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About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please MODERN PERSPECTIVES OF HABITAT 105 for example). PVAs for such species should focus on the genetic and demographic factors that affect especially small populations. (This is the style of PVA that has been done most frequently.) • Organisms, such as most invertebrates and small vertebrates, that are frequently restricted to few habitat patches, but within those patches can reach high population densities. PVAs for those species must emphasize environmental uncertainty and catastrophic factors. Extinction due to environmental and catastrophic stochasticity is more important in small populations, so all factors need to be taken into account in such situations. This is not to say that some factors will not be more important than others in specific cases. Many human-induced and other changes in landscape and ecosystem function can be slow to become apparent, especially when long-lived species are involved. For example, the long-lived razorback sucker (Xyrauchen texanus) remained common in impoundments of the lower Colorado River for many years although no juvenile suckers were found there (Ono et al., 1983). As another example, fire suppression can take a long time to produce effects in an ecosystem. This means that conclusions from PVAs and management based on them should be viewed with caution. CONCLUSIONS • Assessing a conservation and habitat plan must take a retrospective view in many situations. In some cases, metapopulation dynamics in human-populated landscapes suffers from the absence of processes that previously contributed to maintaining the species population (see Ehrlich and Murphy, 1987). Such processes might include succession, disturbance, predation, mutualism, and the like. Processes that have been lost must be replaced, substituted, or compensated for if the species is to be maintained (Walker, 1989; Wagner and Kay, 1993). • Management and planning for metapopulation dynamics in landscapes must be monitored to determine their effectiveness, because the conditions in the landscape might change, or the management may not be as effective as initially thought (Barrett, 1985; National Research Council, 1986; Schroeder and Keller, 1990; Irwin and Wigley, 1993). The status of the component populations must be assessed at intervals. The monitoring interval will be determined by the longevity and generation time of the organism of interest or the expected periodicity of rare events and episodic interactions in which the species is involved. Monitoring must also assess the condition of the occupied habitat and the habitat necessary for dispersal (Hansson, 1992). • Monitoring will indicate the effectiveness of a management strategy. If the management does not maintain an occupied or dispersal habitat in use the print version of this publication as the authoritative version for attribution.

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About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please MODERN PERSPECTIVES OF HABITAT 106 suitable condition for a species, then the tactics and environmental components targeted by the management can be adjusted (Schroeder and Keller, 1990). This strategy of monitoring the results of management to assess the appropriateness and success of the strategy and to adjust it if necessary is labeled adaptive management, a particularly appropriate term, considering the environments of species can undergo many natural and anthropogenic changes. Such changes can be rapid and unexpected or gradual and difficult to detect. In either event, the changes can have untoward results for a target species, necessitating adjustments in conservation efforts. • A second characteristic of successful planning for maintenance of species is including information on the interactions in which they engage. All species exist as parts of food webs and interaction networks (McNaughton, 1989; Pimm, 1991). Interactions include those with prey and resources, potential mates, consumers, competitors, pollinators and dispersers. Management without attention to networks of interaction will fail to maintain critical resources or constraining factors in the species' environment (Holt and Talbot, 1978). Management that accommodates the interaction networks is labeled ecosystem management (see Chapters 9 and 10). Ecosystem management involves a turn from the focus on management for commodities only (Jones, 1987; Hartshorn and Pariona-A, 1993) and focuses instead on the ecosystem processes of population, community, and biogeochemical interactions to maintain the condition and function of a site as a whole (Likens, 1992; Society of American Foresters, 1993). REFERENCES Angelstam, P. 1992. Conservation of communities—The importance of edges, surroundings and landscape mosaic structure. Pp. 9-70 in Ecological Principles of Nature Conservation: Applications in Temperate and Boreal Environments, L. Hansson, ed. New York: Elsevier Applied Science. As, S., J. Bengtsson, and T. Eberhard. 1992. Archipelagoes and theories of insularity. Pp. 201-251 in Ecological Principles of Nature Conservation: Applications in Temperate and Boreal Environments, L. Hansson, ed. New York: Elsevier Applied Science. Austin, M.P. 1985. Continuum concept, ordination methods, and niche theory. Annu. Rev. Ecol. Syst. 16:39-61. Barrett, G.W. 1985. A problem-solving approach to resource management. BioScience 35:423-427. Beier, P. 1993. Determining minimum habitat areas and habitat corridors for cougars. Conserv. Biol. 7:94-108. Bormann, F.H., and G.E. Likens. 1979. Catastrophic disturbance and the steady-state in northern hardwood forests. Am. Sci. 67:660-669. Botkin, D.B., and M.J. Sobel. 1975. Stability in time-varying ecosystems. Am. Naturalist 109:625-646. Ehrlich, P.R., and D.D. Murphy. 1987. Conservation lessons from long-term studies of checkerspot butterflies. Conserv. Biol. 1:122-131. Elton, C. 1927. Animal Ecology. London: Sedgwick and Jackson. use the print version of this publication as the authoritative version for attribution.

