A comparative assessment of water use by Acacia longifolia invasions occurring on hillslopes and riparian zones in the Cape Agulhas region of South Africa.

Publication date: Available online 19 October 2018Source: Physics and Chemistry of the Earth, Parts A/B/CAuthor(s): Y.P. Mkunyana, D. Mazvimavi, S. Dzikiti, Z. NtshidiAbstractThe detrimental impacts of invasive alien plants on ecosystems and water resources have raised concerns in arid and semi-arid countries like South Africa where the average precipitation is approximately 500 mm/yr, which is below the world average of around 860 mm/yr. Several studies have examined the effects of invasive alien plants such as the Australian Acacias on the water resources. However, few studies have quantified the differences in water use between hillslope and riparian Acacia longifolia invasions. A. longifolia is one of the aggressive invader species in South Africa even on hillslopes that contribute substantially to runoff generation. Therefore, the encroachment of invasive alien plants has the potential to reduce runoff, thereby adversely affecting the available water downstream. This paper aims to; 1) compare transpiration rates of A. longifolia growing on hillslopes and along riparian areas, 2) establish the key drivers for water use by this species, and 3) estimate the hydrological impacts of the invasions at the catchment scale in the Heuningnes catchment, in the Western Cape Province of South Africa. Transpiration by the trees was measured using the heat pulse velocity sap flow method. Automatic weather stations and soil moisture sensors were used to monitor weather and soil water co...
Source: Physics and Chemistry of the Earth, Parts ABC - Category: Science Source Type: research