Legume diversity as indicator for botanical diversity on Sundaland, South East Asia

Abstract

The Global Legume Diversity Assessment (GLDA) proposes the legume family (Fabaceae or Leguminosae) – one of the largest and economically important plant families – as a target for a global botanical diversity assessment project. Where in the Neotropics and Africa legumes dominate the rain forest in terms of diversity and abundance, the Dipterocarpaceae claim this role in South East Asia and on Sundaland in particular. This raises the question whether legumes are an indicator for overall botanical diversity on Sundaland? To answer this question we use the largest compiled database of collection records of the region and species distribution modelling techniques. As a proxy for total botanical diversity we selected seven plant families; Dipterocarpaceae, Ericaceae, Fagaceae, Lauraceae, Moraceae, Myristicaceae, and Sapindaceae. Although the legumes were the most diverse family, the predictive power of legume diversity for overall botanical diversity was poor. This related to the fact that the other seven selected families largely represent trees, whereas legume species more equally represent all different growth forms. After assigning individual legume species to different growth habits (tree, liana, herb, miscellaneous) we were able to predict 78% of the variance in botanical diversity on Sundaland. The lianas represent the single growth habit that best predicted (66%) the variance in botanical diversity. The herb- and miscellaneous growth habits had an inverse relationship to botanical diversity. Legumes can be used as a predictor of overall botanical diversity in tropical and seasonal rain forests, but the relationship should be fitted for different biogeographic regions individually.