical …€¦ · Protection of the Physical Environment have been prepared to help resource managers pre-vent, minimize

Forest Management Guidelinesfor the Protection of thePhysical Environment

VERSION 1.0

December 1997

D.J. Archibald, R.P.F.W.B. Wiltshire, R.P.F.D.M. MorrisB.D. Batchelor

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MNR # 51032 ISBN 0-7794-2333-X (Internet)

Executive Summary

The Forest Management Guidelines for theProtection of the Physical Environment havebeen prepared to help resource managers pre-vent, minimize or mitigate adverse effects on thephysical environment when planning and con-ducting forest operations. These guidelines aredesigned to contribute to the maintenance of thehealth and inherent long-term productivity offorested ecosystems on Crown Land in Ontario.

These guidelines provide an overview of themajor site damage issues confronting landmanagers during harvest, renewal and mainte-nance activities. Relationships between site andstand attributes, environmental factors and forestoperations are discussed in terms of potentialimpacts on the physical environment.

A series of site damage fact sheets arepresented for compaction and rutting, erosion,nutrient loss, loss of productive land and hydro-logical impacts. Each fact sheet describes thetype and impact of damage, and the site factors,

environmental conditions and managementactivities that may contribute to increased risk ofdamage. The fact sheets then present BestManagement Practices to consider in areas ofplanning, field layout, implementation andmonitoring to prevent or minimize negativeimpacts. Where appropriate, mitigation tech-niques are described for the rehabilitation ofdamaged sites. Site damage hazard tables weredeveloped for compaction and rutting, erosionand nutrient loss. These tables rate the risk ofdamage to soil and site factors.

The Best Management Practices describedin these guidelines will assist in developing bothForest Units and Silvicultural Ground Rules, asdescribed in the Forest Management PlanningManual. They will also provide direction to landmanagers when formulating site-specific treat-ments when developing Forest Operation Pre-scriptions during preparation of the AnnualWork Schedule.

Forest Management Guidelines for the Protection of the Physical Environment iii

Table of Contents

Executive Summary ............................................................................................................................................ i

Forest Management Guidelines for the Protection of the Physical Environment ............................................... 1

1.0 Introduction .................................................................................................................................................. 1

1.1 About This Guide ................................................................................................................................... 1

1.2 Using This Guide .................................................................................................................................. 1

1.3 Consideration of Statement of Environmental Values ........................................................................... 2

2.0 Concepts and Definitions ............................................................................................................................. 2

2.1 What is Site Damage?. .......................................................................................................................... 2

2.2 What is Site Productivity?. ..................................................................................................................... 3

2.3 Ecosystem Resilience ........................................................................................................................... 3

2.4 What are Sensitive Sites? ...................................................................................................................... 4

2.5 What are Best Management Practices? ................................................................................................ 4

3.0 Altering the Physical Environment: Issues and Concerns ........................................................................... 4

3.1 Potential Impacts on the Physical Environment .................................................................................... 4

3.1.1 Compaction and Rutting .............................................................................................................. 4

3.1.2 Erosion ......................................................................................................................................... 5

3.1.3 Nutrient Loss ................................................................................................................................ 5

3.1.4 Loss of Productive Land .............................................................................................................. 5

3.1.5 Hydrological Impacts ................................................................................................................... 5

3.2 Key Site Characteristics. ....................................................................................................................... 6

3.2.1 Soil ............................................................................................................................................... 6

3.2.2 Terrain .......................................................................................................................................... 7

3.2.3 Forest Vegetation ......................................................................................................................... 7

3.3 Forest Operations .................................................................................................................................. 8

3.3.1 Silvicultural System ...................................................................................................................... 8

3.3.2 Logging Method ........................................................................................................................... 8

3.3.3 Renewal and Maintenance .......................................................................................................... 8

3.4 Environmental Conditions ..................................................................................................................... 8

3.4.1 Season of Operation .................................................................................................................... 8

3.4.2 Rainfall ......................................................................................................................................... 9

4.0 Planning for the Protection of the Physical Environment ............................................................................. 9

4.1 Forest Management Plan ...................................................................................................................... 9

4.1.1 Identification of Issues ................................................................................................................. 9

4.1.2 Determining Objectives ............................................................................................................. 10

4.1.3 Formulating Strategies ............................................................................................................... 10

(Continued...)

iv Technical Series

Table of Contents (...Continued)

4.2 Annual Work Schedule ........................................................................................................................ 11

4.3 Operational Design (On-Site Planning) ............................................................................................... 11

5.0 Compliance Monitoring .............................................................................................................................. 12

6.0 Operator Training and Education ............................................................................................................... 12

Site Damage Fact Sheets ................................................................................................................................ 13

Compaction and Rutting ........................................................................................................................... 14

Erosion ...................................................................................................................................................... 21

Nutrient Loss ............................................................................................................................................. 27

Loss of Productive Land ............................................................................................................................ 32

Hydrological Impacts ................................................................................................................................ 34

Acknowledgments ............................................................................................................................................ 37

Literature Cited ................................................................................................................................................. 38

Appendix 1: Characteristic Soil Types for Forested Ecosites in Northwestern Ontario .................................... 40

Appendix 2: Percentage of Soil Type by Site Type in Northeastern Ontario ..................................................... 41

Appendix 3: Percentage of Soil Type by Ecosite in Central Ontario ................................................................. 42

Forest Management Guidelines forthe Protection ofthe Physical Environment

1.0 Introduction

These guidelines were prepared to help resourcemanagers prevent, minimize or mitigate adverseeffects on the physical environment when plan-ning and implementing forest operations. Thepreparation of this guide was required by EATerm and Condition 94b arising from the deci-sion of the Environmental Assessment Boardduring the Class Environmental Assessment forTimber Management On Crown Lands in On-tario (Environment Assessment Board 1994)1.It complies with Direction ‘90s (OMNR 1992),the Crown Forest Sustainability Act (CFSA;Government of Ontario 1994), and the ForestOperations and Silviculture Manual (OMNR1995). All these documents state that forestsustainability is the primary objective of forestmanagement. Under the CFSA, the OntarioMinistry of Natural Resources (MNR) maydirect forest operations to be stopped or modi-fied if the operations are causing or are likelyto cause site damage that impairs or is likely toimpair Crown forest sustainability (S. 55).

1.1 About This Guide

The Forest Operations and Silviculture Manuallists these guidelines as one of a suite of guide-lines that must be considered during the plan-ning and implementation of forestry activities.Related guidelines which address specificaspects of protecting the physical environmentinclude:

• Silvicultural Guides (OMNR 1997a, 1997b),

• Timber Management Guidelines for theProtection of Fish Habitat (OMNR 1988a),

• Environmental Guidelines for Access Roadsand Water Crossings (OMNR 1988b), and

• Code of Practice for Timber ManagementOperations in Riparian Areas (OMNR1991).

Broadly speaking, the physical environmentincludes soil, water and air. The primary focusof this guide is the effects of forest operationson physical forest site characteristics. Readersare referred to the above documents for furtherinformation on protecting the physical environ-ment.

These guidelines were developed through asynthesis of current information and expertopinion. They will be updated periodically asour understanding of the impacts of forestoperations on site productivity improves.

1.2 Using This Guide

These guidelines relate to the conduct of forestoperations on Crown Forest Land in Ontario.We review the major types of site damage thatcould result from forest operations and presentbest management practices to prevent, minimizeor mitigate these conditions. These guidelinesformalize the requirements for protecting thephysical environment and give forest practition-ers (those involved in both planning and fieldimplementation) a set of tangible objectives forwhich to plan.

1 T&C 94b requires production of guidelines to address operational considerations with the purpose of protecting thephysical environment, and to provide direction in relation to harvest layout, configuration and clearcut sizes. Theseguidelines address the first requirement, while the guidelines regarding forest harvest parameters are forthcoming.

2 Technical Series

A series of site damage fact sheets describethe type, impact, and contributing factors foreach type of damage and introduce Best Man-agement Practices to consider in both planningand field implementation. Often, these practicesare already followed in Ontario, and this guideserves to compile and document them in aconsistent format. The authors recognize theinherent variability of both ecosystem condi-tions and forest operations, and therefore sup-port the application of professional judgment atthe local level to ensure the protection of thephysical environment. These fact sheets willassist in developing both Forest Units andSilvicultural Ground Rules as described in theForest Management Planning Manual (FMPM;OMNR 1996). These guidelines also providedirection for formulating site-specific treatmentswhen developing Forest Operation Prescriptions(FOP) during preparation of the Annual WorkSchedule (AWS).

In addition to the fact sheets, tables areincluded that rate the hazard of particular typesof damage to site, operation or environmentalfactors. Site damage hazard potential is relatedto Forest Ecosystem Classification (FEC) SoilTypes. The intent is to flag those sites andconditions that have moderate-to-high sitedamage potential, so the practitioner can addresssite damage concerns at the planning stage.

1.3 Consideration of Statement ofEnvironmental Values

The MNR is responsible for managing Ontario’snatural resources in accordance with the statutesit administers. In 1991, the MNR released adocument entitled Direction ‘90s, which out-lines the goals and objectives for the Ministry,based on the concept of sustainable develop-ment. Within MNR, policy and program devel-opment take their lead from Direction ‘90s.

In 1994, MNR finalized its Statement ofEnvironmental Values (SEV) under the Environ-mental Bill of Rights (EBR). The SEV describeshow the purposes of the EBR are to be consid-

ered whenever decisions that might significantlyaffect the environment are made in the Ministry.The SEV is based on Direction ‘90s, as thestrategic directions outlined in Direction ‘90sreflect the purposes of the EBR.

During the development of these guidelines,the MNR has considered both Direction ‘90sand the SEV. These guidelines are intended toreflect the directions set out in those documents,and to further the objectives of managing ourresources on a sustainable basis.

2.0 Concepts and Definitions

In the growing body of literature describing thebasis for ecosystem management, forest healthhas been identified as a central issue acrossNorth America. Although we may still be with-out a well-defined and easily-measurable defini-tion of forest health, most attempts imply thatforest health is a condition of the forest ecosys-tem which sustains complexity or diversitywhile providing for human needs (Burnside etal. 1995). This is consistent with the definitionof forest health under the CFSA, and supportsthe need to maintain the productive capacity ofour managed sites.

2.1 What is Site Damage?

Site Damage in this document refers to negativeimpacts on long-term forest health and produc-tivity due to forest operations. Site damage mustbe viewed in context with effects of naturaldisturbances (e.g., wildfire, windthrow, erosion)on ecosystem form and function. Natural distur-bance regimes and their effects are highlyvariable and it is important that effects of humandisturbance stay within the range of naturalvariability. Although some natural disturbancesare severe, the intent of our human activities isto emulate less catastrophic disturbance effects(i.e., although some severe natural disturbanceevents can reduce site productivity, the goal offorest management is to maintain site productiv-ity).

Forest Management Guidelines for the Protection of the Physical Environment 3

2.2 What is Site Productivity?

Site productivity can be defined as the ability ofa given site to accumulate plant biomass overtime. This is the net primary productivity of asite and is commonly expressed in kg/ha/yr. Itrepresents the amount of matter which can beproduced by all the primary producers (plants)on a site. The net primary productivity is thesource from which all the other biota on a sitereceive their energy.

Forest productivity is a more general termwhich refers to the growth and maintenance ofall or any part of the plant and animal communi-ties that live in a forested ecosystem. In contrast,timber production or yield represents the portionof net primary productivity which is allocated tothe production of commercially useable woodproducts. Yield is of great interest to forestmanagers, however, it is a fairly coarse indicatorof absolute site productivity.

The productivity of any given site is deter-mined by the efficiency with which matter andenergy enter, move through, and are stored atvarious trophic levels. This efficiency is deter-mined by many of the physical characteristics ofa site such as soil depth, fertility, temperatureand moisture, and local climate and physiogra-phy. In general, any permanent change to theseimportant physical site characteristics willimpact long-term site productivity.

2.3 Ecosystem Resilience

Stand-replacing disturbance of a forest ecosys-tem, whether arising from natural or humanforces, causes changes in species composition,stand structure and function for a period of time.If the disturbance event is not too severe and thefrequency of disturbance is low relative to thenormal rate of recovery, ecosystems tend torecover to their pre-disturbance condition.Therefore, the period of time that an ecosystemtakes to recover (ecological rotation) is depend-ant upon both the severity of disturbance and theperiod of time between subsequent disturbances,

as well as the inherent stability of the ecosystemunder consideration. For example, a boreal jackpine ecosystem on a moderately productive sitemay be able to withstand repeated clearcuttingon a 60-year rotation; whereas a maple/beechforest in southern Ontario would likely bealtered negatively by the same treatment. Ingeneral, forested ecosystems in Ontario arequite resilient and difficult to permanentlydamage when managed according to generallyaccepted forest management principles andpractices. In addition, natural processes operat-ing in forested ecosystems can repair damage tosoils in terms of rutting or compaction, or evenloss of fertility, given enough time. By usingnormal care and attention to site conditions, theamount of disturbance to sites caused by forestoperations can be kept to levels which can benaturally ameliorated by ecological forces inrelatively short periods of time.

The boreal forest in Northern Ontario isnaturally adapted to frequent stand-replacingdisturbance by forest fire, wind, insects, anddisease. Many of the forested ecosites in thisregion are typically managed under the clearcutsilvicultural system. The Great Lakes–St. Law-rence Forest and the deciduous forest regions ofthe southern part of the province are generallyadapted to less severe disturbance regimes interms of intensity or frequency. Uneven-agedtolerant hardwoods are adapted to frequent, lowintensity disturbances as individual old trees dieand fall out of stands and are replaced; thesestands are successfully managed using theselection silvicultural system. White pine eco-systems are adapted to varying intensities andfrequencies of disturbance. Intense fires maycompletely replace the stand on a fairly infre-quent basis. Lower intensity fires or other formsof disturbance happen more frequently and alterthe stand so that multi-storied conditions arecreated. These types of ecosystems can besuccessfully managed using the shelterwoodsilvicultural system or, in some cases, theclearcut system.

4 Technical Series

2.4 What are Sensitive Sites?

All sites are subject to alteration by forestoperations. Under most conditions and standardoperating practices, the alterations to these sitesdoes not result in site damage. The term “sensi-tive sites,” as used in these guidelines, refers tothose sites which have a high probability of oneor more types of damage occurring if managedaccording to standard operating practices.

Some sites become more sensitive to dam-age under a specific set of environmental condi-tions. For example, loamy soils are sensitive torutting when saturated. Other sites may besusceptible to certain types of damage regard-less of environmental condition. Very shallowsoils over bedrock are often susceptible tosignificant nutrient loss as a result of full treeharvest.

In most cases, sensitive sites can be operatedwithout causing damage through site-specificplanning and implementation of forest opera-tions. Management practices modified to pre-vent or minimize site damage are often called“Best Management Practices.”