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About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please MODERN PERSPECTIVES OF HABITAT 107 Fiedler, P.L., R.A. Leidy, R.D. Laven, N. Gershenz, and L. Saul. 1993. The contemporary paradigm in ecology and its implications for endangered species conservation . Endangered Species Update 10:7-12. Forman, R.T.T. 1987. The ethics of isolation, the spread of disturbance, and landscape heterogeneity. Pp. 213-229 in Landscape Heterogeneity and Disturbance, M.G. Turner, ed. New York: Springer. Forman, R.T.T., and M. Godron. 1986. Landscape Ecology. New York: John Wiley & Sons. Foster, R.B. 1980. Heterogeneity and disturbance in tropical vegetation. Pp. 75-92 in Conservation Biology: An Evolutionary-Ecological Perspective, M.E. Soulé and B.A. Wilcox, eds. Sunderland, Mass.: Sinauer Associates. Franklin, J.F. 1993. Preserving biodiversity: species, ecosystems, or landscapes. Ecol. Appl. 3:202-205. Garwood, N.C., D.P. Janos, and N. Brokaw. 1979. Earthquake caused landslides: A major disturbance to tropical forest. Science 205:997-999. Gilbert, L.E. 1980. Food web organization and the conservation of neotropical diversity. Pp. 11-33 in Conservation Biology: An Evolutionary-Ecological Perspective, M.E. Soulé and B.A. Wilcox, eds. Sunderland, Mass.: Sinauer Associates. Gosz, J.R. 1991. Fundamental ecological characteristics of landscape boundaries. Pp. 8-30 in Ecotones: The role of Changing Landscape Boundaries in the Management and Restoration of Changing Environments. New York: Chapman and Hall. Grubb, P.J. 1977. The maintenance of species-richness in plant communities: The importance of the regeneration niche. Biol. Rev. 52:107-145. Hanski, I. 1982. Dynamics of regional distribution: the core and satellite species hypothesis. Oikos 38:210-221. Hanski, I. 1989. Metapopulation dynamics: Does it help to have more of the same? Trends Ecol. Evol. 4:113-114. Hansson, L. 1992. Landscape ecology of boreal forests. Trends Ecol. Evol. 7:229-302. Hansson, L., L. Söderström, and C. Solbreck. 1992. The ecology of dispersal in relation to conservation. Pp. 162-200 in Ecological Principles of Nature Conservation: Applications in Temperate and Boreal Environments, L. Hansson, ed. New York: Elsevier Applied Science. Hartshorn, G.S., and W. Pariona-A. 1993. Ecologically sustainable forest management in the Peruvian Amazon. Pp. 151-166 in Perspectives on Biodiversity: Case Studies of Genetic Resource Conservation and Development, C.S. Potter, J.I. Cohen, and D. Janczewski, eds. American Association for the Advancement of Science, Washington, D.C. Holland, M.M., P.G. Risser, and R.J. Naiman, eds. 1991. Ecotones: The Role of Landscape Boundaries in the Management and Restoration of Changing Environments. New York: Chapman and Hall. Holt, S.J., and L.M. Talbot. 1978. New Principles for the Conservation of Wild Living Resources, Vo. 59. Wildlife Society, Louisville, Ky. Horn, H.S., and R.H. MacArthur. 1972. Competition among fugitive species in a harlequin environment. Ecology 53:749-752. Irwin, L.L., and T.B. Wigley. 1993. Toward an experimental basis for protecting forest wildlife. Ecol. Appl. 3:213-217. Jones, G.E. 1987. The Conservation of Ecosystems and Species. New York: Croom Helm. Kolasa, J., and S.T.A. Pickett. 1989. Ecological systems and the concept of organization. Proc. Natl. Acad. Sci. USA 86:8837-8841. Kolasa, J., and S.T.A. Pickett, eds. 1991. Ecological Heterogeneity. New York: Springer. Kolasa, J., and C.D. Rollo. 1991. Introduction: The heterogeneity of heterogeneity: A glossary. Pp. 1-23 in Ecological Heterogeneity, J. Kolasa and S.T.A. Pickett, eds. New York: Springer. use the print version of this publication as the authoritative version for attribution.

