摘要
土壤呼吸主要包括大气-土壤界面CO_(2)释放量和土壤中CO_(2)储存量变化两部分,深入理解土壤CO_(2)的产生和迁移过程是全面认识陆地生态系统碳循环的基础。通量梯度法是基于测量扩散驱动的CO_(2)浓度梯度和扩散系数计算CO_(2)通量的方法,依据菲克第一定律可以计算出不同深度土壤CO_(2)及其稳定碳同位素组成(δ^(13)C)通量,进而得到土壤CO_(2)释放量和不同深度土壤CO_(2)储存量。地下土壤CO_(2)浓度(^(13)CO_(2)和^(12)CO_(2)浓度)主要受孔隙曲折度、根分布深度、微生物活性和土壤总CO_(2)产生量控制。地下CO_(2)传输过程受不同深度CO_(2)浓度、孔隙度和含水量等的共同控制,上述土壤理化性质和生物因素是土壤通量梯度法应用过程的关键影响因素,直接决定了CO_(2)及其δ^(13)C通量计算的精度和准确度。通量梯度法是箱式法的有益补充,可以明确不同深度土壤CO_(2)产生和运移过程以及对土壤CO_(2)释放量和储存量的影响,阐明不同深度土壤对CO_(2)排放的相对贡献,揭示其环境和物理控制机制。
Soil respiration is mainly composed of the CO_(2)released from atmosphere-soil interface and change of CO_(2)stored in the soil.Understanding the production and migration of CO_(2)in the soil is essential for measuring the carbon cycle in terrestrial ecosystems.The flux gradient method calculates soil CO_(2)flux by measuring the diffusion-driven CO_(2)concentration gradient and diffusion coefficient.The flux of soil CO_(2)and its stable carbon isotopes composition(δ^(13)C)at different depths can be calculated based on Fick’s law.The amount of CO_(2)released from soil and the amount of CO_(2)stored in different soil layers can thus be measured.The underground soil CO_(2)(^(13)CO_(2)and^(12)CO_(2))concentration is mainly controlled by pore tortuosity,the depth of root distribution,microbial activity and total soil CO_(2)production.The underground CO_(2)transmission process is mainly controlled by the CO_(2)concentrations,porosity and water content at different depths of the soil.These physical,chemical and biological features of the soil are key factors affecting the application of the soil flux gradient method,and directly determine the precision and accuracy of soil CO_(2)and itsδ^(13)C flux calculation.The gradient method is a useful complement to the chamber method,which can clarify the process of production and migration of soil CO_(2)at different depths and thus the impacts on the release and storage of soil CO_(2),elucidating the contribution of soils at different depths to CO_(2)release and uncovering the underlying environmental and physical mechanisms.
作者
王晶苑
魏杰
温学发
WANG Jing-Yuan;WEI Jie;WEN Xue-Fa(Key Laboratory of Ecosystem Network Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100190,China)
出处
《植物生态学报》
CAS
CSCD
北大核心
2022年第12期1523-1536,共14页
Chinese Journal of Plant Ecology
基金
国家自然科学基金(41830860和42077302)
