枯萎期芦苇收割对湿地脱氮过程的影响及其根系作用机制

氮素的过量排放是造成水体富营养化的主要原因之一，湿地对拦截陆向氮素污染源、降低水体中的氮素水平具有重要作用。在亚热带气候条件下，以芦苇为主要植物的湿地具有较强的脱氮能力，即使在冬季芦苇收割后，其根系仍存在活力，并且维持一定的脱氮能力。芦苇在枯萎期不同时间收割可能会使根系呼吸代谢特征发生变化，其可能影响根系泌氧能力和根系分泌物释放，从而改变根际的微生物群落及其对氮的转化过程，引起枯萎期芦苇湿地脱氮过程的变化。为了验证上述假设，本项目通过芦苇湿地模拟实验，系统研究枯萎期芦苇根系呼吸代谢特征、及对根区微环境的影响，根系分泌物对根际微生物的影响，并与生长期进行比较，重点探索枯萎期芦苇收割可能对湿地脱氮过程产生的影响及其根系作用机制。研究结果不仅可以为优化冬季芦苇湿地净化效果提供依据，还可从平衡湿地功能角度提出芦苇最优收割时间，为富营养化水体的治理提供指导。

Excessive emissions of nitrogen is one of the main causes of eutrophication, and wetlands play an important role in intercepting terrestrial nitrogen sources and reducing nitrogen levels in water. In subtropical climate, wetland with reed as main plant has relative strong ability of denitrification. Even after winter harvest, the root system of reed still has vitality and maintains a certain ability of denitrification. Respiration metabolism of reed root may be capable of variation under the different harvest time in withering period, which may affect the ability of oxygen and exudates release from root, thus changing the microbial community in rhizosphere and the transformation process of nitrogen, finally may change the denitrification process of reed wetlands in withering period. In order to verify the above assumptions, the simulation experiment of reed wetlands will use to study the effects of root respiration characteristics on the micro-environment around root zone, and the effects of root exudates on rhizosphere microorganisms in withering period, and compared with growth period, focus on exploring the possible effects of reed harvesting on denitrification process of wetland in withering period and its role mechanism by root. The results can not only provide a basis on efficient denitrification in the winter of reed wetlands, but also provide the optimal harvest time for reed from the perspective of balancing wetland function, and have an important role on ecological restoration of water eutrophication.