A direct comparison of the effects and mechanisms between species richness and genotype richness in a dominant species on multiple ecosystem functions.

Man Jiang,Yulin Liu,Jinlong Wang,Yubao Gao,Tao Wang,Nianxi Zhao,Luoyang He,Yujuan Xu,Xue Yang,Ke Dong

doi:10.1002/ece3.8125

Man Jiang, Yulin Liu + Show 8 more

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https://doi.org/10.1002/ece3.8125

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Abstract

Both species (interspecific) richness and genotype (intraspecific) richness of dominant species have significant effects on ecosystem functioning directly or indirectly by regulating plant community functional structure. However, the similarities and differences of the effects between inter‐ and intraspecific levels are poorly understood. In this study, we selected the main species in the semi‐arid Eurasian typical steppe as study objects and simultaneously carried out a species richness experiment and a genotype richness experiment of Stipa grandis which is one of the dominant species in this region. We investigated how plants at each of the two richness levels affected multiple ecosystem functions (biomass, soil C, N and P cycles) directly and indirectly by regulating community functional structure, including community‐weighted mean trait values (CWM) and functional dispersion (FDis). Both species richness and genotype richness showed significant direct effects on soil P cycle, and FDis significantly mediated the responses of aboveground biomass and soil N cycle to the changes of species richness and the response of belowground biomass to the changes of genotype richness in S. grandis. CWM showed significant effects on biomass in the species richness experiment and soil nutrient cycles in the genotype richness experiment, independently of the levels of plant richness. These findings provide experimental insights of intraspecific richness effects into the relationships between biodiversity and ecosystem functioning, and highlight the importance of conserving the intraspecific diversity of dominant species in the semi‐arid steppe regions.

Highlights

Due to the rapid loss of biodiversity caused by global changes and human disturbances, more and more studies have focused on the relationships between biodiversity and ecosystem functioning (BEF) (Benayas et al, 2009; Maestre et al, 2012)
In order to deeply understand the ecological consequences of biodiversity loss in the semi-arid temperate steppe of northern China, in this study, we further explored how plant diversity at different levels affects multiple ecosystem functions and the potential mechanisms mediated by community functional structure based on two independent richness microcosm experiments by modulating plant species richness and genotype richness in S. grandis (See Yang, Wang, et al, 2019)
The present study shows that the direct effects of species richness or genotype richness in the dominant species S. grandis on the soil P cycle are similar, which could be explained from the point of view of evolution, insurance hypothesis, and facilitative effects between plant and plant, considering the P deficiency in the semi-arid temperate steppe of northern China

Summary

Introduction

Due to the rapid loss of biodiversity caused by global changes and human disturbances, more and more studies have focused on the relationships between biodiversity and ecosystem functioning (BEF) (Benayas et al, 2009; Maestre et al, 2012). Most studies have confirmed that species richness has significant positive direct effects on a single ecosystem function such as biomass production (van der Plas, 2019). There has been an increasing number of studies on the ability of ecosystems to simultaneously provide multiple ecosystem functions and services (multifunctionality). Biomass production, which represents the ability and efficiency of plants in a community to utilize natural resources, is the most widely used ecosystem function in BEF researches (van der Plas, 2019). Soil nutrient cycles, which reflect the ecosystem resource utilization processes (some basic support and regulation of ecosystem services), are very sensitive to the changes in community composition such as plant richness; soil nutrient cycles have attracted more and more attention in BEF researches (Maestre et al, 2009). Environmental conditions or dominant species may cause ecosystem functions to trade off with one another (Gamfeldt et al, 2013)

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