United States 

Department of 

Agriculture 

Forest Sewfce 

Southeastern Forest 

Experiment Station 

General Technical 

Report SE-71 

y Research: 

An Ana 

James W. McMinn 
September I991 

Southeastern Forest Experiment Station 

P.O. Box 2680 

Asheville, North Carolina 28802 
Diversity Research: 

An Ana 

James W. McMinn 

Biodiversity Coordinator 

Southeastern Forest Experiment Station 

Athens, Georgia 

ABSTRACT 

Biological diversity can be defined as the diversity of life, including 

the diversity of genes, species, plant and animal communities, 

ecosystems, and the interaction of these elements. The biodiversity 

issue arises from educated concern that the earth's diversity of life 

is threatened and is diminishing at an accelerated rate. An 

appropriate yardstick for biodiversity programs is how they affect 

the persistence of viable populations - populations that occur with 

sufficient gene pools, over large enough areas, with the requisite 

environments to perpetuate the organisms or ecosystems. Biodiversity is often erroneously understood to mean species diversity 

within stands or communities: the biodi\iersit\p concern is not about 

the local diversity of flora and fauna, but whether species or 

ecosystems are threatened. A coordinated program of biodiversity 

research could be structured under three overlapping subject areas: 

(1) threatened, endangered, and sensitive species; (2) restoration 

of missing, underrepresented, or declining communities; and (3) 

general principles and procedures for ecosystem restoration and 

perpetuation. 

Keywords: Genes, endangered species, plant communities, animal 

communities, ecosystems. 

Introduction 

A scientist who responds to constituentsYemands 

for research on a general subject must often begin 

by more clearly defining the surrounding issues. 

Biological diversity (biodiversity) is different because 

the issue has already been defined by knowledgeable 

professionals among those constituents (Hunter 

1 990; Lubchenco and others 1 991 ; National Research 

Council Committee on Forestry Research 1990; Norse 

and others 1986). Another way in which biodiversity 

differs from some issues is that the program of an 

entire research organization could be structured 

around it. In ultimate application, the issue is aboM 

maintaining ecological or environmentai health while 

producing necessary goods and sewices. Gonsiderable confusion surrounds the biological diversin, issue. 

The purposes of this document are (I) to establish 

working definitions of biological diversity and the 

issues surrounding it consistent with the conclusions 

of our knowledgeable constituencies, and (2) to 

suggest a framework for an efficient, coordinated 

research effort. 

Biological Diversity Defined 

Biojogical diversely can be defined as the diversity of 

life, including the diversity of genes, species, plant 

and animal communities, ecosystems, and the 

interaction of these elements. More succinctly, 

"Biological diversity refers to the variety and variability 

among living organisms and the ecological complexes 

in which they occur" (OFFice of Technology Assessment 

1987). Note that a useful, nontechnical synonym for 

'diversityw is 'variety." These definitions alone provide 

only a hint about the issue and little guidance for 

research or management. 

The Biological Diversity Issue 

The biodiversiv issue arises from educated concern 

over the rapid rate at which the earth" species are 

disappearing or coming close to extinction and the 

real possibility that entire ecosystems will be lost, 

Norse and others (I 986) discussed widely recognized 

reasons for perpetuating biological diversity under 

the general subjea areas of (1) the products of life, 

(2) ecosystem services, (3) a less obvious need for 

living things, and (4) ethics and stewardship. The 

phrase products of IifeVenotes a recognition of 

continuing human dependence on new, as well as 

traditional, plants and animals for necessities of life, 

New food products include kiwi fruit, napa cabbage, 

and monkfish. Soybeans are a relatively recent crop 

and the heavy use of tomatoes-long thought 
poisonous by Europeans - is relatively new. Genes 

from primitive varieties and wild relatives of domesticated species are used to improve productivity as well 

