Part 610 Ecological Principles for Resource Planners · collectors vertebrate predators invertebrate shredders dissolved organic matter fine particulate ... (190-VI-NBH, November

(190-VI-NBH, November 2004)

National Biology HandbookSubpart B—Conservation Planning

United StatesDepartment ofAgriculture

NaturalResourcesConservationService

Part 610 Ecological Principlesfor Resource Planners

610–i(190-VI-NBH, November 2004)

Part 610 Ecological Principlesfor Resource Planners

Contents: 610.00 Ecosystems and landscapes 610–1

610.01 Ecosystem processes 610–2

(a) Energy flow ............................................................................................... 610–2

(b) Water and nutrient cycles ........................................................................ 610–3

610.02 Ecosystem structure and its relation to ecosystem function 610–6

610.03 Ecosystem changes and disturbance 610–7

(a) Stability in ecosystems ............................................................................. 610–7

610.04 Biological diversity 610–8

(a) Hierarchy of diversity ............................................................................... 610–8

(b) Species interactions ............................................................................... 610–10

610.05 Applying ecological principles to habitat conservation, 610–11

restoration, and management

(a) Area of management actions ................................................................. 610–11

(b) Edge effects ............................................................................................. 610–11

(c) Disturbance effects ................................................................................. 610–11

(d) Isolation and distance effects ................................................................ 610–12

(e) Habitat heterogeneity ............................................................................. 610–12

610.06 Literature Cited 610–12

610.07 Glossary 610–13

Table Table 610–1 Indicators of biodiversity at four levels of organization 610–9

National Biology Handbook

Aquatic and Terrestrial Habitat Resources

Conservation Planning

Ecological Principles for Resource PlannersSubpart B

Part 610

610–ii (190-VI-NBH, November 2004)

Figures Figure 610–1 Ecological principles for land management planners 610–1

Figure 610–2 Aquatic food web 610–2

Figure 610–3 Terrestrial food chain 610–3

Figure 610–4 Hydrologic cycle 610–4

Figure 610–5 Carbon cycle and its effect on the Earth's 610–5

atmosphere

Figure 610–6 Nitrogen cycle 610–5

Figure 610–7 Nitrogen pathways on working lands 610–6

Figure 610–8 Landscape elements: patch, matrix, and corridor 610–6

Figure 610–9 Flood pulse concept 610–7

Figure 610–10 Rock and timber revetment on the Willamette River, 610–7

Oregon

Figure 610–11 Black-tailed prairie dog 610–10

Cover photos courtesy of Wendell Gilgert, Tim McCabe,Charlie Rewa, and Gary Wilson, USDA NRCS, and theUtah Division of Wildlife Resources.

610–1(190-VI-NBH, November 2004)

Subpart B Conservation Planning

Part 610 Ecological Principles for Resource Planners

610.00 Ecosystems andlandscapes

An ecosystem is a biological community, or assem-blage of living things, and its physical and chemicalenvironment. The interactions among the biotic andabiotic components of ecosystems are intricate. Con-servation of natural resources can be daunting whenthe social, cultural, economic, and political realities ofour modern world and the complex, multidimensionalnature of ecosystems are considered.

Often fish, wildlife, and plants are dependent uponseveral ecosystems within broader landscapes. Forexample, migratory birds, butterflies, and salmon usedifferent ecosystems that traverse political boundaries(often thousands of miles apart) during phases of theirlife cycles. Conservation of these migratory speciescreates land management challenges that can only beadequately addressed at the landscape scale. Land-

scape ecology considers principles about the structure,function, and changes of interacting ecosystems innatural resource conservation and planning (Formanand Godron 1986).

Dynamic processes occurring over multiple scales oftime and space determine the physical and biologicalcharacteristics of our landscapes. These include:

• Geomorphological processes, such as erosion

• Natural disturbances, such as fires, floods, anddrought

• Human perturbations, such as land clearing andurban development

• Changes in the make-up of biological communi-ties, from days to millions of years

To implement effective conservation practices thattake into consideration the often-extensive migratorypaths of species, think broader than the project siteand longer than the project time (fig. 610–1). Even acursory evaluation of landscape conditions and theirecological and cultural history provides a valuablecontext when considering fish and wildlife resourceconcerns. This can lead to a better understanding ofhow large-scale processes affect individual parcels ofland and the habitats they provide, and how actions onsmall pieces of land can influence ecological pro-cesses and biodiversity at broader scales.

