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Dryad

Data from: The contribution of hydric habitats to the richness of the Cape fynbos flora

Data files

Dec 20, 2024 version files 348.79 MB

Abstract

Aim: The Cape Fold Belt Mountains, underlying the Cape fynbos flora, facilitate widespread moisture collection and groundwater availability across the region, with importance for maintaining hydric habitat niches. We assessed the contribution of hydric habitat associated species (HH species) to the richness of this flora, and how this varies phylogenetically and spatially.

Location: The Cape Floristic Region (CFR), South Africa.

Methods: We compiled data describing habitat preference, and distributions for 3114 species in 23 fynbos clades. We used published habitat descriptions to identify putative HH species and tested how hydric habitat association is structured phylogenetically using both Ornstein-Uhlenbeck models and measures of phylogenetic signal. We used species’ distribution data to identify regional hotspots of HH species and boosted regression trees to identify associated environmental drivers.

Results: Preference for hydric habitats is associated with nearly a fifth of the species in our study, being most strongly represented in monocot clades. HH species are most strongly concentrated in the southwestern CFR, where they contribute to high overall richness. Boosted regression trees (BRTs) indicated that hotspots of HH species are generally associated with saturating, winter precipitation and/or elevated levels of groundwater discharge.

Main conclusions: Our findings indicate that the unique climate, topography and hydrology of the CFR facilitate the formation and maintenance of important hydric habitats, which play host to a large fraction of the flora despite much of the region being semi- or seasonally arid. These findings highlight the threat of climate change and underscore the need for extreme caution regarding activities like groundwater abstraction, which could disrupt the hydrological processes essential to sustaining these habitats and their unique flora.