Wetlands - Minnesota Department of Natural Resourcesfiles.dnr.state.mn.us/eii/profiles/wetlands.pdf · healthy wetlands include land use planning, wetland restoration, and implementation

DEVELOPING ENVIRONMENTAL INDICATORS FOR MINNESOTA

Wetlands

The Environmental Indicators Initiative

State of MinnesotaFunded by the Minnesota Legislature

on recommendation of theLegislative Commission on Minnesota Resources

Sponsored byThe Environmental Quality Board

1998

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Citizens and decision makers useenvironmental indicators to helpeffectively manage and protectMinnesota�s wetlands. Environmentalindicators answer four questions.

What is happening to ourwetlands?Environmental condition can be assessedusing indicators based on ecologicalcharacteristics of wetlands, includingvariety of wetland birds, nutrientsin water and sediment (change inpH, nitrogen, phosphorus) andwater level fluctuations in wet-lands.

Why is it happening?Indicators of human activities thataffect wetlands include conversionof natural habitat, altered watermovement, and fertilizer andpesticide runoff.

How does it affect us?Changes in wetland health maydiminish the flow of benefits. Indica-tors of how we are affected includewater quality, flood frequency,and opportunities for hunting andrecreation.

What are we doing aboutit?Societal strategies to maintain or restorehealthy wetlands include land use

planning, wetland restoration, andimplementation of urban andrural best management plans.

In this chapter we outline importantbenefits from wetland ecosystems,the key ecological characteristics thatdetermine the health of wetlands, thepressures affecting wetlands today,the current status and trends relatingto wetlands, and the most significantpolicies and programs that affectMinnesota wetlands. Throughout thischapter we give examples of indica-tors that provide important informa-tion about Minnesota wetlands.

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HIGHLIGHTSBenefits of HealthyWetlands� Flood attenuation� Removal of sediments and

nutrients from runoff� Transformation of toxic

chemicals� Shoreline stabilization� Fish and wildlife habitat� Commercial uses (e.g., wild rice,

paddy rice, bait industry)� Recreation� Education, science

Important EcologicalCharacteristics� Hydrological regime is the single

most important factordetermining wetland structureand function.

� Differences in water levels,oxygen levels, productivity, soilorganic matter, and plant andanimal species result in differentwetland types with varyingbenefits.

� Increases in nutrients andsediments entering wetlandsstimulate productivity and causeshifts in plant communities,ultimately causing reduceddiversity of types of wetlandsand of wetland species.

Pressures� Altered hydrology� Wetland conversions (urban,

roads, farms)� Increased sediments� Chemical inputs (roadways,

lawns, golf courses, farms, etc.)� Invasive species (purple

loosestrife)

Status & Trends� Nationally, wetlands cover 5%

of land area but support 1/3 ofrare, endangered species.

� Approximately 54% ofpresettlement wetlands remain;greatest losses are in prairiepothole region.

� Rates of loss are below thenational average, but 26,500acres were lost from 1982-92.

� From 1982-92, 38% of losseswere due to agriculture, and38% were due to urbandevelopment.

� Purple loosestrife infests 560sites, but only 9 new sites werefound from 1995-96.

Existing Policies &Programs� Clean Water Act regulates

dredge and fill activities inwetlands.

� Permit required for activities thatalter water basins (MinnesotaWaters Permit Program)

� Minnesota WetlandConservation Act (1991)mandated �no net loss.�

� Permanent Wetland PreservesProgram encourages permanentconservation of existingwetlands.

� Comprehensive wetlandconservation plan for the state

� Restoration of wetlands onfarmlands promoted throughseveral government programs(e.g., Swampbuster, Reinvest InMinnesota (RIM), Flood RiskReduction Program, WetlandReserve Program)

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HOW WE BENEFITFROM HEALTHYWETLANDSWetlands, an important part ofMinnesota�s natural heritage, providevaluable ecological services as well asdirect social and economic benefitsto Minnesotans. Wetlands are anintegral part of the hydrologic cycleand play a very important role in thestorage of floodwater. A measure ofthe benefits derived from wetlands isthe cost of replacing functions onceperformed by wetlands now lost todevelopment. A conservativeestimate of costs to the state forreplacing floodwater storage basinsis $1.5 million a year, and about $125million is spent each year for flooddamage in rural and urban areas(Minnesota Wetlands ConservationPlan 1996). Flood impacts and thecosts associated with them aregenerally lower in watersheds inwhich wetlands have been retained.

Wetland systems are also importantfilters of sediment, nutrients, andchemicals. The dense vegetation andorganic soils of wetlands interceptmaterials that would otherwise enterrivers, streams, lakes, orgroundwater, thus decreasingpollution in those systems andproviding economic benefits that areoften overlooked. Nearly $20 millionhas been spent in the past 10 years bystate and federal agencies to removesediment and nutrients from waterthat would normally have beenfiltered by Minnesota wetlands.Millions of dollars are spent annuallyby the U.S. Army Corps ofEngineers for dredging MississippiRiver sediment that was once

intercepted by riverine wetlands(Minnesota Wetlands ConservationPlan 1996).