Figure 610–1 Ecological principles for land management planners (from Dale et al. 2001)

Time Ecological processes function at many timescales, and ecosystemschange through time.

Species Individual species and assemblages of interacting species have key,broad-scale ecosystem effects.

Place Local conditions (climate, geomorphology, soil quality, altitude) aswell as biological interactions affect ecological processes and theabundance and distribution of species.

Disturbance The type, intensity, and duration of disturbances shape the character-istics of populations, communities, and ecosystems.

Landscape The size, shape, and spatial relationships of land cover types influ-ence the dynamics of populations, communities, and ecosystems

National Biology Hanbook




Part 610

610–2 (190-VI-NBH, November 2004)

610.01 Ecosystemprocesses

(a) Energy flow

Energy flows through and fuels ecosystems and allliving things. Virtually all energy originates from thesun. Organisms can be grouped into food chains, ormore complex food webs, according to the trophic

level that represents where they obtain energy fromtheir environment as shown in figures 610–2 and610–3. From a habitat management standpoint, thesources of available energy at each trophic level affectthe mix of species in an ecosystem, their populations,and how they interact.

Green plants are autotrophs, or primary producers.

They use solar energy for photosynthesis, combiningatmospheric carbon dioxide and water into high-energy carbohydrates, such as sugars, starches, andcellulose (see section (c) Carbon cycle).

courseparticulate

organicmatter

microorganisms(e.g., hyphomycete

fungi)

flocculation

invertebratecollectors

vertebratepredators

invertebrateshredders

dissolvedorganicmatter

fineparticulate

organicmatter

light

larger plants(mossess,red algae)

epilithic algae

invertebratescrapers

invertebratepredators

microorganisms

Figure 610–2 Aquatic food web (from Stream Corridor Restoration: Principles, Processes, and Practices)






Part 610

Animals are heterotrophs; they derive their energyfrom the carbohydrates stored within plants. Het-erotrophs can be herbivores or carnivores. Herbivores,or primary consumers, obtain their energy by directlyconsuming plants. Carnivores, or secondary consum-ers, derive their energy by consuming herbivores andother carnivores. Animals that eat both plants andother animals are referred to as omnivores. Foodchains or webs end with decomposers, usually bacte-ria and fungi, that recycle nutrients from dead or dyingplants and animals of higher trophic levels.

The amount of energy available to organisms at differ-ent trophic levels declines as it moves through anecosystem. Thus, more energy is available to supportplants than herbivores and even less to support carni-vores. As a rule of thumb, only about 10 percent of theenergy that flows into a trophic level is available foruse by species in the next higher level.

For example, if green plants are able to convert 10,000units of energy from the sun, only about 1,000 units areavailable to support herbivores and only about 100 tosupport carnivores. Energy is lost primarily in the formof heat along the food chain.

Figure 610–3 Terrestrial food chain

(b) Water and nutrient cycles

Water and elements, such as carbon, nitrogen, andphosphorus, are critical to life. Unlike energy thatflows through an ecosystem, these materials arecycled and reused repeatedly. In river systems, nutri-ents are said to spiral rather than cycle as they do onland.

Nutrient spiraling is a concept that explains thedirectional transport of nutrients in streams and rivers,rather than closed nutrient cycles associated withterrestrial ecosystems. All of these important pro-cesses provide elements that are essential to all livingthings, and all are powered by energy. Thus, humanactions that disrupt or alter energy flow in ecosystemsalso affect water and nutrient dynamics in thosesystems.

The water, or hydrologic cycle (fig. 610–4), has twophases: the uphill phase driven by solar energy, andthe downhill phase, which supports ecosystems.

