Chapter 1 - Overview

Abstract

This book is organized to emphasize feedbacks among individual, population, and community levels, and the ecosystems they represent. Three themes integrate these ecological levels. First, spatial and temporal patterns of environmental variability and disturbance determine survival and reproduction of individuals and patterns of population, community, and ecosystem structure and dynamics. Second, energy and nutrients move through individuals, populations, communities, and abiotic pools. The net foraging success and resource use by individuals determine energy and nutrient fluxes at the population level. Trophic interactions among populations determine energy and nutrient fluxes at the community and ecosystem levels. Third, regulatory mechanisms at each level serve to balance resource demands with resource availability (carrying capacity) or to dampen responses to environmental changes. Regulation results from a balance between negative feedbacks that reduce population sizes or process rates and positive feedbacks that increase population sizes or process rates. Anthropogenic alteration of ecosystem structure and function can create conditions suitable for outbreaks by some species or threaten the survival of others, thereby altering ecosystem conditions and capacity to deliver ecosystem services on which human survival depends.