Ecology can be viewed at different levels of organisation, from individuals to the global ecosystem. Whatever the scale, flows and movements are important in conceptualising how nature works. This theme is best developed within the field of landscape ecology, which deals with the effects of spatial pattern on ecological processes, especially the movement of organisms, abiotic materials and energy across landscapes. Reiners and Polzer introduce a conceptual framework for the study and understanding of propagation of ecological influences across landscapes, and provide examples of models that describe and predict propagation.