Modelling Vegetation Patterns in Semiarid Environments

The aim of this work is to deepen our understanding on the mutual relationship between climate, vegetation and soil water budget within an ecohydrological framework. To this end a coupled hydrological/ecological model is adopted to describe simultaneously soil water budget and vegetation pattern evolution in a semiarid river basin in New Mexico (USA). This basin represents an ideal area to study the properties of water-controlled ecosystems. Analyses have been carried out using a recently formulated framework for the water balance at the daily level linked with a vegetation model for the description of the spatial organization of vegetation. Using this approach, we identified the dynamic water stress of vegetation during the growing season, taking into account effects of morphology on the spatial distribution of solar radiation and the initial soil moisture condition at the beginning of the growing season. Several different variants of the vegetation model have been tested with the aim to identify the main drivers for the spatial organization of the vegetation. Results clearly show that the observed vegetation patterns emerge from the minimization of water stress and the maximization of water use.