Relationships Between Plant Diversity and Aboveground Biomass Correlated with Soil Phosphorus Stresses in a Tropical Cloud Forest

Abstract

The present projected rates of global species loss emphasize the need to precisely understand how biodiversity promotes ecosystem function in different types of ecosystems. Some known mechanisms such as niche complementarity and selection effects have been tested to explain the biodiversity-ecosystem function (BEF) relationships in several ecosystems, but less work has been done in high-altitude forests with environmental stresses. Therefore, we measured key diversity attributes including species richness (SR), functional trait diversity (Rao’s quadratic entropy, RaoQ), and mean pairwise distance (MPD) in functional trait space and compare them to an important functional attribute (aboveground biomass, AGB, as a proxy for productivity) and resource stress (soil phosphorus). The results showed that both SR and RaoQ showed positive relationships with AGB, while MPD exhibited a negative relationship with AGB, suggesting that increases in plant species ameliorated by neighboring plants with similar functional and evolutionary roles in a stressful environment will help enhance ecosystem productivity. Together with plant diversity, the proportion of variance in AGB increased from 23.90 to 65.80% when soil phosphorus was added into analyses, suggesting that SR, RaoQ, and MPD all exhibit potentiality in the variation of AGB and that soil nutrients play important roles in the BEF relationships. The BEF relationships in tropical cloud forests are mediated by facilitative interactions due to low soil phosphorus. Our findings suggested that conservation of neighboring plant species with functional similarity and close relatedness be important in these forest managements. Additionally, our results showed a comprehensive consideration of environmental factors in BEF relationship analysis.KeywordsBiodiversity and ecosystem functionEnvironment stressFacilitationFunctional diversityPhylogenetic diversitySpecies diversityTropical forest