as to enhance tolerance to environmental stress, 

pests, and diseases. These gene pools will become 

more important with further development of genetic 

engineering. Pollination of many plants of direct 

significance to humans depends on an array of 

insects. Animals, fungi, and microorganisms are of 

growing importance in biological pest control. Wild 

populations continually provide new sources of 

medicines, energy, and industrial feedstocks for 

products such as high-quality lubricants. Ecosystem 

services include the most basic life-support systems; 

air, water, and soils. Natural ecosystems play a critical 

role in water purification, atmospheric composition, 

soil formation and stabilization, flood control, and 

amelioration of global climate. The less obvious need 

for living things refers to the beneficial effects of 

animals and natural landscapes on human health 

and well-being. When people are allowed to hold 

and pet dogs, for example, their blood pressure and 

pulse rates are reduced, and patients whose windows 

face trees recover faster than those whose windows 

face buildings. Related to this is the popularity of 

zoos, botanical gardens, aquaria, and the many 

forms of outdoor recreation. The ethics and stewardship aspect is not linked to human benefits, Increasing 

numbers of people simply believe that perpetuating 

biological diversity is the right thing to do. Whether 

this ethical concern is based on science or religion, 

they are uncomfortable about eliminating life forms 

because living things, they believe, have a right to 

exist. They feel that human dominance of the planet 

confers an associated responsibility for stewardship, 

In shon, the reasons for perpetuating biodiversity 

are varied, backed by a good bit of scientific evidence, 

and politically appealing. 

A key concept associated with biodiversity Is that 

of viable populations - populations that occur with 

sufFficient gene pools, over large enough areas, 

with the requisite environments to perpetuate the 

organisms or ecosystems. An appropriate yardstick 

for biodiversity programs is how they affect the 

persistence of viable populations, rather than how 

they affect local diversity per se. In the ecosystem 

context, it is vital to maintain structure and function 

as well as taxonomic composition. Ecologists have 

defined the general problem (Wilson 1985) and have 

formally addressed suggested approaches for forest 

management generally (Hunter 1990) and for national 

forest management specifically (Norse and others 

1986). The National Research Council Committee on 

Forestry Research (1 990) identified the loss of 

biological diversity as one of the major issues that 

society faces concerning forests. The Ecological 

Society of America proposes biological diversity as 

one of the three major priorities for ecological research 

(Lubchenco and others 1991). The issue is mentioned 

frequently in the press. Jerry Adler, writing in the 

December 31, 1990, Newsweek, noted: 

. . . EPA is likely to devote an increasing proportion of its resources to life on earth - and relatively 

less to life in, say, the dioxin-tainted town of Times 

Beach, Mo. The inhabitants of the former, unlike 

the latter, have nowhere else to go. 

The agency has already laid the groundwork for 

this reassessment. In a report last fall ("Reducing 

Risk"), the agency's Science Advisory Board 

identified four "relatively high-riskQnvironmenta1 

priorities in the coming years, all of them global in 

scope: climate change, ozone depletion, destruction and alteration of wildlife habitat, and 

species extinction. [emphasis added] 

Adler also noted that many of EPA's traditional 

concerns, including herbicides and pesticides, toxic 

pollutants in general, and acid precipitation are in 

the "relatively medium-risk-ategory. The "relatively 

low-risk* categoly includes groundwater pollution, 

=id runoff to suaface water, thermal pollution (of 

waters from power plants), and oil spills. The EPA 

rankings indicate that biological diversity is perceived 

as a high-priority political and scientific issue. 

For clarification there Is a need to explicitly 

recognize what biological diversity is not. Biological 

diversity is not about maximizing the number d 

species within a given area (Noss 1990): in this contea 

it is irrelevant, for example, to refer to the biological 

diversity of a forest stand. Neither is it about maximizing the variety of communities, age classes, or 
management regimes in a spatiat paaern of land 

allocation. It dms not imply the designation a48 

presewes or natural areas unless such designaion 

is necessaw to perpetuae some species or csmrnunities (Soul6 and khm 1989). 