Wetlands add greatly to the state�sbiodiversity. Many terrestrial andaquatic animals depend on wetlandsfor habitat and feeding areas duringsome part of their life. Numerousunique plants occur in wetlands. Infact, wetlands support 31 percent ofthe plant species in the continentalUnited States (Wilen and Tiner 1993).Wetlands sustain fish and waterfowlpopulations by providing protected,well-vegetated, nutrient-rich areasthat are wet much of the time.Spawning and nursery grounds forfish and leeches contribute $50million to Minnesota�s economy eachyear (Minnesota WetlandsConservation Plan 1996).

Each year more people enjoywetlands and the plants and animalsthey support through hunting,fishing, hiking and natureobservation. Over 1 millionMinnesotans participate in wildlifeobservation, and over 2 millionparticipate in fishing and hunting.These wildlife-related activities arevalued at $40 million each year(Minnesota Wetlands ConservationPlan 1996). The natural areas andwildlife that are the focus of theseactivities are part of an integratedlandscape in which wetlands areoften a primary component.

Wetlands also provide directeconomic benefits as sites for wildrice and paddy rice industries. Theseindustries contribute $27 millionannually to the state�s economy.

ENVIRONMENTALINDICATORSWhat are environmental indicators,and how can they help us maintainhealthy wetland ecosystems?Indicators are selected measures ofthe environment or of humanactivities that affect the environment.They help us understand thecondition of our wetlands, alert us topotential problems, and point toways to prevent or fix problemsbefore they become crises. Thefollowing scenario demonstrates thevalue of environmental indicators.

Urban development expands into arural landscape that includes a mix ofagricultural lands and natural habitatswith woodland corridors, wetlands,and clean lakes and streams. Ducksand herons are abundant in thewetlands scattered throughout thelandscape, and the sounds of frogsand toads calling in the evening arefamiliar. As housing developmentexpand into the area, woodlands andnative vegetation around wetlandsand streams are replaced with housesand manicured lawns. Improvedroads, storm drainage systems, andservice facilities alter the natural waterlevels and flows across the landscape.As natural habitats are converted andwater flows are altered, changesoccur in the wetlands. Large patchesof exotic species, such as purpleloosestrife, and invasive nativespecies, such as cattails, replace theoriginal diverse assemblage ofwetland rushes, sedges, and herbs.These changes reduce the quality ofthe habitat for wildlife; animalpopulations, from ducks and heronsto crayfish and frogs, begin todecline. The altered wetlands lose

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their capacity to filter nutrients fromrunoff and to moderate floods,essential services that protect waterquality in adjacent lakes and streams.As the landscape�s wetlands aregradually degraded, polluted lakesand streams with excessive algalblooms and declining fisheriesbecome more common.

The wetland development scenario isrepresentative of the complex issuesaffecting our wetlands. TheEnvironmental Indicators Initiativeframework provides insights into therelationships between humanactivities and environmental changeand helps select indicators thatmeasure progress toward solvingcomplex problems. Some humanactivities adversely affect ecosystemhealth and diminish the flow ofbenefits. In the wetland scenario(Table 1), human activities that changethe density and pattern of housingdevelopment impose severalpressures on the environment.Indicators that measure thesepressures include conversion of

natural habitat, the percentage ofland in impervious surface,altered water movement,diversion of storm water tosewers, and levels of fertilizers,pesticides, and road salts enteringarea lakes and wetlands. Thesepressures alter environmental conditions,which can be charted with indicatorssuch as abundance of nativevegetation and invasive species,bird diversity, water quality inwetland and adjacent lakes andstreams, and water-levelfluctuations in wetlands. Theseindicators of human activities andenvironmental condition help assessenvironmental trends and provideinsights into complex cause-and-effect relationships.

This information may suggest theneed for citizens to implementappropriate programs andmanagement strategies, such aspromoting environmentallysensitive development (i.e.,guiding development to thoseareas most able to handle growth

and away from sensitive areaslike prime agricultural land andnatural areas), constructinginfiltration ponds, applying lawnchemicals in an environmentallysensitive way, restoring backyardhabitat, and reestablishingvegetated strips along waterways.These management activities can helpmaintain or restore healthy wetlandsand natural habitats by takingproactive measures to modify thepressures that cause environmentaldegradation.

Healthy wetlands provide residentswith a number of important benefits,such as flood control, clean water,fish and wildlife, hunting, andoutdoor recreation. These strategiesare effective in large part becausethey address the human activities thatcause declines in the health of thewetland. An integrated set ofindicators helps us understand howour actions alter ecosystems and theirability to provide the benefits onwhich we depend.