2.5 What areBest Management Practices?

Best Management Practices are practices thatare not considered part of normal operatingprocedures and are conducted specifically toprevent or minimize damage to the physicalenvironment. The concept behind Best Manage-ment Practices is that such practices shouldminimize any deviations in forest developmentfrom the range of conditions following naturaldisturbance. The purpose of Best ManagementPractices is to provide resource managers withoptions to consider when operating on sensitivesites. The Best Management Practices includedin these guidelines are not to be considered theonly management practices that may be used toprevent, minimize or mitigate site damage.

3.0 Altering thePhysical Environment:Issues and Concerns

Site productivity is a key indicator of forestecosystem health. In order to maintain siteproductivity, attention must be paid to the inter-action of the physical properties of the site(i.e., soil texture, moisture, fertility and topogra-phy) with environmental conditions (i.e.,weather and season), and the types of forestoperations which are applied to the site. Theimpact of identical treatments on different siteswill be vastly different based on the particularsensitivity of the site to disturbance under thecurrent set of environmental conditions.

The major types of damage due to forestoperations that can affect long-term site produc-tivity are identified in Section 3.1. The contrib-uting factors (site, operations and environmentalconditions), their interactions and their potentialimpacts on the environment are described.When selecting Best Management Practices,there are general principles to understand, site-specific information to acquire and operationalfactors to consider.

3.1 Potential Impacts on thePhysical Environment

3.1.1 Compaction and Rutting

Soil structure is simply defined as the manner inwhich soil particles are assembled into aggre-gates (Hausenbuiller 1985). The formation andstability of soil aggregates are dependent largelyupon the quantity and state of clay particles, thepresence of various forms of organic matter, andthe natural forces (e.g., freezing and drying) thatorganize them into specific structural units(peds) of definable shape and size. The mostnotable disturbances to soil structure caused byforest operations are soil compaction and rut-ting. These disturbances alter surface drainageand infiltration, soil pore distribution and soilwater-to-air ratios—all critical factors control-


ling certain ecosystem functions (e.g., root andmicrobial respiration, plant uptake of water anddissolved nutrients). Generally, finer-texturedsoils, especially those with a silt or clay compo-nent, are more susceptible to compaction andrutting than are coarser textured soils. Thissusceptibility increases significantly as moisturecontent approaches saturation. Organic soils arealso highly susceptible to rutting and, in somecases, compaction.

3.1.2 Erosion

Erodible soils are susceptible to loss or move-ment of soil particles by wind, water or gravity.Soil texture, mode of deposition, ‘soil’ depth,depth of organic layer and slope influence therisk of erosion. Site conditions which are ofparticular concern include:

• Aeolian (wind deposited) soils. These areasare usually composed of a consistently finegrained sand which can be eroded by windor water, if exposed.

• Fine sandy and silty soil textures are quiteerodible, particularly where there is a uni-formity of soil particle sizes. Loamy texturesand the presence of coarse fragments(stones) tend to increase soil stability.

• As slope increases, the risk of erosion ofexposed mineral soil increases. Little ero-sion can occur on slopes of less than tenpercent. Sites with greater than 30 percentslope are at significant risk of erosion,particularly when mineral soil is exposed.

• Thin soils (<30 cm) over bedrock pose agreater risk of erosion than deep soils foundon similar slopes.

• The presence of an intact organic layer(forest floor) significantly reduces erosionrisk on most site conditions.

3.1.3 Nutrient Loss

The traditional argument regarding nutrientremovals via harvesting on nutrient poor sites isthat due to the limited soil nutrient reserves, a

large percentage of total site nutrient capital isfound in the above ground pool (tree stratum).Once these nutrients are removed, it could takean excessive amount of time for them to bereplaced (i.e., beyond the length of normalforest rotations). The length of this recoveryperiod (replacement time) varies with:

• The degree of site nutrient depletion accom-panying harvesting (Timmer et al. 1983,Mahendrappa et al. 1987).

• The rate of replacement of these nutrient losses(Wells and Jorgensen 1979). However, thisharvest-related nutrient loss and subsequentreplacement is complex, varying amongspecies (Kimmins 1977, Alban et al. 1978,Mahendrappa et al. 1987, Maliondo 1988), sitequality factors, age (White and Harvey 1979,Freedman 1981) and stand density.

3.1.4 Loss of Productive Land

As a result of timber harvesting operations,some of the productive landbase is lost to roads,slash and bark piles, skid trails and landings. Itis important at both the planning and implemen-tation phases of timber harvesting to minimizethe area affected and rehabilitate the affectedarea after the wood is extracted.

3.1.5 Hydrological Impacts

Of particular importance in forested wetlands arethe hydrological impacts caused by forest opera-tions. The most obvious hydrological disturbanceafter harvesting is watering-up (a rise in the watertable) which is largely the result of reducedevapotranspiration (due to tree removal) from thesite. Watering-up can reduce the depth of theaerated zone in the soil which reduces the rootingspace available to trees and other plants, depressdecomposition rates, and cause denitrification dueto anaerobic conditions. The sites which are mostsusceptible to watering-up are organic soils orpoorly-drained mineral soils (Dubé et al. 1995).The lateral flow of nutrient-enriched water throughthe soil profile due to gravity is critical to main-taining the productivity of some sites. This is

6 Technical Series

especially true of some organic soils. Deep ruttingor the creation of barriers to the flow of groundwater movement as a result of road or trail con-struction can reduce productivity of sites where theflow of nutrient-rich ground water is one of themajor sources of nutrient input.

The removal of forest cover by harvesting ornatural processes, such as fire or windthrow,increases the yield of water from the affectedlands. Significant impacts on water quality,water temperature and water yield do not gener-ally occur if less than 50 percent of a forestedwatershed is cleared (Plamondon 1993). Theimpact of forest operations on watershed hydrol-ogy is greatest in the upper reaches of water-sheds.

3.2 Key Site Characteristics

3.2.1 Soil

i) Soil Depth

Limited soil volume on shallow-soiled uplandsites can limit site productivity. Low nutrientand water holding capacity, and inherent physi-cal site features, can lead to longer ecologicalrotations and increased erosion potential afterdisturbance. The risk of site damage rises withincreased disturbance or loss of the forest floor.Benefits of increased soil depth are significantup to approximately 60 cm (i.e., rooting zone),after which other factors may become limiting.Overall, soil depths throughout the CanadianShield are highly variable, and shallow till soilsover bedrock are characteristic of much ofOntario. In contrast, soil depths are consistentlydeeper in the Clay Belt Region of northeasternOntario and much of southern Ontario.

ii) Soil Texture

Mineral Soil - Mineral soil texture refers to therelative proportion of sand, silt and clay in thesoil medium. Finer textured soils (silts andclays) have the ability to hold more moistureand nutrients. Coarser textured soils (sand),

although more sensitive to nutrient removals,generally have better aeration and drainage.Risk of compaction and rutting increases onfiner-textured soils. Uniformly fine grainedsands and soils with a high silt content are themost erodible. As coarse fragments (gravel,cobble, stone, etc.) content increases, soilsbecome more resistant to damage bycompaction and rutting.

Organic Soil - These soils are derived predomi-nately from mosses, and herbaceous and woodymaterial. Soils are classified as organic if thedepth of organic matter is 40 cm or greater. Siteswith organic horizons less than 40 cm in depthmay still exhibit characteristics similar to or-ganic soils in terms of their susceptibility tovarious forms of site damage.

Organic soils are characteristic of lowlandswamps, fens and bogs. Organic soils are classi-fied according to the state of decompositionfrom fibric (weakly decomposed), throughmesic (moderately decomposed) to humic(highly decomposed). Organic soils are gener-ally wet and have less load-bearing capacity formachinery than mineral soil. More highly de-composed organic soils have a weaker (morewatery) consistency which reduces their loadbearing capacity and therefore makes them moreprone to rutting disturbance. Conditions of highmoisture, high acidity and low temperaturesresult in slow rates of decomposition. This mayresult in low levels of nutrient availability de-spite high levels of stored nutrients in organicmaterial.

iii) Forest Floor and Soil Organic Matter

Both unincorporated organic matter (forestfloor) and soil organic matter (organic fractionwithin the upper soil levels) play an importantrole in regulating chemical, physical and bio-logical relations. Organic matter accumulatesover mineral soil when the rate of organicdecomposition is less than the rate of accumula-tion. On some sites, this layer constitutes asignificant proportion of total site nutrient


capital, while regulating both moisture andtemperature regimes. Well-decomposed organicmaterial is incorporated into the mineral soil bythe leaching action of water, action of plantroots, and activity of microorganisms, insects,earthworms, etc. Forest operations that mini-mize severe disturbance to the organic layer willgenerally minimize the risk of site damage.

iv) Soil Moisture Condition

The soil moisture condition reflects the currentmoisture content of the soil. It is meant to be animmediate and transitory condition affectedlargely by precipitation. Soil moisture regime isdetermined on the basis of soil texture, drainage,depth and slope position, and indicates thelonger term average moisture conditions of asite. On many dry, coarser textured sites or onwet organic sites, soil moisture may be the mostlimiting factor for plant growth. In general, sitedamage potential from forest operations aremore dependent on current moisture content ofthe upper soil strata than the longer term mois-ture regime. Soils are more prone to disturbance(compaction, rutting, and erosion) when satu-rated through precipitation or snowmelt.

v) Nutrient Status

Nutrients are distributed in the mineral soil,forest floor and above ground vegetation, andare continuously cycled between the various“pools” in the system. In addition, system inputs(i.e., atmospheric deposition, weathering ofparent material, subsurface water flow andnitrogen fixation) and exports (i.e., deep leach-ing, surface runoff and denitrification) are alsooccurring. These imports and exports are gener-ally equivalent to each other under relativelystable (e.g., mature) forest conditions. At anypoint in time, most nutrients are in organic formand as such are unavailable for plant uptake. It isthrough the decomposition of organic matterand release in inorganic form (termed minerali-zation) by microorganisms that they becomeavailable for plant uptake and use.

3.2.2 Terrain

Critical elements of terrain include slope, aspectand topographic position. As slope increases,soils are drier due to accelerated surface runoffand reduced water infiltration. Soils on a slopeare also more susceptible to erosion due togravity and surface water runoff. Aspect canaffect productivity primarily by increasing ordecreasing soil temperature. Sites with a southfacing aspect have a longer growing season andhigher rates of nutrient cycling than sites with anorth aspect.

Topographic position (relative position on aslope) affects the potential for soil erosion,hydrological change and nutrient status. Depres-sions will generally be wetter than upslope areasand will be more susceptible to watering-up iftree cover is removed. Crest positions tend to bethe most well-leached and therefore the mostnutrient poor. They are also the driest part of thelandscape and generally not susceptible toerosion. Mid-slope sites vary according to theirdegree of slope and slope position. Lower slopesare often enriched by the subsurface flow ofwater and nutrients from upper slopes and willgenerally be moister than upper and mid-slopepositions. Upper and mid-slope positions tend tobe drier but are more susceptible to erosionresulting from forest operations.

3.2.3 Forest Vegetation

The development stage and type of vegetationcan influence the physical, chemical and bio-logical properties of a site. Deciduous-domi-nated stands tend to have less acidic soil andfaster nutrient turnover than conifer stands.Forest types and associated site conditionslargely dictate the silvicultural system (even-ageor uneven) and therefore harvest, renewal andmaintenance treatments. On nutrient-limiting orerosion-prone sites, rapid post-disturbancevegetation development can minimize nutrientleaching and stabilize soil movement.

8 Technical Series

3.3 Forest Operations

3.3.1 Silvicultural System

Silvicultural systems describe a planned set oftreatments designed to achieve specific manage-ment objectives. The choice of system(i.e., clearcut, shelterwood, selection) is basedupon a combination of management objectivesand the forest ecosystem under consideration. Ingeneral, clearcutting is the most ecologicallyappropriate system for the characteristic even-aged, fire-driven ecosystems of the boreal forest.Partial cutting systems (shelterwood and selec-tion) are more appropriate to ecosystemsadapted to gap replacement disturbance regimes(white and red pine, maple, beech, etc.). Thereare various modifications to these silviculturalsystems (e.g., careful logging around advancegrowth, seed tree), and careful planning andimplementation of forest operations can avoid orminimize risk of site damage.

3.3.2 Logging Method

Logging method relates to the felling of treesand their movement to roadside. A variety ofequipment combinations and harvest layout andtraffic patterns have evolved in Ontario, eachadapted to meet both management objectivesand local site conditions. By far, most sitedamage from harvest operations occurs duringthe movement of wood to roadside. Repeateduse of skid trails can lead to concentrated areasof disturbance on a small percentage of the site,while dispersed skidding may result in widespread damage (or no damage) across the entiresite. In order to minimize damage to the physi-cal environment, the forest manager can selectthe season of harvest, plan optimal skiddingsystems, and match the ground pressure ofequipment to site conditions. The manager maychoose to delimb at the stump to maintainnutrient capital and distribute slash to increasethe load bearing capacity of the soil for skid-ding. Matching harvest systems to dominant siteconditions or site limitations is key to avoidingsite damage.

3.3.3 Renewal and Maintenance

The forest renewal practice which poses thegreatest risk of physical site damage is mechani-cal site preparation. This is due to the heavyequipment involved (e.g., prime movers) and thedeliberate modifications of the soil profile tomeet micro-site objectives (e.g., plowing).Prescribed fire, where fire severity is matched toecological site conditions and managementobjectives, may be the best site preparationmethod for many sites.

Maintenance activities include tending forvegetation management, insect/disease controland pre-commercial thinning. As with sitepreparation, risk of site damage is primarilyrelated to mechanized operations on the ground.However, any elimination of vegetation whichresults in less than full site occupancy may leadto site degradation due to nutrient loss or ero-sion of slopes.

3.4 Environmental Conditions

3.4.1 Season of Operation

Harvesting on frozen soils reduces grounddisturbance, minimizing compaction, rutting,erosion potential and disruption of drainagepatterns. On some sites, minimizing grounddisturbance will reduce the risk of promotingexcessive competing vegetation, while protect-ing desirable advance growth and residuals.Dormant season harvest, particularly on nutri-ent-poor deciduous sites, can help preservenutrient capital.

Generally, greater snow cover depth resultsin better site protection during harvest opera-tions. Under certain sites and conditions, highsnow loads may delay frost penetration into thesoil. The most hazardous seasons are spring andfall, when excessive soil moisture occurs due tosnowmelt or late fall precipitation.


3.4.2 Rainfall

The amount, duration and frequency of precipi-tation largely determine upper soil moistureconditions. In general, the greater the soil mois-ture, the greater the risk of site damage fromforest operations. On sites susceptible tocompaction or rutting, monitoring site condi-tions during or immediately after significantrainfall is essential. In many cases, operationsshould be modified or temporarily halted. Thisis an on-the-ground decision based on profes-sional judgement and experience.

