Partitioned beta diversity patterns of plants across sharp and distinct boundaries of quartz habitat islands

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  • Pia Maria Eibes
  • Jens Oldeland
  • Severin David Howard Irl
  • Alina Twerski
  • Nicole Kühne
  • Ute Schmiedel

Questions: Habitat islands are often characterized by the presence of more or less sharp boundaries to adjacent matrix habitats. However, knowledge on boundaries of natural habitat islands is scarce, especially regarding patterns of beta diversity and its two underlying components: species turnover and nestedness. We therefore aim to quantify the effects of fine-scaled and sharp boundaries of quartz islands (quartz gravel-covered soils) on the different components of plant beta diversity and how they are linked to different soil environmental drivers. Location: Knersvlakte, Western Cape, South Africa. Methods: We sampled plant species richness in 56 fine-scale transects of 6 m × 1 m plots across eight different boundary types (four quartz island to matrix, four between habitats on quartz islands). Soil depth and chemistry (pH, electrical conductivity) were analyzed for each 1 m2 plot. Differences in the two beta diversity components (turnover and nestedness) for each boundary type were tested by t tests. We used linear models to test relationships between species and environmental dissimilarity. Results: All boundary types showed high beta diversity. Species turnover was the prevailing component for six boundary types, the nestedness component was only important for two boundary types. We found a significant linear increase of species dissimilarity with increasing dissimilarity in soil pH and distinct plant communities for the habitat types, but no significant increase for electrical conductivity or soil depth. Conclusions: The spatial distinctiveness of the quartz islands leads to sharp boundaries, which result in high beta diversity, mainly through species turnover. This reflects the high levels of diversification and adaptation of the local plant communities. Nestedness occurred at two boundaries to the matrix, indicating that the latter does not necessarily represent an impermeable boundary for all species of the respective ecosystem. Studying diversity patterns across boundaries contributes to the question of applicability of island biogeography theory to habitat islands.

Original languageEnglish
Article numbere13036
JournalJournal of Vegetation Science
Issue number3
Number of pages11
Publication statusPublished - 01.05.2021
Externally publishedYes

Bibliographical note

This research was funded by the German Research Foundation (DFG project number 404519812) and by the German Federal Ministry of Education and Research (BMBF project number 01LG1201N–SASSCAL). The field work of AT and NK was financially supported by the Deutsche Kakteen Gesellschaft (DKG)

    Research areas

  • beta diversity, boundary dynamics, community ecology, diversity indices, ecotone, edge effects, habitat island, nestedness, quartz fields, soil diversity, species turnover, Succulent Karoo, transition zone
  • Ecosystems Research