Tree-grass coexistence in savannas: The role of spatial dynamics and climate fluctuations

The codominance of trees and grasses in savannas is explained as resulting from the minimization of vegetation stress. It is shown that under differen t climate, soil and vegetation conditions local interactions dictated by th e spatial competition for soil moisture lead to an optimal state of minimum global water stress involving a stable coexistence of trees and grasses. T he optimal state matches the observed canopy cover and soil moisture charac teristics. Moreover, changes in canopy cover in the savanna environments ar e also suggested to result from climate fluctuations.