Abundance and diversity of lianas in a Neotropical dry forest: the influence of soil moisture

Abstract

Background and aims – Based on data across tropical forests, a leading hypothesis posits that lianas are better competitors than trees under water shortage. Evaluating this hypothesis at a local scale may provide insights into its generality. We tested whether the abundance of lianas –relative to trees– decreases with soil moisture in a Neotropical dry forest. We also evaluated the influence of water availability on liana diversity.Methods – Lianas (≥ 1 cm diameter) and trees (≥ 1.5 m height) were counted and identified, and soil moisture was measured, in twenty 10 × 10 m plots at different distances to water sources. Linear regressions assessed the relationships between water availability and relative abundance and diversity of lianas.Key Results – We found a significant an d positive relationship between the relative abundance of lianas and water availability. Liana density ranged from 21 to 77 individuals per plot. Soil moisture did not influence liana species richness (S) or Fisher's α. Eighteen liana species were recorded , from ten families.Conclusions – Our results show that, in contrast with geographic and regional patterns, relative abundance and diversity of lianas at a local scale are not favoured by water shortage. This suggests that different mechanisms may prevail in the liana-tree interaction across water availability gradients.