Recipe for orchid diversity: Mix habitat temperatures, topography and water

Climatic variety and topographic complexity prove to be powerful indicators of island species richness and endemism

Data resources used via GBIF : 8,935 species occurrences

Philippine Ground Orchid (Spathoglottis plicata) by Leon Perrie via iNaturalist. Photo licensed under CC BY-NC 4.0.

Age, area and isolation—researchers studying island biogeography have long presumed this trio to be the three critical factors in determining species richness. 

With its dust-like seeds that disperse easily in the breeze, the famously diverse orchid family makes significant contributions to the plant species richness across the Pacific Islands. Relying on GBIF-mediated data from eight southwestern Pacific archipelagoes, this study builds on recent research suggesting that measuring the variation in an island's climate and topography can effectively predict habitat diversity and, in turn, species richness.

The authors found that indicators of topographic complexity, temperature and precipitation can match the power of land area in predicting orchid richness and endemism in the southwest Pacific. And while isolation does help explain the decreasing pattern of Orchidaceae diversity from west to east, age fails to predict the species richness across islands and archipelagos. As a result, the study suggests refinements toward improving our understanding of the tangled banks of island biodiversity.

Keppel G, Gillespie TW, Ormerod P and Fricker GA (2016) Habitat diversity predicts orchid diversity in the tropical south-west Pacific. Journal of Biogeography. Wiley-Blackwell 43(12): 2332–2342. Available at doi:10.1111/jbi.12805.