Biological diversw is not a new discipline, bla it 

does provide an alrernative point of view that can 

help to guide and coordinate natural resources 

research and management. It is a new way of viewing 

the sustainability of all natural resources. It provides 

a philosophical basis for arriving at an accevable 

balance when ecological health is in conflict with 

commodity production or other land uses. A primaw 

research chailenge is la determine the types and 

levels of management compatible with the perpetuation of viable populations and ecological units. 

Traditional Diversity Definitions and 

Measures 

Definitions and measures are discussed For two 

reasons. First, there is a general need to know and 

distinguish between the technical use of the term 

*diversitym and the biodiversity issue, because they 

are often confused. The Committee of Scientists 

(1 979) suggested that in the National Forest Management Act (NFMA) Congress intended the ". , . term 

diversity to refer to biological variety rather than any 

of the quantitative expressions now found in the 

biological literature.' Second, although there is a 

distinction between the No, some diversity measures 

will be useful in addressing specific biodiversity 

questions. One of the major conclusions from a 

Southeastern StationlSARRMG conference on diversity related to the NFMA was, "Diversity indices must 

be used as an analfiical tool and not used to define 

diversity" (Cooley and Gooley '1 9U), 

Biodiversity is often eraoneous%y understood to 

mean species diversity wrthln stands or communities, probably because that has been the mast 

Gammon use of the term *diversity* in the literature. 

Compounding the ml"saanderstmdlrng Is MacAdhur's 

(1 955) once widely accepted theor)g that community 

stability Is related to diversity. Much ecologicari 

evidence has since beers collected suggesting 

that the relatisnship of s%abiiiv to diversity is 

unpredictable (Klkkzswra 1986; Klimrnlinzr 198c May 

"174; Watts 1968), Ecslsglstis ns longer generafly 

assume that high species diversity ensures stability 

(Ifr8iison 1 989). 

Aceording to Kimmins (1 9871, 'Biversiw can refer to 

all organisms in the community, but it is more 

frequently used to refer to one type or group of 

organism, Thus we can talk about the diversity of 

vascular plants, of birds, of mammals, and of the soil 

fauna." Diversity is a simple general concept that 

grows rapidly complex with attempts at measurement 

and comparison. The simplest charaGterization of 

diversity - a species enumeration - has very limited 

usefulness (Kinamins 1987). There is a generally 

recognized need to include some measure of how 

evenly impoflance or abundance is distributed among 

the different species. Pielou (1 969) maintained that 

diversity is essentially '. . . a single statistic in which 

the number of species and evenness are confounded.' 

Peet (1 974) demonstrated that several different 

concepts have been grouped under the title sf diversity 

and that many different indices have been legitimately 

used. He concluded that (1) species richness, or the 

number of species in a community, and (2) equitability, 

or the evenness with which importance is distributed 

among species, are particularly pertinent. The most 

widely used indices of diversity combine species 

richness and evenness in a single quantitative 

expression. Specific indices will not be discussed 

here, but it should be noted that indices differ in 

significant ways. Some indices are strongly afiected 

by sample size and others are not. Some indices are 

more sensitive to the rarer species, whereas others 

are more afiected by the dominant species in a sample. 

Such considerations will obviously be critical in 

addressing specific biodiversity problems. It should 

also be recognized that some diversity indices are 

inherently subject to manipulation, misuse, or misinterpretation. Since calculation for the most popular 

indices involves evenness, as welt as richness, the 

index value can be increased by reducing the 

abundance of the most prevalent species without 

changing the abundance of the rarer species. 

Another critical consideration is the trait selected to 

represent the importance OF abundance component 

of diversity indices, The simplest is number of 

individuals. However, is it meaningful to compare 

trees with herbaceous plants on this basis? or mature 
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was determined, Furthermore, working with individual 

species ad infinitum focuses on symptoms rather 

than the basic problem. One of the ma~or threats to 

biological diversity is declining habitat area generally 

and reduced size of contiguous habitat (habitat 

fragmentation) in particular (Soul6 and Kohm 1989). 