4.0 Planning for the Protectionof the Physical Environment

Effective planning at both the forest and standlevels represents a key proactive action to mini-mize impacts or damage to the physical environ-ment. Strategies that ensure forest operationscomplement site conditions are central to pro-tecting the physical environment and ensuringthat silvicultural objectives are attained.

Forest Management Planning in Ontario isgoverned by the Forest Management PlanningManual. The planning process is comprised ofthree interrelated levels which describe forestoperations in varying levels of detail:

• At the forest management planning (FMP)level, forest operations are described interms of broad objectives and strategies for a20 year term, and specific operations for thefirst five years are identified. Treatmentpackage options which may be applied togiven site types are described.

• Areas are selected for operations and in-cluded in an Annual Work Schedule (AWS)during each of the five years of the FMP. Aspart of the development of a Forest Opera-tion Prescription (FOP) for each operationoutlined in the AWS, actual site conditionsare verified and the silvicultural treatment tobe used on that site is selected.

• Operational design (on-site planning),conducted at the field level, is not regulatedby the FMPM. The level of detail associatedwith this planning level varies with thecomplexity of the forest condition, and thetype of forest operation being conducted. Itis often at this level where many of the BestManagement Practices outlined in thisdocument can be implemented.

Determining that a site is “sensitive” will not byitself be interpreted as a requirement to under-take Area of Concern (AOC) planning as de-scribed in the FMPM. AOC planning is requiredfor areas identified as containing values forforest users or uses which may be affected byforest management activities. The application ofthese guidelines will help protect the health andproductivity of sites, regardless of future humanuse or value. Similarly, the Best ManagementPractices described in these guidelines are not tobe interpreted as “modified operations” in thesense that this term is used in relation to AOCplanning.

4.1 Forest Management Plan

4.1.1 Identification of Issues

The first step in planning for the protection ofthe physical environment is to recognize thepotential site damage issues on a managementunit level. Issues may relate to the impact offorest operations on specific site types whichoccur on the management unit or, they may berelated to the cumulative impact of operationsacross the management unit.

i) Site Level Issues

Recognizing site level issues is based on identi-fying the types of sites that occur on thelandbase which could be sensitive to damagedue to the standard forest operations practised inthe area. These sensitive sites are therefore thefocus for designing modified managementtechniques and employing the Best Management

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Practices found in this document. In most casesstandard operating practices will continue to beemployed on the majority of sites, however,significant changes to these normal practicesmay be required to protect sensitive sites.

To assist in recognizing site damage poten-tial, soil-based hazard tables are provided alongwith the fact sheets. These fact sheets alsoinclude treatment options (Best ManagementPractices) to be used when developingSilvicultural Ground Rules. Issues which areidentified based on specific site conditions maybe documented in the Issues section of the FMP,or they may simply be identified as part of therationale for determining Forest Units orSilvicultural Ground Rules.

ii) Management Unit Level Issues

Some issues related to protecting the physicalenvironment need to be considered at a manage-ment unit level. These broader level issues mayinclude:

• The impact of the forest access system onthe amount of land removed from produc-tion, and on watersheds.

• The impact of forest harvesting on wateryield needs to be considered. As the percent-age of a watershed harvested increases, sodoes the impact of operations on water yieldand the attendant risk of deteriorating waterquality and damage to aquatic environments.

• The need to balance operations on a forest toensure that the types of equipment availableand the required schedule of wood deliveriesis attainable given the limitations of sitesacross the management unit.

Management unit level issues may be docu-mented in the Issues section of the FMPM.

4.1.2 Determining Objectives

Where appropriate, specific objectives related tothe protection of the physical environmentshould be documented in the objectives sectionof the FMPM.

Objectives may be general or very specificin nature. Examples include:

• Numerical targets for limiting the amount ofland lost to the construction of roads andlandings.

• Commitment to conducting forest operationson a certain site type in such a manner as tominimize the potential nutrient loss fromthose sites.

4.1.3 Formulating Strategies

Strategies that will be used to achieve statedmanagement objectives must be developed asoutlined in Section 2.3.3.2 of the FMPM. Strate-gies related to managing specific species andstands of trees are documented through thedevelopment of Forest Units and SilviculturalGround Rules.

Other strategies will relate to broad manage-ment unit level objectives or other objectives notspecifically linked to the harvesting and renewalof trees (i.e., watershed management concepts)and are therefore documented outside of theSilvicultural Ground Rules.

i) Forest Units

Stands are aggregated in the FMP into forestunits on the basis of similarity of managementpotential. The selection criterion for definingforest units is based primarily on species withadditional determining factors including siteclass, age and broad site type. In managementunits where a large proportion of a particularworking group is found on sensitive sites, thesestands may be stratified into a separate forestunit for management purposes. There must besufficient area within each grouping to justify itsidentification as a unique forest unit.

ii) Silvicultural Ground Rules

Silvicultural Ground Rules identify one or moresets of acceptable silvicultural treatments (treat-ment packages) for each identified forest unit. Itis at this level that some of the critical elements


of forest operations can be prescribed to dealwith the sensitivity of certain sites to particulartypes of damage. Treatment packages can beassigned to sensitive sites whether they havebeen aggregated into separate forest units or aresubsets of other forest units.

Treatment packages set out in theSilvicultural Ground Rules for sensitive siteareas should consider and apply those BestManagement Practices (as discussed in the factsheets) to the following specific forest opera-tions:

• harvest method,

• logging method, and

• site preparation, regeneration and tending.

iii) Other Strategies

Many strategies for protecting the physicalenvironment cannot be addressed by theSilvicultural Ground Rules. In some cases theyshould be documented separately or they maybe elements which extend beyond the FMP intoforestry business planning. The following areexamples of such strategies:

• Many types of site damage can be preventedby season of harvest. Consequently, seasonalwood flows need to be planned in the con-text of the availability of sites. Strategiesneed to be formulated to manage mill andbush inventories to ensure continued woodavailability during periods of the year whenforest operations are reduced to protect sitesfrom damage (i.e., spring break-up).

• Specialized equipment (e.g., high flotationequipment) can be used to prevent damageto some sites. Business planning mustrecognize the need to manage forestryequipment purchases, not only from theperspective of silvicultural and harvestingefficiency, but also from the vantage point ofacquiring the equipment best suited tomanaging sustainably.

• The forest access program needs to considersite damage issues. Access strategies shouldbe formulated which will:

• minimize the impact of roads on water-ways, natural drainage patterns and sitehydrology, and

• remove the minimum amount of landfrom production by optimizing the bal-ance of all-weather access with seasonalaccess and maximum economic skiddistances.

• Areas selected for harvest need to be viewedas a percentage of watershed area, andaffected watersheds should be examined asto their sensitivity to disturbance. In somecases the sensitivity of a watershed to distur-bance may be a factor in determining theextent and type of forest operations.

The Best Management Practices contained inthe site damage fact sheets provide examples offactors to consider when selecting areas foroperations in the FMP.

4.2 Annual Work Schedule

The AWS is a list of those treatments whichwere identified in the FMP which will be con-ducted on a year to year basis. When developinga FOP for each operation outlined in the AWS,actual site conditions are verified and thesilvicultural treatment to be used on that site isselected. At this point, additional details regard-ing the treatment packages can be added.

4.3 Operational Design(On-Site Planning)

During on-site planning, before or during imple-mentation of a forest operation, is when some ofthe most important elements of the Best Man-agement Practices identified in this documentcan be applied.

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Specific techniques for dealing with sensi-tive elements of a site, such as erodible slopesor wet swale areas, have to be prescribed in thefield. Limiting factors and contingency plansshould be determined (e.g., In the case of exces-sive rain, operations should move from Area Xto Area Y). The extent of tertiary road access,and the strategy for forwarding and landingwood needs to be determined. The location oflandings should be chosen to minimize grounddisturbance and loss of productive area.

Proper crew training and communication ofspecific objectives are important on all sites.However, it is even more important on sensitivesites where the potential for site damage will attimes be greater. Field staff need to understandnot only the specifics of the plans for a site butalso the reasons behind modifying operations toprotect the sensitive nature of some sites.

Involve field staff in the development of on-site planning, including the best locations forroads, landings and skid trails, and specificactions to prevent or minimize site damage.Explain clearly what the post harvest conditionsshould look like. If special operating conditionsare required (e.g., placing slash on main skidtrails to reduce rutting, limiting operations basedon temperature or rainfall), then these condi-tions must be communicated to everyone in-volved.

5.0 Compliance Monitoring

Everyone involved in forest operations needs tobear some of the responsibility for monitoringcompliance. In the context of site protection thismeans that there needs to be a general recogni-tion of what the job should or should not looklike. Forest operators should feel personallyaccountable for the quality of the job that isdone and should be prepared to cease or modifyoperations to protect forest sites from damage.

Both the OMNR and the forest industry areresponsible for recording the occurrence of anyundesirable conditions described in these guide-lines that are observed in the areas of operationsand in the forest, that appear to be related toforest management activities (e.g., roadwashouts in AOCs and their observed environ-mental effects).

6.0 OperatorTraining and Education

Adequate training and education of field staffare the most critical factors in protecting thephysical environment during forest operations.Machine operators must be able to recognizesite damage potential and occurrence, and theoptions available to prevent or minimize nega-tive impacts on the site. Therefore, coordinationbetween planners, field supervisors and equip-ment operators is required.

Fostering an understanding of the benefits ofBest Management Practices to both the com-pany and the environment will provide consider-able motivation for field staff. Developingworkshops, field exercises, training manuals,videos, and recognition and reward programsare effective means to train forest workers inunderstanding the interaction between opera-tional and environmental conditions that con-tribute to site damage.


Site Damage Fact Sheets

Site damage fact sheets are presented for each ofthe following potential impacts on the physicalenvironment:

• Compaction and Rutting

• Erosion

• Nutrient Loss

• Loss of Productive Land

• Hydrological Impacts

These fact sheets are divided into two mainsections:

• Description: The particular type and impact ofdamage, and the site factors, environmentalconditions and management activities thatmay contribute to increased risk of damage.

• Best Management Practices: Practices toconsider in the areas of planning, fieldlayout, implementation and monitoring toprevent, minimize or mitigate negativeimpacts. Where appropriate, mitigationtechniques are described for the rehabilita-tion of damaged sites.

The use of the term Best ManagementPractices does not imply that these are theonly acceptable practices for a given condi-tion. Local conditions and circumstancesmay dictate the use of treatments not listedhere.

Planning, in the fact sheets, refers to formalactivities outlined in the FMPM, on-site deci-sion making, and some elements of businessplanning. Site-level planning may be relativelystructured, or simply represent problem-solvingtechniques for dealing with site protection in thefield.

Site damage hazard tables were developedfor compaction and rutting, erosion and nutrientloss. Site damage hazard is rated as low, moder-ate or high based on broad soil and site condi-tions. Corresponding Forest Ecosystem Classifi-cation soil types are listed for northwestern,northeastern and central Ontario (Racey et al.1996; McCarthy et al. 1994; Chambers et al.1997). These matrices are based on currentscientific evidence and expert opinion, and canbe used to identify those sites most susceptibleto site damage. Once verified in the field, forestoperations can then be designed after consider-ing the Best Management Practices identified inthe site damage fact sheets.

Appendices 1 to 3 relate the regional soiltypes to the broader ecosite/site type classifica-tions which exist for each administrative region.Based on these relationships and a knowledge oflocal site conditions, managers can customizesite hazard ratings to ecosites for their landbase.

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Description

Compaction is the increasing of soil bulk densityprimarily by the application of pressure throughthe use of heavy equipment in forest operations.When soils are compacted, natural soil structureis damaged or destroyed resulting in reduced airspace between soil particles. Soil compaction isnormally associated with soil rutting. Compactionis differentiated from rutting by the extent andintensity of impact. Compaction occurs overbroader areas but does not necessarily result inthe visible depressions associated with rutting.

Rutting is the creation of trenches or furrowsin the ground by breaking through the forest floor(slash, litter and humus layers) and compactingor displacing mineral or organic soil. Ruts are theresult of having exerted ground pressures inexcess of the weight bearing capacity of the soil.They are normally associated with the use ofheavy wheeled or tracked logging equipment.

Puddling is a specialized form of disturbancethat results in a compacted surface mineral soillayer. Puddling results from the destruction ofsoil structure in fine textured soils when thesesoils are exposed to the impact of rainfall.

Impacts

Compaction of forest soil may impact sites by:

• reducing porosity of the soil resulting ingreater amounts of surface runoff and lessinfiltration of rainfall or melt water; movementof water and nutrients within the soil profile(hydraulic conductivity) may also be im-paired;

• increasing the bulk density of the soil to thepoint where root penetration is inhibited;

• causing surface soil to warm up less quicklyin the springtime, effectively shortening thegrowing season for new seedlings andcausing silviculture operations to be de-layed;

• impeding gas exchange between roots andsoil (smothering);

Figure 1: Example of rutting damage caused byforest operations.

• reducing germination potential of some soilsand impeding early seedling establishment(however the germination potential of sphag-num peats is increased by moderatecompaction); and,

• reducing the overall productive capacity ofan area.

Additionally, the creation of ruts may impact asite by:

• reducing the productive area of a site, bycausing deformation of the forest floor and/or by creating an opportunity for waterponding (i.e., less area available for immedi-ate renewal);

• compacting the soil on the sides and be-neath the rut such that water infiltration isimpeded;

• inhibiting rooting and gas exchange;

• impeding lateral drainage of water on wettersites; and,

• contributing to erosion and soil displacementif ruts are located on side slopes.

Compaction and Rutting Description


Site Factors InfluencingCompaction and Rutting

Generally, finer texture soils (fine loamy–clayey)are more susceptible to compaction and ruttingthan coarse textured mineral soils (coarse loamy–sandy). Fine textured soils have physicalproperties (very small and uniform particle size)which allow them to exist in very compacted,massive forms. The productivity of fine texturedsoils (clays in particular) is dramaticallyimproved as the surface layers of these soils arestructured by the actions of biological organismsand weathering; this soil structure is fragile andsubject to damage.

Sandy soils are generally far less prone torutting and or compaction. However, very finesands and fine sands characteristic of lacustrine(beach) or aeolian (dunes) deposits may besusceptible to some compaction and rutting, par-ticularly when wet. Soils with a high percentageof coarse fragments (e.g., stony tills or outwash)are less prone to rutting than stone free soils.

