Bedrock geochemistry influences vegetation growth by regulating the regolith water holding capacity

Zihan Jiang,Jian Peng,Hongyan Liu,Sophie M Green,Hongya Wang,Jeroen Meersmans,Timothy A Quine,Zhaoliang Song,Xiuchen Wu

doi:10.1038/s41467-020-16156-1

Abstract

Although low vegetation productivity has been observed in karst regions, whether and how bedrock geochemistry contributes to the low karstic vegetation productivity remain unclear. In this study, we address this knowledge gap by exploring the importance of bedrock geochemistry on vegetation productivity based on a critical zone investigation across a typical karst region in Southwest China. We show silicon and calcium concentrations in bedrock are strongly correlated with the regolith water loss rate (RWLR), while RWLR can predict vegetation productivity more effectively than previous models. Furthermore, the analysis based on 12 selected karst regions worldwide further suggest that lithological regulation has the potential to obscure and distort the influence of climate change. Our study implies that bedrock geochemistry could exert effects on vegetation growth in karst regions and highlights that the critical role of bedrock geochemistry for the karst region should not be ignored in the earth system model.

Highlights

Low vegetation productivity has been observed in karst regions, whether and how bedrock geochemistry contributes to the low karstic vegetation productivity remain unclear
The regolith water loss rate (RWLR) was evaluated by variations in regolith moisture during dry spells, while the regolith moisture was represented by the temperature vegetation drought index (TVDI, see Estimation of RWLR in Methods for more details)
With a comprehensive, broad-scale assessment of the influence of bedrock properties on the regional variations in vegetation productivity, we determined that bedrock geochemistry can strongly regulate vegetation productivity at the regional scale by influencing the regolith water storage capacity

Summary

Introduction

Low vegetation productivity has been observed in karst regions, whether and how bedrock geochemistry contributes to the low karstic vegetation productivity remain unclear. Areas dominated by soluble rock substrates are often characterized by large temporal variations in plant water availability that are induced by rainfall intermittency and droughts during periods without precipitation[19] These droughts will have an important influence on the vegetation growth potential[20]. A novel and key aspect of our approach is the consideration of the RWLR in order to evaluate the impact of the temporal variability in regolith moisture levels during dry spell events at the regional scale This estimation allowed us to compare the relative strength of bedrock geochemistry versus other competing models (Table 1), and examine the bedrock geochemistry-RWLR-vegetation productivity relationships

Methods

Results

Conclusion