Most rainfall comes from water evaporated from thesea by solar energy (uphill phase). In fact, about athird of the solar energy reaching the Earth’s surface isdissipated in driving the hydrologic cycle.

Approximately 80 percent of rainfall recharges surfaceand groundwater reservoirs and only 20 percent re-turns directly to the sea. As water moves throughecosystems (downhill phase), it shapes the physicalstructure of the landscape through erosion and deposi-tion. It also affects the distribution and abundance ofliving things as it regulates availability of nutrients insoil that must be dissolved by water to be utilized byplants. Soil is thus an essential component in the watercycle.

The water cycle links the land to aquatic ecosystemswhere the flow rate and nutrient levels determine themake-up of their biological communities. Carbondioxide (CO2) in the Earth’s atmosphere, and thatwhich is dissolved in water, serves as the reservoir ofinorganic carbon from which most carbon compoundsused by living things are derived. During photosynthe-sis, plants use CO2 to manufacture carbon compoundssuch as glucose and lignin, thus beginning the carbon

cycle.





Part 610

610–4 (190-VI-NBH, November 2004)

Lakestorage

Ocean

Precipitation

Rain clouds

Cloud formation

Evaporation

from

vege

tatio

nfr

omst

ream

s

from

soil

fro

moc

ean

from

tran

spir

atio

n

Infiltration

Percolation

Ground water

Deep percolation

Rock

Surface runoff

Figure 610–4 Hydrologic cycle (from Stream Corridor Restoration—Principles, Processes, and Practices)






Part 610

Figure 610–5 Carbon cycle and its effect on the Earth's atmosphere

During plant respiration, some CO2 is released backinto the atmosphere, but much is stored, or seques-tered, in both live and dead plant tissues (fig. 610–5).The majority of climate researchers believe that hu-man activities, including the burning of fossil fuels andclearing of forests, have increased the amount of CO2in the atmosphere (Houghton et al. 2001). A green-house effect results as CO2 increases the amount ofheat trapped in the atmosphere.

One of the most biologically important elements forliving things is nitrogen, which constitutes about 78percent of Earth’s atmosphere as nitrogen gas (N2).Although important, nitrogen gas is virtually unusableby all but a few living things.

The nitrogen cycle (fig. 610–6) is dependent on bacte-ria and algae in soil and water capable of using atmo-spheric nitrogen to synthesize or fix nitrogen. Theresulting nitrogen-containing compounds can then beused by higher plants and animals. Some legumes andother plants fix nitrogen through bacteria that live inspecialized nodules on their roots. Nitrogen stored in

OrganicN

NO3

NH4+

NO2

N2

N2O

Storage

Storage

Storage

Storage

Anthropogenic Anthropogenic

Outputs

Natural

Inputs

Natural

Figure 610–6 Nitrogen cycle

plants is available to plant-eating heterotrophs. Asanimals die or are consumed by other organisms, thenitrogen eventually enters the soil where denitrifica-tion returns it to the atmosphere (fig. 610–7).

Photosynthesis+Respiration in the Global Carbon Cycle

The Global Carbon Cycle

A network of interrelated processes that transport

carbon between different reservoirs on Earth.

• P+R occurs in land plants and in aquatic systems

Ocean-atmosphereexchange

Atmosphere

Surfaceocean

Deepocean

Phytopla

Terrestrialbiosphere

Lithosphere

Land-usechanges

Riverrunoff

Sinkingparticles

Photosynthesisand respiration

Oceancirculation

Photosynthesisand respiration

Fossil fuelcombustionand cementmanufacture





Part 610

610–6 (190-VI-NBH, November 2004)

In the phosphorus cycle, plants and bacteria take upphosphorus from soil. Phosphorus is required forenergy transformations within the cells of organisms.Animals obtain it from plants and other animals. Phos-phorus returns to an ecosystem’s reservoir throughexcretion and decomposing organic tissue of bothplants and animals.