Soil susceptibility to compaction or rutting isgreatly influenced by the moisture content at thetime of disturbance. A dry clay, for example maybe less prone to rutting or compaction than awet loam would be. Since finer textured soils areinherently able to hold more water at fieldcapacity than coarser textured soils, they will bemore negatively influenced in terms ofcompaction and rutting risk when exposed to thesame intensity and duration of precipitation.Moisture regime, which reflects the longer termaverage moisture conditions in a soil, is lesssignificant in determining rutting hazard than theimmediate moisture content of the upper hori-zons of the mineral soil and the organic layers.

The depth and type of litter, slash andorganic material on a mineral site increases theload bearing capacity of the ground surface.Coarse woody debris such as tree tops andlimbs can greatly increase the trafficability of asite. Ruts, by definition, cannot occur unlessthese surface layers of organic material arebroken or removed. Overlying organic layersalso protect the structure of the mineral soil bydiffusing the potentially damaging impact ofraindrops on the surface of the soil (i.e., pud-dling).

Organic and peaty phase soils are inherentlymore susceptible to rutting damage than mineralsoils. Organic soils may also be compacted.However, unless the surface of the organic layeris broken (i.e., unless a rut is created) thiscompaction is short-lived and less significantthan the compaction of mineral soil. Compactionof the living moss and fibric peat at the surfaceof an organic soil may be beneficial in terms ofincreasing seedbed receptivity.

Organic soils with surface horizons com-posed of highly decomposed peats (mesic andhumic) are more susceptible to rutting thanthose with surface horizons of less well decom-posed peats (fibric). Organic sites with Labradortea and other ericaceous shrubs may be lessprone to rutting disturbance than are the richerorganic sites characterized by alders.

Environmental Factors InfluencingCompaction and Rutting

Season of Harvest

The risk of damage by compaction or rutting isgreatly reduced when soil is frozen. Normalwinter conditions in northern Ontario result insufficient ground frost to increase the loadbearing capacity of the soil to the point where itcan support most types of equipment used inlogging. Extended autumns and earlier springsin southern Ontario may greatly reduce orentirely eliminate the frozen season. Duringwinters with early or abnormally high snowloads, ground may not freeze sufficiently tosupport operations on some sites. A significantsnowpack may itself prevent damage to the soil.

Spring snowmelt and ground thawing resultin the maximum seasonal compaction andrutting hazard. The depth of winter snowpackand the duration of the spring thaw dictates howsevere compaction hazard will be during thespring breakup period. Summer conditionsusually reduce compaction and rutting hazard byreducing overall moisture content. Above normalrainfall may, however, increase the compactionhazard at this and any time of the year. In manyparts of the province, autumn rains increasecompaction and rutting hazard to spring levels.

Compaction and RuttingDescription

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Precipitation

Wet soil is more prone to compaction and ruttingthan dry soil. Susceptibility to compaction andrutting is therefore a function of the amount,frequency and duration of rainfall. The actualimpact of rainfall on the moisture content of asoil depends on its moisture holding capacity(i.e., soil texture and organic component), thequality of soil drainage and the surface infiltra-tion rate of a site. Prolonged droughty periodsfollowed by high intensity but short durationrainfall may result in excessive surface runoffwith little increase in actual soil moisture. Onexposed fine textured soils, even brief periods ofprecipitation may significantly increase the riskof compaction and rutting.

The Impact of Forest Operationson Compaction and Rutting

Ruts occur when the ground pressure exerted byequipment exceeds the load bearing capacity ofthe surface of the ground. Therefore, weight andtype of equipment (particularly forwarding orskidding equipment) has a great deal of influ-ence on the degree of rutting. Ground pressureis a function of machine weight and groundcontact area; therefore, equipment with widetires or tracks will exert less pressure thanconventional equipment of the same weight.

Soil compaction is often associated withrutting damage; however, compaction may occurin the absence of ruts since the degree ofground pressure needed to compact the soilmay be less than that needed to break throughthe organic layers of the forest floor and deformthe soil profile. Forest operations that break, ordisplace the forest floor may in turn contribute tocompaction by reducing the overall load bearingcapacity of the ground.

Repeated traffic on the same trail will in-crease severity of rutting and compaction whilereducing the percentage of a site that is dam-aged. Conversely, dispersion of traffic mayreduce the intensity of damage but may result ina higher percentage of the site being damagedto some degree. There is greater opportunity to

disperse skid trails in conventional clearcutsystems than in partial cut systems whererepeated use of a few main trails is dictated.Maximum rutting often occurs where machineryis turned as on a corner of a main skid trail.Landings and trail convergence points aresubjected to the most traffic and therefore arevery likely to be damaged by rutting and orcompaction.

Skidding and f orwarding equipment that donot have the ability to reach or winch, pose agreater degree of rutting hazard. Grappleskidders, for example, which must drive up toevery pile (bunch) of wood, are less able to beused on selected trails than are cable skidders.They are also less able to avoid wet areas thana cable skidder which may use its winch to pullwood across wet areas. Equipment with greaterload capacities, such as forwarders or clambunkskidders, cause less overall ground disturbanceas fewer passes are required to move the samevolume of wood.

Forest operations that break or displace thelitter and organic layer of the soil may in turncontribute to rutting by reducing the overall loadbearing capacity of the ground. The use ofbroadcast forms of site preparation such assummer blading (on fine textured silts and clays)can contribute to site damage by compaction.Damage may occur directly as a result of theground pressure of the equipment used and alsoindirectly as a result of exposing the mineral soilto the impact of rainfall which can result in theloss of surface soil structure (i.e., puddling). Thecreation of furrows by site preparation equip-ment such as scarification drags, Young’s teethor disk trenchers is normally beneficial from asilvicultural perspective. Inappropriate or exces-sive use of these types of equipment can resultin a form of rutting damage and may lead tosubsequent problems with erosion.

Road construction activities result in deliber-ately compacted soils with greatly reducedproductivity. Lands converted to all weatherroads are lost to forest production permanentlyor for an extended period of time. These issuesare discussed in the Loss of Productive Landfact sheet.

Compaction and Rutting Description


Planning

Under non-frozen conditions, a certain degree ofcompaction and rutting is inevitable on all siteswhere heavy equipment is used. The degree ofdamage on most sites is not problematic how-ever. As with most types of site damage,compaction and rutting can usually be avoidedthrough careful planning beginning with theForest Management Plan, through the AnnualWork Schedule, and down to field level planningon a cut block level.

A Forest Management Plan should recog-nize that some sites are sensitive to compactionand rutting disturbance. Selection of areas forharvest must be made in recognition of these“sensitive sites” and a balance sought betweenstands that can be operated at any time of theyear and those best operated in the winter or inthe driest part of the summer months. If suffi-cient flexibility is provided in the plan, it shouldbe possible to avoid operations on sites that aresensitive to compaction and rutting until thehazard is reduced by season or environmentalcondition. Traditional scheduling of winter andsummer operations has been based primarily onthe availability of access to the site and theability of equipment to work without gettingmired down. This level of site differentiation isoften inadequate to prevent potential site dam-age. Unacceptable damage due to compactionand rutting may occur when equipment is stillable to operate without getting mired down.Planning must be done in the context of equip-ment availability and the flexibility or limitationsthat it provides.

To differentiate those areas selected forharvest on the basis of site susceptibility todamage, a basic knowledge of local forest sitetypes is required. The Forest Management Planshould address sensitive sites within theSilvicultural Ground Rules and identify specialmeasures to minimize damage potential. Fieldinspection of sites during the preparation ofFOPs will ensure that all forms of site sensitivityare recognized.

Recognition of the annual variations in millrequirements is critical to ensuring that the rightblend of stands is chosen over a five-year term

to allow that strategy to be translated down toAnnual Work Schedules. Bush and/or mill yardinventories should be used to limit the need foroperations at times of the year when sites aremost susceptible to damage (i.e., spring break-up period).

Proper access planning helps to prevent orminimize the hazards associated withcompaction and rutting (and other site damageissues). In the Forest Management Plan, theaccess plan must compliment the balancedseasonal areas selected for harvest. Whereverpossible, roads must be built sufficiently inadvance so that the lack of access does notrequire off-season operations on sensitive sites.

A choice of operating blocks in the field is agood planning tool to allow for flexibility to avoidmore sensitive areas during periods of abnormalenvironmental conditions (e.g., high rainfall). Allfield blocks should be walked in advance ofoperations to identify areas within stands thatcould be prone to damage and an approach todealing with these areas should be made andcommunicated to the operators. Similarly, anapproach to access within the block (i.e., skidtrails) should be developed and communicatedto the operators. Forest Operations Prescriptionswill document the techniques that are to be usedfor both harvest and renewal treatments. Aneven finer degree of operational planning detailis required for sensitive sites, and the cut super-visor and/or operators should have a clearlydefined approach that will include:

• the location of areas prone to compactionand rutting and how they will be addressed;

• the general plan for skidding or forwarding,or the specific locations of skid trails;

• the general plan for the progression of thecut;

• the location of landings, chipper pads, etc.;and,

• depending on the nature of the operation,(workers, closeness of supervision, etc.)specifics of the logging plan may need to bewritten and distributed to everyone involvedin the operation. An accurate map of the cutblock should be available to all operators.

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Field Layout

Cut block boundaries should be flagged in thefield using a specific, agreed-upon colourscheme. If it is necessary to limit traffic within theblock through the use of a limited number ofmain skid trails, then these will normally beflagged using a different colour scheme from theblock boundaries. Clearly identified skid trails arenecessary to effectively implement theshelterwood or selection system. Sensitive areaswithin the block must be recognized by alloperators and flagged if necessary.

The block can be subdivided into daily orweekly operating compartments by the operator,if desired. This subdivision of the block ensurespersonal accountability on the part of operatorsfor problems caused by the operation and allowsthe supervisor to manage the progression of thecut.

Notwithstanding the sensitive spots within ablock, in a clearcut system, less damage willoccur if skidding across the block is as widelydistributed as possible. It is not practical to havean infinite number of log landings, so conver-gence zones will develop. If these areas areidentified and a primary trail is located where theground has the greatest load bearing capacity,or if the convergence zones are strengthenedwith slash matting, then damage will be mini-mized. During operations to protect advancegrowth or in partial cut systems, the use of maintrails is required throughout the block so thelocation of these should be chosen to takeadvantage of areas with the greatest loadbearing capacity. Some damage to main trailareas is expected as a cost of minimizing dam-age to residual trees and the rest of the site.

Implementation

Careful planning and scheduling of operationscan reduce the risks of compaction and ruttingdamage on most sites. On occasion, operationsmay be required when the risk of damage ishigher. The following Best Management Prac-tices can be used to minimize damage on theseoccasions:

• In a clearcut system, skid trails will normallybe widely distributed while avoiding wetpockets or other sensitive areas. The excep-tion to the above noted rule is where there isa significant risk of compaction or ruttingdamage caused by only a few skidderpasses. In this case, skidder traffic should beconcentrated on main trails. Locate maintrails on areas with the highest load bearingcapacity. Ensure that all operators arecompletely aware of their location. On maintrails or convergence trails, a mat of slashcan be used to increase the bearing capac-ity of the soil. In some cases gravelling ofmain skid trails may be considered.

• In partial cutting operations, such as theshelterwood and selection systems, skiddingmust be confined to a network of main trailsand these should be located in advance ofoperations whenever possible. Locate skidtrails on areas with good load bearingcapacity and keep them as straight or asgently curving as possible while avoiding wetspots. The amount of area used for skidtrails should not exceed 30 percent forshelterwood systems and 20 percent forselection systems (OMNR 1997b). As muchas possible, wood should be winched to theskidder to minimize the extent of skid trailswhich are necessary.

• If summer logging chances must includelarge areas of organic soil, then high floata-tion equipment should be used. Operationsshould be closely monitored to ensure thatdamage is minimal. Summer logging onorganic soils, even with low ground pressureequipment, is most suitable for fibric peats.Harvesting operations on more stronglydecomposed mesic or humic peats shouldbe avoided during frost-free conditionswhenever possible. Sensitive wet swaleareas can be dealt with by:

• Avoiding them completely during har-vesting or site preparation.

• Reaching into them with a felling head orwinching out of them using conventionalcut and skid systems.

Compaction and Rutting Best Management Practices


• Having feller-bunchers cut them andbring bunches back to solid ground.

• Using limbs and tops to increase theload-bearing capacity of the ground.

• The load bearing capacity of soil is greatlyimproved through the use of slash mattingon equipment traffic areas. Cut-to-lengthsystems that limb and top on site shouldplace the slash in front of the machine onsites susceptible to compaction and rutting.

• Care should be taken in both harvesting andsite preparation operations to minimize thedisturbance/removal of the organic layers ofthe soil as these layers increase the soil’sresistance to compaction and rutting. On finetextured soils, maintaining organic layers willprevent damage to soil structure bypuddling. Broadcast site preparation tech-niques such as blading that expose largeareas of mineral soil should not be employedon fine textured soils.

• Operations may be allowed or discontinuedbased on the actual compaction and ruttingwhich is occurring. For example, in the latewinter/early spring it may be possible tooperate on night shift and until midmorning iffrost conditions are satisfactory and thenstop operations when the ground warms up.A shut down for a few days may be requiredafter a period of high precipitation; if sched-uling of operations has allowed sufficientflexibility then perhaps the operation can betemporarily located to less sensitive areas.

• Whenever possible, non-productive areassuch as rock outcrops should be selected forlanding sites.

• Proper planning of operations is required atall stages including day to day on-siteplanning. It is important that operators arecompetent and properly trained, and thatthey are aware of the objectives and plansfor specific sites.

Monitoring

Continuous monitoring of all operations is criticalto minimizing all types of site damage. A morecomplete understanding of site types and howthey are impacted by forest operations, andbetter subsequent planning is the goal. Fieldsupervisors and the operators must feel empow-ered and accountable for stopping or modifyingoperations to minimize compaction and ruttingdamage before it becomes a serious problem.Compaction is fairly insidious and may bedifficult to detect in the field. The occurrence ofrutting on a site may indicate that significant sitecompaction is also occurring.

Mitigation

Sites that have been rutted or compacted due toforestry operations, will naturally recover in partor completely, given enough time. Based on areview of the literature, Arnup (1997) suggeststhat soil recovery to pre-harvest conditions forsoils compacted by harvesting operations onheavy-traffic areas varies from 5 to 10 years forwell drained clayey soils, to 10 to 20 years forpoorly drained clayey soils. In some cases, thesetypes of damage can by mitigated through theuse of the following techniques:

• Loosening the compacted surface soil withmechanical site preparation equipment suchas a disc trencher.

• Mulching exposed fine textured soils toprevent further loss of soil structure and toencourage the restoration of structurethrough micro and macro faunal activity.Mulching can be done by distributing slashor chipper residue.

• Regenerating compacted sites with speciesthat can tolerate these conditions (e.g., jackpine does better on compacted sites thanspruce).

• Choosing plug stock seedlings or regeneratefrom seed rather than using bare root stockon compacted sites.

