青藏高原高寒草地不同植物功能群与土壤碳同位素特征及影响因素

Characteristics and main drivers of different plant functional groups and soil carbon isotopes across alpine grassland of the Tibetan Plateau

青藏高原海拔高、面积广,是全球范围内最典型的高寒地区之一,探究青藏高原高寒草地植物和土壤碳稳定同位素组成(δ^(13)C)特征及其控制要素,对深刻理解高寒生态系统碳循环过程具有重要意义。研究采集并测定了青藏高原不同区域135个草地样点中的植物和土壤碳稳定同位素自然丰度,探讨了不同植物功能群和表层(0—10 cm)土壤δ^(13)C特征及其与气候、土壤因素的关系。结果表明:(1)杂类草δ^(13)C显著低于禾本科、莎草科和豆科植物δ^(13)C(P<0.05)。表层土壤δ^(13)C与禾本科、莎草科、豆科植物δ^(13)C呈显著正相关(P<0.05),与杂类草δ^(13)C无显著相关关系,且表层土壤δ^(13)C对三种植物功能群δ^(13)C的敏感性为禾本科>豆科>莎草科。(2)在影响禾本科、莎草科、豆科植物和表层土壤δ^(13)C的环境因子中,气候因子的相对贡献率均大于土壤因子,气候因子中太阳辐射相对贡献率最大,杂类草δ^(13)C与气候和土壤因子均不存在显著相关关系。研究表明,太阳辐射是决定高寒草地生态系统植物和表层土壤δ^(13)C的主要因子。研究可为青藏高原高寒草地植物和土壤δ^(13)C特征与有机碳动态循环提供数据支撑和理论参考。

The Tibetan Plateau,characterized by its high altitude and extensive area,is one of the most prototypical alpine regions in the world.Exploring the characteristics and determinants of carbon stable isotope composition(δ13 C)in plants and soil across its alpine grasslands holds significant implications for comprehensively understanding carbon cycling processes within this unique ecosystem.Our study entailed the collection and measurement of carbon stable isotope natural abundances of plants and soils from 135 grassland sites across the Tibetan Plateau.Theδ^(13)C characteristics of different plant functional groups and surface soil(0—10 cm)were measured,and the relationships betweenδ^(13)C abundances and climate,edaphic factors were determined.The results showed that:(1)Theδ^(13)Cin Forb was significantly lower than that in Poaceae,Cyperaceae and Fabaceae(P<0.05).Theδ^(13)C of surface soil was significantly positively correlated with that in Poaceae,Cyperaceae and Fabaceae(P<0.05),but not with that in Forb.The sensitivity of surface soilδ^(13)Cto the three plant functional groups followed the order of Poaceae>Fabaceae>Cyperaceae.(2)Analysis of environmental factors influencingδ^(13)C in Poaceae,Cyperaceae,Fabaceae,and surface soil indicated that a greater relative contribution of climate factors over edaphic factors,with solar radiation exerting the most substantial influence among climatic factors.Notably,no significant correlation was detected between theδ^(13)Cof Forb and climatic,edaphic factors.Our results also underscored solar radiation as a pivotal determinant of theδ^(13)Ccharacteristics in plants and surface soil.These findings can provide valuable empirical data and theoretical insights for theδ^(13)C characteristics and organic carbon dynamic cycle of plants and soil in alpine grassland ecosystems.