氮素添加对科尔沁沙质草地物种多样性和生产力的影响

物种多样性和生产力是生态系统结构和功能的重要指标.以科尔沁沙质草地为对象，通过对其进行不同梯度的氮素添加处理，研究氮素添加对沙质草地生态系统物种组成、物种多样性和生产力的影响.结果表明：氮素添加改变了群落物种组成和群落中的优势种，使植被的高度和盖度增加，植被的透光率减小；随着氮素水平的增加，群落中物种丰富度减小，物种多样性降低；不同水平的氮素添加均显著增加了(P<0.01)群落地上生物量；物种丰富度与植被透光率呈线性正相关(P<0.01)，与植被盖度呈线性负相关关系(P<0.01)，说明长期的氮沉降与人为氮素输入将影响沙地生态系统的物种组成、物种多样性以及生产力.

Effects of nitrogen addition on grassland species diversity and productivity in Keerqin Sandy Land

Species diversity and productivity are the important indices of the structure and functioning of ecosystems. With Keerqin sandy grassland as test object, this paper studied its species composition, species diversity, and productivity under effects of different level nitrogen (N) addition. Nitrogen addition altered the species composition and the dominant species in the community, increased the vegetation height and coverage, and decreased vegetation light penetration. With the increase of N addition, both the species richness and the diversity decreased. Nitrogen addition increased the aboveground biomass significantly (P<001). There was a significant positive relationship between species richness and vegetation light penetration (P<001), and a significant negative relationship between species richness and vegetation coverage (P<001). It was suggested that  nitrogen deposition and artificial nitrogen addition would affect the species composition, species diversity, and productivity of sandy grassland ecosystem.