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paction and Rutting

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Site Damage Hazard Rating

Low: Minimal risk of compaction and rutting, providing that normal care is exer-cised during forest operations.

Moderate: Normal operating procedures may cause compaction and rutting. Theuse of Best Management Practices will normally avoid or minimize site damage.

High: Normal operating procedures will cause site damage. Best ManagementPractices may be able to minimize damage, however, in many cases operationsshould not be conducted until conditions change.

Soil Moisture Condition

Frozen: Organic or mineral soil horizons frozen due to normal winter frost.

Table 1: Compaction and rutting hazard for soils in Ontario. This table broadly classifies the risk of compaction and rutting into three categories (low,moderate, high) based on soil texture, soil depth and moisture condition.

Dry: Organic matter and surface horizons of the mineral soil are dry. Moisturecontent is nearing the permanent wilting point. This condition represents typicalmid-summer conditions, where there has likely been no significant rain for severaldays. In organic soils, water table is at least 20 cm below surface.

Moist: Surface soil at average moisture condition, organic matter is moist, mineralsoil is below field capacity. Normal precipitation has occurred, clay soils areslightly sticky. In organic soils, water table is between 10 and 20 cm below surface.

Wet: Surface soil is saturated, organic matter is soaked, and mineral soil is at orabove field capacity. There has probably been considerable rain over the past 48hours, or spring melt water conditions. Typical conditions for early spring andduring wet autumns, clay soils very sticky. In organic soils, water table is between0 and 10 cm below surface.

Soil Description Forest Ecosystem Classification Soil Type Site Damage Hazard Rating

Texture Depth Depth Northwestern Northeastern Central Soil Moisture ConditionMineral Organic Ontario Ontario Ontario(cm) (cm) frozen dry moist wet

mineral–all 0–5 0–20 SS1, SS2, SS4 SS1, SS2, SS4 SS1, SS2, SS4 (S17) low low mod high

mineral–all 6–30 0–20 SS3, SS4, (SS5–SS8) SS3, SS4 SS3, SS4 low low mod high

sandy 31–60 0–20 SS5, (SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 low low low mod

sandy 61+ 0–20 S1, S2, S7, (SS5, SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 low low low mod

coarse loamy 31–60 0–20 SS6, (SS8) S5, S6, S7, S8, (S15) S3, S7, S11, S15 low low mod high

coarse loamy 61+ 0–20 S3, S8, (SS6, SS8) S5, S6, S7, S8, (S15) S3, S7, S11, S15 low low mod high

silty 31–60 0–20 SS7, (SS8) S9, S10, S11, S12, (S15) S3, S7, S11, S15 low low mod high

silty 61+ 0–20 S4, S9, (SS7, SS8) S9, S10, S11, S12, (S15) S3, S7, S11, S15 low low mod high

f. loamy–clayey 31–60 0–20 SS7, (SS8) S13, S14, (S15) S4, S8, S12, S16 low low mod high

f. loamy–clayey 61+ 0–20 S5, S6, S10, (SS7, SS8) S13, S14, (S15) S4, S8, S12, S16 low low mod high

organic–fibric all 21–40 SS9, S11 S16 SS5, S18 low mod high high

org.–mesic/humic all 21–40 SS9, S11 S16 SS5, S18 low high high high

org.–fibric all 41+ SS9, S12F, S12S S17 S19 low mod high high

org.–mesic/humic all 41+ SS9, S12F, S12S S18, S19 S20, S21 low high high high

Note: Brackets () indicate that these soil types are not closely related to the soil description i.e., they are defined by other soil parameters and may be found on severallines in the table.


Description

Erosion is the accelerated movement of soilmaterials by the actions of water, wind or gravity.Surface erosion is normally the result of erodiblemineral soils being exposed to the elements ofwind and water. Gravitational erosion usuallyoccurs on a more massive scale in the form oflandslides, creeps and flows; these phenomenonare common on steep slopes and are catego-rized by the pattern of movement and the dura-tion of the event. In general, the potential forerosion increases as percentage slope, length ofslope and percentage of silt contained in the soilincreases.

Impacts

Soil erosion may impact a site by:

• reducing productivity through the removal ofnutrient rich, upper soil layers;

• rendering certain severely eroded sitesunproductive because of the resultantorientation of soil (i.e., exposed bedrock,steep gullies, nutrient poor exposed sub-soilmaterials or sub-soil materials smotheringproductive profiles);

• destroying vegetation through catastrophicerosion such as land slides;

• degrading water quality and fish habitat bydepositing soil particles and nutrients intostreams and water bodies; and,

• damaging or destroying soil structure in finetextured soils and depositing structurelesseroded soil materials.

Site Factors Influencing Erosion

Topographic position (i.e., crest, sideslope,depression) and slope influence soil susceptibil-ity to erosion from both surface water runoff andgravity. Slopes in excess of a soil’s natural angleof repose (slopes > 60 percent) are inherentlyunstable and subject to gravitational erosion.Lesser slopes, though more stable, are oftensubject to erosion due to surface water runoff.The risk of surface water erosion increases with

slope and the degree of mineral soil exposure ona site. Topographic features such as gullieschannel surface runoff, concentrating the effects.

The presence of organic matter on thesurface of the soil has a great influence on thepermeability of the soil, its resistance to defor-mation by the impact of rain drops and, ulti-mately, its susceptibility to erosion by wind orwater. Exposed mineral soil is the most erodiblesubstrate while soils that have a reasonabledepth of litter and humified organic material canwithstand greater erosional forces withoutdamage.

Surface runoff is inversely proportional tothe permeability of soil. A well developed layer oflitter and humus can increase permeability andabsorption and therefore limit surface runoff.Compacted soils also have lower infiltration ratesand promote surface runoff on moderate tosteep slopes. Uniformly fine textured soils suchas clays and silts inherently have lower infiltra-tion rates than coarse textured soils. The lowpermeability of clays can be reduced evenfurther if soils are subjected to prolonged peri-ods of drying followed by periods of high rainfall(flood events). Clay soils with an intact organiclayer generally develop a well-defined structureover time, thereby increasing permeability. Thissoil structure is easily damaged if mineral soilsare either compacted or exposed to the effectsof rain drop impact by removal of the organiclayers. This loss of soil structure is calledpuddling.

Wind erosion is a factor on uniformly tex-tured fine and very fine sands when the organiclayers of the soil are removed by forest opera-tions. Soils which are of aeolian origin (i.e., winddeposited sands) are obviously the most sus-ceptible to further wind erosion.

Soil depth is an important factor influencingthe erodibility of sites. Shallow soils have lowersoil volume and therefore lower total waterholding capacity. When that capacity is ex-ceeded, surface runoff must inevitably occur. Onshallow soils over bedrock, there is a consider-able amount of subsurface water flow at theinterface between rock and mineral soil that canreduce the adhesion of the shallow soil to its

ErosionDescription

22 Technical Series

Erosion Description

rock substrate and increase the risk of erosion.Shallow till deposits over Precambrian Shieldbedrock, such as are typical of much of northernOntario, are often characterized by the ruggedand complex slopes of the underlying strata. Onthese sites, soil deposited on or near the edge ofprecipitous bedrock slopes is highly susceptibleto erosion; the typical pattern of practically bareridges and depressions filled with moderatelydeep soils is due in part to progressive erosionof these soils since glaciation. Table 2 broadlyclassifies erosion hazard potential for soil andsite conditions in Ontario.

An intact root mat, and forest slash and litterlayers are perhaps the most important factors inprotecting sites from erosion. Plant species suchas grasses that have wide spreading intercon-nected root systems are effective protectionagainst erosion due to surface runoff. Theabove-ground parts of plants and trees shelterthe ground from the impact of rainfall and there-fore also serve to reduce the risk of erosion.

Environmental FactorsInfluencing Erosion

Precipitation and soil moisture have a consider-able influence on erosion. Gravitational erosionusually occurs when soils are saturated. Incontrast, surface erosion is a phenomenon ofhigh intensity, short duration precipitation.Obviously very little erosion occurs during thewinter in Ontario, however, the spring meltgreatly increases water yield from a watershedand can result in erosion problems.

Unlike compaction or rutting, only theimmediate risk of erosion is limited by seasonand soil moisture. Erosion is an effect thatoccurs after forest operations, rather than duringthem. Selecting winter operations on steepslopes for example is not necessarily an effec-tive means of preventing erosion as the condi-tions created by the forest operations will still besubject to erosionary forces after the springthaw. Winter operations may lessen the risk oferosion by minimizing disturbance to groundvegetation and the forest floor.

The Impact ofForest Operations on Erosion

While erosion of soils is a natural phenomenon,certain forest operations have the potential tosignificantly accelerate these processes. Forestoperations such as road construction and sitepreparation, which expose mineral soil, increasethe risk of erosion, especially where theseoperations occur on moderate or steeper slopes.Ditches or ruts created up and down a slopechannel surface runoff and often result in ero-sion. Skidding wood up or down a slope is ahigh-risk activity from an erosion perspective.

Where forest operations have resulted insites being damaged by compaction or rutting(See the Compaction and Rutting fact sheet),the risk of subsequent erosion is significantlyincreased.

Road construction and water crossingactivities are the most high-risk forest opera-tions. Surface runoff from forest roads, ditchesand cleared right-of-ways can be a major sourceof sedimentation and nutrient enrichment inlakes and streams. The Environmental Guide-lines for Access Roads and Water Crossingscontain mandatory standards, Best ManagementPractices and mitigation techniques to deal witherosion associated with access road construc-tion. Forest road construction and maintenancemust comply with the provisions of this docu-ment.

Forest harvesting (and natural disturbanceevents) inherently increases the risk of erosionby removing forest cover. Rapid reforestation is amajor factor in limiting erosion. Choice ofsilvicultural system and regeneration method aretherefore the principal factors in establishing thebase level of erosion risk. For example,clearcutting is inherently more risky than partialcutting systems such as selection orshelterwood. The choice of species with pro-longed regeneration periods for reforestationpurposes may increase the risk of erosion asdoes the removal of competing vegetationthrough broadcast spraying or cutting.


ErosionBest Management Practices

Planning

Erosion damage associated with forest opera-tions is largely preventable; certainly severeerosion is avoidable. The Code of Practice forTimber Management Operations in RiparianAreas is used in planning and implementingforest operations in areas near water. Thedirections in the code are designed to preventdeposition of unwanted soil and soil nutrientsinto streams and lakes, but also offer somepractical guidance for preventing erosion else-where in the ecosystem. Adherence to this codeof practice is mandatory on Crown lands inOntario. Similarly the Timber ManagementGuidelines for the Protection of Fish Habitatshould be followed; adherence to these guide-lines provides for a filtering buffer of vegetationadjacent to streams and water bodies but maybe insufficient to protect sites from erosionbeyond the reserve area. The EnvironmentalGuidelines for Access Roads and Water Cross-ings provide excellent direction and techniquesthat cannot only be used in riparian areas, butare valuable erosion control measures for theentire forest ecosystem.

Massive gravitational erosion (i.e., land-slides) is almost exclusively confined to theriparian areas of the larger rivers in the province.These events are quite infrequent and notentirely preventable, although they can havelong-term effects on a landscape and watershed.Broad sloping alluvial deposits are the mostsensitive and potentially destructive conditionsencountered in Ontario. These areas shouldhave a custom designed strategy geared to-wards land stabilization.

Past policies and practices have beendesigned to prevent or limit erosion damage inriparian areas. In the interest of maintaining siteproductivity, it is necessary to view erosion as apotential problem over the entire landscape.

As with the prevention of most types of sitedamage, the first step is to recognize potentialproblems within a specific management unit. If amanagement unit contains a high percentage ofshallow soils perched on undulating bedrock, or

large areas of productive forest located onmoderate slopes along a major river, then it isprudent to identify those sites for the purposesof developing treatment packages within theSilvicultural Ground Rules.

Field Layout

On deep alluvial soil deposits associated withlarge river valleys, consideration needs to bepaid to developing an allocation strategy toensure a staged removal of timber. On moderateto steep slopes, simple protection of the riparianarea with a reserve may be insufficient to protectagainst the threat of broad scale landslides andslumping. On broad sloping alluvial areas, careshould be taken to orient cut blocks such thatthe entire width (with slope) of the area is not cutin a single operation. Clearcut blocks in theseareas should generally be smaller than theaverage for the management unit.

Progressive reserves based on slope arerequired by the Timber Management Guidelinesfor the Protection of Fish Habitat. For the mostpart these reserves should be viewed as theminimal acceptable treatment. On steep slopesor on long gentler slopes, special care must betaken over the entire length of the slope adjacentto a riparian area. At a minimum, it is critical thereserves be laid out by ribboning in advance ofoperations.

Stream crossing locations and right-of-wayapproaches to crossings should be flagged inadvance of operations. Depending on the experi-ence of operators, it may be beneficial to notonly ribbon the road centerline but also thenarrowed right of way at the crossing location.

The layout of logging roads, and skidding/forwarding trails in areas of moderate or exces-sive slopes is critical. The natural tendency toskid logs downhill may create a severe risk oferosion. In cases where logs must be skidded upor down slopes, the best approach may be todisperse skidding so that repeat traffic does notcause rutting and compaction and, in turn,surface erosion. Within the limits of safe opera-tion, cross slope skid trails are preferable.

24 Technical Series

Regardless of the approach taken, adequatecommunication between supervisors and opera-tors, and good field layout are the critical firststeps to ensuring that the planned approach isimplemented in the field.

Implementation

The following Best Management Practices willhelp to protect sites from damage by erosion:

• Identify sites with a high risk of erosion andemploy a combination of Best ManagementPractices to reduce risk.

• Carefully adhere to the Best ManagementPractices outlined in the fact sheets forCompaction and Rutting in areas with slopesgreater than 10 percent.

• Adhere to the mandatory standards andgood practices found in the EnvironmentalGuidelines for Access Roads and WaterCrossings.

• Apply the Timber Management Guidelinesfor the Protection of Fish Habitat as aminimum on all riparian areas. Whereoperations are permitted within a riparianArea of Concern, ensure that the highestpossible standards of care are taken toeliminate the risks of compaction, ruttingand erosion. On long simple slopes, extendthe width of the reserve on the riparian areato the top of the slope or use a combinationof Best Management Practices to reduceerosion risk.

• Wherever possible, avoid locating haul roadsand skid trails on moderate to steep slopes.Wherever possible, winch wood off areaswith slopes greater than 30 percent, orreach onto slopes with a feller buncher andplace piles at the bottom or top of the slope,rather than skidding or forwarding it. Sideslopes may be used for skidding and haulingto minimize erosion potential within thebounds of safe operations. Where roadsmust be located across contours, use runoffditches rather than long continuous ditchesto reduce the velocity and magnitude ofsurface runoff flow. Protect erodible roadsurfaces with aggregate on slope areas.

