The global biogeography of semi-arid periodic vegetation patterns
Résumé
Aim: Vegetation exhibiting landscape-scale regular spatial patterns has been reported for arid and semi-arid areas world-wide. Recent theories state that such structures are bound to low-productivity environments and result from a self-organization process. Our objective was to test this relationship between periodic pattern occurrence and environmental factors at a global scale and to parametrize a predictive distribution model. Location: Arid and semi-arid areas world-wide. Methods: We trained an empirical predictive model (Maxent) for the occurrence of periodic vegetation patterns, based on environmental predictors and known occurrences verified on Landsat satellite images. Results: This model allowed us to discover previously unreported pattern locations, and to report the first ever examples of spotted patterns in natural systems. Relationships to the main environmental drivers are discussed. Main conclusions: These results confirm that periodic patterned vegetations are ubiquitous at the interface between arid and semi-arid regions. Self-organized patterning appears therefore to be a biome-scale response to environmental conditions, including soil and topography. The set of correlations between vegetation patterns and their environmental conditions presented in this study will need to be reproduced in future modelling attempts.