Microscale to macroscale feedbacks between vegetation and water

It has been suggested in several studies that large-scale feedbacks between vegetation and the water cycle may lead to large-scale hysteresis and alternative stable states. This is important, because small changes in climate may lead to dramatic effects on the vegetation and vice versa. Here, we analyse a simple spatially explicit soil-vegetation-atmosphere model in which both the effects of large-scale vegetation-precipitation and small-scale vegetation-soil water feedbacks are studied. We show that it is the small-scale vegetation-soil water feedback that causes large-scale hysteresis and alternative stable states, and not the large-scale vegetation-precipitation feedback. This is because the positive vegetation-precipitation feedback is counterbalanced by limited soil moisture and increased loss of evapotranspiration in the atmosphere. So, small changes in climate may lead to dramatic effects on the vegetation and vice versa because of small-scale vegetation-soil water feedback.