Browsing by Author "Pronk, Bianca Mignon"

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    Grasshoppers of azonal riparian corridors and their response to land transformation in the Cape Floristic Region
    (Stellenbosch : Stellenbosch University, 2016-03) Pronk, Bianca Mignon; Samways, Michael J.; Pryke, James S.; Bazelet, Corinna S.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
    ENGLISH ABSTRACT: The Cape Floristic Region (CFR) is a global biodiversity hotspot with high levels of endemism across many taxa, including Orthoptera. Azonal vegetation, a much forgotten component of the CFR, is a unique vegetation type that forms part of the riparian corridor. This is a complex, unique and diverse ecosystem with high levels of local biodiversity that connects the aquatic and terrestrial realms. The riparian corridor is highly disturbed through anthropogenic activities and invasion by alien vegetation causing deterioration of riparian corridors. Most natural riparian corridors are now confined to the mountainous slopes and higher elevations. Grasshopper assemblages are good bioindicators of environmental change and habitat deterioration. In response to this I determined the grasshopper assemblage which characterizes the natural riparian and adjacent terrestrial zone and their dispersion across the two zones. I also investigated how grasshoppers respond to riparian corridor disturbances (land transformation) and if they are viable candidates for bioindication of riparian corridors. In Chapter 2 I investigated the ecology of grasshoppers (Orthoptera: Acridoidea) within a non-biome specific natural riparian zone along an important river in the CFR (Lourens River). Grasshopper sampling took place in the natural riparian and terrestrial zones along seven sampling units (SU‟s) that were 25 m in length and 35 m wide, in both the riparian and terrestrial zones. The riparian sites were along the river in the riparian corridor whereas the terrestrial sites were farther away. I did find a significant difference between the natural riparian and terrestrial grasshopper assemblages, but I indicated that grasshopper abundance and species richness may be more associated with the riparian vegetation. In Chapter 3, I investigated how grasshoppers respond to land transformation along the riparian corridor of an important river in the CFR (Lourens River), whilst investigating the possibility of grasshoppers as bioindicators. Grasshopper sampling took place in different land use types (LUTs) (natural, agricultural, cleared of invasive alien-trees, invaded by alien-trees and an urbanized riparian area) along the riparian corridor. Each LUT had seven SU‟s per site where grasshopper sampling took place (as per Chapter 2). I found that grasshopper diversity is significantly influenced by the different LUTs and no CFR endemic grasshoppers were present within the invaded or urbanized riparian area. I found that the agricultural and cleared riparian areas had the highest abundance of grasshoppers and were most speciose with a great abundance of CFR endemic grasshoppers. I found that the cleared riparian LUTs had the most CFR endemic grasshopper richness and abundance. In general I found that grasshoppers respond to the different LUTs. In conclusion, there exists a riparian grasshopper assemblage in the natural riparian zone of the CFR. Conservation is hereby critical in this area as it adds to the biodiversity of the region. Land uses had significant influences on grasshopper assemblages, especially on CFR endemic grasshoppers along the riparian corridor. The conservation and maintenance of the mixture between riparian and fynbos plants are important for grasshopper assemblages and more so for the persistence of CFR endemic grasshoppers. Riparian corridor conservation and maintenance is critical for the maintenance and enhancement of grasshopper biodiversity in a biodiversity hotspot, the CFR.