CHARACTERISTICS OF REPRODUCTION METHODS - ESF 14...2 Remember this … Now note the reproduction methods After Nyland et al. 1983 Some silviculturists argue that successful regeneration

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CHARACTERISTICS OF REPRODUCTION METHODSCHARACTERISTICS OF REPRODUCTION METHODS

Ralph D. NylandDepartment of Forest and Natural Resources Management

SUNY College of Environmental Scienceand Forestry

Syracuse, NY 13210

Nyland - 2010All rights reserved

Use of all or parts of this permission prohibitedwithout express consent of Ralph D. Nyland

Background reading:

Chapter 9, in Nyland, R.D. 2002. Silviculture: Concepts and Applications.Waveland Press. Long Grove, Il. 2ed.

Sources cited:

Bormann, D.B., and G.E. Lineks. 1979. Pattern and Process in a Forested Ecosystem. Springer-Verlag. NY.

Barlowe, R. 1958. Land Resource Economics. The Political Economy of Rural and Urban Land Resource Use. Prentice-Hall. Englewood Cliffs, NJ.

Kimmins, J.P. 1987. Forest Ecology. MacMillan Publ. NY.

Nyland, R.D., C.C. Larson, and H.L. Shirley. 1983. Forestry and Its Career Opportunities. McGraw-Hill Book Co., NY. 4ed.

Oliver, C.D. 1981. Forest development in North America following disturbances. For. Ecol. & Manage. 3:153-168.

Runkle, J.R. 1982. Patterns of disturbance in some old-grow5th mesic forests of eastern North America. Ecol.63(5):1522-1546.

Ryle, R.J., and W. Beyschlag. 2000. Gap dynamics. Pp. 251-279, in Leaf Development and Canopy Growth. B. Marshall and A.J. Roberts (eds.). Sheffield Acedem. Press. Sheffield, England

Smith, D.M. 1986. The Practice of Silviculture. John Wiley & Sons, Inc. NY. 8ed.

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Remember this …

Now notethe reproduction methods

After Nyland et al. 1983

Some silviculturists argue that successful regeneration is the most important factor leading to sustainable forestry ...

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But always through

a PROCESSPROCESS

Some silviculturists argue that successful regeneration is the most important factor in sustainable forestry ...

... certainly, if you do not regenerate cohorts of an appropriate density and composition

... you will have nothing to tend and eventuallyharvest

So we insure timely regeneration by a group of techniques

that we call the reproduction methodsthe reproduction methods

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… used to sustain the forest and its benefits

… of every kind

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REPRODUCTION METHOD:

- A processprocess for establishing and renewing a forestcommunity or age class

- Includes removing the old trees and establishing a newcohort to replace them

- Also includes any supplemental site preparation andimmediate post-seeding care necessary for success

Like clearcutting (even-aged ) …

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… or with selection system (uneven-aged)

… or two-aged silvicultureD.W. Smith

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It involves ...

- removing the mature trees and establishing anew cohort to replace them

- doing supplemental site preparation and post-establishment care

A PROCESS ... not an event

… using timber harvestingas a means to that end

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By manipulating the overstory (the reproduction method) we …

INCREASE ground surface temperature

CHANGE light quality and intensity at ground level

REDUCE withdrawals of soil moisture

STIMULATE decomposition of surface liter, releasing nutrients

… and the amount or degree depends uponthe type and intensity of cutting used

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After Smith 1986

Increasing degree of overstory removal

Full shade Full sunlight

Som

e en

viro

nmen

tal f

acto

rs

Consider this model Consider this model ……

So always ask ....

What conditions will best serve the purpose?

How to create those effects?

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Make the reproduction method into

A PROCESSPROCESS

… that may pass quickly in some cases

... like an event

... or it may take years or decades to complete

… done deliberately

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Some essential questions to consider in selecting an appropriate reproduction method:

What does the owner seek?What species will satisfy those goals?What species characteristics make one or more techniques

more useful than others ?What kind of stand does the owner want or need, given the

species sought or the uses intended?What biologic or economic limitations do I face in

producing these results?What constraints does the physical environment impose?What will it cost, and will the owner willingly pay to get it?

And timber sales give us a way to

implement the treatment

while also generating revenues …

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Ecologically appropriate …… economically advantageous

… and financially attractive

… and linked to a regulation scheme as well

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So how do we control / regulate these reproduction methods?

... in stands AND across a forest

THE REPRODUCTION METHODSAfter Nyland et al. 1983

We have four methods of control …

Treat equal areaeach time

Yields depend upon what standscut each time

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Like using an even-aged reproduction method …… to regenerate a fixed area of forest each year

May cut different number of acreseach time

Consistent yields determine theamount of area cut each time

Not all standshave the samevolume to remove ...

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Like regenerating as much area as needed …… recover the requisite volume from a forest annually

Not all standshave the samevolume to remove ...

