Effect of plant diversity on the diversity of soil organic compounds.

Lamiae El Moujahid,Serge Michalet,Florian Bellvert,Alexandra Weigelt,Franck Poly,Xavier Le Roux,Shiping Wang

doi:10.1371/journal.pone.0170494

Abstract

The effect of plant diversity on aboveground organisms and processes was largely studied but there is still a lack of knowledge regarding the link between plant diversity and soil characteristics. Here, we analyzed the effect of plant identity and diversity on the diversity of extractible soil organic compounds (ESOC) using 87 experimental grassland plots with different levels of plant diversity and based on a pool of over 50 plant species. Two pools of low molecular weight organic compounds, LMW1 and LMW2, were characterized by GC-MS and HPLC-DAD, respectively. These pools include specific organic acids, fatty acids and phenolics, with more organic acids in LMW1 and more phenolics in LMW2. Plant effect on the diversity of LMW1 and LMW2 compounds was strong and weak, respectively. LMW1 richness observed for bare soil was lower than that observed for all planted soils; and the richness of these soil compounds increased twofold when dominant plant species richness increased from 1 to 6. Comparing the richness of LMW1 compounds observed for a range of plant mixtures and for plant monocultures of species present in these mixtures, we showed that plant species richness increases the richness of these ESOC mainly through complementarity effects among plant species associated with contrasted spectra of soil compounds. This could explain previously reported effects of plant diversity on the diversity of soil heterotrophic microorganisms.

Highlights

During the past decades, many studies have analysed the role of biodiversity on ecosystems, demonstrating that a loss in biological diversity can affect ecosystem characteristics and functioning [1,2,3]
LMW1 compound richness was higher for each of the 53 different plant species studied as monocultures than for bare soil: LMW1 richness ranged from 38 compounds for bare soil up to 138 compounds for Lotus corniculatus (Fig 1a)
The number of LMW2 compounds detected for bare soil was 51, which was higher than values reported for 17% of plant monocultures

Summary

Introduction

Many studies have analysed the role of biodiversity on ecosystems, demonstrating that a loss in biological diversity can affect ecosystem characteristics and functioning [1,2,3]. Key mechanisms underlying the effects of plant diversity on ecosystems have been debated. Several authors distinguished causal mechanisms such as facilitation or complementarity involving interactions between several species which potentially results in overyielding, i.e. better performance for assemblages of species than the best one observed for monoculture of each of the species [4]; and probabilistic mechanisms through a PLOS ONE | DOI:10.1371/journal.pone.0170494. Relationship between plant and soil organic compound diversity the manuscript. There was no additional external funding received for this study

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Conclusion