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About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please MODERN PERSPECTIVES OF HABITAT 108 Levins, R. 1969. Some demographic and genetic consequences of environmental heterogeneity for environmental control. Bull. Entomol. Soc. Am. 15:237-240. Levins, R. 1970. Extinction. Pp. 77-107 in Some Mathematical Questions in Biology, Vol. 2, M. Gerstenhaber, ed. American Mathematical Society, Providence, R.I. Likens, G.E. 1992. Excellence in Ecology. 3: The Ecosystem Approach: Its Use and Abuse. Ecology Institute, Oldendorf/Luhe, Germany. Liu, J. 1992. ECOLECON: A Spatially Explicit Model for Ecological Economics of Species Conservation in Complex Forest Landscapes. Ph.D. Dissertation. University of Georgia, Athens, Ga. Luken, J.O. 1990. Directing Ecological Succession. New York: Chapman and Hall. Marcot, B.G., and R. Holthausen. 1987. Analyzing population viability of the spotted owl in the Pacific Northwest. Trans. North Am. Wildl. Nat. Res. Conf. 52:333-347. McDonnell, M.J., and S.T.A. Pickett. 1988. Connectivity and the theory of landscape ecology. Münstersche Geographische Arbeiten 29:17-21. McKelvey, K., B.R. Noon, and R.H. Lamberson. 1993. Conservation planning for species occupying fragmented landscapes: The case of the northern spotted owl. Pp. 424-450 in Biotic Interactions and Global Change, P.M. Kareiva. J.G. Kingsolver, and R.B. Huey, eds. Sunderland, Mass.: Sinauer Associates. McNaughton, S.J. 1989. Ecosystems and conservation in the twenty-first century. Pp. 109-120 in Conservation for the Twenty-First Century, D. Western and M.C. Pearl, eds. New York: Oxford University Press. Menges, E. 1990. Population viability analysis for an endangered plant. Conserv. Biol. 4:52-62. Menges, E., D.M. Waller, and S.C. Gawler. 1986. Seed set and seed predation in Radicularis furbishiae, a rare endemic of the St. Johns River, Maine. Am. J. Bot. 73:1168-1177. Merriam, G., and A. Lanoue. 1990. Corridor use by small mammals: Field measurement for three experimental types of Peromyscus leucopus. Landscape Ecol. 4:123-131. Murphy, D.D., K.E. Freas, and S.B. Weiss. 1990. An environment-metapopulation approach to population viability analysis for a threatened invertebrate. Conservation Biology 4(1):41-52. NRC (National Research Council). 1986. Ecological Knowledge and Environmental Problem Solving: Concepts and Case Studies. Washington, D.C.: National Academy Press. NRC (National Research Council). 1993. Setting Priorities for Land Conservation. National Research Council, Washington, D.C. Neilson, R.P., and L.H. Wullstein. 1983. Biogeography of two southwest American oaks in relation to atmospheric dynamics. J. Biogeogr. 10:275-297. Noss, R.F. 1983. A regional landscape approach to maintain diversity. BioScience 33:700-706. Noss, R.F. 1987a. From plant communities to landscapes in conservation inventories: A look at The Nature Conservancy (USA). Biol. Conserv. 41:11-37. Noss, R.F. 1987b. Protecting natural areas in fragmented landscapes. Natural Areas J. 7:2-13. Noss, R.F. 1991. Landscape connectivity: Different functions at different scales. Pp. 27-39 in Landscape Linkages and Biodiversity, W. E. Hudson, ed. Washington, D.C.: Island Press. Noss, R.F., and L.D. Harris. 1986. Nodes, networks, and MUMs: Preserving diversity at all scales. Environ. Manage. 10:299-309. Ono, R.D., J.D. Williams, and A. Wagner. 1983. Vanishing Fishes of North America. Washington, D.C.: Stone Wall. Pattee, H.H. 1973. The physical basis and origin of hierarchical control. Pp. 71-108 in Hierarchy Theory: The Challenge of Complexity, H.H. Pattee, ed. New York: Braziller. use the print version of this publication as the authoritative version for attribution.

