南水北调中线工程对丹江口库区生物多样性的影响分析

丹江口库区生态环境问题是南水北调工程建设和运营中关注的热点,生物多样性是生态环境的重要组成部分以及主要评价指标.本文通过资料收集和对库区野外调查,对丹江口库区野生植物、陆生动物和水生生物三个方面进行了生物多样性资源统计,重点从大坝加高蓄水淹没、移民安置破坏两方面分析了南水北调中线工程可能对库区生物多样性造成的影响,并根据目前库区生物多样性的现状以及面临的威胁,提出了生物多样性保护措施.

Environmental Impact of the Middle Section of the South-to-North Water Transfer Project on Biological Diversity in the Danjiangkou Reservoir Area

Danjiangkou Reservoir area is the primary water resource of the middle section of South-to-North Water Transfer Project and the ecological environment of this area directly influences drinking water quality in North China. The effect of the South-to-North Water Transfer Project on the ecological environment of Danjiangkou Reservoir area, especially after water impoundment and the disruption caused by invasion of exotic species has caused concern. Biological diversity is an important component of ecological stability. In this study, the biological diversity of plants, animals and aquatic organisms in the Danjiangkou Reservoir area was investigated and analyzed, based on field investigations and previously collected data. The goals are to (1) assess the influence of the South-to-North Water Transfer Project on the ecological environment of the Danjiangkou reservoir area, (2) provide a base for conserving biodiversity and the ecological integrity of the resource and (3) protect the quality of drinking water. A total of 2,059 species of vascular plant (752 genera and 171 families), 306 terrestrial vertebrate species (96 families, 28 orders and 4 classes), 100 phytoplankton species (60 genera, 8 phyla), 96 zooplankton species (4 categories) and 88 fish species (17 families, 7 orders) were recorded during the investigation. Construction and operation of the South-to-North Water Transfer Project required immigrant resettlement and deforestation resulting in habitat loss for terrestrial vertebrates and water impoundment inundated plant habitat and altered the aquatic environment. The plankton composition in Danjiangkou Reservoir did not change markedly, but plankton biomass increased significantly after the dam height was increased. The zoobenthos community structure also remained about the same, but the distribution of the zoobenthos increased with reservoir width after water impoundment and seasonal variation increased. After impoundment, the decrease in reservoir water flow severely affected spawning of four major Chinese carp species and other fish species producing pelagic eggs, but had no obvious adverse effect on fish producing demersal eggs. Suggestions for the protection of biodiversity were offered, including the construction of a shelter forest belt in the reservoir area, restoration of wetland vegetation in the newly created water-level fluctuation zone, prohibition of hunting of wild animals, fish species conservation and implementation of fish breeding and release program.