流域城市化对湿地生态系统的影响研究进展

城市化是人类社会发展的必然趋势和现代化的必经阶段,同时城市化也对区域湿地生态系统产生重要影响。从城市化的水文效应、城市化对水环境的影响和城市化产生的气候变化对湿地生态系统影响3方面综述了城市化对湿地生态系统结构和功能影响的研究进展。城市化引起流域内人口增加,通常伴随商业和工业活动的增加,这些活动需要更多的城市土地,从而导致流域内不透性增加,这给流域内湿地生态系统造成了重要的影响,表现为:①城市化所及地区的产汇流过程发生显著变化,导致湿地径流的调节作用和维持生态系统生产力的作用发生退化;②城市地表径流中含有大量的污染物质,致使对湿地水环境、水生生物、野生动物栖息地都产生了重要的影响,并污染城市饮用水水源,危及人类健康;③城市化导致流域气候变化,影响湿地水文、生物地球化学过程、植物群落及湿地生态功能等。最后,指出了国内外城市化对湿地生态系统影响研究的不足之处,对国内外的研究趋势进行展望,并对国内的研究提出了几点建议。

Research Progress in Effects of Urbanization on Wetland Ecosystem in Watershed

Urbanization is an inevitable trend of human society,and it is a necessary step of a country's modernization,at the same time it also have an important impact on wetland ecosystem.During the rapid urbanization,the process of the wetland environment in watershed change becomes more complex due to the combined influence of natural and human factors.The effects of urbanization on structure and function of wetland ecosystem were analyzed from 3 aspects: hydrological effects of urbanization,effects of urbanization on water environment and impact of climate change caused by urbanization on wetland ecosystem.In urban areas,increasing population is usually accompanied with increasing commercial and industrial activities,and these activities need more urban land utilization,which amounts to increasing impervious areas.Wetlands are formed by the interaction between terrestrial system and aquatic system.And wetlands are among the world's most productive environment.The wetland ecosystem changed a lot in watershed due to the effects of urbanization.First of all,the formation and evolvement of wetlands are controlled by hydrological processes and the biotic and chemical characteristics of wetlands are affected by hydrological regimes,therefore the process of production and convergence of runoff changed notably in urbanized watershed,this result in degradation of wetland's function on runoff regulation and maintenance of ecosystem productivity.Secondly,there are a large number of pollutants including sediment loadings,heavy metals,nutrients,bacteria and so on in urban surface runoff,which cause important impact on wetland water environment,aquatic organisms and wildlife habitats.Urbanization also reduces native plant species and increases introduced plant species.Moreover,the drinking water can be polluted and then causes health problems on human body.Thirdly,urbanization caused climate change which affect wetland hydrology,water quality,water cycle,energy balance biogeochemical processes,plant communities and the ecological functions of wetlands.As a result,the wetland degraded.Human factors have intensified this trend to a certain degree.Meanwhile,some shortcomings in the existing researches were stated,including the deficiency in basic mechanism of urbanization on wetland system and lack of a tempory and spatial combination of time,space and the multi-dimensional perspective of the research.At last,several issues of the advancing research in the world were raised,and some suggestions on the research in China were made.Such as the develop of application of 3S(RS,GPS and GIS) to many aspects of wetland researches,investigation of wetland resources,dynamic monitoring of change of wetland landscape pattern and resources evolution of the environmental impact and evolution the interaction mechanism of urbanization and wetland from the perspective of macroscopic and microscopic;and focus on dynamic,three-dimensional perspective of the region and the combination of innovative research from the temporal and spatial gradients and more comprehensive and systematic study of urbanization on the wetland ecosystem impact and so on,which are the directions linking of domestic and international research.