Small-scale soil patterns drive sharp boundaries between succulent “dwarf” biomes (or habitats) in the arid Succulent Karoo, South Africa

Quartz fields, which are densely covered by angular quartz gravel, represent edaphically special habitats in the Succulent Karoo, a winter rainfall desert in South Africa. They are home to an endemic flora and vegetation communities that show strong species turnover at their boundaries. We interpret the vegetation changes along these boundaries as analogous to biome boundaries: a functional shift is accompanied by a change in structure. Our study aims to identify which abiotic variables are associated with the abrupt shift in species and life form composition at the boundaries and whether these variables change as abruptly as the species composition.