Precipitation Variability Affects Aboveground Biomass Directly and Indirectly via Plant Functional Traits in the Desert Steppe of Inner Mongolia, Northern China.

Huan Cheng,Yuanbo Gong,Xiaoan Zuo

doi:10.3389/fpls.2021.674527

Abstract

Clarifying the response of community and dominance species to climate change is crucial for disentangling the mechanism of the ecosystem evolution and predicting the prospective dynamics of communities under the global climate scenario. We examined how precipitation changes affect community structure and aboveground biomass (AGB) according to manipulated precipitation experiments in the desert steppe of Inner Mongolia, China. Bayesian model and structural equation models (SEM) were used to test variation and causal relationship among precipitation, plant diversity, functional attributes, and AGB. The results showed that the responses of species richness, evenness, and plant community weighted means traits to precipitation changes in amount and year were significant. The SEM demonstrated that precipitation change in amount and year has a direct effect on richness, evenness, and community-weighted mean (CWM) for height, leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC), and leaf carbon content (LCC) and AGB; there into CWM for height and LDMC had a direct positive effect on AGB; LA had a direct negative effect on AGB. Three dominant species showed diverse adaptation and resource utilization strategies in response to precipitation changes. A. polyrhizum showed an increase in height under the precipitation treatments that promoted AGB, whereas the AGB of P. harmala and S. glareosa was boosted through alterations in height and LA. Our results highlight the asynchronism of variation in community composition and structure, leaf functional traits in precipitation-AGB relationship. We proposed that altered AGB resulted from the direct and indirect effects of plant functional traits (plant height, LA, LDMC) rather than species diversity, plant functional traits are likely candidate traits, given that they are mechanistically linked to precipitation changes and affected aboveground biomass in a desert steppe.

Highlights

For the past decades, studies on the relationship between climate change and ecosystem attributes, and potential feedback of plants have sprung up (Bai et al, 2004; Griffin Nolan et al, 2018; Zhang B. et al, 2020) because of growing unexpected climate changes and ecosystem responses
The present study indicated that community-weighted mean (CWM) of plant height, leaf area (LA), leaf dry matter content (LDMC), and leaf carbon content (LCC) increased, and leaf nitrogen content (LNC) decreased with increasing precipitation, which supported the leaf economics spectrum (Wright et al, 2004), indicating higher acquisition and turnover of resources in plants with increasing water availability
Our results suggested the significant responses of species diversity and plant functional traits were found when water deficiency was alleviated along a precipitation gradient

Summary

Introduction

Studies on the relationship between climate change and ecosystem attributes, and potential feedback of plants have sprung up (Bai et al, 2004; Griffin Nolan et al, 2018; Zhang B. et al, 2020) because of growing unexpected climate changes and ecosystem responses. Researchers confirmed that precipitation has experienced intense changes in intensity and variability since the last century (Alexander et al, 2006; Trugman et al, 2018; Paschalis et al, 2020). Water availability fluctuations induced by changes in precipitation modulate plant community dynamic and ecosystem function (Yang et al, 2011; Wu et al, 2016; Peralta et al, 2019). The response of a plant to variation in environment can differ among species, communities, and ecosystems, while a mechanistic comprehension of this modifiability remains open to question

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