祁连山区亚高山灌丛林碳-氮-水通量相互关系及耦合研究

Carbon, nitrogen and water are source of all life. To understand the mechanism by the increasing of carbon sink and decrease the carbon equilibrium budget in land ecosystem will be based on the interaction of carbon - nitrogen - water flux and influent factors. Little is currently known about carbon - nitrogen - water flux of the sub-alpine scrub forest, to further our understanding of sub-alpine scrub forest ecosystem in Qilian Mountains, there is a clear need to analysis the sub-alpine scrub ecosystem carbon - nitrogen - water flux components and their interaction. With adoption of the methods of eddy covariance technique, stable isotope technique, plant eco-physiology technique, and combing the methods of typical ecosystem dynamic observation and field investigation to obtain long-term and continuous observation, this project will be carried out the research based on the existing research results of the sub-alpine scrub forest ecosystem. To reveal the relationship of sub-alpine scrub forest ecosystem carbon - nitrogen – water flux, its annual variability and process mechanism according to variations of temperature, precipitation, and atmospheric nitrogen deposition in Qilian Mountains. These results undoubtedly will be vital to understand the patterns of the carbon and nitrogen cycle of sub-alpine scrub forest ecosystem in Qilian Mountains, and to maintain the ecologic environment stabilization of whole river basin. At the same time, it will be offer important testing data and theory for the carbon, nitrogen and water cycle research in arid ecosystem in China.

碳、氮、水是地球上一切生命的源泉和重要组成物质，陆地生态系统碳氮水通量组分的相互关系及其影响机制是揭示陆地生态系统增汇机制，降低全球碳平衡预测的不确定性必须解决的科学问题，而关于祁连山区亚高山灌丛林（箭叶锦鸡儿、高山吉拉柳、金露梅等）碳氮水通量及相互关系的研究相对比较缺乏，针对这一现状，本项目以祁连山区亚高山灌丛林为研究对象，采用涡度相关技术、稳定性同位素技术和植物生理生态学方法，开展亚高山灌丛林碳氮水通量的综合观测，分析祁连山区亚高山灌丛林碳-氮-水通量特征和年际变异规律及过程机理，确定亚高山灌丛林碳-氮-水通量的组分及其相互关系，阐明祁连山区亚高山灌丛林碳-氮-水通量对温度、降水和大气氮沉降变异的响应特征与机制，对祁连山水源涵养功能的维持具有重要的现实意义和理论价值，为维护区域生态环境稳定，实现地区的可持续发展等重大决策方面提供重要的科学依据。

碳、氮、水是地球上一切生命的源泉和重要组成物质，陆地生态系统碳氮水通量组分的相互关系及其影响机制是揭示陆地生态系统增汇机制，降低全球碳平衡预测的不确定性必须解决的科学问题，而关于祁连山区亚高山灌丛林碳氮水通量及相互关系的研究相对比较缺乏，针对这一现状，本项目以祁连山区亚高山灌丛林为研究对象，开展了亚高山灌丛林碳氮水通量的综合观测，分析了祁连山区亚高山灌丛林碳-氮-水通量特征和年际变异规律及过程机理，通过对于观测数据的收集和整理，得到如下主要结果：（1）初步掌握了祁连山亚高山灌丛林土壤有机碳累积特征、土壤有机碳输出特征及水分运动对土壤有机碳输入的影响，结果显示亚高山灌丛林在土壤碳年净变化方面表现出了明显的增加，显示了土壤碳汇的功能；（2）祁连山亚高山灌丛林土壤水分入渗性能显示，5种典型灌木林（吉拉柳、箭叶锦鸡儿、金露梅、鲜黄小檗、甘青锦鸡儿）土壤蓄水能力和入渗性能存在较大差异，吉拉柳的蓄水能力和入渗性能均好于其他灌丛类型，干青锦鸡儿最小；土壤初渗速率和稳渗速率与土壤有机质含量、自然含水量和孔隙度尤其是非毛管孔隙度呈极显著正相关，与土壤密度呈极显著负相关。（3）通过对祁连山亚高山灌丛林不同植被类型(箭叶锦鸡儿、高山吉拉柳、金露梅)的叶面积指数(LAI)与叶片氮积累量(TFN)、叶片磷积累量(TFP)比较发现，在整个亚高山灌丛群落中，LAI与TFN和TFP之间都有较强的相关性，并且TFN和TFP比值的变化表明不同植被类型叶片的生长都受到N、P的共同限制，只是随着LAI的增加，高山吉拉柳主要受到氮素的限制，箭叶锦鸡儿主要受到磷素的限制，而金露梅则受到N、P的共同限制，研究结果有利于探索水分限制条件下祁连山灌丛林生态系统植物叶片与养分元素之间关系，对于研究干旱区高寒灌丛生态系统在全球气候变化中的作用及其对全球气候变化的响应与反馈，具有重要的理论价值和实践意义。