太湖湖泊缓冲带草林复合系统氮沉降阻滞解析

Analysis of nitrogen deposition retardation of grass-forest composite system in buffer zone of Taihu Lake

根据植物生长特征,设置5种草林复合系统,利用径流小区试验,分析不同草林复合系统对氮沉降的阻滞与拦截特征,以筛选出拦截效能高的草林复合系统,降低氮随降雨径流进入湖泊水体的风险.结果表明:疏林与草被配置有利于降雨径流的入渗,减少地表径流的产生;林下种植常绿草坪能够减少氮的溶出风险,促进氮的吸收与利用;草林复合系统对氮沉降的阻滞与拦截主要通过地下径流在土壤-植被中的消纳实现,通过地下渗漏流失的氮基本达到地表水排放标准;草林复合系统通过地表径流输出的氮大幅度减少,氮的截留率达到77%以上,以疏林麦冬与疏林马蹄金复合系统氮截留率较高.

According to the characteristics of plant growth,five grass-forest composite systems were set up,and the blocking and intercepting characteristics of different grass-forest composite systems to nitrogen deposition were analyzed by runoff plot test,so as to screen out the grass-forest composite system with high intercepting efficiency and reduce the risk of nitrogen entering into lake water with rainfall runoff.The results showed that the arrangement of sparse forest and grass was beneficial to the infiltration of rainfall runoff and reduce the generation of surface runoff.Planting evergreen lawn under the forest could reduce the risk of nitrogen dissolution and promote the absorption and utilization of nitrogen.The blocking and intercepting of nitrogen deposition by grassforest composite system was mainly realized by the absorption of underground runoff in soil vegetation,and the nitrogen lost by underground leakage basically reached the discharge standard of surface water.The nitrogen output of grass-forest composite system through the surface runoff reduced greatly,and the nitrogen retention rate was over 77%.The nitrogen retention rate of sparse forest with Ophiopogon japonicas or Dichondra erpens composite system was higher.