Relationships between functional diversity and aboveground biomass production in the Northern Tibetan alpine grasslands.

Juntao Zhu,Yangjian Zhang,Lin Jiang

doi:10.1038/srep34105

Abstract

Functional diversity, the extent of functional differences among species in a community, drives biodiversity–ecosystem function (BEF) relationships. Here, four species traits and aboveground biomass production (ABP) were considered. We used two community-wide measures of plant functional composition, (1) community weighted means of trait values (CWM) and (2) functional trait diversity based on Rao’s quadratic diversity (FDQ) to evaluate the effects of functional diversity on the ABP in the Northern Tibetan alpine grasslands. Both species and functional diversity were positively related to the ABP. Functional trait composition had a larger predictive power for the ABP than species diversity and FDQ, indicating a primary dependence of ecosystem property on the identity of dominant species in our study system. Multivariate functional diversity was ineffective in predicting ecosystem function due to the trade-offs among different traits or traits selection criterions. Our study contributes to a better understanding of the mechanisms driving the BEF relationships in stressed ecosystems, and especially emphasizes that abiotic and biotic factors affect the BEF relationships in alpine grasslands.

Highlights

Raising the question of whether the various species diversity-productivity relationships found in nature[30] would apply to functional diversity
The aboveground biomass production (ABP) significantly increased with community-weighted means of plant coverage (CWMC), leaf mass per area (CWMLMA) and leaf dry matter content (CWMLDMC) (P < 0.001), but significantly decreased with community-weighted means of plant height
Consistent with this general pattern, we found a positive relationship between species richness (SR), Shannon-Weaver index (H) and aboveground biomass production (ABP)

Summary

Introduction

Raising the question of whether the various species diversity-productivity relationships found in nature[30] would apply to functional diversity. Ecosystems are subject to natural environmental conditions with temporal and spatial variations, such as temperature, precipitation and nutrient availability[31], as well as to influences from other species and human activities[25,32]. In the Northern Tibetan plateau, there are three main natural vegetation types, alpine meadow, alpine steppe and alpine desert steppe[38], and most of plants are perennial herbs The vegetation in this area is exposed to extreme environmental conditions, including intense radiation, strong winds, low temperatures, low soil nutrients and drought stress[38,39]. We related aboveground biomass production and trait-based indices to assess whether CWM, i.e. functional identity of dominant species, or FDQ, i.e. functional dissimilarity among species, are better predictors for ecosystem functioning

Methods

Results

Conclusion