610.02 Ecosystem struc-ture and its relation toecosystem function

The physical structure of ecosystems varies accordingto climatic patterns, soil types, soil qualities, distur-bance patterns, geologic events, biological interac-tions, and human perturbations. Individual ecosystemsof a landscape can be thought of as patches or corri-dors within a matrix where flow of energy, materials,and species occurs (fig. 610–8). The components ofecosystems, such as animals, plants, biomass, heatenergy, water, and mineral nutrients, are heteroge-neously distributed among patches or corridors thatvary in size, shape, number, type, and configuration.

NO3- NO2

-

NH4+

N2

AmmonificationLysis, excretion

Amino acids

NitrificationNitrate reduction

Nitrogenfixation

Dentrification

Nitrification

Amino acidsynthesis

Dissolved Organic N

Figure 610–7 Nitrogen pathways on working lands

Figure 610–8 Landscape elements: patch, matrix, andcorridor (photo courtesy Iowa NRCS)






Part 610

610.03 Ecosystem changesand disturbance

(a) Stability in ecosystems

Many of the familiar ecosystems have changed dra-matically over the last 10,000 years. For example,following the last glacial period, North America be-came more arid and deserts now occupy areas thatwere once coniferous forests. Ecosystems and theirprocesses may appear static because the frame-of-reference is typically limited to the perspective of ahuman life span.

In reality, ecosystems are in a constant state of flux.The stability and health of ecosystems are humanconcerns. This stability is measured by the resilienceto natural disturbances or human perturbations. Natu-ral disturbances, although temporarily disruptive, areimportant for maintaining many ecosystem processesand thus biological communities. They can also wreakhavoc on infrastructure and human economies. On theother hand, human-induced perturbations that cause adeparture from normal ecosystem processes maydisrupt ecosystem sustainability and the associatedproduction of goods and services.

Natural disturbances, such as fire, floods, hurricanes,and tornadoes, all affect and change ecosystems. Theymay significantly alter the existing community ofplants and animals, making conditions favorable toother species, including alien invasive species. Thecommunity progresses through a series of overlapping,successive steps that provide habitat for differentspecies. Over time, succession may lead back to anecosystem similar to the original. However, if therehave been climatic changes or new species havemoved into the area, the biological community may besignificantly different. Fire is one of the most impor-tant natural disturbances because of its high frequencyand the extent of area it affects. Where fire is frequent,plants and animals have adapted to it. In fact, theseeds of many plant species lie dormant in the soilwaiting for a fire event to release nutrients and pro-vide sunlight that was once blocked by the previouscanopy of vegetation. Fire and other natural distur-bances create a diversity of habitats within the land-scape.

In river and stream ecosystems, recurring floods arecritical to sustained production of fisheries, flood plainforests, wetlands, and riparian habitat. Rivers andstreams derive most of their biomass from within theflood plain and their biological communities are de-pendent on lateral exchanges of water, sediment, andnutrients among the flood plain, the riparian area, andriver channel (fig. 610–9).

Aquatic species move into the flood plain at rising andhigh water levels because of feeding and spawningopportunities; terrestrial animals along the rivers thenexploit the available food sources that result fromreceding water. Dams, dikes, and extensive revet-ments along rivers have significantly reduced thefunction of flooding in sustaining ecosystem processesin large rivers (fig. 610–10).

Figure 610–9 Flood pulse concept

Flood Pulse Concept

Nutrientrecycling

Lateral exchange

Flood plain

Figure 610–10 Rock and timber revetment on theWillamette River, Oregon (photocourtesy Kathryn Boyer, USDA NRCS)





Part 610

610–8 (190-VI-NBH, November 2004)

Ecosystems are dynamic, and change is the normalcourse of events. Change in vegetation structure oftencreates a more diverse or heterogeneous array ofhabitats for terrestrial wildlife. Many past managementdecisions, such as fire suppression and flood preven-tion, have been undertaken to minimize the dynamicnature of some ecosystem processes to protect andpromote human interests. From a fish and wildlifestandpoint, this has tended to simplify habitats, dis-connect the flow of nutrients, and isolate populations.

