The effect of different vineyard management systems on the epigaeic arthropod assemblages in the Cape Floristic Region, South Africa
Thesis (MScConsEcol (Conservation Ecology and Entomology)--Stellenbosch University, 2008.
In the Cape Floristic Region of South Africa, where wine grape production and biodiversity conservation are of major importance, innovative management of the landscape is necessary to integrate the two activities. Alternative farming, such as organic and biodynamic farming, focuses on the preservation of biological processes in agroecosystems with the aim of increasing the sustainability of these sytems. It has been demonstrated in other regions that alternative farming can enhance biodiversity. This study assessed the potential of alternative vineyard management to conserve biodiversity, in particular epigaeic arthropod diversity, relative to the more widespread integrated vineyard management in the CFR. A hierarchical design was used, consisting of three localities, with three land-uses nested within each locality. The land-uses were alternative vineyards, integrated vineyards and natural vegetation sites as reference habitats. Sampling was done in June and October 2006 using pitfall traps. Nested ANOVAs were used to test for differences in abundance and species richness of the total assemblages, functional feeding guilds and selected generalized predatory taxa. Assemblage patterns were assessed using hierarchical agglomerative clustering and non-metric multidimensional scaling. Canonical correspondence analyses were used to evaluate the effects of environmental variables, management practices and landscape variables on community composition. Alternative vineyards supported a significantly higher overall arthropod abundance and species richness, more diverse predatory, saprophagous, phytophagous and omnivorous guilds, as well as more abundant and speciose spider and rove beetle assemblages than the integrated vineyards. Integrated vineyards harboured a greater abundance of predators, whereas results for nectarivores, wood borers, parasitoids and carabid beetles were variable. The differences could be explained in part by higher non-crop vegetation complexity and reduced management intensity of the alternative vineyards. Community composition was influenced by a combination of management practices, the surrounding landscape and geographic locality, which highlighted the interdependence of the cultivated land and its surroundings.