Habitat preferences of the encroacher shrub, Seriphium plumosum

Abstract

The ecology of Seriphium plumosum is not yet fully understood and therefore requires in-depth research to assist with the control of this encroacher plant. The habitat preferences of the plant were quantified for terrain morphological units in terms of soil fertility, saline/sodic conditions and soil–water relationships. The influence of S. plumosum density on grass production was also quantified. It is clear that the distribution (both occurrence and density) of S. plumosum is associated with soil characteristics. The study indicated the sensitivity of S. plumosum towards wet conditions, perennial and transient water tables, overly high soil pH, clay content, high soil fertility (organic matter and phosphate) and sodium chloride. The deeper the soil profile, the more favourable the habitat for S. plumosum, owing to a decrease in waterlogged conditions. The habitat prevalence of S. plumosum is possibly a reflection of not only climatologically wetness but also of topographic wetness. There was no clear general trend for the individual cations along the terrain units. A significant relationship was established between aboveground phytomass production loss of the grass sward and S. plumosum density. These results confirm the threat posted by S. plumosum in semiarid grassland areas, following changes in environmental characteristics.