610.04 Biologicaldiversity

(a) Hierarchy of diversity

Biological diversity or biodiversity is the variety andvariability among living organisms and the ecologicalcomplexes in which they occur.

Biodiversity is organized hierarchically, beginning withthe genetic diversity of individual organisms andending with the diversity of ecosystems available inlandscapes (Noss 1990) (table 610–1). It includes thefull range of species, from viruses to plants and ani-mals, the genetic diversity within a species, and thediversity of ecosystems in which a community ofspecies exists. Land management goals that includeconservation of biodiversity require that decisions bemade over spatial scales that are much larger thanindividual parcels of land.

A species is a group of individuals that are morphologi-cally, physiologically, or biochemically distinct. Inaddition, they have the potential to breed amongthemselves and do not normally breed with individualsof other groups. Species that range over wide geo-graphical areas often are divided into subspecies iftheir morphological characteristics vary enough tomake them distinctive.

A population is a group of individuals of the samespecies that share a common gene pool. This meansthey are in close enough proximity to each other topotentially interbreed, although they often do not.Populations of many species have wide distributionsand to a greater or lesser extent are geographicallyisolated from each other by physical barriers or dis-tance. A population of frogs in a small pond is isolatedfrom a population of frogs in another pond many milesaway. The probability that the two populations willinterbreed is low.

A metapopulation is the collective group of discretepopulations of a species across a landscape uponwhich the species’ continued existence depends. Forexample, a natural disturbance, such as fire, maycause local extermination of an amphibian speciespopulation. The existence of other populations in a






Part 610

Table 610–1 Indicators of biodiversity at four levels of organization (Noss 1990)

Organizational level Compositional factors Structural indicators Functional indicators

Regional landscape Identity, distribution, Heterogeneity, connectivity, Disturbance processes,richness, and proportions spatial linkage, patchiness, nutrient cycling rates,of patch (habitat) types, porosity, degree of frag- energy flow rates, patchcollective patterns of mentation, juxtaposition, persistence and turnoverspecies distributions perimeter-area ratio, rates, rates of erosion(richness, endemism) pattern of habitat layer and deposition, human

distribution land-use trends

Community ecosystem Identity, relative abund- Substrate and soil variables, Biomass and resourceance, frequency, richness, slope and aspect, vegetation productivity, herbivory,evenness, and diversity of biomass and physiognomy, parasitism, predationspecies and guilds; propor- foliage density and layering, rates, colonization andtions of endemic, exotic, horizontal patchiness, local extinction rates,threatened, and endan- canopy openness and gap patch dynamics (fine-scalegered species proportions, abundance, disturbance processes),

density, and distribution of nutrient cycling rates,key physical features, water human intrusion rates andand resource availability intensities

Population species Absolute or relative abund- Dispersion, population Demographic processesance, frequency, import- structure (sex ratio, age (fecundity, recruitmentance or cover value, bio- ratio), habitat variables rate, survivorship, mortal-mass, density (see community- ity), metapopulation

eco-system structure, dynamics, population above) genetics (see below),

population fluctuations,physiology, life history,growth rate (of individu-als), adaptation

Genetic Allelic diversity, presence Effective population size, Inbreeding depression,of particular rare alleles, heterozygosity, chromo- outbreeding rate, rate ofdeleterious recessives, or somal or phenotypic poly- genetic drift, gene flow,karyotypic variants morphism, generation mutation rate, selection

overlap, heritability intensity





Part 610

610–10 (190-VI-NBH, November 2004)

landscape that allows their dispersal increases thechances that the species will eventually recolonize theburned area as it recovers.

Genetic diversity among individuals of a populationallows for greater flexibility of a species to adapt tochanging environmental conditions. For example,genes of one population may offer resistance to adisease that members of another population do nothave. If the disease eliminated the other population(s),the resistant group serves as a source for reestablish-ment of populations in other areas.

Some populations may go extinct on a local scale, andnew populations may become established on nearbysuitable sites. The close proximity of another popula-tion of the same species allows colonization of adisturbed site following natural disturbance or humanperturbation. For example, draining and converting awetland basin to agriculture results in loss of wetland-associated species from the site. However, wherewetlands are restored, dispersal of plant seeds andemigration of animals from nearby wetlands provide aready means of recolonization.

