Light Rainfall and Plant Survival in E. Africa II. Dry Grassland Vegetation

Abstract

Rain-water penetration of the soil beneath a number of dry grassland communities was examined a few hours after a light shower in Kenya Masailand. It was found that for the particular communities studied, the type of soil present and the amount of rainfall, the depth of rain-water penetration is approximately equal to the height of the plant plus the normal penetration of the shower into the bare soil. The sectional area of the wet soil mass beneath each vegetation clump is also approximately equal to the sectional area of the clump showing above ground plus an area corresponding to the amount which would have fallen there had there been no plant cover. It is considered that in the overgrazed dry grassland parts of Kenya Masailand, stem-flow and rain-water penetration around trees of B. aegyptiaca may now be playing a part in changing the character of the local vegetation. It is also suggested that leaf catchment-stemflow systems may be involved in the maintenance of grassland vegetation patterns noted in other regions by other workers.