陆地生态系统氮饱和监测指标及氮沉降控制研究进展

土壤和大气中存在较多的氮,但大多以稳定态的有机氮和氮气形式存在,被植物生长利用的可获得性氮素较少。工业革命以来,人口数量剧烈增长及生活方式的改变带来的化石燃料燃烧、化肥施用和畜禽养殖等活动向大气中排放了大量活性氮,提高了植物可获得性氮水平,并影响到陆地生态系统氮循环和碳循环。长期的氮沉降在全球多个地区引起了氮饱和问题,使得全球工业发达地区及其周边陆地生态系统面临退化风险,我国所在的东亚地区逐步成为继欧洲和北美之后的第三大氮沉降区。严峻的事实及不断加重的氮沉降污染趋势,迫使我们亟需借鉴发达国家的经验以开展相关研究。文章综述了从20世纪80年代起在氮饱和研究中采用的多种氮饱和监测指标,涵盖了陆地生态系统土壤、植被、水体、气体等多个部分的最新进展。文章还总结了我国氮饱和研究的现状,并提出了一些改进措施,以期对我国开展氮沉降观测、氮沉降模拟实验及氮沉降控制有所借鉴。

Review on Nitrogen Saturation Monitoring Indices and Nitrogen Deposition Control in Terrestrial Ecosystems

Limited nitrogen element can be uptaken by plants because most of them exist in the form of organic nitrogen and N2 in soil and atmosphere respectively.However lots of reactive nitrogen is released to atmosphere due to fossil fuel combustion,nitrogen fertilization and livestock industry booming from the dramatic population growth and lifestyle changes since the beginning of industrial revolution,which have eased the reactive nitrogen deficiency for terrestrial plants,and pose some impacts on nitrogen and carbon cycles in the system.Long-term nitrogen deposition has globally caused severe problem called nitrogen saturation in many industrialized regions,pushing the terrestrial ecosystems to the edge of degradation.East Asia area has been recognized as the third largest region suffering from nitrogen deposition and future nitrogen saturation after the European and North America.Previous studies on nitrogen saturation in the past 20 years were reviewed,including the new progress of nitrogen monitoring indices related with soil,plants,water and nitrogen gas.The existing status of nitrogen saturation in China was also described,and it was proposed that more attentions should be paid to nitrogen deposition monitoring,nitrogen saturation research and nitrogen deposition control measures.