According to Norse and others (1 986), "Of the various 

threats to biological diversity on National Forest 

lands, habitat fragmentation is perhaps the most 

serious." It follows that with limited resources the 

only truly successful research and management 

programs for biodiversity will be oriented primarily 

towards maintaining an array of representative 

ecosystems. Blockstein (1 990) maintains that 

: . . preservation of multiple examples of all the 

natural communities occurring within the United 

States should be a national goal." The assumption is 

that maintaining communities or ecosystems automatically ensures perpetuation of a large proportion of 

the component species. However, the validity of this 

approach depends on the selection and application 

of community classification systems. Most systems 

are based on a small number of dominant species: 

the mere occurrence of those species at any age or 

stage of communiw development does not ensure 

that all potential component species and functions 

exist. The Nature Conservancy uses the term "coarse 

filter* for the community approach and "fine filter" for 

the individual species approach (Noss 1987). Both 

approaches are necessary because ecosystem 

classification schemes are not comprehensive enough 

to encompass every species (Hunter 1990). Also, 

Puiliam (I 988) argues convincingly that the perpetuation of some species depends on reproduction in 

source areas to replace mortality in certain "sink" 

habitats and that this dynamic relationship is evolutionarily stable, 

Given the preceding priorities and limitations, a 

coordinated program of biodiversity research could 

be structured under three general subject areas: 

(1) threatened, endangered, and sensitive species; 

(2) restoration of missing, underrepresented, or 

declining forest communities; and (3) general principles and approaches for ecosystem restoration and 

perpetuation. These areas of research are not 

mutually ~?x~ltl~fve. In fact, they must overlap with 

a high degree of coordination to be eRlclent and 

effective, The necessary overlap should be kept in 

mind in reviewing the Following descriptions: 

Threatened, Endangered, and Sensitive 

SpeciesrES) 

"This area is aiready defined by current and planned 

work with, For example, the red-cockaded woodpecker, 

neotropical migrant passerines, and nonmigratory 

avian species. A primary focus on individual species 

is what distinguishes TES from other subject areas 

in the suggested structure, 

Restoration of Missing, Underrepresented, 

and Declining Forest Communities 

This work is distinguished by a focus on specific 

target communities. It includes identiwing and 

prioritizing them; defining their critical attributes 

(minimum viable area, species composition, structure, 

function, interior species, keystone species, indicator 

species); locating potential sites and evaluating site 

suitability; and developing alternatives for restoration 

and perpetuation. 

For each community the types and levels of management that are compatible with the perpetuation of 

the community will have to be determined. Two 

additional areas of research will apply to each 

community: (1) the degree to which small islands or 

fragments of the community can substitute for larger 

contiguous areas if the fragments are connected by 

corridors of similar type, and (2) determining minimum 

viable populations for certain critical component 

species, Questions associated with the first area 

relate to size, shape and proximity of fragments and 

to corridor characteristics in the conrext of organisms 

that will move along the corridors (Hunter 1990). 

Maintenance of viable populations was suggested 

earlier as a criterion for judging success of biodiversity 

programs. In fact, determining what constitutes a 

viable population will be a major research undefiaking 

for many species. Akhough there are general rules 

of thumb, such as 50 breeding individuals for the 

short term and 500 for indefinite survival (Frankel 

and Soul6 1981), more recent work suggests that 

minimum viable populations could range from 

hundreds to millions, depending on the organism 

(Soul6 1987). Many factors influence population 

viability (Shaffer 1981 ), and population viability 

analysis is emerging as a recognized field of work 

(Hunter 1990). In attempting to estimate the minimum 

viable population, genetic composition is often more 

irnpoflant than pure numbers (Soul4 and Kolm 1989). 
There is a potential need for community restoration 

in ail three physiographic provinces of the Southeast. 