WETLAND

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ECOLOGYWetland ecosystems are areas whereaquatic and terrestrial systemsintergrade. Because of this, theyexhibit some of the characteristics ofeach. Wetlands frequently are foundaround lakes and rivers but canoccur anywhere in which watersaturates soils and creates conditionsthat support characteristic wetlandplants and inhibits others. The plantsgrowing on these sites are adapted tothe saturated (hydric) soilscharacteristic of wetlands. In general,low oxygen levels also limit the kindsand number of plants and animalsthat can inhabit many wetlands.

HydrologyWetland ecosystems are an integralcomponent of the hydrologic cycle,serving as reservoirs that store waterand facilitate its movement to otherreservoirs. Water may remain insurface or groundwater bodies forlong periods of time beforereturning to the atmosphere viaevaporation and transpiration. Aswater moves between air and land, itaccumulates minerals, nutrients, andother compounds that change itschemistry. Climate, geology,topography, and human activities allaffect water movement andchemistry.

The hydrologic regime is the singlemost important factor determiningthe structure and function ofwetlands (Mitsch and Gosselink1993) and is a prime example of theimportance of natural disturbance inecosystems. The source and qualityof water and the frequency, duration,and intensity of flooding stronglyinfluence wetland plant and animal

communities, levels of productivity,rates of material cycling, and soilconditions. Many wetlands occurwhere groundwater discharges at thesurface as springs or seeps or wherethe water table is close to the surface.In some wetlands, however, waterpercolates down through soils androcks and replenishes groundwaterreserves. The source of water inmost wetlands is a combination ofprecipitation, groundwater, andsurface water. The dominant sourceof water helps determine wetlandtype. The distribution and diversityof wetlands in Minnesota are theresults of differences in wateravailability, flooding regimes, andwater chemistry. Wetlands lose wateras it flows to lakes or rivers,percolates to groundwater reservoirs,is taken up by plants, or evaporates.

In most wetlands, water levelsfluctuate seasonally in response tochanges in water table levels that aredriven by precipitation andevapotranspiration. Often, periodsof low water or complete dryingalternate with periods of saturated orflooded soils. Such fluctuations aremost dramatic in wetlandsdominated by precipitation andsurface flow and are lesspronounced in wetlands fed bygroundwater. Periods of high waterhelp support aquatic plant andanimal communities and serve toreplenish soil nutrients in riverinesystems, and periods of dryingstimulate nutrient cycling anddecomposition.

One of the greatest challenges in theconservation of wetland ecosystemsis maintaining the groundwater andsurface-water sources that sustain

them. Alterations in local andregional flow of water result from avariety of causes, including beaverdams, drought, floods, and humanactivity. Humans strongly influencesurface water and groundwatercomponents of the hydrologic cycle.For example, levees around riversand streams, and drainage systems(ditches, channels, drainpipes, stormsewer systems) concentrate flowfrom the surface and hasten itsmovement into lakes and rivers.Dams on rivers and streams maycause flooding of upstreamlandscapes but withhold water fromformerly flooded areas.Impermeable surfaces concentrateflow into localized areas.Groundwater wells for personal andindustrial uses may lowergroundwater levels by extractingwater faster than it is replenished.Large-scale construction projects thatdivert water flow, changes to surfacewater bodies that feed groundwaterreservoirs, and increases inimpermeable cover that preventsdownward percolation also affectgroundwater.

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Change in the hydrologic regime,compared to that which existedhistorically, is an important indicatorof wetland ecosystem health. Forexample, reduced inputs of calcium-rich waters into a calcareous fen mayresult from natural variability inupwelling with no long-term effects.On the other hand, extreme or long-lasting changes may indicate that

wetland health is threatened. Asdrying of the soils persists, thewetland plants adapted to calcium-enriched waters may not haveadequate resources and may bereplaced by a different plantcommunity. Similarly, dramaticchanges in frequency or durationof water level fluctuations in otherwetlands also may be an indication

of reduced wetland health. Waterlevel changes may result from naturalvariability in climate, but they mayalso result from increases inimpermeable cover that preventpercolation of storm water into soilsand divert more water to thewetlands. Fluctuations that are morefrequent and more extreme maycreate conditions that harm many

small stream riparian wetlands and inclosed basins with very shallowwater or saturated soil. They arecovered with herbs, grasses, andsedges. Persistent wetnesscontributes to a spongy accumulationof peat.

Calcareous fens are the rarestwetlands in the state. They occurwhere calcium- and magnesium-richgroundwater reaches the surface.Except under drought conditions orafter alterations to groundwaterhydrology, these sites remainsaturated but lack deep standingwater. Calcareous fens support acommunity of herbaceous vegetationthat is not found in any otherwetland type.

Bogs are a type of wetlandcharacterized by a mat of Sphagnummoss, unique herbs, and sedges. Inthe older, more developed bogs,evergreen shrubs and trees arecommon. The saturated, acidic soilsfound in bogs inhibit breakdown ofplant material and allow deepaccumulations of peat. Bogs oftenreceive a combination ofgroundwater, surface water, andprecipitation inputs.

WETLAND TYPES

Many types of wetlands occur inMinnesota (Edgers and Reed 1987,Narrowing 1989).

