Water use by black wattle (Acacia mearnsii): implications for the link between removal of invading trees and catchment streamflow response

Abstract

This paper reviews relevant available information on rates of total evaporation from black waffle and from grasslands and fynbos shrublands. These data provide an indication of the likely change in catchment water yield following invasion or clearing of black wattle. The assumption is made that over the long term, reductions in total evaporation equate to water yield increases. Soil water storage and leakage from catchments are therefore considered to be small and constant under the different vegetation covers. Author’s review shows that very high rates of total evaporation are possible from dense infestations of black waffle occurring in riparian zones, where there are no soil water deficits through the year. Annual total evaporation from such sites may exceed 1500 mm, a figure that is comparable to many evergreen tropical lowland forests.