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About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please MODERN PERSPECTIVES OF HABITAT 109 Pickett, S.T.A. 1976. Succession: an evolutionary interpretation. Am. Naturalist 110:107-119. Pickett, S.T.A., and J.N. Thompson. 1978. Patch dynamics and the design of nature reserves. Biol. Conserv. 13:27-37. Pickett, S.T.A., and P.S. White, eds. 1985. The ecology of natural disturbance and patch dynamics. Orlando, Fla.: Academic. Pimm, S.L. 1991. The Balance of Nature? Ecological Issues in the Conservation of Species and Communities. Chicago: University of Chicago Press. Pulliam, H.R. 1988. Sources, sinks, and population regulation. Am. Naturalist 132:652-661. Pulliam, H.R., and B.J. Danielson. 1991. Sources, sinks, and habitat selection: A landscape perspective on population dynamics. Am. Naturalist 137:S50-S66. Pulliam, H.R., J.B. Dunning, and J. Liu. 1992. Population dynamics in complex landscapes: A case study. Ecol. Appl. 2:165-177. Risser, P.G. 1987. Landscape ecology: State of the art. Pp. 3-14 in Landscape Heterogeneity and Disturbance, M. G. Turner, ed. New York: Springer. Rotenberry, J.T., and J.A. Wiens. 1980. Temporal variation in habitat structure and shrub steppe bird dynamics. Oecologia 47:1-9. Schoener, T.W. 1986. Overview: Kinds of ecological Communities—Ecology becomes pluralistic. Pp. 467-479 in Community Ecology, J. Diamond and T.J. Case, eds. New York: Harper and Row. Schroeder, R.L., and M.E. Keller. 1990. Setting objectives: A prerequisite of ecosystem management. Pp. 1-4 in Ecosystem Management: Rare Species and Significant Habitats. New York State Museum, Albany, N.Y. Shafer, C.L. 1990. Nature Reserves: Island Theory and Conservation Practice. Washington, D.C.: Smithsonian Institution Press. Shipley, W., and P.A. Keddy. 1987. The individualistic and community-unit concepts and falsifiable hypotheses. Vegetation 69:47-55. Society of American Foresters. 1993. Task force report on sustaining long-term forest health and productivity. Society of American Foresters, Bethesda, Md. Soulé, M.E., ed. 1987. Viable Populations for Conservation. Cambridge, U.K.: Cambridge University Press. Soulé, M.E., and B.A. Wilcox, editors. 1980. Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, Mass.: Sinauer Associates. Stacey, P.B., and M. Taper. 1992. Environmental variation and persistence of small populations. Ecol. Appl. 2:18-29. Thompson, J.N. 1982. Interaction and Coevolution. New York: John Wiley & Sons. Turner, M.G., Y. Wu, L.L. Wallace, and W.H. Romme. 1994. Simulating winter interactions among ungulates, vegetation, and fire in northern Yellowstone Park. Ecol. Appl. 4:472-496. van Home, B. 1982. Population density as a misleading indicator of habitat quality. J. Wildl. Manage. 47:893-901. Verner, J., K.S. McKelvey, B.R. Noon, R.J. Gutierrez, G.I. Gould, and J.W. Bock. 1992. The California Spotted Owl: A Technical Assessment of its Current Status. USDA First Service Report PSW GJR-133. U.S. Department of Agriculture, Forest Service, Washington, D.C. von Bertelanffy, L. 1968. General System Theory: Foundations, Development, and Applications. Rev. Ed. New York: Braziller. Wagner, F.H., and C.E. Kay. 1993. "Natural" or "healthy" ecosystems: Are U.S. national parks providing them. Pp. 257-270 in Humans as Components of Ecosystems: The Ecology of Subtle Human Effects and Populated Areas. New York: Springer. Walker, B. 1989. Diversity and stability in ecosystem conservation. Pp. 121-130 in Conserva use the print version of this publication as the authoritative version for attribution.

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