• Consider extremely steep slope areas asinoperable and do not conduct forest opera-tions.

• To minimize the risk of erosion on high risksites, consider the use of winter only opera-tions to minimize ground disturbance andeliminate rutting and compaction risk.

• On shallow soil areas, modify silviculturalsystems (particularly the clearcut system) toretain some trees adjacent to precipitousslope areas. Narrow winter strip cuts parallelto the contours of the land may be used tostabilize steeper slopes on shallow soils.Avoid harvesting those areas that clearly willerode as a result of the removal of trees(i.e., areas with only a discontinuous layer oforganic material over bedrock).

• Where practical and within the limits of safemachinery operation, ensure that sitepreparation patterns run across slopes (i.e.,with the contour of land). Site prepare toprovide the minimum amount of mineral soilexposure that is acceptable to meetsilvicultural objectives. Avoid the use ofextreme site preparation techniques such assummer shear blading or the Martinni plow.Use natural regeneration, planting withoutsite preparation, hand scalping and seedingor other light touch methods to regeneratesteep slope areas. In this context, steeprefers to those areas where mechanical sitepreparation cannot safely occur across thecontour of the site.

• Consider erosion risk in the choice ofspecies and regeneration method. Erosionrisk is reduced by rapid reforestation so theuse of fast growing species is advisable onhigh-risk sites. The use of species with aprolonged regeneration period that requireextensive vegetation control is counterpro-ductive.

• Proper planning and scheduling of opera-tions is required at all stages including day-to-day on-site operations. It is important thatoperators are competent and properlytrained, and that they are aware of theobjectives and approaches to be taken onspecific sites.

Erosion Best Management Practices


ErosionBest Management Practices

Monitoring

Continuous monitoring of all operations is criticalto minimizing all types of site damage. A morecomplete understanding of site types and howthey are impacted will ultimately lead to im-proved planning in the future. Some soil move-ment is expected and acceptable as the result offorest operations. Erosion becomes unaccept-able when:

• Best Management Practices are not em-ployed on high-risk sites and site damageoccurs.

• Soil erodes into streams and other waterbodies.

• Massive gravitational erosion occurs as aresult of forest operations.

• Land is rendered unproductive as a result oferosion.

Mitigation

If minor erosion appears on slopes followingforest operations, the following techniques maybe used to mitigate further damage to the site:

• Identify ruts or furrows on slopes that arechannelling runoff and causing erosion.

• Limit further erosion by filling these ruts withslash, debris, or non-erodible soil.

• Divert mid-slope ruts with cross drains,obstacles, or berms (i.e., water bars).

• Ensure prompt regeneration of exposederodible slopes.

26Technical S

eries


Low: Minimal risk of erosion, providing that normal care is exercised during forestoperations.

Moderate: Normal operating procedures may cause erosion. The use of BestManagement Practices will normally avoid or minimize site damage.

High: Normal operating procedures will likely cause erosion where mineral soil isexposed. Best Management Practices may be able to minimize damage.

Table 2: Erosion hazard for soils in Ontario. This table broadly classifies the risk of erosion into three categories (low, moderate, high) based on soiltexture, soil depth and percent slope.

Notes: Brackets () indicate that these soil types are not closely related to the soil description i.e., they are defined by other soil parameters and may be found on severallines in the table.

*Erosion hazard across all soil types and slope classes is reduced if organic material (forest floor, slash) is left intact on the site.

Erosion

Best M

anagement P

ractices

Soil Description Forest Ecosystem Classification Soil Type Site Damage Hazard Rating*Texture Depth Depth Northwestern Northeastern Central Slope (%)

Mineral Organic Ontario Ontario Ontario(cm) (cm) 0–10 11–30 >30

mineral–all 0–5 0–20 SS1, SS2, SS4 SS1, SS2, SS4 SS1, SS2, SS4 (S17) low mod to high mod to high

mineral–all 6–30 0–20 SS3, SS4, (SS5–SS8) SS3, SS4 SS3, SS4 low mod mod to high

sandy 31–60 0–20 SS5, (SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 low low to mod mod to high

sandy 61+ 0–20 S1, S2, S7, (SS5, SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 low low to mod mod to high

coarse loamy 31–60 0–20 SS6, (SS8) S5, S6, S7, S8, (S15) S3, S7, S11, S15 low low to mod mod to high

coarse loamy 61+ 0–20 S3, S8, (SS6, SS8) S5, S6, S7, S8, (S15) S3, S7, S11, S15 low low to mod mod to high

silty 31–60 0–20 SS7, (SS8) S9, S10, S11, S12, (S15) S3, S7, S11, S15 low low to mod high

silty 61+ 0–20 S4, S9, (SS7, SS8) S9, S10, S11, S12, (S15) S3, S7, S11, S15 low low to mod high

f. loamy–clayey 31–60 0–20 SS7, (SS8) S13, S14, (S15) S4, S8, S12, S16 low low to mod mod to high

f. loamy–clayey 61+ 0–20 S5, S6, S10, (SS7, SS8) S13, S14, (S15) S4, S8, S12, S16 low low to mod mod to high

organic–fibric all 21–40 SS9, S11 S16 SS5, S18 low low

org.–mesic/humic all 21–40 SS9, S11 S16 SS5, S18 low mod

org.–fibric all 41+ SS9, S12F, S12S S17 S19 low

org.–mesic/humic all 41+ SS9, S12F, S12S S18, S19 S20, S21 low


Description

Part of the total nutrient capital on a forest site isheld in tree biomass, particularly in branchesand foliage. On nutrient poor sites, the percent-age of total site nutrients found in the aboveground parts of trees is much greater than onricher sites. Forest operations on these nutrientpoor sites may reduce total nutrient capital tocritical levels, resulting in extended nutrientreplacement time.

Impacts

It is widely believed that nutrient removals due tologging are not significant on most sites. Naturalnutrient cycles replenish lost nutrient capital withminimal impact on ecosystems. The length ofthis recovery period is a function of the degreeof site nutrient depletion and the rate of nutrientreplacement. On some sites, nutrient loss due tologging is very significant since there is very littlenutrient capital stored on the sites, except in thetrees themselves. On these sites nutrient lossmay:

• slow the growth and ultimately the yield oftrees and other plants in subsequent gen-erations,

• reduce overall tree and stand vigour therebyincreasing vulnerability to subsequentdisease and insect infestation, and

• reduce wildlife habitat and food production.

Site Factors Influencing theSignificance of Nutrient Loss

The largest store of nutrients on most borealsites is found in the organic material of the forestfloor and incorporated in the upper mineral soilprofile. The boreal forest is often characterizedby large accumulations of relatively rich organicmaterial because of the slow rate of decomposi-tion on many sites. Low average temperatures,high soil acidity, and moisture conditions oftenreduce the rate of microbial decomposition,resulting in most nutrients being unavailable forplant uptake and growth. Historically, wildfire has

been the dominant disturbance agent that hasrestored these nutrients back into circulation.Logging, mechanical site preparation andprescribed fire can cause locked up nutrients tobe cycled and made available for plant growth.

Fine textured soils with a clay componentare able to hold nutrient cations within themineral soil profile. This nutrient holding capacityis far less on coarse textured mineral soils suchas outwash sand flats, or on sites where themineral soil is extremely shallow. On these sites,the presence of organic matter represents acritical nutrient sink. The sites where nutrientlosses due to forest management practices posethe greatest threat to long term productivity arethose which have the least nutrient capital storedin the soil. These include :

• coarse textured sands with very low cationexchange capacity;

• soils with little or no accumulated organicmatter and little organic incorporation in themineral soil profile; and

• very shallow soils, especially where theorganic mat may be lost or damaged afterforest management (e.g., very shallow soilover bedrock where the organic mat mayeither dry out and wind erode after logging,or may be removed by mechanical sitepreparation or prescribed burning).

Figure 2: Example of nutrient-poor, shallow soil sitewhich is sensitive to nutrient loss.

Nutrient LossDescription

28 Technical Series

Hardwood trees tend to be more effectivenutrient cyclers than conifers. Hardwood standstypically have a well-developed soil profile withincorporated organic matter. Aspen and birch inboreal forests are able to capture calcium andpotassium from deep in the soil and accumulateit for further cycling in tree biomass.

Site history (types, intensity and frequencyof disturbances) largely dictates the currentnutrient status of a site. Those sites that alreadyhave a low nutrient status will be most suscepti-ble to additional depletions by forest operations.

Environmental FactorsInfluencing Nutrient Loss

The risks associated with nutrient depletion area function of the amount of nutrient capital on asite and the amount removed by the forestoperation; the direct influence of environmentalfactors on this relationship is limited. Subsequentdamage to the site, such as erosion, may exac-erbate the impact of nutrient depletion on a site.Factors influencing the potential for subsequenttypes of site damage may therefore be supple-mentary factors in determining the magnitude ofnutrient loss.

During winter periods, less overall nutrientcapital is contained within the upper parts oftrees; annual leaf litterfall is complete and someof the trees’ food stores and mineral nutrientcapital is translocated to the roots. This isespecially true for hardwood stands, but lessclear for conifers. This nutrient shift within thetree, coupled with an overall reduction in sitedamage potential, suggests that sites mostsusceptible to nutrient loss may be better suitedto winter harvesting. Season of harvest in thiscase, however, is far less related to actualnutrient loss than is the type of harvesting.

Rates of decomposition and cycling ofnutrients increase as soil temperature increases.On sites with a closed conifer canopy whichhave not been disturbed for long periods, therecan be a considerable accumulation ofundecomposed organic matter.

The Impact of ForestOperations on Nutrient Loss

On high-risk sites, forest management opera-tions that displace organic material, such asharvesting and site preparation, may reduce thenutrient capital on the site to the point wherelong-term site productivity is impacted. Reducednutrient capital following forest harvesting andrenewal operations coincides with the period ofhighest nutrient demand in the developing crop.

High severity fires or full tree harvesting onhigh-risk (nutrient poor) sites pose the greatestthreats to nutrient depletion. Immediately afterfire (wildfire or prescribed burning), there is anincrease in available nutrients resulting from thecycling of nutrients locked in undecomposedorganic matter. A portion of these nutrients iscaptured by rapid vegetative re-growth whilesome is lost due to runoff and leaching.

In general, full tree harvesting poses agreater risk of serious depletion of nutrientcapital than do systems that leave limbs andtops in the cutover. Experimental comparisons innorthwestern Ontario suggest that full treeharvesting, through its increased nutrient remov-als, increases replacement times by 10 to 20years, depending on the macroelement inquestion (Morris 1997). The most susceptibleelements appear to be K, Ca and Mg.

Short rotation forest cropping on sensitivesites may cause nutrient losses in excess ofwhat natural cycles can replace in a singlerotation. The potential exists for repeated shortrotation harvest cuts to result in a substantialcumulative loss of nutrient capital.

Extremely heavy site preparation (which isno longer normally practised) such as the use ofthe Martinni plow or the use of summer bladingon high risk sites could also result in significantsite degradation. Slash and litter piling canremove 6 to 10 times more nitrogen than tree-length logging. The combined effect of nutrientremovals due to forest harvesting and nutrientdisplacement due to heavy site preparation canseriously deplete nutrient reserves on sensitivesites.

Nutrient Loss Description


Planning

To protect sites from damage due to nutrientloss, it is first necessary to be able to identifythose sensitive sites within the landbase. TheForest Resource Inventory stratifies the leastproductive sites within the landbase on the basisof site index. While not sufficiently accurate foroperational purposes, this is a good start atidentifying the least productive sites, some ofwhich will be susceptible to damage by nutrientloss. Soils and ecosite maps, and local fieldknowledge may serve to improve the identifica-tion of these sites. The sites which are most atrisk to damage from nutrient losses due to forestoperations are relatively easily identified. It ismore difficult, however to define the line wheresites are marginally at risk. The accountability forsite damage rests with the forest manager andconsequently a conservative and adaptiveapproach should be taken to managing thisissue. At a minimum, the following site conditionsshould be considered to be sensitive to potentialsite damage from nutrient loss associated withforest management practices:

• Extremely shallow sites. Sites with a discon-tinuous mat of organic material and/or lessthan 5 cm of mineral soil.

• Very coarse textured soils (pure medium tovery coarse sands and gravels such asglacio-fluvial outwash plains).

• Soils with little or no accumulated or incor-porated organic material. These conditionsmight be found on sites that were previouslysubjected to extreme or repeated wildfires.

Silvicultural Ground Rules should addresshow these sites will be managed to prevent orminimize damage due to nutrient loss. It may beappropriate to separate these sensitive sites byworking groups into separate forest units formanagement purposes with their own allowableharvest calculation and their own customizedrotation age which reflects the length of timerequired to allow nutrient poor sites to recovertheir soil nutrient equilibrium.

Implementation

Nutrient losses from full tree harvesting aremore significant than from tree length or cut-to-length operations since a substantial percentageof the nutrient reserves in a tree are in the smallbranches and foliage. The use of harvestingtechniques that maximize the amount of slashleft on site is therefore recommended for nutrientpoor site conditions.

The use of winter harvesting on shallowsites that are susceptible to nutrient losses isrecommended. Winter harvesting will conserveslightly more mineral nutrients on site and is lesslikely to cause other subsequent forms of sitedamage such as erosion, compaction or rutting.

Full tree logging results in vast stores ofnutrients being piled at roadside. These slashpiles are often burned. In the case of full treechipping, the debris left is an admixture of bark,leaves and needles which is very rich in mineralnutrients. There is considerable benefit inspreading this chipper debris back over the sitedespite the rather inefficient methods availableto do this at this time. Using a grapple skidder totake a grapple full of debris back with eachreturn trip is one method that is currently beingemployed. Another option to reduce chippingdebris is to tree-length harvest.

Maintaining a diversity of tree and plantspecies on a site, including a hardwood compo-nent, will improve the cycling and capture ofnutrient capital. Alder, for example, has a par-ticularly valuable role as a nitrogen fixer. Wherepossible, maintain some trees and plants on siteto act as a nutrient sink to capture mobilenutrient ions made available following harvestand site preparation. This reduces the risk ofloss of these ions due to deep, post-harvestleaching. It is important to consider the value ofnon-crop species as a nutrient sink on sites thathave been regenerated with spruce that maytake a long time to establish. Herbicide releaseof slow growing spruces at too young an age(i.e., before they are ready to capture the site)reduces the potential benefits of the non-cropspecies as nutrient sinks.

Nutrient LossBest Management Practices

30 Technical Series

Nutrient poor sites should be matched with lowernutrient demanding species when these sitesare regenerated. In some cases, locally adaptedspecies may be better able to cope with poorsite conditions, therefore, good seed sourcecontrol of regeneration material and or naturalregeneration is important.

