Species dynamics and global environmental change: a perspective from ecosystem experiments
Global environmental change acts on ecosystems through its effects on organisms. It is almost inevitable that changes in the environment will alter metabolic and demographic rates and the distributions of populations. The new configurations of species that arise from global change will have no evolutionary history of association and will not have been studied previously by ecologists. Their interactions, stability, and resistance to future changes are difficult to predict. Yet predicting these community properties is fundamental to anticipating and mitigating the effects of global change on ecosystems. In this chapter, global environmental change is defined as anthropogenic stress that acts over large regions of the earth and may affect biospheric fluxes of radiation, gases, water, and solutes. These stressors include global climate change, global land use change, many pollutants, species invasions and extirpations, and others. The ecological consequences of global climate shifts must be gauged against the background of ongoing change driven by land use, pollution, species replacement, etc. In a statistical sense, these factors are confounded: independent variables are changing simultaneously, and their separate effects on the dependent variables are difficult to discern. However, some information on the effects of perturbations is available from case studies. The lessons learned have important implications for our efforts to anticipate consequences of global climate and land use change.
Sinauer Associates, Inc.