Indirect drivers of plant diversity-productivity relationship in semiarid sandy grasslands

X A Zuo,T H Zhang,Y R Guo,X Y Zhao,H L Zhao,J M H Knops,Y Q Li

doi:10.5194/bg-9-1277-2012

Abstract

Abstract. Although patterns between plant diversity and ecosystem productivity have been much studied, a consistent relationship has not yet emerged. Differing patterns between plant diversity and productivity have been observed in response to spatial variability of environmental factors and vegetation composition. In this study, we measured vegetation cover, plant diversity, productivity, soil properties and site characteristics along an environmental gradient (mobile dune, semi-fixed dune, fixed dune, dry meadow, wet meadow and flood plain grasslands) of natural sandy grasslands in semiarid areas of northern China. We used multivariate analysis to examine the relationships between environmental factors, vegetation composition, plant diversity and productivity. We found a positive correlation between plant diversity and productivity. Vegetation composition aggregated by the ordination technique of non-metric multidimensional scaling had also a significantly positive correlation with plant diversity and productivity. Environmental gradients in relation to soil and topography affected the distribution patterns of vegetation composition, species diversity and productivity. However, environmental gradients were a better determinant of vegetation composition and productivity than of plant diversity. Structural equation modeling suggested that environmental factors determine vegetation composition, which in turn independently drives both plant diversity and productivity. Thus, the positive correlation between plant diversity and productivity is indirectly driven by vegetation composition, which is determined by environmental gradients in soil and topography.

Highlights

Diversity-productivity relationships have shown several patterns in ecology over the last decades (Grace et al, 2007; Partel et al, 2007; Partel et al, 2010; Xiao et al, 2010)
Based on the ordination analysis of plant species compositions, the 60 plots can be classified into six vegetation types in order of increasing species richness, Shannon-Wiener index and biomass: mobile dune, semi-fixed dune, fixed dune, dry meadow, wet meadow and flood plain grasslands (Fig. 1, Table 1 and all P < 0.01)
We found a positive correlation between plant diversity and productivity in sandy grasslands (Fig. 2)

Summary

Introduction

Diversity-productivity relationships have shown several patterns in ecology over the last decades (Grace et al, 2007; Partel et al, 2007; Partel et al, 2010; Xiao et al, 2010). Theoretical and experimental studies have greatly increased our knowledge of how plant diversity influences ecosystem productivity in the past decades. Manipulative experiments in which plant diversity is changed by drawing plant species from a random species pool have shown that increasing species diversity frequently enhances productivity (Tilman et al, 1997; Hector, 1998; Hector et al, 1999; Tilman et al, 2001). These experimental studies are often performed in a uniform environment with

Methods

Results

Conclusion