Direct forest fertilization could theoreticallybe used as a technique to restore nutrientcapital on depleted sites. The economics offorest fertilization is questionable, and thetechnique is not currently approved under theterms of the Class Environmental Assessmentfor Timber Management on Crown Lands inOntario.

Monitoring

Effects monitoring is essential to ensure that thelandbase is properly stratified and that manage-ment strategies are working. Early establishmentsuccess is not an effective measure of themaintenance of soil nutrient capital. Signs ofnutrient stress include reduced height increment,reduced tree vigour, insect and disease prob-lems, yellowing, delayed crown closure, standstagnation and poor natural thinning. Forestunits that have been identified as being sensitiveto nutrient loss should be monitored to assessthe effectiveness of treatments.

Nutrient Loss Best Management Practices

Forest Manag

ement G

uidelines for the P

rotection of the Physical E

nvironment

31


Low: Minimal risk of nutrient loss, providing that normal care is exercised duringforest operations.

Table 3: Nutrient loss hazard for soils in Ontario. This table broadly classifies the risk of nutrient loss into three categories (low, moderate, high) basedon soil texture, soil depth, silvicultural system and logging method.

Notes: Brackets () indicate that these soil types are not closely related to the soil description i.e., they are defined by other soil parameters and may be found on severallines in the table.

1. The category “Tree Length” indicates any logging method that leaves limbs and tops in the cutover.

2. For sandy, shallow soil sites, increase hazard rating one class if sand texture is very coarse to medium.

Soil Description Forest Ecosystem Classification Soil Type Site Damage Hazard Rating

Texture Depth Depth Northwestern Northeastern Central Clearcut SelectionMineral Organic Ontario Ontario Ontario and(cm) (cm) Full Tree Shelter-

Tree Length wood

mineral–all 0–5 0–5 SS1, SS2, SS4 SS1, SS2, SS4 SS1, SS2, SS4 (S17) high high mod

mineral–all 0–5 6–20 SS1, SS2, SS4 SS1, SS2, SS4 SS1, SS2, SS4 (S17) high high mod

mineral–all 6–30 0–5 SS3, SS4, (SS5, SS8) SS3, SS4 SS3, SS4 high high low

mineral–all 6–30 6–20 SS3, SS4, (SS5, SS8) SS3, SS4 SS3, SS4 high mod low

sandy 31–60 0–5 SS5, (SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 high–mod mod–low low

sandy 31–60 6–20 SS5, (SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 mod low low

sandy 61+ 0–5 S1, S2, S7, (SS5, SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 mod low low

sandy 61+ 6–20 S1, S2, S7, (SS5, SS8) S1, S2, S3, S4, (S15) S1, S2, S5, S6, S9, S10, S13, S14 low low low

coarse loamy 31–60 0–20 SS6, (SS8) S5, S6, S7, S8, (S15) S3, S7, S11, S15 low low low

coarse loamy 61+ 0–20 S3, S8, (SS6, SS8) S5, S6, S7, S8, (S15) S3, S7, S11, S15 low low low

silty 31–60 0–20 SS7, (SS8) S9, S10, S11, S12, (S15) S3, S7, S11, S15 low low low

silty 61+ 0–20 S4, S9, (SS7, SS8) S9, S10, S11, S12, (S15) S3, S7, S11, S15 low low low

f. loamy–clayey 31–60 0–20 SS7, (SS8) S13, S14, (S15) S4, S8, S12, S16 low low low

f. loamy–clayey 61+ 0–20 S5, S6, S10, (SS7, SS8) S13, S14, (S15) S4, S8, S12, S16 low low low

organic–fibric all 21–40 SS9, S11 S16 SS5, S18 low low low

org.–mesic/humic all 21–40 SS9, S11 S16 SS5, S18 low low low

org.–fibric all 41+ SS9, S12F, S12S S17 S19 low low low

org.–mesic/humic all 41+ SS9, S12F, S12S S18, S19 S20, S21 low low low

Moderate: Normal operations may cause nutrient loss. The use of Best Manage-ment Practices will normally avoid or minimize site damage.

High: Normal operating procedures will cause site damage. Best ManagementPractices may be able to minimize damage.

Nutrient Loss

Best M

anagement P

ractices

32 Technical Series

Description

In the process of conducting forest operationssome productive land is removed from produc-tion on a long term or permanent basis as aresult of the construction of roads, landings, andas a result of smothering by piles of slash orchipper debris.

Impacts

The removal of productive land reduces theoverall productivity of harvest blocks and man-agement units. Unlike other forms of site dam-age, land loss is a total removal of the affectedlands from production rather than a reduction ofproductivity. It is in the best interest of the forestindustry to limit these self imposed losses ofproductive land to maintain long term yields.

Site Factors Influencingthe Loss of Productive Land

The principal cause of loss of productive land isroad construction. Landscapes that are dis-sected by natural obstacles such as ridges,lakes and streams may require a more extensiveroad network per unit area accessed.

On sites that are only accessible by winterroads, the permanent loss of land to roadbeds isgreatly reduced. Highly trafficable sites (i.e., drycoarse textured soils) result in easy road con-struction with little need for aggregate use or thebuilding of roadbeds. On these sites, the ten-dency is to build more roads because they arerelatively inexpensive to construct. Finer texturedsoils are usually moister necessitating moreextensive roadbed construction, ditching andapplication of aggregate resulting in permanentlynon-productive areas.

Sites that have good deep subgrade mate-rial enable roads to be constructed with aminimum amount of grubbing. This results in anarrower disturbance area, thereby reducing theamount of land lost to production.

The Impact of Forest Operationson Loss of Productive Land

Construction of winter access results in less landloss than all-weather access roads. Upland winterroads can be built with a minimal amount ofbulldozing of mineral soil resulting in very little lossof productive area. Lowland swamp roads built inthe winter are not permanently lost from productionwhen ground disturbance is minimal.

Roads constructed with a minimal right-of-wayon areas with good road building material on siteare more efficient in terms of disturbing less landthan are roads which are constructed in areaswhere a bulldozer has to scrape sub-grade mate-rial from a broad area to construct a road bed.

All landings result in some loss of productiveland due to rutting, compaction and smothering ofthese sites. Efficiency in the extent of landings canminimize the amount of land lost.

The burning of roadside slash piles helps torecover productive land as does the redistributionof slash or chipper residue. Limbing at the stump intree length or cut-to-length systems results in lesssmothering of land by top and limb piles near theroadside. These systems may, however, increasethe costs of silviculture and limit the treatmentoptions available. Site preparation techniques thatresult in the creation of windrows or hummocks ofslash reduce productive land. Increasing theeffective distance between roads by moving fromskidding to forwarding equipment can result in lessland being lost to road development.

Figure 3: Land loss due to full-tree chipping debris.

Loss of Productive Land Description


Planning

Strategic roads planning is key to minimizing thearea lost to access development. It is importantto ensure that planning of primary road corridorsis done well, as these form the basic gridlinesupon which an efficient secondary and tertiaryroad system can be built.

Use natural boundaries such as majorriverways and lake systems to subdivide the unitfor planning primary access. Secondary andtertiary roads should be planned as a network.To minimize the amount of road disturbance,ensure that roads are located far enough apartthat operators are working at their maximumcost effective skidding or forwarding distancefrom the road. On very good ground the ten-dency is to over-access; this approach is verycost effective in the short term but it maximizeslong term loss of productive land.

Excessive use of loop turnarounds results ina higher percentage of road area. The roadnetwork should be designed to as closelyapproximate a grid as possible.

Consider opportunities for the use of winterroads in strategic access planning. Where thedemands of the silviculture program allow forwinter-only access, every effort should be madeto adapt the harvesting and delivery schedule toaccommodate winter operations and accessdevelopment. Winter-only access is often auseful tool for resolving tourism/harvestingissues where access is a major concern.

Field Layout

All roads, including tertiary roads, should beplanned, then located with ribbon in the field inadvance of operations. It is not advisable toallow equipment operators to develop tertiaryaccess within the cut block on their own, withouta strategy, as this will almost always result in aless efficient road network (e.g., over-accessing,trespassing, poor locating).

The number and location of landings shouldbe decided upon and communicated to equip-ment operators before operations begin. Planthe size and extent of landings required; adopt-ing a laissez faire approach to landings willresult in more land being used than necessary.

Implementation

The following Best Management Practices willhelp to minimize the amount of productive landlost due to forest operations.

• Invest in good road location to ensure thatroads are as direct as possible.

• Build roads with a backhoe rather than adozer to minimize width of disturbed area.

• Locate landings on areas of non-productivesoil (e.g., bedrock) whenever possible.

• Choose equipment that can maximize thedistance between roads (e.g., forwarders mayextend the distance between roads in somecases).

• When possible, select cut-to-length or treelength logging systems to minimize the sizeof slash piles at roadside.

• Soil contamination with fuel and oil is entirelyunacceptable. Practice environmentally friend-ly, zero discharge maintenance and refueling.

• Pile roadside wood as high as safety permits.

• Minimize bush inventory. Haul wood asquickly as possible to minimize the amount oflanding area required.

• Wherever possible, site prepare and regener-ate tertiary roads, ditches, right-of-ways andlandings which will not be in periodic use.

• Do not use site preparation techniques whichrely on piling slash in unproductive windrowsor mounds unless these will be burned.

• Burn slash piles and redistribute chipperresidue piles.

Monitoring

The amount of land lost to roads, landings andslash piles will be significant. Common senseshould dictate when techniques employed areresulting in more productive land being lost thanis necessary. Road construction, harvesting andsilviculture operations should be scrutinized toensure that minimal disturbance occurs. Minimiz-ing roads and landings may increase loggingcosts. Therefore, operators need to be informedas to why this is beneficial in the long term.

Loss of Productive LandBest Management Practices

34 Technical Series

Description

Water moves through the soil, plants, animalsand atmosphere of a forested ecosystem inpathways termed the hydrological cycle. Forestoperations may have a negative influence on thehydrological cycle in terms of site productivityand site regrowth in both the short and longterm.

Impacts

Typical hydrological impacts resulting from forestoperations include:

• Watering-up: Removal of tree cover byharvesting (particularly in the clearcutsilvicultural system) can result in the watertable on some lower land sites coming closeto or above the surface of the soil, as theeffect of transpiration by trees is reduced oreliminated. This effect is greatest immedi-ately after harvesting. In extreme cases,where this condition persists for severalyears, poor revegetation and/or substantialchanges in plant cover may result (e.g.,creation of alder swales or grass and sedgemeadows). Watering-up effectively reducesthe rooting zone available for plants andtrees. On sites where the water table isalready at the surface of the soil, harvestingmay have the opposite effect and may causethe site to dry out slightly as a result ofincreased evaporation.

• Surface drying: Well drained soils may besubject to excessive surface drying whenforest cover is removed, due to greatlyaccelerated evaporation rates. On somesites, loss of organic material due to theeffect of drying winds is possible underthese conditions.

• Disruption of lateral water flow through thesoil: Road construction, rutting and occa-sionally furrowing resulting from site prepa-ration can cause the lateral drainage/movement of water in soil to be interruptedor altered. This can result in ponding or otherchanges in the position of the water table

(e.g., strategically placed furrows or ruts caneffectively drain some forest sites). Thelateral flow of water is a major source ofnutrient flow on some sites (telluric flow) anddisruption of this flow may result in areasbecoming impoverished from a nutrientperspective.

• Disruption of infiltration rates in soil: Soilcompaction, rutting and smothering by roadand landing construction can effectivelyreduce or eliminate water infiltration into thesoil and thereby impact site productivity.Conversely the removal of forest cover canincrease the amount of water which perco-lates down through soil horizons and there-fore can also increase the amount of leach-ing of nutrient cations which occurs.

• Increased water yield: Extensive forestharvesting in a watershed can greatlyincrease the flow of water through thatwatershed (i.e., greater stream flow andpossibly greater surface flow resulting inpotential erosion problems). With increasingwater flows, nutrient loading into streamsand water bodies is likely to increase to thedetriment of cold water fisheries. Springsnowmelt occurs earlier and is more rapid incutover areas and could result in increasederosion, nutrient leaching and downstreamflooding.

Figure 4: Raised water table resulting from disruptionof lateral drainage during harvest.

Hydrological Impacts Description


Site FactorsInfluencing Hydrological Impacts

Sites which have excessively dry moistureregimes and very rapid drainage, and siteswhich have extremely wet moisture regimes andpoor drainage tend to be the most adverselyaffected by forest operations with respect tohydrological change. For example, areas that arerelatively poorly drained because of soil textureor topographic position, will be most prone towatering-up as a result of timber harvesting.Conversely, those sites that are very welldrained and dry prior to harvest may experienceexcessive drying of the soil surface after timberharvest due to increased evaporation rates.

Sites that are susceptible to compaction andrutting, as discussed in the Compaction andRutting fact sheet, are therefore also susceptibleto hydrological impacts as a result of forestoperations.

Environmental FactorsInfluencing Hydrological Impacts

Frozen conditions may reduce the influence offorest operations on the lateral flow of water andinfiltration rates to the extent that winter opera-tions reduce compaction and rutting. There is noappreciable difference in the impact of winterversus summer harvesting operations on water-ing-up.

Hydrological changes relate to changes inthe potential rates of flow of water throughvarious parts of the forest ecosystem. Changesin precipitation may either exaggerate or reducethe impact of hydrological changes on actual siteconditions. These circumstantial changes pro-vide only a short-term respite from the long-terminfluence of hydrological change.

The Impact of Forest Operationson Hydrological Changes

Forest operations that result in compacted orrutted soil (see Compaction and Rutting factsheet) also result in poorer water infiltrationthrough the soil and impeded lateral movementof water in the soil.

The construction of all-weather roads acrosspeatlands using corduroy or fill can effectivelycreate a dam that interrupts the lateral flow ofwater in the soil. Even winter roads constructedacross peatland areas can effectively limit theflow of water through a bog area for a prolongedperiod of time. This effect can also occur onupland soils where roadbeds are not designed toallow sufficient cross drainage.

Changes in the height of the water table dueto watering-up or excessive drying are hydrologi-cal changes which are most exaggerated whensites are cut clear. Modified clearcutting orpartial cutting greatly reduces the degree ofhydrological change resulting from harvesting.

Water and nutrient yields from a watershedincrease proportionately with the amount of areaharvested in one cut or in a series of cuts over ashort period of time. The effect of large scalecutting on a watershed increases as the slope ofthat watershed increases, as the depth of soildecreases, and as the rates of infiltration of thesoils in the watershed decrease. The upperreaches of watersheds are the most sensitive tohydrological change since slopes are oftengreatest in this area, and stream beds arenarrower and less likely to be able to accommo-date increased flows. If a small valley containingthe headwaters of a feeder stream is completelyclearcut then the impact on that part of thewatershed will obviously be very great(i.e., greatly increased water and nutrient flow,erosion, siltation) even though the effects felt atthe bottom end of the watershed may be negligi-ble.