Littoral wetlands occur as a fringeor emergent vegetation, includingbulrushes, cattails, wild rice, andother grasses, surrounding lakes andponds. Wave activity and water-levelfluctuations are strong influences.Soils range from poor to fairly richin organic material, depending onanimal activity and on the availabilityof oxygen for microbes andinvertebrates.

In marshes (including prairiepotholes) standing water is presentfor much of the year. Water depthmay range from a few inches toseveral feet, with fluctuationsdependent on seasonal weatherpatterns. In very dry years marshesmay dry completely. Emergentvegetation, such as cattails, sedges,and bulrushes, typically grows inmucky soils and may grow in solidstands or in a ring around the basinedge, with open water in the center.

Wet meadows and sedgemeadows occur in association with

Shrub swamps and woodedswamps are saturated or seasonallyflooded wetlands. Shrub swampsare dominated by tall shrubs, such aswillow and dogwood or alder, alongwith grasses, sedges, and herbs.Organic-rich mucky to peaty soils arecommon. Shrub swamps mayreplace wet meadows and oftenoccur in river and streamfloodplains. Wooded swamps areassociated with ancient lake basins(now filled in) or with old meandersof a river. They are dominated byconifers, such as tamarack andnorthern white cedar, or byhardwoods, such as elm, ash, andmaple.

Floodplain forests are tightly linkedto river systems. They are seasonallyinundated during periods of highflow, such as spring runoff andflooding, but during much of theyear they are well drained. Thealluvial soils are reworked frequently,eroded and redeposited withchanges in flow regimes. Floodplainforest are dominated by deciduous,hardwood trees such as Americanelm, eastern cottonwood, green ash,and silver maple, with an understoryof tall herbaceous plants.

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plants and may alter the character ofa wetland dramatically.

Nutrient cyclingBreakdown and transformation ofplant and animal material in wetlandsprovide nutrients for the plantsgrowing there. These plants are, inturn, an important source of foodfor the many animals that usewetlands. Microorganisms andinvertebrates are responsible formost of the initial conversions fromplant and animal biomass to mineralsand nutrients, and they also areimportant for transformation ofother compounds entering thewetland.

Water flowing into a wetland fromsubsurface flows or from thesurrounding landscape carriessediment, nutrients, pesticides,fertilizers, and other chemicals. Soilorganisms absorb and metabolizemany nutrients and minerals fromthe water. Over the long term,materials accumulate in the wetlandsoils and may remain there until thesystem is disturbed. The removal ofchemical compounds improves thequality of the water that leaves thesite but may degrade the wetlanditself. To maintain the long-termhealth of wetlands, it is important toprevent excessive inputs of sedimentsand associated nutrients andpesticides into the wetland basin.

Monitoring levels of nutrients andcontaminants in wetland soils andwaters provides useful informationabout the health of the wetland andthe animals that use it. Indicatorssuch as water pH or concentrationof nitrogen and phosphorus help

us assess wetland nutrient status. Anincrease in the level of nutrients isoften accompanied by a change inthe pH and a change in the plantcommunities at a site and may resultfrom inputs of nutrient-enrichedgroundwater or surface water fromadjacent landscapes. Whatever thecause, changes in the plantcommunity likely result in shifts inthe community of animals (insects,mammals, amphibians, and birds)using the site. Because of thesensitivity of plants to nutrientavailability, changes in the plantcommunity can be an indication ofaltered wetland health.

Biological productivityThe regular availability of water andnutrients makes wetlands, particularlymarshes, some of the mostproductive systems in the world.Each year, large quantities of newleaves, roots, stems, and seeds areproduced in wetlands. Plantproductivity and the metabolism andreproduction of soil organisms areinfluenced by oxygen availability andtemperature. High water levels maylimit oxygen availability but a varietyof adaptations allow many plants tosurvive in low oxygen conditions.Some plants grow on tufts of otherplants to remain above the waterlevel, while others transfer oxygendown to roots from the surface,improving conditions not only forthe plant but also for themicroorganisms nearby.

Wetlands support a large number ofanimal species. Nationwide, about150 bird species and 200 fish speciesdepend on wetlands during somepart of their life cycle (Niering 1987).

The prairie pothole region, whichincludes parts of western Minnesota,accounts for only 10 percent of thenation�s wetlands but produces 50percent of the mallards, pintails, andgreen-wing teals. Grebes, pelicans,herons, egrets and many other non-game birds also use prairie wetlands(Tester 1995). The combination ofemergent vegetation with open waterprovides diverse habitat and foodresources, resulting in conditionsconducive to many birds (Weller1987). Frogs and toads depend onwetlands for breeding habitat. Infact, some northern Minnesotaprairies and prairie wetlands areestimated to support tens ofthousands of toads per square mile(Tester 1995). Littoral wetlands arehighly productive systems as well,providing important nesting habitatfor loons and other waterfowl andprotected breeding grounds formany fish.

