An assessment of water use by Acacia longifolia trees occurring within the hillslopes and riparian zone of the Heuningnes Catchment, Western Cape
Abstract
The increasing expansion of Acacia longifolia trees along the riparian zones in South Africa
demands an urgent intervention as the species is listed in the National Environmental
Management: Biodiversity Act (2004). This list includes species that are prohibited from
growing, or being imported into South Africa. The detrimental effects of alien vegetation
have been observed on the hydrology of the ecosystems invaded. However, the actual water
use by Acacia longifolia has never been quantified. Therefore, there is inadequate knowledge
of the actual rates and the differences in water use rates by A. longifolia occurring in the
riparian zones and hillslopes. This study addresses this gap in knowledge by quantifying the
diurnal and seasonal transpiration dynamics of hillslope and riparian A. longifolia. The
variations of climate and soil water content on the hillslope and riparian zones were also
examined in this study. The study was conducted on the Spanjaardskloof hills and along the
Nuwejaars River (Moddervlei) in the Heuningnes Catchment, Cape Agulhas.