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...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.展开更多
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)+1 种基金Youth Innovation Promotion Association CAS(201832,2020199)the Key Research Program from CAS(KFZD-SW-305-002).
文摘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.
