Dark diversity reinforces the importance of climate, soil and disturbance for Caatinga plant diversity

Abstract

Abstract Species richness is the most commonly used metric to quantify biodiversity. However, examining dark diversity, the group of absent species which can potentially inhabit a site, can provide insights about the factors influencing species assembly. In this study we aimed to understand how climate, soil, acute, and chronic disturbance factors affect not only observed diversity but also dark diversity, completeness (how large is the observed diversity compared to dark diversity) and species pool size (observed and dark diversity together) patterns of a Seasonally Dry Tropical Forest in Brazil. Along 144 0.4-ha plots for trees and 0.04-ha plots for shrubs, herbs, and lianas, we recorded 2148 stems from 232 native species. In general, rainfall was the major drive of plants diversity, whereas soil fertility, deforestation and chronic anthropogenic disturbance had a minor effect. Dark diversity, completeness, species pool and observed diversity respond differently to the different predictors, indicating the complex biodiversity relationship with environmental and disturbance factors. These results highlight the importance of using different metrics of species richness and considering different groups in plant communities’ studies.