Livestock paths on Namaqualand quartz fields: Will the endemic flora disappear?

Abstract

a b s t r a c tQuartz fields are rare features that contribute significantly to vegetation diversity and endemism of South Africa's Succulent Karoo Biome. The Riethuis-Wallekraal quartz fields in the north-western Namaqualand area of South Africa contain 17 quartz field specialist species of which seven are endemic to this specific area. Hoofaction by livestock has formed paths of approximately 0.30 m on these quartz fields. It would be important to conservationists to understand whether direct (e.g. trampling) and indirect effects (e.g. burial of flora by sediment movement) associated with the livestock paths holds any threat to the dwarf succulent (b 0.05 m) and micro-chamaephytes (0.06-0.15 m) endemic to the quartz fields. We tested the hypotheses that the unique quartz field vegetation and biological soil crusts would be affected by loose soil particles transported downslope from the paths. The soil stability index, total vegetation cover, cover of specialized quartz field species and species diversity were lower on livestock paths but did not differ between upslope and downslope locations. Livestock paths also had lower cover and fewer quartz field specialist species. It is concluded that under conditions of intense and continuous grazing, livestock are likely to have an even stronger negative impact on the specialist quartz field flora.

Do image resolution and classifier choice impact island biogeographical parameters of terrestrial islands?

“…This is particularly difficult in vast and remote areas with reduced access by road. Remote sensing provides the means to extract this information from satellite imagery with high reproducibility, objectivity, and low cost.Quartz islands, also referred to as quartz fields (Schmiedel & Jürgens, 1999;Van Tonder, Milton, & Cameron, 2014), quartz patches (Curtis, Stirton, & Muasya, 2013), quartz-lag gravel habitat , or quartz gravel plains (Ellis, Weis, & Gaut, 2006), are edaphic habitat islands in the Succulent Karoo and adjacent biomes of southern Africa, which present a unique, edaphically arid ecosystem surrounded by matrix vegetation on zonal soils (Schmiedel & Jürgens, 1999). These quartz islands have their own vegetation, which differs strongly from the matrix vegetation in terms of structure, composition, and diversity (Eibes et al, 2021;Schmiedel & Jürgens, 1999).…”