Donald R. Strong

Bio: Donald R. Strong is an academic researcher from University of California, Davis. The author has contributed to research in topics: Spartina alterniflora & Spartina. The author has an hindex of 56, co-authored 164 publications receiving 15004 citations. Previous affiliations of Donald R. Strong include Florida State University.

Food Web Complexity and Community Dynamics

Abstract: Food webs in nature have multiple, reticulate connections between a diversity of consumers and resources. Such complexity affects web dynamics: it first spreads the direct effects of consumption and productivity throughout the web rather than focusing them at particular "trophic levels." Second, consumer densities are often donor controlled with food from across the trophic spectrum, the herbivore and detrital channels, other habitats, life-history omnivory, and even trophic mutualism. Although consumers usually do not affect these resources, increased numbers often allow consumers to depress other resources to levels lower than if donor-controlled resources were absent. We propose that such donor-controlled and "multichannel" omnivory is a general feature of consumer control and central to food web dynamics. This observation is contrary to the normal practice of inferring dynamics by simplifying webs into a few linear "trophic levels," as per "green world" theories. Such theories do not accommodate commo...

Ecological Communities: Conceptual Issues and the Evidence

Abstract: This work is the first to focus systematically on a much-debated topic: the conceptual issues of community ecology, including the nature of evidence in ecology, the role of experiments, attempts to disprove hypotheses, and the value of negative evidence in the discipline.Originally published in 1984.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

Are trophic cascades all wet? differentiation and donor-control in speciose ecosystems'

Abstract: Trophic cascades mean runaway consumption, downward dominance through the food chain. Especially vulnerable are the autotrophs. Standing crop and coverage of the plant community are reduced wholesale when one or a few species of potent herbivores are not suppressed. In archetypical trophic cascades, overwhelming effects propagate down through three trophic levels. Primary carnivores or diseases, by suppressing herbivores, switch the substrate from open and virtually bare to well occupied by plants. The discovery that these potent forces extend through four levels, in some instances (Carpenter and Kitchell 1988, Power 1990b), is surely one of the most important in all of ecology of the last decade; secondary carnivores, by suppressing primary carnivores, unleash herbivores that clear the substrate and greatly decrease standing crop of plants. In true trophic cascades, pervasive topdown influence combines with the always strong bottom-up influence through the food chain to produce acute intertwining between population, community, and ecosystem processes (Carpenter and Kitchell 1988, Oksanen 1990, Power 1992; M. J. Wiley, personal communication). True trophic cascades imply keystone species (Paine 1980), taxa with such top-down dominance that their removal causes precipitous change in the system. But all trophic interactions do not cascade, and simple top-down dominance is not the norm of communities or ecosystems. This point is central to the issues of this Special Feature, to Hunter and Price's (1992) proposal that the null hypothesis of food webs should be bottom-up forces, and Power's (1992) search for appropriate models of population dynamics of consumer and consumed. My premise is that true trophic cascades in the community sense are a relatively unusual sort of food web mechanics. I argue that, over the full range of ecological communities, evidence is that these cascades are restricted to fairly low-diversity places where great influence can issue from one or a few species; the majority of examples of true trophic cascades have algae at the

Biodiversity hotspots for conservation priorities

Abstract: Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Behavioral decisions made under the risk of predation: a review and prospectus

Abstract: Predation has long been implicated as a major selective force in the evolution of several morphological and behavioral characteristics of animals. The importance of predation during evolutionary ti...

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

Abstract: Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.