Effects of plant intraspecific variation on the prediction of C_(3)/C_(4)vegetation ratio from carbon isotope composition of topsoil organic matter across grasslands  

植物种内变异对草地表层有机质碳同位素组成预测C_(3)/C_(4)植被比的影响

作　　者：Wentao Luo Xiaoguang Wang Karl Auerswald Zhengwen Wang Michael I.Bird Christopher J.Still Xiao-Tao Lv Xingguo Han 

机构地区：[1]Erguna Forest-Steppe Ecotone Research Station,Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang 110016,China [2]College of Environment and Resources,Dalian Minzu University,Dalian 116600,China [3]Technische Universität München,Lehrstuhl für Grünlandlehre,Alte Akademie 12,85350 Freising-Weihenstephan,Germany [4]College of Science and Engineering and ARC Centre of Excellence for Australian Biodiversity and Heritage,James Cook University,Cairns,Queensland 4870,Australia [5]Department of Forest Ecosystems and Society,Oregon State University,Corvallis,OR,USA [6]State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China [7]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Plant Ecology》2021年第4期628-637,共10页植物生态学报（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(31971465,31822006,31770503,41807108);National Basic Research Program of China(2016YFC0500601,2016YFC0500700);Youth Innovation Promotion Association CAS(201832,2020199);the Key Research Program from CAS(KFZD-SW-305-002).

摘　　要：Aims Understanding the patterns and drivers of carbon isotope discrimination(13Δ)in C_(3)and C_(4)functional groups is critical for predicting C_(3)/C_(4)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 13Δvalues and the associated prediction of C_(3)/C_(4)vegetation ratio.Methods We investigated 13Δof 726 individual plants(96 species;C_(3)and C_(4)functional groups)and topsoil organic matter in 26 grassland communities along an aridity gradient in northern China.The fraction of C_(4)contribution was calculated with mixing models that considered:(i)both intra-and interspecific effects on the 13Δvalues of C_(3)and C_(4)functional groups;(ii)only interspecific effects;or(iii)none of these effects.Important Findings We found divergent responses of plant 13Δat the intraspecific level to the changes of aridity across the gradient.The 13Δof both C_(3)and C_(4)functional groups was negatively correlated with an aridity index,with higher sensitivity for C_(3)than for C_(4)functional groups.Intraspecific 13Δvariation played a key role in driving the total 13Δvariations of C_(3)plants.Overlooking such intraspecific effect in mixing models led to a greatly increased fraction of C_(4)contribution to soil organic carbon.A correction for the effects of intraspecific variation is therefore essential for correctly inferring C_(3)/C_(4)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.植物群落中C_(3)和C_(4)植物的比例和组成对诸多生态系统过程具有重要影响。解析C_(3)和C_(4)植物碳同位素的环境驱动过程与调控因子,对于从土壤碳同位素的角度来预测C_(3)/C_(4)植被比和组成具有重要意义。本研究旨在评估草原植物碳同位素特征的种内变异将如何影响C_(3)和C_(4)植物的碳同位素组成以及C_(3)/C_(4)植被比的预测。沿中国北方草原的自然干旱梯度选择26个植物群落,通过分析植物和土壤的碳同位素组成,采用混合模型来预测C_(4)植物对土壤有机碳的相对贡献。本研究对比分析了如下3种情境:(1)考虑C_(3)和C_(4)植物碳同位素的种内和种间效应;(2)仅考虑碳同位素的种间变异;(3)忽略碳同位素的种内和种间变异。研究结果表明,植物碳同位素组成沿中国北方草原自然干旱梯度的变化具有物种特异性。C_(3)和C_(4)植物的碳同位素组成与干旱指数之间呈显著负相关关系,但C_(3)植物比C_(4)植物对环境的干旱变化更为敏感。植物碳同位素特征的种内变异在驱动C_(3)植物功能群碳同位素沿干旱梯度的分布格局中发挥着重要作用。如果忽略植物碳同位素特征的种内变异将会显著高估C_(4)植物的相对贡献。本研究结果表明,草原植物碳同位素特征的种内变异对于准确预测C_(3)/C_(4)植被组成具有重要意义。

关 键 词：arid and semiarid grasslands interspecific variation intraspecific variation soil organic matter two-member mixing models vegetation ratio 

分 类 号：Q948[生物学—植物学]