Higher tree diversity increases soil microbial resistance to drought

Lauren M Gillespie,Alexandru Milcu,Bruno Buatois,Nathalie Fromin,Clovis Pontoizeau,Stephan Hättenschwiler

doi:10.1038/s42003-020-1112-0

Abstract

Predicted increases in drought frequency and severity may change soil microbial functioning. Microbial resistance and recovery to drought depend on plant community characteristics, among other factors, yet how changes in plant diversity modify microbial drought responses is uncertain. Here, we assessed how repeated drying-rewetting cycles affect soil microbial functioning and whether tree species diversity modifies these effects with a microcosm experiment using soils from different European forests. Our results show that microbial aerobic respiration and denitrification decline under drought but are similar in single and mixed tree species forests. However, microbial communities from mixed forests resist drought better than those from mono-specific forests. This positive tree species mixture effect is robust across forests differing in environmental conditions and species composition. Our data show that mixed forests mitigate drought effects on soil microbial processes, suggesting greater stability of biogeochemical cycling in mixed forests should drought frequency increase in the future.

Highlights

Predicted increases in drought frequency and severity may change soil microbial functioning
When CO2 fluxes were cumulated over the entire experiment, they were 16% lower in the DRW treatment compared to the control (Fig. 1f)
This study examined how drying-rewetting (DRW) cycles influence soil microbial activity related to C and N cycling in soils from different mature, natural European forests composed of one or three tree species

Summary

Introduction

Predicted increases in drought frequency and severity may change soil microbial functioning. We assessed how repeated drying-rewetting cycles affect soil microbial functioning and whether tree species diversity modifies these effects with a microcosm experiment using soils from different European forests. We asked how DRW cycles influence soil microbial driven carbon and nitrogen cycling by measuring aerobic respiration (CO2 fluxes) and denitrification (N2O fluxes when N2 transformation is impeded) and potential soluble carbon and nitrogen leaching from soils originating from boreal, temperate, and Mediterranean forests across Europe, and whether these effects are modified by tree species mixing. Soil microbial communities from mixed forests resisted drought better than those from monospecific forests This positive tree species mixture effect was robust across forests differing in environmental conditions and species composition and suggests potentially more stable biogeochemical cycling in mixed forests with future climate change induced drought

Methods

Results

Conclusion