May cut different number of acreseach time

ALSO, regulate intensityof cutting by a a basalarea or volume controlin the stand

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Like using a basal area control to regulate the intensity of a thinning …… and thinning sufficient stands to produce the required volume from a forest

Treat equal areaeach time

ALSO, regulate intensityof cutting by a a basalarea or volume controlin the stand

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Like using a basal area and structural control to regulate stand density and the diameter distribution with selection system …

… across a fixed area of forest

XXXXXX

The components of growth in a stand:

G = A + I – M

G = Net growthA = AccretionI = Ingrowth

M = Mortality

Also think about growth ...

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We want to optimize (A + I)

Accretion

-- by maintaining appropriate

stocking for full site utilization

-- by promoting rapid diameter

growth of residual trees

Ingrowth

-- by insuring good results from a

reproduction method

-- by taking measures to insure both

survival and development of each cohort

-- by controlling stand density to keep trees in

a vigorous condition

-- by timely regeneration of an age class to

minimize losses

We devote much thought to controlling

MORTALITY

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Consider how these affectstand growth and development ...

... starting with even-aged

Look at the

production function

After Barlowe 1958

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… with a clear pattern of development through time… within a single stand

Aging

Recall how even-aged stands develop through time …

… and in each stand across a forest

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All trees in a stand regenerated at the same time …… all developing to maturity together

… all coming of age at the same time

So …

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Var

iabl

e ou

tput

uni

ts

Variable input units

Marginal difference due toeach successive additional input

Average up to somespecific level of inputs

“Marginal” means added

And we can convert the total physical productcurve to measures of marginal and average outputs …

Peak levelof outputs

Put all together like this …

After Barlowe 1958

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Applied to even-aged stands ...

... substituting volume and age

Physiologicalmaturity

After Barlowe 1958

Vol

ume

Stand age

Mean annual increment-- m.a.i.

Periodic annual increment-- p.a.i.

Physiological maturity

… when p.a.I. = 0

And this biologic event …

Look at the average and marginal physical product curves ...

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After physiological maturity the mortality exceeds (Accretion + Ingrowth) …

... delineating the maximum logical rotation for commodity productionobjectives

Vol

ume

Stand age

Mean annual increment-- m.a.i.

Periodic annual increment-- p.a.i.

The peak ofm.a.i.

So what associated with the peak of m.a.i. …

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Vol

ume

Stand age

Mean annual increment-- m.a.i.

Periodic annual increment-- p.a.i.

Optimum rotationOptimum rotationfor fiber cropsfor fiber crops

… the culmination of m.a.i. delineates the optimal rotation

for FIBER PRODUCTIONFIBER PRODUCTION

Stand age

Vol

ume

Physiological maturity

Optimum rotationfor fiber crops

The zone of rational actionfor sawtimber production

The range of rotation lengths for commodity production …

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And how long we grow a stand betweenculmination of m.a.i. and physiologicalmaturity …

… depends on the financial objectives

… grown to financial maturityfinancial maturity

Giving us this model ...

… portraying even-aged stand development

After Barlowe 1958

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Depicted in ecologic terms ...

After Bormann and Likens 1979Physiological

maturity

Ecologic stages of even-aged stand development:

1. REORGANIZATION or stand initiation phase

2. AGGRADATION or stem exclusion phase

3. TRANSITION or understory re-initiation phase

4. STEADY-STATE or old-growth phase

Borman and Likens 1979; Oliver 1981

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After Kimmins 1987

Visualized like this …

(Uneven-aged)

Past

A transition from even- to uneven-aged occursdue to gap-phase replacement …

After Runkle 1982, Ryel and Beyschlag 2000

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Like this …

Old-growth orsteady state

Transition stage

Physiologicalmaturity

Changing the production function like this …

(Uneven-aged)

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But with commodity objectives we “NEVERNEVER”

let stands pass beyond the AGGRADATION PHASEAGGRADATION PHASE

SO ...

… how much of this applies touneven-aged communities

... if at all

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Uneven-aged stands have several age classes ...... each developing “of itself”

… but only one reaching maturity at a time

… multiple age classes… all growing together in the same stand

Recall the nature of uneven-aged stands …

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… with ages and sizes interspersed across a stand

… and in stands across a forest

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Parts regenerated at different times …… young, middle-aged, and old all present

… each comes of age at a different time

So …

… a separate production function for each cohort

Suggesting …

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... multiple age classes ...

... each at a differentstage of development

At any point in time ...

With uneven-aged silvicultural system we:

1. Remove the mature age class to regenerate a replacement cohort

2. Simultaneously tend the immature age classes to enhance their development

... dual functions using harvesting as a TOOL

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… periodic regeneration and tending to maintainmultiple age classes

Regulating stocking so it fluctuates between predetermined levels ...

... increasing with growth

... drawn down by harvesting

... within pre-set levels

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The production function for uneven-agedcommunities under selection system

To look like this through time ...

Always searching for answers …

After Nissen 2010