Newly discovered landscape traps produce regime shifts in wet forests

• David B. Lindenmayer, and others
• Proceedings of the National Academy of Sciences

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12 September 2011In many environments worldwide, key drivers of ecosystem change interact and reinforce one another to trigger cascades of ecosystem modification that are difficult or impossible to reverse. These cascades are often referred to as regime shifts. Examples of significant regime shifts include overfishing and trophic cascades in marine predator–prey systems and human disturbance-driven losses of detritivore populations and subsequent changes in the decomposition of organic matter. Regime shifts are almost always identified in retrospect, making it difficult to know how to avoid them in advance and problematic to reverse their effects. Therefore, understanding of the mechanistic processes by which regime shifts occur may provide opportunities to change resource management and avoid irreversible and undesirable ecological changes.

In this paper, the authors describe the “landscape trap” concept, of which the outcome is a regime shift triggered by a series of feedback processes resulting from interacting natural and anthropogenic disturbances. They define a landscape trap as that wherein entire landscapes are shifted into a state in which major functional and ecological attributes are compromised. These shifts in a landscape lead to feedback processes that either maintain an ecosystem in a compromised state or push it into a further regime shift in which an entirely new type of vegetation cover develops. Landscape traps are large-scale ecological phenomena that arise through a combination of altered spatial characteristics of a landscape coupled with synergistic interactions among multiple human and natural disturbances. Thus, changes in the frequency and spatial contagion of large-scale disturbances are the key interacting factors driving entire landscapes into an undesirable and potentially irreversible state (i.e., landscape trap). The authors demonstrate the concept with examples involving spatial and temporal feedback between logging and fire in forest ecosystems and also provide examples of landscape traps in other environments.

Authors: David B. Lindenmayer, Richard J. Hobbs, Gene E. Likens, Charles J. Krebs, and Samuel C. Banks.