Integrating patch and boundary dynamics to understand and predict biotic transitions at multiple scales

Human modification of landscapes overlying natural environmental heterogeneity is resulting in an increase in the numbers and types of ecological patches and their intervening boundaries. In this paper, we describe an operational framework for understanding and predicting dynamics of these biotic transitions for a range of environmental conditions across multiple spatial scales. We define biotic transitions as the boundary and the neighboring states, a more general definition than typically denoted by the terms boundary, ecotone, edge or gradient. We use concepts of patch dynamics to understand the structural properties of biotic transitions and to predict changes in boundaries through time and across space. We develop testable hypotheses, and illustrate the utility of our approach with examples from arid and semiarid ecosystems. Our framework provides new insights and predictions as to how landscapes may respond to future changes in climate and other environmental drivers.