Preface from Applied Population Ecology

Applied Population Ecology:
Principles and Computer Exercises using RAMAS^® EcoLab

by H. Resit Akçakaya, Mark A. Burgman, Lev Ginzburg

Preface

        Practical ecological problems such as preservation of threatened species, design of nature reserves, planned harvest of game animals, management of fisheries, and evaluation of human impacts on natural systems are addressed with quantitative tools, such as models. A model is a mathematical representation of a natural process. Many biologists now use models implemented as computer software to approach the quantitative aspects of these practical problems.

        In addition to their practical use, such models are excellent tools for developing a deeper understanding of how nature works. You can use the program described in this book, RAMAS EcoLab, to apply most of the concepts discussed in the book, and develop your own models. At the end of each chapter, there are a set of exercises. Some of these require only pencil and paper, some require a calculator, and others require the program. Although the book can be used without the program, we believe that most of the more complicated concepts will be much easier to understand when you demonstrate them to yourself using the program.

        We hope that, in addition to teaching you the principles of, and practical methods used in, population ecology, this combination of textbook and software will also stimulate you to learn more about modeling, mathematics and programming. It might even inspire you to write your own computer program for developing ecological models. The principles of building models using a software such as RAMAS EcoLab are the same as those of writing your own equations or computer programs (even though the technical details are very different). Our focus here is not the mechanics of how a model is implemented, but rather understanding how various interacting ecological factors should be put together, and understanding the implications of the model's assumptions. Our aim is to discuss principles of population ecology, to show a collection of methods to implement these principles, and to help you appreciate both the advantages and limitations of addressing ecological problems with the help of models.

To the teacher

        This book introduces principles of population ecology, with special emphasis on applications in conservation biology and natural resource management. Each chapter includes examples and laboratory exercises based on the software RAMAS EcoLab. While less powerful than the research-grade software developed by Applied Biomathematics, RAMAS EcoLab incorporates all features of the RAMAS Library essential for teaching the basic principles of population ecology, at a level accessible to undergraduate students.

        In an introduction to population ecology, most undergraduate students consider learning the mathematics required by traditional texts to be an unnecessary hindrance. The aim of this book is to teach quantitative methods that are necessary to develop a basic understanding and intuition about ecological processes, without intimidating or discouraging students who do not have extensive mathematical backgrounds. Even students who are intimidated by mathematical equations are not usually afraid of using computers. We hope that our integration of software that implements mathematical models in population ecology with an undergraduate textbook will make these models accessible to undergraduates in biological and environmental sciences.

        It should be emphasized that we do not consider developing models with the use of software as an alternative to learning the underlying mathematical concepts. The goal of this book is to introduce mathematical ecology by developing an intuitive understanding of the basic concepts and by motivating the students through examples that put these concepts to practical use. We believe that use of software greatly enhances the understanding of the concepts while encouraging the use of, and emphasizing the need for, quantitative methods.

        In addition to the use of software, there are a number of other points in which this text diverges from the more traditional textbooks on population ecology. For example, we decided to develop the models almost exclusively in discrete time (with difference equations), and only briefly mention such things as instantaneous birth and death rates. The equations we use are qualitatively equivalent to the corresponding differential equations, but we believe they are much more intuitive and easy to grasp.

        Another important difference is our emphasis on, and early treatment of variability and uncertainty. Use of software instead of analytical models has allowed us to incorporate these important concepts from early on, in a way that is simple enough to be easily understood by undergraduate students without strong mathematical backgrounds.

        We develop the models from the very beginning in a way that will make the later addition of concepts such as demographic stochasticity and age structure very natural and intuitive. In discussing population regulation, we postponed writing down the famous logistic equation almost to the end of the chapter, concentrating instead on the general, qualitative aspects and dynamic consequences of density-dependent population growth. We started the chapter on age structure with analyzing census data to build a matrix model, rather than the more traditional life-table approach. We suspect that starting with life tables causes some of the confusion that arises when life table variables are to be used to build age-structured models.

        We designed the book and the software with sufficient flexibility to allow their use in lecture classes, computer laboratories, or both. They can be used in a lecture class accompanied by a computer laboratory, or in a lecture class in which the examples that require software are assigned as homework exercises, or in a laboratory course where the exercises are the main focus and the conceptual material is read by students. Our hope is that the software tool we provide, in combination with our practical approach, will make population ecology easier to learn and to teach.

Also see:

RAMAS EcoLab features
Table of Contents

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