Environmental indicators that focuson trends in biologicalproductivity help measure wetlandhealth. Monitoring changes in thesize of populations of waterfowland amphibians, changes insongbird bird diversity, andchanges in the abundance ofmacroinvertebrates (e.g., crayfish,aquatic insects) helps track wetlandhealth.

Biological diversityAlthough wetlands occupy only 5percent of the national land base,they help sustain about one-third ofall threatened and endangered plantand animal species. Species such asthe northern bog lemming, thesandhill crane, and the gray wolf use

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bogs and fens for cover and forforaging. The northern cricket frog,Blanding�s turtle, and numerousother threatened and endangeredspecies depend on floodplain forests.Prairie marshes and littoral wetlandsare important habitat for the dakotaskipper and Karner blue butterflies,the horned grebe, Forster�s tern,several rushes, and many other rareplants and animals.

In addition to supporting species atrisk, wetlands support healthypopulations of many unique andinteresting plant and animal species,many of them restricted to wetlands.The star-nosed mole, the arcticshrew, pitcher plants, and numeroussedges, for example, depend on fensand bogs for survival. A host ofbirds, including grebes, pelicans,sandpipers, owls, and warblers, nestand feed in marshes and prairiepotholes. Marshes and littoralwetlands are important fishspawning and nursery grounds.Voles, lemmings, and shrews buildnests in the moss of bogs or the leafyand woody debris of swamps. Deer,moose, and other large animalsbrowse in swamps and bogs.Floodplain forests and backwaterareas are essential for reproduction,feeding, and protective cover fornumerous mammals, fish, and birds,including those that use rivers asmigratory flyways.

The diversity of organisms inMinnesota is in large part a functionof the number and variety ofwetlands occurring in the state.Maintaining the conditions thatsupport Minnesota�s wetland-dependent species requires that manytypes of wetlands in many locations

be preserved. This is particularlyevident in the prairie pothole region.Here, natural variability in regionaland local hydrology results inirregular wet and dry cycles andunpredictable habitat availability. Atany point in time, some wetlandssupport animal populations, whileothers do not because they arepoorly vegetated or dry. Aninterconnected network of wetlands,including wetlands with a range ofhydrologic characteristics, may bestmaintain waterfowl, amphibians,insects, fish, and mammals over thelong term (Galatowitsch and van derValk 1994). Such a network alsohelps to maintain diverse plantcommunities by promoting thedispersal of plants from one wetlandto another and allowing revegetationafter extreme drought, high levels ofanimal activity, or humandisturbance.

Humans have converted manymeadow and marsh wetlands withdiverse plant communities to cattailor reed-canary grass wetlands.Although these wetlands supportmany species, the increase of moreaggressive plant species occurs at theexpense of other plants and animals.The long-term impact is an overallreduction in the biological diversityassociated with wetlands of the state.Monitoring changes in theabundance and distribution ofkey plants and animals helps trackthe health of wetlands. In areas withincreasing diversity of native littoralcommunities, we would expect amore diverse animal community anda wetland ecosystem that is moreresilient after disturbances (Tilman etal. 1996). Reduced biologicaldiversity of native species may

signify declining conditions within thewetland or surrounding landscapethat limit the ability of plant andanimal species to thrive.

Linkages with othersystemsWetlands influence adjacent uplandsand aquatic ecosystems. Theyprovide feeding grounds and nestingmaterial for both terrestrial andaquatic animals. Sediment andnutrients carried by wind or surfacewater are often intercepted bywetland ecosystems before enteringadjacent water bodies. The rootedaquatic vegetation found along theedges of many lakes, rivers, andstreams reduces streambank erosionand slows undercutting by stabilizingsediments, slowing the currentvelocity, and dampening waveaction. Wetlands have the capacity toassimilate nutrients, sediments, andtoxins transported from upland areasthrough binding with soils, uptake byplants, and transformation bymicroorganisms. When this capacityis exceeded, however, a result is theexport of these materials togroundwater or to downslope waterbodies. Because of connections withother landscape elements, the healthof wetlands, and all aquatic systems,is a direct reflection of the health ofthe watershed. Environmentalindicators for wetlandstell us not only about the health ofwetlands but also about the health ofthe surrounding landscape.

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PRESSURES ONWETLANDSWetland conversionsWetland systems once covered morethan 392 million acres in the UnitedStates. From 1780 to 1980, 53percent of the wetlands within thelower 48 states were drained (Figure1), filled, channelized, or otherwiseconverted for human use (Dahl1990), the equivalent of 60 acres lostper hour for 200 years. Agriculturalpractices caused the majority of theselosses, and urban development androad construction led to additionallosses (Figure 2).

