植物及土壤碳同位素组成对环境变化响应研究进展

A Review on the Responses of Plant and Soil Carbon Stable Isotope Composition to Environmental Change

植物和土壤的δ^(13)C(碳同位素组成)能可靠记录环境信息,综合反映植物的生理生态特征以及碳循环过程中的生物化学过程,为人们理解生态系统碳循环提供有用信息.因此,研究植物和土壤的δ^(13)C与环境因子的关系可以揭示生态系统碳循环的格局及其控制因子,进而有效预测全球变化及其对生态系统的影响.对植物和土壤的δ^(13)C以及二者的差值(Δδ^(13)C)与气候因子(如温度、降水量、大气压强等)、土壤因子(如C/N、土壤质地、土壤pH等)的关系进行了综述.现有研究表明:C3植物的δ^(13)C与降水量、大气压强均呈负相关,与温度的关系非常复杂,而针对C4植物和在群落水平上开展的研究还较少;土壤δ^(13)C与降水量、土壤C/N、土壤w(粉粒)及w(黏粒)均呈负相关,与温度、土壤pH、土壤w(砂粒)均呈正相关,然而环境因素间的耦合作用使得情况复杂化,多种环境因素的匹配关系究竟如何影响土壤δ^(13)C的机制问题仍有待深入研究;Δδ^(13)C能够更加全面准确地反映土壤碳循环信息,但对其与环境因子关系的研究较少,并且影响Δδ^(13)C的驱动因子及机制也不明确.因此,在土壤-植物体系内,同时在物种和群落水平上,进行植物和土壤δ^(13)C特别是Δδ^(13)C与环境因子关系的研究,能够更加准确地预测和揭示环境变化对生态系统碳循环的影响,这也将是今后该领域的研究重点.

Plant and soil carbon stable isotope composition(δ^13C) can reliably record environmental information,comprehensively reflect the physio-ecological characteristics of plants and biochemical carbon cycle processes,and provide useful information for understanding ecosystem carbon cycles. Thus,investigating the relationships between plant and soil δ^13C and environmental factors can reveal the patterns and controlling factors of ecosystem carbon cycles,and the potential effects of climate change on ecosystems. In this study,the relationships between plant δ^13C,soil δ13C and Δδ^13C( the differences between plant and soil δ^13C) and temperature,precipitation,atmospheric pressure,soil C/N ratio,soil texture and soil pH were reviewed. The δ^13C of C3 plant was negatively related to precipitation and atmospheric pressure,while the relationship between temperature and the δ^13C of C3 plant was complex. Only limited studies were available on C4 plants,or mixed C3/C4 communities. Soil δ^13C was negatively related to precipitation,soil C/N,soil clay and silt content,positively related to temperature,soil pH and soil sand content. However,the coupling effects of environmental factors suggest that the integrated effects of environmental factors on soil δ^13C were worth further study. Although Δδ^13C could comprehensively reflect this integrated effect,studies on the relationships between Δδ13C and environmental factors were limited,and the control factors of Δδ^13C and influencing environmental mechanisms were unclear. Based on the deficiency of existing research,we suggest that measuring plant δ^13C at both species and community levels,soil δ^13C and Δδ^13C simultaneously can more accurately reveal and predict the effects of environmental change on ecosystem carbon cycle,and this should be the focus of future research.