Ecologists and managers need to identify effective ways to apply ecological knowledge to deal with the wide range of environmental problems that confront us all. In this chapter we discuss ecological applications of theory and knowledge at the level of individual organisms and of single populations. This is the first of a trio of chapters; the others will address, in a similar manner, the application of the fundamentals of ecology at the level of population interactions (Chapter 15) and of communities and ecosystems (Chapter 22).

Management strategies often rely on an ability to predict where species might do well, whether we wish to revegetate contaminated land, restore degraded animal habitats, predict the future distribution of invasive species (and through biosecurity measures prevent their arrival) or conserve endangered species in new reserves. We describe how our understanding of niche theory provides a vital foundation for many management actions.

The life history of a species is another basic feature that can guide management. Particular combinations of ecological traits help determine lifetime patterns of fecundity and survival, which in turn determine the distribution and abundance of species in space and time. We consider whether particular traits (such as seed size, growth rate, longevity and behavioral flexibility) can be of use to managers concerned with the likelihood of a species being a successful part of a habitat restoration project, a problematic invader or a candidate for extinction and therefore worthy of conservation priority. Body size turns out to be a particularly important indicator of extinction risk.

A particularly influential feature of the behavior of organisms, whether animals or plants, is their pattern of movement and dispersion. Knowledge of migratory behavior and dispersion behavior in a patchy environment can underpin attempts to restore damaged and suboptimal habitats and in the design of conservation reserves. Moreover, a detailed understanding of patterns of species transmission by human agency permits us to predict and counter the spread of invaders.

Conservation of endangered species requires a thorough understanding of the dynamics of small populations. Theory tells conservation biologists to beware genetic problems in small populations, which needs to be taken into account when devising conservation management plans. Small populations are also subject to particular demographic risks that make extinction more likely. We focus on an approach called population viability analysis (PVA) - an assessment of extinction probabilities that depends on knowledge of life tables, population rates of increase, intraspecific competition, density dependence, carrying capacities and, when appropriate, metapopulation structure. Careful analysis of populations of particular species at risk can be used to suggest management approaches with the greatest chance of ensuring their persistence.

One of the biggest future challenges to organisms, ecologists and resource managers is global climate change. We deal with the way we can use knowledge about the ecology of individual organisms, coupled with predicted global changes in patterns in physicochemical conditions across the face of the globe, to predict and manage the spread of disease-carrying organisms and other invaders, and to determine the appropriate positioning of conservation reserves.

Part 2

Species Interactions ■ *

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