A hierarchical view of the interactions of runoff and infiltration with vegetation and microtopography in semiarid shrublands

Measurements of runoff and infiltration were made at five spatial scales, terracette (<1 m), hummock (10–20 m2), part-slope (1000–2000 m2), slope (1 ha) and catchment (50 ha), on a shrubland and an open forest site. The study was aimed at understanding the relationships between runoff production, vegetation patterns and microtopography at different spatial scales within a sparsely vegetated, semiarid area. The results of runoff monitoring and rainfall simulation experiments showed that runoff did not occur at the slope scale. It was buffered at the terracette level by nonuniform infiltration at the rims of terracettes and at the hummock scale by rapid infiltration under oak shrubs and trees. Slope and catchment runoff were not connected to runoff at these fine scales. The field evidence is discussed within the context of hierarchy theory, and the implications for management of these shrublands are related to maintaining both the vegetation mosaic and runoff on these slopes.