Ecosystem Collapse and Recovery

Abstract

This book is not a textbook nor practical guide on how to tackle ecosystem collapse or recovery. It is rather an extensive, thorough account of a topic that has recently attracted a lot of attention, seen from a variety of angles. It is noteworthy that it references over 1 200 citations on a subject that, one would assume, is relatively new or rather limited. This wealth of information actually reflects the fact that the book is written by integrating viewpoints from a variety of disciplines, among them that of theoretical ecology and of conservation biology. Typically, ecosystem collapse is related to the existence of alternative stable states and tipping points, a rather theoretical concept that is hard to prove. Lately, however, ecosystem collapse has also found a place in conservation science featured under the IUCN Red List of Ecosystems. This is reflected in the book, which reviews the variety of ways that different communities have defined these two terms. Yet, although the terms and the topic sound self-explanatory, there is no formal definition of ecosystem collapse or recovery. In the book, the definition adopted for ecosystems collapse is a transformation of identity, a loss of defining features and a replacement by a different ecosystem type. Ecosystem recovery is the reverse process. Chapter 1 includes the aims of the book and marks the boundaries of what the book covers. A series of questions that address what ecosystem collapse is, why it occurs, what are the implications, whether it is possible to provide early-warning for collapse to be prevented, as well as what are the mechanisms of recovery and whether they are the same across ecosystems, are few examples of what the book is after. The reader finds potential answers to these questions in the last chapter of the book (Conclusions). Chapter 2 presents the subject from a more theoretical perspective. Notions of ecological disturbance, succession, state-and-transition models, bifurcation theory, planetary boundaries, critical thresholds, resilience and even ecological networks and extincion cascades are covered. At places, the connection between these concepts appears hard to establish. It, however, reflects the different starting points of different communities on the topic, as well as the intention of the book to stress the connection between species communities and ecosystem responses, while emphasising less consciously the perspective of ecosystem functioning and collapse. The following two chapters switch to the empirical side of the topic. Chapter 3 travels to past, deep time examples from the fossil record. It covers the big five mass extinctions on the paleological record, the loss of Australian megafauna, and the relatively more recent examples of extinctions in New Zealand and Madagascar following human colonisation, as well as the transformation of the green Sahel to the present desert state. Chapter 4 provides current case studies that motivate the idea that ecosystem collapse happens and it is thus repeatable and probable under global change. Examples contain the usual suspects, corals reefs, fisheries, lakes, savannas, and less prominent examples, like forests (covered quite extensively), and temperate agroecosystems. For every example ecosystem, there is a part on collapse and a part on recovery. Chapter 5 is the most challenging part of the book as it aims to evaluate the relationship between the theory and the empirical examples. There are propositions on generalisations that are derived from the empirical examples, key findings that can help understand the mechanisms of collapse, but also implications for conservation policy and practice. The latter range from defining ecosystem collapse to risk assessment, management and recovery, and even implications for people. There appears a provocative question of whether ecosystem collapse would actually matter for people or not. Chapter 6 is a concluding chapter that summarises the findings of the book and provides suggestions for further research. It is a much needed and well-structured chapter that facilitates the reader to navigate through the wealth of information presented in the previous chapters. What is particularly helpful in the structure of the book are the conclusions at the end of each chapter and a series of tables that aim to summarise and highlight ideas, conclusions and propositions. Also the structure allows for the book to be read in different ways: one could concentrate on the theoretical aspects (Chapter 2) or the empirical cases (Chapter 3 and Chapter 4), focus on particular examples of interest (Chapter 4), or read directly the synthesis and conclusions (Chapters 5 and 6). Book Review