General exampies of candidate target communities 

are the longleaf pine-wiregrass on the Coastal Plain, 

various upland hardwood communities in the Piedmont and Mountains, and specific wetland communities in at1 three provinces. 

General Principles and Approaches for 

Ecosystem Restoration and Perpetuation 

Research in this area is distinguished by problems 

and solutions that generalize across communities. 

Included are development of methods for locating 

and evaluating potential sites and for introducing 

missing species as well as determination of the 

potential role of human disturbances (such as 

harvesting and burning) in changes in species 

composition. Other questions addressed under this 

heading would be the general function of coarse 

woody debris in southeastern communities; the 

degree to which younger communities can be 

structured to mimic old growth; the importance of 

structural diversity in southeastern communities; the 

degree to which features such as roads, powerlines, 

trails, and firelines fragment communities by creating 

barriers to animal and plant movement; and approaches for population viability analysis. Associated with 

these questions should be landscape-level investigations into the frequency with which species are 

perpetuated by the source-sink habitat relationships 

discussed by Pulliam (1988). 

Specific problems under all three general subject 

areas must be addressed in different ways and on 

different scales than traditional investigations. There 

are obvious limitations on where and by whom effective 

research on some biodiversity questions can be 

conducted. Certain questions will require landscapelevel investigations with (1) firm control over human 

perturbations; (2) security for costly field instrumentation; (3) a continuing level of multidisciplinary research; 

and, perhaps most importantly, (4) landowner commitment, often for very long periods. These criteria are 

SO restrictive that any organizations with the capacity 

and willingness to meet them could attain a global 

reputation in biodiversity research. 
Selected References 

Noss, R.F. 1987. From plant communities to landscapes in 

conservation inventories: a look at the Nature Consewancy 

(USA). Biological Conservation 41 : 1 1-37. 

Bioekstein, David E. 1990. Toward a federal plan for biological 

diversw. Journal of Forestry 8d(3):15-19. 

Committee of Scientists. 1979. Final report, Federal Register 

44 (88) :%599-26657. NOSS, R.F. 1990. Indicators for monitoring biological diversity: a 

hierarchical approach. Conservation Biology 4:355364. 

Cooley, James L; Cooley, June H., eds. 1384. Natural diversity 

in forest ecosystems, Proceedings of the workshop; 1982 

November 29 - December 1 ; Athens, GA. Athens, GA: University 

of Georgia, Institute of Ecology: page ii. 290 pp. 

Onice of Technology Asssssment. 1987. Technologies to maintain 

biological diversity. Summary. Washington, DC: U.S. Government Printing Office. Stock No. 052-003-01058-5. 

Peet, Robert K. 1974. The measurement of species diversity. Annual 

Review of Ecology and Systematics 5:285-307. 

Elliott, Catherine A. 1990. Diversity indices. In: Hunter, Malcolm 

L., Jr. Wildlife, forests, and forestry: principles of managing 

forests for biological diversity. Englewood Cliffs, NJ: Prentice 

Hall, Inc: 297-302. Pielou, E.C. 1969. An introduction to mathematical ecology. New 

York: Wiley-lnterscience. 286 pp. 

Frankel, O.H.; Soule, M.E. 1981. Conservation and evolution. 

Cambridge, Great Britain: Cambridge University Press. 327 pp. Probst, John R.; Crow, Thomas R. 1991. Integrating biological 

diversity and resource management. Journal of Forestry 

Harris, Larry €3. 1984. The fragmented forest: island biogeography 89(2) :12-17. 

theory and the preservation of biotic diversity. Chicago: 

University of Chicago Press. 21 1 pp. Puiliam, H. Ronald. 1988. Sources, sinks, and population 

regulation. The American Naturalist 132(5) :652-661. 

Hunter, Malcolm L., Jr. 1990. Wildlife, forests, and forestry: 

principles of managing forests for biological diversity. Englewood 

Cliffs, NJ: Prentice-Hall. 370 pp. 

