The pattern behind vegetation patterns and what does it tell us about desertification

The significance of vegetation patchiness to ecosystem function is well recognized. During the past decade an increasing number of studies have appeared, reporting on the observations of self-organized patchiness in a variety of terrestrial and marine ecosystems. In parallel, model studies have uncovered small-scale biomass-resource feedbacks that give rise to periodic and disordered patterns at large scales, and thus explain the observations. However, the implications of vegetation pattern formation for various ecological processes, such as biodiversity change, desertification and rehabilitation have hardly been studied. In this talk I will focus on pattern formation aspects of desertification and rehabilitation. Unlike the common view of desertification as an abrupt transition from a productive stable state to a less productive alternative stable state, pattern formation theory suggests the likelihood of gradual transitions involving extended pauses at many intermediate stable states of decreasing productivity. This finding calls for re-examination of currently proposed warning signals of imminent desertification. Pattern formation theory also suggests a novel view of rehabilitation of degraded landscapes – rehabilitation as a spatial resonance problem. Motivated by this application, we studied the impact of 1d periodic spatial forcing on 2d pattern forming systems, revealing instabilities that shed new light on current rehabilitation practices. I will conclude with a few comments on the significance of integrating pattern formation theory into spatial ecology.

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