农田排水沟渠的环境效应与生态功能综述

Review of environmental impact and ecological function of agricultural drainage ditches

农田排水沟渠作为农业景观中重要的景观单元,能够调节农田生态系统水分平衡,改变流域水文情势。农田养分可以随排水过程迅速流失,也可以通过沉淀与吸附机制被农田沟渠所截留或者通过植物吸收后收割与反硝化去除等机制脱离农田生态系统。作为农田生态系统边缘的交错带,农田排水沟渠较高的植物多样性可以提供动物栖息地和避难场所,增加农田生态系统生物多样性。清淤、收割和控制排水等管理措施对于农田排水沟渠的环境效应和生态服务功能有着不同的影响。今后应加强从多个学科研究农田排水沟渠的环境效应和生态功能,探索生态排水沟渠的构建和管理技术,实现农田排水沟渠水利功能和生态功能的"双赢"。

The agricultural drainage ditch,a vital component of agriculture hydrological facilities,plays an important role in agricultural production and national food security.As the problems of eutrophication and water quality deterioration are becoming more and more serious,a strong focus on the environmental impact and ecological function of agricultural drainage ditches has been getting attached.An agricultural drainage ditch is not only an most important element of agricultural landscape but also is able to regular the water balance of agricultural ecosystem and to improve the agricultural ecosystem.Nutrient in farmland can be rapidly lost from the farm land to the drainage ditch through the draining process.Nutrient can also be removed from the agricultural ecosystem through the process of plant absorption and denitrification.A portion of nutrient losses to the ditch can be retained through the sedimentation and adsorption processes.Being the ecotone of the agro-ecosystem,rich plant diversities provide habitats and shelter places to animal species,which increases the agro-biodiversity in the system.Effects of different management practices,such as dredging,plant mowing and controlled drainage on environment and ecological function may vary in various aspects.In order to achieve a win-win result among utilizing of agricultural drainage ditches and eco-environmental protection,multi-discipline research on environmental impact and ecological function of agricultural drainage ditches should be strengthened in the future.We should explore new techniques to build ecological drainage ditches,and introduce advanced management for ditch operation.