The faster a site is revegetated, the fasternormal hydrological flows and processes willresume. Vegetation management that is used topromote a slow growing conifer species at theexpense of more rapidly growing species, canprolong the period that site hydrology is im-pacted following forest harvesting.

Site productivity on some organic soils canbe significantly increased through the use ofpeatland drainage. Drainage is not currentlyapproved under the terms of the Class Environ-mental Assessment for Timber Management onCrown Lands in Ontario.

Hydrological ImpactsBest Management Practices

36 Technical Series

Planning

As with most types of site damage, the key toavoidance is recognizing those sites that aresensitive to disturbance. Sites most sensitive tonegative hydrological change are those “exces-sively” moist to wet peatland or mineral soil sites.Most of these sites will also be sensitive torutting and compaction disturbance and couldpossibly be stratified for management planningpurposes into separate forest units. Modifiedclearcutting (e.g., strip cutting, group seed treeharvest, careful logging around advance growth)should be examined in the Silvicultural GroundRules for wet peatland areas. If modifiedclearcutting techniques are considered, theimpact on the allowable harvest must be consid-ered in the preparation of the management plan.Where silviculturally appropriate, selection and/or shelterwood harvesting greatly reduces theimpact of harvesting on the water table.

The development of allocation strategiesshould consider the impact of harvesting onwater yield at the watershed level. A general ruleof thumb is to harvest no more than 50 percentof the watershed in a single operation or overseveral operations, where the previously cutareas have not yet reached free-to-grow condi-tion (Plamondon 1993). Pay particular attentionin the upper reaches of watersheds wheretopography is rolling or hilly (i.e., where slopesare commonly in excess of 10 percent).

Implementation

The following Best Management Practicesshould be considered in order to protect sitesand ecosystems from damage due to hydrologi-cal change:

• The overall degree of harvesting in a water-shed should be considered when areas areselected for harvest. Where greater than 50percent of a watershed is planned forharvest during a five-year management planterm or where cumulative cutting (harvestedareas not yet free-to-grow) will include morethan 50 percent of a watershed, the issue ofwater yield should be addressed in themanagement plan.

• On sites which are sensitive to hydrologicalchange (i.e., wet organics and extremelyxeric sites), modified clearcutting techniquesshould be considered, including the use ofstrip cutting, preservation of advance growthand reduction in the extent of cut blocks.

• On very dry sites, the retention of sometrees, shrubs and even slash can reduceoverall ground temperatures and thereforecontrol excessive drying.

• Adherence to the Best Management Prac-tices outlined in the Compaction and Ruttingfact sheet will lessen changes to waterinfiltration rates and rates of lateral watermovement of water through the soil.

• Both the placement and methods used inthe construction of forest access roadsshould be sensitive to potential changes inhydrology. Roads built in upland areasshould have sufficient cross drainage toallow for surface or subsurface flow of water.This is especially true where roads areconstructed on midslope positions. Loca-tions of springs and intermittent streamsshould be considered in road construction.All-weather roads built across peatlandsmay significantly disrupt internal drainage.Roads should be located to minimize thiseffect, with drainage culverts used to preventponding.

• Landings should be located so that skiddingtraffic is not forced to cross and disruptnatural drainage patterns.

• Sites should be reforested as quickly aspossible.

Monitoring

Forest operations must be monitored for hydro-logical change in order to design future manage-ment programs and to ensure that Best Manage-ment Practices are being applied. Removingtrees will inevitably alter hydrological cycles(particularly in the clearcut system) as willnatural disturbance events. Past harvestingpractices which resulted in the watering-up oflowland mineral soil areas and peatlands haveresulted in regeneration periods for black sprucewhich are, in some cases, unacceptably long.

Hydrological Impacts Best Management Practices


Acknowledgments

The authors wish to acknowledge the followingpersons for their contributions during the devel-opment of these guidelines:

Dave Hogg for providing guidance andsupport throughout the writing of this document,and providing key editorial comment during itspreparation.

Maureen Kershaw for support during theearly planning stages of this document, and forgenerously providing background information,photos and a draft of her comprehensive docu-ment on forestry practices for maintaining siteproductivity.

Kent Virgo, Rich Greenwood and Bob Wattfor reviewing the technical content of theseguidelines and providing valuable insights intoscientific content and Best Management Prac-tices.

Doug Haldane, Crandall Benson, JohnParton, Ron Waito, Neville Ward, WilfredRuland, Bruce Adamson and Ruth Berzel formanuscript review.

Al Bisschop, Joe Churcher and FrankKennedy for editorial comments which signifi-cantly helped in aligning these guidelines withthe MNR planning process.

The scoping team, which met over a periodof two days, to define the purpose, content andstructure of these guidelines. Members includedAlf Aleksa, Rob Arnup, John Copeland, AlCorlett, Mike Dawe, Dan Dey, Rich Green-wood, Dave Hogg, Chris Hollstedt, Paul Jewiss,Maureen Kershaw, Richard Raper and KentVirgo.

Ruth Berzel and Sherry Kozak for publica-tion design and production.

38 Technical Series

Literature Cited

Alban, D.H., Perala, D.A. and Sclaegel, B.E.1978. Biomass and nutrient distribution inaspen, pine and spruce stands on the samesoil type in Minnesota. Can. J. For. Res. 8:290–299.

Arnup, R.W. 1997. Soil Disturbance on clay andorganic soils in northeastern Ontario– A literature review. Ont. Min. Natur.Resour. Northeast Sci. & Technol. (In Prep.)

Burnside, R.J., See, J. and Phillips, S. 1995.Forest health on the Kenai Peninsula. West-ern Forester 40: 12–13

Chambers, B.A., Naylor, B. and Nieppola, I.1997. A field guide to forest ecosystems ofcentral Ontario. Ont. Min. Natur. Resour.,Central Sci. and Technol., North Bay,Ontario. (In Progress)

Dubé, S., Plamondon and A.P., Rothwell, R.L.1995. Watering-up after clear-cutting onforested wetlands of the St. Lawrence low-land. Water Resour. Res. 31: 1741–1750.

Environmental Assessment Board. 1994. Rea-sons for decision and decision. Class envi-ronmental assessment by the Ministry ofNatural Resources for timber managementon Crown lands in Ontario. Min. Environ.Toronto, Ontario. EA-87-02. 561 pp.

Freedman, B. 1981. Intensive forest harvest: Areview of nutrient budget considerations.Can. For. Serv., Maritimes For. Res. Cent.,Fredericton, N.B., Inf. Rep. M-X-121.

Government of Ontario.1994. An Act to revisethe Crown Timber Act to provide for thesustainability of Crown Forests in Ontario.Legislative Assembly of Ontario. 37 pp.

Hausenbuiller, R.L. 1985. Soil science: princi-ples and practices. 3rd Edition. Wm. C.Brown Publishers. Dubuque, Iowa. 610 pp.

Kershaw, H.M., Jeglum, J.K. and Morris D.M.1997. Long-term productivity of borealforest ecosystems. Volume III. Forestrypractices aimed at maintaining site produc-tivity. (In Prep.)

Kimmins, J.P. 1974. Sustained yield, timbermining, and the concept of ecological rota-tion: A British Columbian View. For Chron.50: 27–31.

Kimmins, J.P. 1977. Evaluation of the conse-quences for future tree productivity of theloss of nutrients in whole-tree harvesting.For. Ecol. Mgmt. 1: 169–183.

Kimmins, J.P. 1994. Identifying key processesaffecting long-term site productivity.Pp. 119–150 In Dyck, W.J., Cole, D.W. andComerford, N.B. (eds.). Impacts of ForestHarvesting on Long-Term Site Productivity.Chapman & Hall, London.

Mahendrappa, M.K., Maliondo, S.M. andvan Raalte, G.D. 1987. Potential acidifica-tion of sites due to intensive harvesting inNew Brunswick. Pp. 100–114.In Z. Stiasny (ed.). Sixth CanadianBioenergy R&D Seminar. Elsevier AppliedScience.

Maliondo, S.M. 1988. Possible effects of inten-sive harvesting on continuous productivityof forest lands. For. Can., Fredericton, N.B.,Inf. Rep. M-X-171.

McCarthy, T.G, Arnup, R.W., Nieppola, J.,Merchant, B.G., Taylor, K.C. andParton, W.J. 1994. Field guide to forestecosystems of northeastern Ontario. Ont.Min. Natur. Resour., Northeast Sci. &Technol. Field Guide FG-01. 222 pp.

Morris, D.M. 1997. The role of long-term siteproductivity in maintaining healthy ecosys-tems: A prerequisite of ecosystem manage-ment. For. Chron. (In Press).


OMNR. 1988a. Timber management guidelinesfor the protection of fish habitat. Queen’sPrinter for Ontario. 14 pp.

OMNR. 1988b. Environmental guidelines foraccess roads and water crossings. Queen’sPrinter for Ontario. 64 pp.

OMNR. 1991. Code of practice for timbermanagement operations in riparian areas.Toronto: Queen’s Printer for Ontario. 20 pp.

OMNR. 1992. Direction ’90s. Toronto: Queen’sPrinter for Ontario.

OMNR. 1995. Forest Operations and Silvicul-ture Manual. Toronto: Queen’s Printer forOntario. 64 pp.

OMNR. 1996. Forest management planningmanual for Ontario’s Crown forests. To-ronto: Queen’s Printer for Ontario. 452 pp.

OMNR. 1997a. Silviculture guide to managingfor black spruce, jack pine, and aspen onboreal ecosites in Ontario. Ont. Min. Natur.Resour. (In Press).

OMNR. 1997b. Silviculture guide for the toler-ant hardwood forests in Ontario. Ont. Min.Natur. Resour. (In Press).

Plamondon, A.P. 1993. Influence of forestcutting on water runoff and water quality.–Review of the literature. Quebec Ministryof Forests. Environment Branch. Unpub.Rep. (original French). 178 pp.

Racey, G.D., Harris, A.G., Jeglum, J.K., FosterR.F. and Wickware, G.M. 1996. Terrestrialand wetland ecosites of northwestern On-tario. Ont. Min. Natur. Resour., NorthwestSci. & Technol. 86 pp.

Timmer, V.R., Savinsky, H.M. and Marek, G.T.1983. Impact of intensive harvesting onnutrient budgets of boreal forest stands.Pp. 131–147 In Wein, R., Riewe, R.R. andMethven, I.R. (eds.). Conf. Proc. Resourcesand dynamics of the boreal zone, ThunderBay, Ontario, August, 1982. Association ofCanadian Universities of Northern Studies,Ottawa.

Wells, C.G. and Jorgensen, J.R. 1979. Effect ofintensive harvesting on nutrient supply andsustained productivity. Pp. 212–230 InLeaf, A.L. (chairman). Impact of intensiveharvesting on forest nutrient cycling. August13–16 1979, State University of New York,Syracuse, N.Y.

White, E.H. and Harvey, A.E. 1979. Modifica-tion of intensive management practices toprotect forest nutrient cycles. Pp. 264–278In Leaf A.L. (ed.). Impact of IntensiveHarvesting on Forest Nutrient Cycling:Symposium Proceedings. Syracuse, N.Y.August 13–16, 1979. State University ofNew York, College of Environmental Sci-ence and Forestry.

40 Technical Series

Appendix 1 Characteristic Soil Types forForested Ecosites in Northwestern Ontario*

* adapted from Racey et al. (1996)

Ecosite Characteristic Soil Types

ES11, ES12 SS1–SS4, SS5, SS9

ES13, ES14, ES15, ES16 S1, S2, SS5

ES17 S3, S4, S6, S9, S10, SS7

ES18, ES21 S3, SS6

ES19, ES20 S1–S3, SS5, SS6

ES22, ES23 S7, S8, SS8

ES24, ES25, ES27, ES28, ES30 S4, S5, SS7

ES26, ES29 S5, S6, SS7

ES31, ES32, ES33 S9, S10, S11

ES34, ES35 S12S, S12F

ES36 S12S, S12F, S11

ES37 S12S, S12F, S11

ES38 S9, S10, S11


Appendix 2 Percentage of Soil Type bySite Type in Northeastern Ontario*

Soil Type

Site

Typ

e

SS1–4 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19

1 89

2a 15 11 3 10 33 5

2b 24 11 10 3 8

3a 12 7 17 11 3

3b 34 39 20 11 43 25 35

4 13 37 44 7 8 12 20

5a 17 14

5b 4 20 7 15

6a 30 31 3

6b 19 20 7 33

6c 15 36 13 33 20 25 23 20 3

7a 49 31

7b 35 47 31 15 16

8 3 11 9 20 6 3 44

9 4 7 40 10 22 9 20 44

10 10 5 4 7 7 4 4 9 57 13

11 38 9 27

12 33 27 17

13 16 50 57

14 14 14

15 11 10 2 12 10 3

16 3 7 2 15 10 3

* adapted from McCarthy et al. (1994)

42 Technical Series

Appendix 3: Percentage of Soil Type byEcosite in Central Ontario*

Soil Type

Site

Typ

e

SS1–SS4 SS5, SS6 S1–S4 S5, S9 S6, S10 S7, S11 S8, S12 S13, S14 S15 S16 S17, S18 S19–S21

26.1 14 86

26.2 10 70 20

25.1 32 68

25.2 3 11 82 5

24.1 27 73

24.2 3 9 77 9 3

23.1 33 67

23.2 6 77 18

35 11 11 41 5 3 5 22 3

34 2 5 3 16 2 8 26 10 3 25

29.1 100

29.2 5 8 73 5 3 8

27.1 13 87

27.2 1 10 9 54 6 8 5 5

28.1 11 89

28.2 2 9 81 1 1 3 2

30.1 28 72

30.2 5 13 64 5 4 5 2 2

17.1 9 91

17.2 3 3 10 62 7 10 3

18.1 16 84

18.2 2 5 11 58 7 4 5 9

19.1 9 91

19.2 22 72 6

20.1 18 82

20.2 27 47 13 7 7

21.1 41 59

21.2 25 38 6 6 6 19

14.1 27 74

14.2 2 9 80 7 2

11.1 28 73

11.2 4 31 24 35 3 1 1

12.1 12 88

12.2 19 15 63 4

13.1 55 45

13.2 14 29 50 7

32 2 4 7 2 2 2 6 76

22 24 17 7 7 45

33 3 11 24 8 5 49

16.1 59 41

16.2 8 4 12 42 12 15 8

15.1 42 58

15.2 7 7 36 21 21 7

31 4 4 11 7 14 61

* adapted from Chambers et al. (1997)

Forest Management Guidelinesfor the Protection of thePhysical Environment

VERSION 1.0

December 1997

D.J. Archibald, R.P.F.W.B. Wiltshire, R.P.F.D.M. MorrisB.D. Batchelor

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