Following an extreme disturbance, the ecosystem may go through the process of primary succession, which is characterized by a predictable series of developmental stages that culminate in a climax community – a stable biotic community that represents the final stage of succession. In many cases a disturbance will only kill some of the organisms within the ecosystem. In these cases, the ecosystem may go through a process of secondary succession, in which many factors, including the intensity of the disturbance, the life history traits of colonizing species, and the presence of biological legacies influence the recovery process. Ecologists have described three conceptual models of succession – facilitation, tolerance, and inhibition – that apply under different conditions in different ecosystems. Animals play an important role in the recovery process. Many animal species are excellent dispersers and can quickly return to a disturbed ecosystem. Even if they are unable to establish a breeding population, animals can import seeds or nutrients into a disturbed habitat. Alternatively, animals can inhibit the recovery process by eating seeds or young plants before they get established. In some cases, disturbance can cause ecosystems to experience a regime shift – a very rapid change from one stable state to another.

This chapter provides a synthesis of the information presented in the previous chapters. First, the empirical evidence presented in Chapters 3 and 4 is evaluated in relation to the theoretical ideas described in Chapter 2. This is achieved through the evaluation of some tentative propositions, based on available theory. Selected issues that emerged during the review of empirical evidence are then considered, and an attempt is made to answer the overarching questions identified at the start of the book. A second section then examines the implications of our current understanding for conservation policy and practice. Specifically, how can we avert the collapse of ecosystems and support their recovery?