Effects of plant intraspecific variation on the prediction of C3/C4 vegetation ratio from carbon isotope composition of topsoil organic matter across grasslands,Journal of Plant Ecology

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Effects of plant intraspecific variation on the prediction of C3/C4 vegetation ratio from carbon isotope composition of topsoil organic matter across grasslands
Journal of Plant Ecology ( IF 3.0 ) Pub Date : 2021-03-09 , DOI: 10.1093/jpe/rtab022
Wentao Luo ₁ , Xiaoguang Wang _{1,

2} , Karl Auerswald ₃ , Zhengwen Wang ₁ , Michael I Bird ₄ , Christopher J Still ₅ , Xiao-Tao Lü ₁ , Xingguo Han _{1,

6,

7}

Affiliation

Abstract

Aims

Understanding the patterns and drivers of carbon isotope discrimination (¹³Δ) in C₃ and C₄ functional groups is critical for predicting C₃/C₄ vegetation ratio from the isotopic composition of soil organic matter. In this study, we aimed to evaluate how intraspecific variation will modify functional group-level ¹³Δ values and the associated prediction of C₃/C₄ vegetation ratio.

Methods

We investigated ¹³Δ of 726 individual plants (96 species; C₃ and C₄ functional groups) and topsoil organic matter in 26 grassland communities along an aridity gradient in northern China. The fraction of C₄ contribution was calculated with mixing models that considered: (i) both intra- and interspecific effects on the ¹³Δ values of C₃ and C₄ functional groups; (ii) only interspecific effects; or (iii) none of these effects.

Important Findings

We found divergent responses of plant ¹³Δ at the intraspecific level to the changes of aridity across the gradient. The ¹³Δ of both C₃ and C₄ functional groups was negatively correlated with an aridity index, with higher sensitivity for C₃ than for C₄ functional groups. Intraspecific ¹³Δ variation played a key role in driving the total ¹³Δ variations of C₃ plants. Overlooking such intraspecific effect in mixing models led to a greatly increased fraction of C₄ contribution to soil organic carbon. A correction for the effects of intraspecific variation is therefore essential for correctly inferring C₃/C₄ vegetation ratio in the past. Our findings provide basic information for the reconstruction of past vegetation change from bulk materials in arid and semiarid biomes.

更新日期：2021-04-19

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