Historically, losses of wetlands inMinnesota followed the nationaltrend and were due primarily toconversion of land for agriculture(Figure 3). Conversion of wetlandsto urban development and roads,however, is increasing. Nationally, 20percent of the loss of wetlands from

1982 to 1992 was due to agriculturalactivity, and 57 percent wasattributed to urban development.During this same period, 38 percentof wetlands in Minnesota were lostto agriculture and about 38 percentto development (Figure 4; NationalResources Conservation Service1992). In recent years, increasednumbers of lakeshore homes andrecreational facilities on lakes havecontributed to loss of littoralwetlands. The cumulative effects ofremoving wetlands include reducedfish and wildlife habitat andincreased shoreline erosion, turbidity,and nutrient loading. In watershedswhere no wetlands remain, floodingand degraded water quality are morelikely.

Indicators can provide importantinformation about watershed andwetland ecosystem integrity.Changes in land use or plans fornew land uses can be an early

indicator of likely impacts to wetlandecosystems. Indicators of wetlandacreage should be accompanied byassessment of wetland functions (e.g.,changes in hydrologic regime,plant species diversity).

Sediment and chemicalcontaminantsDegradation of wetlands resultsfrom inputs of sediments, fertilizer,pesticides, fecal bacteria, oil, gasoline,salts, and other chemical substancescarried in surface water, stormwater,wastewater, and wind. In manycases, nutrient enrichment results inthe conversion of diverse wetlandcommunities to less valuable cattailor reed-canary grass stands. Many

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contaminants are transferred fromsediment or water into plants oranimals that are then consumed bylarger animals and humans.Bioaccumulated toxins interfere withreproduction and reduce the healthof aquatic and semi-aquatic animals.Tracking changes in soil and watercontaminant levels can help topinpoint the cause of wetlanddecline. Monitoring changes inamphibian and waterfowlpopulations also helps track theeffects of chemical contaminants inwetlands.

Biological pressuresInvasive species that outcompetenative species alter the naturalfunctioning of wetlands. In manywetlands, for example, cattails,sedges, and rushes are being replacedwith uniform, dense stands of purpleloosestrife. This attractive plant is

aggressive and may cover largewetlands quickly. It replaces plantsthat are important as food andnesting cover and provides pooranimal habitat (Skinner et al. 1994).Today, purple loosestrife occurs inwetlands across the state but isconcentrated in wetlands and lakes inthe Minneapolis-St. Paulmetropolitan area (Figure 5). As of1996, 560 wetlands were infestedwith purple loosestrife. The MDNRPurple Loosestrife Program attemptsto control the spread of this plantwith both chemical and biologicalmethods. Only nine new wetlandswere contaminated from 1995 to1996 (Exotic Species Program 1996).The occurrence and coverage of

invasive species that displace nativeplants and animals indicate potentialor imminent decline in wetlandhealth.

Climate changeGlobal warming is expected to causesignificant alterations in wetlandlocation and functioning byincreasing evaporation and alteringwater levels. Changes in the waterbalance and in nutrient cycling mayresult as temperatures increase, andthese changes are likely to result inaltered plant communities and theanimal populations they support.New wetlands are likely to developin northern climates, while southernwetlands are more likely toexperience significant drying. Aswetlands dry out, natural fires maythreaten areas having large quantitiesof plant litter, releasing previouslystored carbon and nitrogen to theatmosphere.

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WETLAND STATUSAND TRENDSNational trendsSevere flood damage, reducedwaterfowl populations, decreasedfish and shellfish harvests, increasederosion of soil, and reduced waterquality have stimulated a nationwideincrease in awareness of theimportance of wetland systems.Laws that protect wetland systems,and increased efforts at restoring andcreating wetlands, have greatlyreduced wetland losses in recentdecades. Nationwide, losses ofwetlands from 1982 to 1992amounted to 50,000 acres per year,far lower than the 157,000 acres peryear lost in the previous decade(Natural Resources ConservationService 1995).

Status of MinnesotawetlandsWetland Gains and LossesBased on the distribution of hydricsoils, it is estimated that 44 percentof Minnesota, nearly 22 million acres,was wetland before the arrival ofEuropean settlers (Figure 6a).Marshes and wet meadows occurredthroughout much of the state. Bogsand fens were more common in thenorthern half of the state, prairiewetlands were most common inwestern and southwesternMinnesota, and floodplain forestsand backwaters were most commonalong the Minnesota and MississippiRivers (Coffin 1988; MinnesotaWetlands Conservation Plan 1997).Only 10.6 million acres, or 54percent of these wetlands, remain

(Figure 6b, National ResourcesConservation Service 1992).

The proportion of original wetlandslost varies widely across the state. Innorthern Minnesota between 80 and100 percent of presettlementwetlands still remain. Here, bogs,sedge meadows, and shrub swampsare common. In contrast, severalcounties in western and southernMinnesota have lost 100 percent oftheir presettlement wetlands(Minnesota Wetlands ConservationPlan 1997). On average, however,less than 50 percent of presettlementwetlands remain in this area (Figure6b).

