Diverging responses of taxonomic, functional, and phylogenetic plant diversity to biogeographic parameters in arid habitat islands of southern Africa

Habitat islands conceptually bridge true islands and habitat patches, adding new perspectives to island biogeographic principles that shape community assembly processes. Despite growing interest, empirical studies are scarce, and the drivers of biodiversity in these systems, such as different aspects of island shape, isolation, and habitat diversity, remain unclear. Our aim was to assess how biogeographic parameters influence taxonomic, functional, and phylogenetic plant diversity on habitat islands using quartz islands in South Africa as our model system. We conducted floristic surveys on 20 quartz islands in the harsh and arid summer-rainfall region around Pofadder (Nama–Karoo, South Africa) to quantify species richness, functional dispersion, and phylogenetic mean pairwise distance. Via remote sensing, we derived island metrics and evaluated their effects on the diversity metrics, using multivariate regression analysis. We fitted negative binomial generalized linear models for specie..., , # Diverging responses of taxonomic, functional, and phylogenetic plant diversity to biogeographic parameters in arid habitat islands of southern Africa

Dataset DOI: [10.5061/dryad.15dv41p8x]([https://doi.org/10.5061/dryad.15dv41p8x]\(https://doi.org/10.5061/dryad.15dv41p8x\))

## Description of the data and file structure

**Summary**:

The data were collected during field surveys (February and March 2024) on 20 quartz islands in the Pofadder region (Northern Cape, South Africa) to investigate vascular plant species composition, plant functional traits, and island biogeographic characteristics. Species occurrence was recorded as presence–absence per island, and functional traits of perennial plant species were measured on multiple individuals to derive species-level mean trait values. In addition, island shape, isolation, and habitat diversity indices were calculated on the basis of island polygons derived from a quartz island classification using satellite imagery and elevation-based ...,