Interpretation And Implications Of Variability In Ecological Systems

Interpretation and Implications of Variability in Ecological Systems

Numerous hypotheses have been proposed to explain the dynamics in abundance of individual species, how species interact, how communities assemble, and how interactions between biotic and abiotic processes shape ecosystem stability. Many if not most of these hypotheses find some degree of support, but often only within relatively narrow spatial and temporal ranges. This is because conditions vary over time and from place to place, and so the strength and extent of processes that were the focus of a given a hypothesis become altered by other forces. Ecologists have confronted variability from two perspectives; conceptual and statistical. Conceptually, spatial and temporal variability are now recognized as being scale dependent and hierarchical. Statistically, there are many models that ecologists readily use that account for the hierarchical and scale-dependence of variability present in many datasets. But linking the two perspectives into a meaningful understanding of what variability means in real systems has been much less successful. For example, it is common to see studies where the fixed effects of a generalized linear mixed model are reported, but very often random effects are completely ignored or, at best, given scant attention. The likelihood of this being a significant problem increases greatly in what are rapidly becoming more common studies that utilize datasets spanning long temporal and/or large spatial scales, or when extreme and often unpredictable events (gray and black swans) occur.

The Impact of Environmental Variability on Ecological Systems

Fluctuations in the environmental conditions impacting life are ubiquitous. These fluctuations induce changes in the vital processes occurring within individual organisms (such as cellular metabolism) and the ecological processes occurring among individuals (such as competition, mutualism, and predation), ultimately leading to observable fluctuations in the commonly measured characteristics of ecological systems. From a very simple perspective, these processes are all modulators of environmental variability. We might best be able to understand the final form of this modulation – the impact of environmental variability on ecological systems - by building from an understanding of the responses of these life processes in isolation to an understanding of their responses in harmony. The impact of environmental variability on ecological systems is an issue that has been at the forefront of ecological research for many years. Research is taking place on many fronts, including theoretical mathematical based analyses, natural ecosystem observation and experimentation. This book brings together contributions from these three fronts to provide readers with a comprehensive look at the challenges for ecological systems and ecological research alike.

Ecological Assessments of Effluent Impacts on Communities of Indigenous Aquatic Organisms