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The Minnesota Board of Water andSoil Resources annually reports to theMinnesota Legislature on the statusof implementation of state laws andprograms relating to wetlands. Datacollected from the second year offull Wetland Conservation Act(WCA) implementation (January1995-January 1996) found that of7,673 proposed wetland projects,71% (5,456) were resolved with nodisturbance to a wetland (anestimated protection of 3,493 acresof wetlands). In addition, 381wetland acres were replaced and 237acres were drained or filled underthe WCA (�unavoidable wetlandimpacts,� BWSR 1996) . However,significant wetland losses continue tooccur through activities that requireno approvals or permits, makingthem impossible to track (BWSR1996). While Minnesota�s regulatoryprograms are protecting wetlands, itis likely that losses still exceed gains inwetland acreage (Minnesota WetlandConservation Plan 1997).Furthermore, newly created wetlandsoften do not function as well asnatural wetlands�failing toachieve the goals for hydrology andfor plant and animal communities.

Ecological Functions andBenefitsQuantitative and qualitative data onwetland functions (natural processes)and benefits is currently not available(Minnesota Wetland ConservationPlan, 1997; BWSR 1996). TheMinnesota Routine AssessmentMethod For Evaluating WetlandValues (MNRAM), is a recentlydeveloped analytical method toevaluate wetland functions andvalues. MNRAM assigns a low,medium, high, exceptional, or not-

applicable rating to a consolidatedset of nine wetland functions andvalues (flood and storm water,shoreline protection, groundwaterinteraction, water quality protection,wildlife habitat, fishery habitat, floraldiversity and integrity, aesthetics,recreation and education, andcommercial uses). The methodologyis now available for use statewide,and may be improved in futureeditions (Minnesota WetlandsConservation Plan, 1997).

Wetland creation and restoration isintended to offset wetland losses andallow economic development. Fewof these projects have beenmonitored for long-term ecosystemhealth, however, making it difficultto determine whether these wetlandsperform the same ecologicalfunctions as do natural wetlands.Furthermore, long-term evaluationof wetland creation projects can bechallenging because wetlands arecreated for a variety of purposes.Because wetlands are complexsystems, comparisons across wetlandtypes or from location to locationare difficult (D�Alvanzo 1986).

Galatowitsch and van der Valk(1996) studied 62 wetlands in thesouthern area of the prairie potholeregion (which includes counties inMinnesota, Iowa and South Dakota).Wetlands were restored byinterrupting drainage tile lines, byplugging drainage ditches, or byblocking natural drainage ways.Restoration resulted in a pattern ofwetland distribution very differentfrom the predrainage pattern ofmany types of wetlands in a varietyof sizes Galatowitsch and van derValk, 1996). They concluded that

wildlife species (e.g., common yellowthroats, marsh wrens, swampsparrows (Delphey and Dinsmore1993 as sited in Galatowitsch andvan der Valk 1996)) that require well-developed sedge meadow andshallow emergent vegetation,extensive wetland complexes,ephemeral/temporary wetlands andlarge wetlands are poorly served bycurrent wetland restorations(Galatowitsch and van der Valk1996).

Significant gains in Minnesota�swetland resource base will not beachieved through the mitigationrequired by regulatory programs,because the goal of those programsis to offset wetland losses(Minnesota�s Wetland ConservationPlan, 1997) . Restoration, however,seeks a net gain of wetland functionsand values in targeted areas of thestate, and the maintenance orimprovement of the ecological andhydrological integrity of watersheds.A variety of non-regulatoryprograms are designed to restorewetlands; their effectiveness can beenhanced through targeting areas forrestoration programs and improvingcoordination among non-regulatoryprograms (Minnesota�s WetlandConservation Plan, 1997).

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EXISTING POLICIESAND PROGRAMSRecognition of the economic andecological costs of wetland losses hasstimulated a number of regulatoryand non-regulatory initiatives andprivate and public programs at thestate, national and international levelsto protect and restore wetlands.

State initiativesMinnesota has long been a leader inrecognizing the importance ofwetlands for long-term ecologicalhealth. Preservation of wetlandsbegan in the 1950s, under the DNR�sSave the Wetlands Program. Underthis and similar programs more than1,000 Wildlife Management Areashave been established, totaling nearly900,000 acres. About one half of thisland is wetland.

Public waters wetlands are protectedunder state laws governing all publicwaters. These include shallow marsh,deep marsh, and shallow open waterwetlands that are 10 or more acres insize in unincorporated areas or 2 1/2acres or larger in incorporated areas.Wetlands protected under theWetland Conservation Act (WCA)are delineated according to theUnited States Army Corps ofEngineers Wetland DelineationManual (January 1987).

The 1991 Wetland Conservation Actestablished in state law the policy of�no net loss� of existing wetlands.Under this law, those who proposeto fill or drain wetlands are requiredto demonstrate that no feasiblealternatives exist and to compensatefor unavoidable wetland loss byrestoring or creating other wetlands.