A biological community is an assemblage of popula-tions of many species. Within the biological commu-nity each species uses resources that constitute itsniche. For example, a niche for a bird includes whereit nests, what it feeds on, how it obtains water, whereit migrates, and even its daily time of activity.

When managing for a single species, it is important tounderstand its role in the biological community andhow it interacts with the assemblage of other speciesthat are part of its ecosystem. Community compositionis often affected by predator-prey interactions andcompetition among species. Predators can dramati-cally reduce the numbers of herbivore species. Thisalters the trophic structure of the entire community.Reduction in one herbivore species lessens consump-tion of specific plants within the community and mayallow another species to use the resource and increaseits population size.

Predators can also increase the biological diversityand individual species numbers of an area. For ex-ample, coyotes control mid-size predators, such asfoxes and cats that prey on songbird populations. Areduction in foxes and cats allows songbird numbersand diversity to increase.

(b) Species interactions

Within biological communities, thousands of organismspecies interact. Some species may be consideredmore valuable because their presence is critical to theability of other species to persist in the community.

Keystone species are those that have an ecologicalfunction on which other species and components ofthe ecosystem depend. The black-tailed prairie dog(fig. 610–11) is an example of an organism consideredby many to be a keystone species of the shortgrassprairie ecosystem.

Indicator species are species whose presence indi-cates a particular state or condition of an ecosystem.For example, stream conditions are often assessed bymonitoring the presence of aquatic insects, such asmayflies, stoneflies, and caddisflies. In stream ecosys-tems these species serve as indicators of water qualityand good coldwater habitat.

Figure 610–11 Black-tailed prairie dog(photo courtesy US FWS)

610–11(190-VI-NBH, November 2004)





Part 610

610.05 Applying ecologi-cal principles to habitatconservation, restoration,and management

The loss and fragmentation of natural habitats havereduced biological diversity and resulted in consider-able loss of fish and wildlife resources important tosociety. Land use changes are not the only culprit,however. Another factor affecting the loss of biologi-cal diversity and decline of species important toecosystems is the introduction or invasion of alienspecies.

Nearly half of the imperiled species in the UnitedStates may be threatened directly or indirectly by alienspecies (Wilcove et al. 1998). Considering thesethreats, the following topics are important issueswhen working with fish and wildlife habitat andshould be considered during planning activities.

(a) Area of management actions

The number of individuals and species an area cansupport is related to its size and the life histories anddynamics of the biotic community it supports. In someecosystems, such as grasslands, areas smaller than250 acres may not be able to withstand significantperturbations without the loss of many species ofvertebrate animals and plants (Crooks and Soule1999).

Small areas of habitat are usually insufficient to sup-port larger species. Therefore, conservation andrestoration efforts should consider project size andconnectivity potential to the extent possible. In addi-tion, efforts should be made to work with adjacentlandowners to build contiguous blocks of habitat andlink isolated patches of both terrestrial and aquatichabitats.

(b) Edge effects

The ratio of edge to habitat interior increases geo-metrically as fragment size decreases. Edge occurswhen habitat meets a road, crop field, land use change,or other feature, such as a stream. Wildlife manage-ment has historically focused on creating edge habitatfor the benefit of specific species. However, increasededge can adversely affect many species. These adverseeffects are:

• Greater rates of habitat desiccation and loss ofnative vegetation

• Greater frequency and increased severity of fire

• Greater rates of predation by native and exoticpredators (e.g., house cats, foxes, crows, bluejays)

• Higher probability of nest parasitism

• Greater windfall damage

• Greater intensities of browsing, grazing, andother forms of disturbance that favor the growthand spread of weedy and alien invasive species,both plants and animals (Wilcove et al. 1986,Noss and Cooperrider 1994)

Roads are the most frequent source of new edge andmay facilitate the movement of weeds and pests. Theyalso cause erosion, stream sedimentation, pollution,and increases in mortality rates of wildlife from colli-sions (Noss 1992). Especially in situations where area-sensitive species needs are considered, habitat conser-vation, restoration, and management efforts shouldreduce edge and minimize roads to the greatest extentpossible.

