滇西北高原入湖河口退化湿地生态修复效益分析

选取滇西北高原典型退化湿地剑湖,对入湖河流永丰河入湖河口退化湿地进行的生态修复措施及其效益进行研究,评估其恢复效果,为高原退化湿地的修复和污染湖泊的治理提供依据。研究地修复2a后,入湖河口湿地景观格局得到较大改善,空间结构得到优化配置;水质状况明显改善,水体透明度提高101%,水体中总氮(TN)、氨氮(NH+4-N)、硝氮(NO-3-N)、总磷(TP)、化学需氧量(COD)的含量较恢复前明显下降,去除率分别达到62.5%、89.3%、62.5%、91.7%、68.0%,这一水质降解结果表明:基底修复促进了入湖河口水文状况的改善,而依据植物对不同浓度污水的适应状况进行多生活型、多种类的植物配置,并适当增加沉水植物比例,有效发挥了植物的净化作用,但不同湿地植物群落之间净化效果存在差异,显示了植物对氮磷的喜好程度和植物间的互作关系,而相同植物群落在不同浓度污水条件下的表现同样存在差异。因此,污染水体的治理必须选择性利用适合不同污水浓度的水生植物进行合理的群落配置,同时,根据水质变化及时对植物进行适应性调整,有利于植物的生长和湿地生态系统的稳定,以及湿地生态系统结构和功能的恢复。该退化湿地修复后,每年可产生以净化功能效益为主的生态系统服务功能价值185万元,以水源涵养和生物多样性保育、生态旅游等的生态系统服务功能价值32.7万元,以及以生态农业系统为主的市场价值270万元,呈现了较好的经济、社会效益和生态效益价值。

The ecological restoration effort of degraded estuarine wetland in Northwest Yunnan Plateau, China

In the present study, Jianhu, a typical degraded plateau wetland in Northwesten Yunnan, is selected as the study site and for the efficiency assessment of an ecological restoration project. The aim of the this study is to provide a scientific basis for restoring degraded wetlands and treating water pollution problems in Yunnan Plateau area, and to maintain ecological stability of associated lake ecosystems. The result showed that after two years' ecological restoration effort, estuarine landscape structure has been greatly improved with diversified landscape and optimized spatial structure. Also, water quality has been improved, with the transparency of the water body increased by 101%, and the concentrations of TN, NH₄⁺-N, NO₃^--N, TP and COD significantly decreased by 62.5%, 89.3%, 62.5%, 91.7% and 68.0%, respectively. The purification process of water suggests that the sediment treatment has improved the hydrological conditions in the estuarine environment, and the selection of plant species should be based on nutrient content of the sewage. Also, a high proportion of submerge plants could be used to enhance purification effect. However, the purification effect varied for wetlands with different plant communities, which suggest that aquatic plants have different preference to nitrogen and phosphorus, and they have established complex interactions. Also, once exposed to different nutrient content, the same plant species could display varying levels of water purification function. Therefore, to better deal with sewage problem, it is essential to select the right plant species for community assembly purpose according to water pollution levels. Meanwhile, it is necessary to adjust the composition of plant community according to the change of water quality so that plants could grow well, the stability of the wetland ecosystem could be maintained, and the recovery of ecosystem functions and services could be sustained. After the degraded wetland is restored, it would offer multiple ecosystem services each year, with the yield value of the water purifying effect estimated as RMB 1850000 yuan, the yield value of biodiversity conservation, ecological tourism and other ecosystem services estimated as RMB 327000 yuan, and the market value of the ecological agriculture system estimated as RMB 2700000 yuan. Therefore, the comprehensive benefits of economy, society and ecology could be accomplished, and the goal of demonstrating restoration feasibility of a degraded plateau wetland is fulfilled.