大气CO2浓度升高对典型草原优势种养分利用的影响

An increase in atmospheric CO2 concentration, as one of the driving factors in global climate change, has important impact on plant growth and community structure and function. There have been numerous stuies on the effect of elevated atmospheric CO2 concentration on plant growth and development, but most of the studies so far have mainly focused on physiological processes in the aboveground, while little has been known on the response of underground processes to CO2 elevation in general and rhizosphere-related processes in particular. Nutrient deficiency due to low water supply and low temperature is one of the environemtal factors limiting productivity of temperate grassland in northern China. In the farmland ecosystem, the effects of elevated CO2 concentration on plant growth are closedly dependent on nutrient availabiliy in soil, while there has been limited stduy on the effect of elevted CO2 concentration on dominant species of temperate grassland. More importantly, there has been no stduy to evaluate the role of nutrient availabiliy in soil played in resposne of grassland species to elevated CO2 concentration. In this project, we will study the effect of elevated CO2 concentration on nutrient acquisition in the two dominant species, Stipa krylovii, Artemisia frigida, in a typical steppe of Inner Mongolia grassland using open-top chamber (OTC), CO2 incubator as well as in situ field experiments. We will pay particular attention to the role of rhizophere-depenent processes in nutrient utilization by the two dominant sepecies under evleated CO2 concentration. The outcome of the project will allow us to predict the potential of nutrient acquisition, changes in biodiversity and community structure under global change scenario, which in turn will provide scientific knowledge on improvement of grasslnad productivity.

大气CO2浓度升高作为全球气候变化的驱动因子通过影响植物生长发育，进而影响生态系统的结构与功能。尽管国内外针对这一领域已开展了大量研究，而对地下过程的研究相对较少，特别是对根际生理生态过程的影响研究甚少。水热不足和土壤养分匮乏是制约我国北方草地生产力的限制因子。植物对大气CO2浓度升高的响应与土壤养分活化利用的相互关系在农田生态系统已有报道，但是对草原生态系统根际生理生态过程对CO2升高的响应尚缺乏系统研究。本项目以我国北方典型草原生态系统的优势物种（克氏针茅、冷蒿）为研究对象，通过室内控制实验结合野外原位模拟，以根际过程为切入点，系统研究大气CO2浓度增加对草原优势种养分利用策略的影响，揭示大气CO2浓度-根际动态变化-土壤养分吸收利用之间的相互关系。研究结果对有助于预测全球气候变化背景下，草原生态系统优势种的土壤养分利用潜力，为草原生产力提高和可持续利用提供理论依据。

大气CO2浓度升高作为全球气候变化的驱动因子通过影响植物生长发育，进而影响生态系统的结构与功能。尽管国内外在相关领域已开展了大量研究，而针对大气CO2升高如何影响地下过程的研究相对较少，特别是针对典型草原优势物种根际生理生态过程影响的研究未见报导。水热不足和土壤养分匮乏是制约我国北方天然草地生产力的重要限制因子。植物对大气CO2浓度升高的响应与土壤养分活化利用的相互关系在农田生态系统已有报道，但是对草原生态系统根际生理生态过程对CO2升高的响应尚缺乏系统研究。本项目以我国北方典型草原生态系统的优势物种（克氏针茅、冷蒿）为研究对象，通过室内控制实验和野外原位长期养分添加实验平台 ，以根际过程为切入点，探讨了全球气候变化的驱动因子（大气CO2浓度升高、氮输入增加）对典型草原优势种养分利用策略的影响。研究结果表明，禾草和杂类草在根际过程、土壤微生物群落结构与功能、养分利用策略等方面在响应全球气候变化的驱动因子具有明显的差异；譬如，禾草和杂类草在根际动态、土壤微生物群落结构与功能、养分利用策略等方面表现出对全球变化不同的响应机制。 研究结果对有助于预测全球气候变化背景下，草原生态系统物种共存土及土壤养分利用潜力，为草原生产力提高和可持续利用提供理论依据。