(c) Disturbance effects

Natural disturbances, such as fire, storms, floods, anddisease outbreaks, can increase the mosaic of habitatand increase biological diversity within a large habitatarea. They can also overwhelm small habitat patches.Small areas are more likely to burn completely, result-ing in loss or degradation of the community. Thesefactors require careful management and control ofdisturbance in smaller habitat patches.





Part 610

610–12 (190-VI-NBH, November 2004)

(d) Isolation and distanceeffects

Fragmentation is the alteration of natural patterns oflandscapes or ecosystems, creating smaller patches ordisrupting the continuity or connectivity of corridorsand networks. As habitat patches become isolated andthe distance between patches increases, it is harderfor many species to disperse and migrate betweenthem. Life cycles of the organisms that make up abiological community are dependent upon the abilityof the organism to safely disperse or migrate. Lowerdispersal and migration rates increase the likelihood aspecies will be extirpated from the area, and possiblybecome threatened or endangered in the long term.

Habitat conservation should focus on maintaininghabitat connectivity and linking isolated patches.Maintaining connections on land and in streams andrivers is critical to the long-term survival of fish, wild-life, and all of the ecological components on whichthey depend.

(e) Habitat heterogeneity

Heterogeneity is the complexity or variation in physi-cal structure of habitats. For example, in streams,water depth, velocity, substrate, wood, and pool/rifflecomplexes add to the heterogeneity of the habitat.Increased heterogeneity creates a variation in habitatsfor terrestrial and aquatic organisms and supports agreater diversity of species. It also provides moreflexibility for species as they seek different types ofhabitats during different stages of their life cycles.

The complexity of interactions within and amongspecies in ecosystems often defies our capacity tounderstand how to effectively manage natural re-sources. Actions and practices that maintain habitatand nutrient linkages, allow dispersal and migration,and sustain the processes that support the biologicalcommunity as a whole are likely to be more effectiveat enhancing habitat for all dependent species, includ-ing those featured in specific management objectives.

610.06 Literature Cited

Bayley, P.B. 1995. Understanding large river-floodplainecosystems. Bioscience 45:153-158.

Crooks, K.R., and M.E. Soule. 1999. Mesopredatorrelease and avifauna extinctions in a fragmentedsystem. Nature 400:563-566.

Dale, V.H., and R.A. Haeuber. 2001. Applying ecologi-cal principles to land management. Springer,New York, New York. 346 pp.

Federal Interagency Stream Restoration WorkingGroup. 1998. Stream corridor restoration: prin-ciples, processes, and practices.

Forman, R.T., and M. Godron. 1986. Landscape ecol-ogy. John Wiley and Sons, New York, New York.

Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J.van der Linden, X. Dui, K. Maskell, and C.A.Johnson, eds. 2001. Climate change 2001: thescientific basis. Contribution of Working Group Ito the Third Assessment Report of the Intergov-ernmental Panel on Climate Change. CambridgeUniversity Press.

Noss, R.F. 1990. Indicators for monitoring biodiversity:a hierarchical approach. Conservation Biology4:355-364.

Noss, R.F. 1992. The wildlands project land conserva-tion strategy. Wild Earth Special Issue 10-25.

Noss, R.F., and A.Y. Cooperrider. 1994. Saving nature’slegacy: protecting and restoring biodiversity.Island Press, Washington, D.C.

Quammen, D. 1996. The song of the dodo: islandbiogeography in an age of extinctions. Scribner,New York, New York.

Soule, M. 2000. An unflinching vision: networks ofpeople for networks of wildlands. Wild Earth9:34-46.

610–13(190-VI-NBH, November 2004)





Part 610

Wilcove, D.S., C.H. McLellan, and A.P. Dobson. 1986.Habitat fragmentation in the temperate zone. InM.E. Soule (ed.), Conservation Biology: Scienceof Scarcity and Diversity. Sinauer Associates,Sunderland, Massachusetts.