Reid, Walter V.; Miller, Kenton R. 1989. Keeping options alive: 

the scientific basis for conserving biodiversity. Washington, DC: 

World Resources Institute. I 1 1 pp. 

Kikkawa, J. 1986. Complexity, diversity, and stability. In: 

Kikkawa, J.; Anderson, D.J., eds. 1986. Community ecology: 

pattern and process. Melbourne, Australia: Blackwell: 41 -62. 

Salwasser, Hal. 1990. Gaining perspective: forestry for the future. 

Journal of Forestry 88(11):32-38. 

Sepik, G.F.; Owen, R.B., Jr.; Coulter, M.W. 1981. A landowner's 

guide to woodcock management in the Northeast. Misc. Rep. 

253. Orono, ME: Maine Agricultural Experiment Station. 

Kimmins, J.P. 1987. Forest ecology. New York: Macmillan 

Publishing Company. 531 pp. 

Lendres, P.B.; Verner, J.; Thomas, J.W. 1988. Ecological uses 

of vertebrate indicator species: a critique. Conservation Biology 

231 6:328. 

Shaffer, M.L. 1981. Minimum population sizes for species conservation. BioScience 31 (2):131-134. 

Lubchenco, J.; Olson, A.M.; Brubaker, L.B. [and others]. 1991. 

The sustainable biosphere initiative: an ecological research 

agenda. Ecology 72:371-412. 

Soule, Michael E., ed. 1986. Conservation biology: the science of 

scarcity and diversity. Sunderland, MA: Sinauer Associates. 

584 PP. 

MacArthur, R.H. 1955. Fluctuations of animal populations, and a 

measure of community stability. Ecology 33533-536. 

Soule, M.E., ed. 1987. Viable populations for conservation. 

Cambridge, Great Britain: Cambridge University Press. 189 pp. 

MacArthur, R.W.; MacArthur, J.W. 1961. On bird species diversity. 

Ecology 42~594-598. 

aul6, Michael E.; Kohm, Kathryn A., eds. 1989. Research priorities 

for conservation biology. Washington, DC: Island Press. 97 pp. 

"Tample, S.A. 1977. Plant-animal mutualism: coevolution with dodo 

leads to near extinction of plant. Science 197:885-886. 

Magurran, Anne E. 1988. Ecological diversity and its measurement. 

Princeton, NJ: Princeton University Press, 179 pp. 

May, W.M. 1974. Stabilily and complexity in model ecosystems. 2d 

ed. Princeton, NJ: Princeton Universiq. Press. 265 pp. 

Wan, K.E.F. 1968. Ecology and resource management: a quantitative approach. New York: McGraw-Hill. 450 pp. 

National Research Council Commiaee on Forestry Research. 

19"30. Forestry research: a mandate for change. Washington, 

DC: National Academy of Sciences. 84 pp. 

Norse, EIlioM A,, Rosenbaum, Kenneth L, Wilcove, David S. 

[and others). 1986. Conserving biological diversity in our 

National Forests. Washington, DC: The Wilderness Society. 

116 pp. 

Whinaker, Robsrl H. 1975. Communities and ecosystems. 2d ed. 

New York: Macmillan. 385 pp. 

Wilcox, B.A.; Murphy, D.D. 1985. Conservation strategy: the effects 

of fragmentation on extinction. American Naturalist 125:879-887. 

Wilson, Edward 0. 1985. The biological diversity crisis. BioScience 

35:700-7m. 

Noss, R.F. 1983. A regional landscape approach to maintain 

diversity. BioScience 333706-706. 

Wilson, Edward 0.1989. Threats to biodiversity. Scientific American 

261 (3):10&116. 

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The Forest Service, U.S. Department of 

Agriculture, is dedicated to the principle of 

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for sustained yields of wood, water, forage, wildlife, and 

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