Changes in the act in 1996 clarify theroles of state and local governmentsin wetlands issues and allow moreflexibility in meeting the �no net loss�goal in parts of the state with anabundance of wetlands. Additionalchanges increased exemptions foragricultural wetlands and reducedfinancial burdens on farmers(Helland 1996). The WetlandConservation Act also established thePermanent Wetland PreservesProgram (PWP) that offerscompensation to landowners willingto place certain types of wetlands ina permanent conservation easement.These wetlands are then protectedfrom grazing and cropping. PWP isadministered by the Bureau of Waterand Soil Resources and implementedby soil and water conservationdistricts at the local level. As of 1995,276 easements have been acquired,perpetually protecting 11,225 acresof wetlands and surrounding uplands(BWSR 1996).

Not all wetlands are regulated underMinnesota or federal law.Exemptions exist for some kinds ofcurrent and historic land uses(Minnesota Wetlands ConservationPlan 1997).

Non-regulatory initiativesThe Minnesota WetlandsConservation Plan (1997) usedexisting wetlands policies as thestarting point to develop an umbrellawetlands policy framework. Theframework strives to help coordinatestate and federal agencyresponsibilities, create policyimprovements, enhance informationfor decision making, and addressconcerns of landowners and localgovernments. The Plan was created

through the combined efforts andcontributions of a diverse group ofcitizens and professionals fromthroughout the state ( MinnesotaWetlands Conservation Plan 1997 ).

The Reinvest in Minnesota (RIM)program attempts to protect andimprove water quality byencouraging landowners to retireenvironmentally sensitive land fromagricultural production. RIMreimburses farmers for placing theirland in a permanent conservationeasement, and provides assistance tothe landowner to reestablish grassand tree cover and wetlands. Nearly2,000 private landowners enrolled45,000 acres of land (including10,000 acres of wetland restorationeasements) into the RIM ReserveProgram between 1986 and 1993(BWSR 1994).

The Minnesota WaterfowlAssociation (MWA) is a private, non-profit organization with a mission ofprotecting, preserving, and restoringhabitat in the state for waterfowl andother wildlife populations. TheMWA acquires land throughdonations, easements, and purchases,has active research and restorationprograms, and provides manyeducational opportunities for youth.

National initiativesThe 1977 Clean Water Act (CWA)prohibits dredging or filling awetland except as permitted by theArmy Corps of Engineers. TheCWA does not adequately protectwetlands against chemicalcontamination or degradation ofplant and animal communities. Itdoes, however, give authority to

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states to provide this protectionunder other provisions. The state ofMinnesota has standards for waterquality that help prevent suchcontamination and degradation.

The Conservation Reserve Program(CRP), authorized under the 1985Food Security Act (FSA) andamended by the 1990 and 1996Farm Bill, protects fragile farmlandby encouraging farmers to stopgrowing crops on highly erodibleand environmentally sensitive lands.The Wetland Reserve program(WRP) is another FSA programaimed at restoring and protectingwetlands on private property. WRPis a voluntary, incentives programthat provides governmentalpayments to farmers who agree notto drain or alter wetlands on theirland.

Other federal regulatory programsprotect or conserve wetlandsindirectly, including the WetlandConservation �Swampbuster�provision of the FSA, the NationalPollution Discharge EliminationSystem (administered by MPCA), theMigratory Bird Conservation Act,and the Endangered Species Act.

International initiativesThe North American WaterfowlManagement Plan (NAWMP) is aninternational agreement, signed in1986 by the United States andCanada, and in 1994, by Mexico, forthe conservation of wetland andwaterfowl resources in thosecountries. Recognizing thatwaterfowl populations are anindicator of environmental health, theNAWMP is a strategic document for

guiding the implementation ofwaterfowl population goals andwetland and associated grasslandhabitat goals. The Plan isimplemented through joint venturesand their management boards�localpartnerships among governments,private organizations, andindividuals�that secure funding andimplement projects to conserve andenhance waterfowl habitat at thelocal level (Minnesota WetlandsConservation Plan 1997; Gerlach1995 ).

Ducks Unlimited is an international,non-profit organization that restores,preserves, and creates waterfowlhabitat in order to increase NorthAmerica�s waterfowl populations.Much of its work focuses on theprairie potholes, but includes otherwetland types as well, totaling morethan 7 million acres of wetlands.During the last decade, migrationcorridors, stopover habitat, andwintering habitat have received agreat deal of attention.

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EXAMPLEINDICATORSTable 2 collects the indicators used inthis chapter. The indicators areorganized within the EII framework,which helps illustrate relationshipsamong human activities,

environmental condition, the flow ofbenefits, and strategies for sustaininga healthy environment. The indicatorsused in this chapter are examples thatillustrate how indicators may helpassess wetland health. The process ofdeveloping a comprehensive set ofindicators that assess wetland health

and inform environmental decisionsis ongoing. Developing indicatorswill require input from stakeholdersinterested in their use, testing,refinement, and standardization.

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Coffin, B. A. 1988. The naturalvegetation of Minnesota at the timeof the Public Land Survey 1847-1907. Biological Report No. 1,Minnesota Department of NaturalResources, St. Paul.

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