Wilcove, D.S., D. Rothstein, J. Dubow, A. Phillips, andE. Losos. 1998. Quantifying threats to imperiledspecies in the United States: assessing the rela-tive importance of habitat destruction, alienspecies, pollution, overexploitation, and disease.BioScience 48(8).

610.07 Glossary

Anthropogenic—Caused by humans.

Autotrophs—Primary producers, such as greenplants, that use solar energy for photosynthesis, com-bining atmospheric carbon dioxide and water intohigh-energy carbohydrates, such as sugars, starches,and cellulose.

Biological diversity (biodiversity)—Variety andvariability among living organisms and the communi-ties, ecosystems, and landscapes in which they occur.

Community—An assemblage of populations of manyspecies living and interacting in close proximity toeach other.

Decomposers—Organisms, such as bacteria andfungi, that are found at the bottom of the food chain.They recycle nutrients from dead or dying plants andanimals of higher trophic levels.

Ecosystem—A conceptual unit of living organismsand all the environmental factors that affect them; abiological community or assemblage of living things,and its physical and chemical environment.

Genetic diversity—Array of different genes availablein a population’s gene pool. Genetic diversity is neededamong individuals of a population to allow for greaterflexibility of a species to adapt to changing environ-mental conditions.

Heterogeneity—Complexity or variation in physicalstructure of a habitat.

Heterogeneous habitat—Diverse or consisting ofmany different structural components, substrates,types of vegetation, climates, etc.

Heterotrophs—Animals that derive their energy fromthe carbohydrates stored within plants. Heteroptrophscan be herbivores or carnivores.

Indicator species—Those species whose presenceindicate a particular state or condition of an ecosys-tem.





Part 610

610–14 (190-VI-NBH, November 2004)

Keystone species—Species that have an ecologicalfunction on which other species and components of anecosystem depend.

Landscape—(1) An area of land consisting of a num-ber of ecosystems; (2) A heterogeneous land areaconsisting of three fundamental elements: patches,corridors, and a matrix. A patch is generally a plantand animal community that is surrounded by areaswith different community structure. A corridor is alinear patch that differs from its surroundings. Amatrix is the background within which patches andcorridors exist and which defines the flow of energy,matter, and organisms.

Landscape ecology—Study of the spatial and tempo-ral relationships of interacting ecosystems, especiallytheir structure, function, and ecological processes.

Natural disturbance—Any relatively discrete eventin nature that disrupts ecosystem, community, orpopulation structure and changes resources, habitatavailability, or the physical environment. Naturaldisturbances include floods, wildfire, earthquakes,volcanic eruptions, tornadoes, hurricanes, and tidalwaves.

Metapopulations—Collective group of discretepopulations of a species across a landscape uponwhich the species' continued existence depends.

Niche—All of an organism's interactions with itsenvironment.

Nutrient spiraling—Directional transport of nutri-ents in streams and rivers, rather than closed nutrientcycles associated with terrestrial ecosystems.

Omnivores—Animals that eat both plants and otheranimals.

Perturbations—A departure from the normal state,behavior, or trajectory of an ecosystem; alteration ofecosystem processes as a result of human actions,such as land use. Examples of perturbations includedisruption of natural flow regimes with dam construc-tion or changes in groundwater hydrology caused bypoor livestock management or wetland drainage.

Population—A group of individuals of the samespecies that share a common gene pool. They areclose enough to each other to potentially interbreed,although they often do not.

Primary consumers—Organisms that eat greenplants, or herbivores.

Secondary consumers—Organisms that eat herbi-vores, or carnivores.

Species—A group of individuals that are morphologi-cally, physiologically, or biochemically distinct.

Subspecies—Division of species into subcategoriesthat best describe the relationships of their morpho-logical characteristics.

Trophic level—An organism's position in a food chainor food web.

Documents

Part 610 Ecological Principles for Resource Planners · collectors vertebrate predators invertebrate shredders dissolved organic matter fine particulate ... (190-VI-NBH, November