水位变动影响下三峡库区汉丰湖鸟类群落及多样性

受三峡水库夏落冬涨的水位调控方式影响,位于三峡库区腹心的重庆开州区汉丰湖形成22.5m水位落差。为了解汉丰湖鸟类群落结构与动态水位变化之间的响应关系,2015年3月—2016年2月对汉丰湖鸟类群落结构及多样性进行了调查。共记录鸟类97种,隶属12目32科,其中湿地鸟类49种,主要包括雁鸭类(18种)、鸻鹬类(13种)、鹭类(7种)及秧鸡类(5种)。研究表明:受水位变化影响,鸟类群落结构及其多样性变化显著。夏季(8月)低水位期(水位高程152.50m),鸟种数最高,为34种,Shannon-Wiener指数最高;肉食性鸟与食虫鸟是主要取食功能群;与夏季低水位期生境类型多样、消落带植物正处于生长旺盛期、食物资源丰富有关,是雀形目鸟类、鹭类、秧鸡类等适宜的栖息地。冬季(12月)高水位期(水位高程174.50m),鸟种数为30种,Shannon-Wiener指数、均匀度指数均最低,植食性鸟类是主要的取食功能群,鸟类数量最高;与冬季高水位期水面开阔、生境类型单一有关,高水位期的大水面有利于鸭类集群越冬。冬季在退水期(水位高程170.01m),水位下降导致汉丰湖生境结构变化,越冬鸟类数量和物种丰度降低,空间分布格局也随之变化。鸟类是三峡水库生物多样性的重要组成部分,为保护和提升三峡水库生物多样性,恢复和营造鸟类栖息地,应针对繁殖鸟和越冬水鸟的功能需求进行生态设计。

Impact of water level fluctuation on avian community and diversity in Hanfeng Lake of the Three Gorges Reservoir

Impacted by the water level control (summer down, winter up) of the Three Gorges Reservoir, the water-level fluctuation of the Hanfeng Lake located at the center of the Three Gorges Reservoir reaches 22.5 m. In order to determine the response relationship between the avian community structure and water-level fluctuation, we conducted a survey on the structure and diversity of the avian community in this area from March 2015 to February 2016. We recorded 97 bird species belonging to 32 families of 12 orders. Of these species, 47 were wetland birds comprising waterfowls (18 species), shorebirds (13 species), egrets (7 species), and rallidaes (5 species). The research showed that the structure and diversity of the avian community of the Hanfeng Lake were significantly affected by its water-level fluctuation. During the low-water-level period in summer (August, at the water level of 152.50m), the avian richness (34 species) and Shannon-Wiener index were the highest, and the carnivorous and insectivorous birds were the main feeding functional groups. Owing to the vast habitat diversity, the vigorously growing plants and abundant food resources were available. This period provided suitable habitats for passeriformes, egrets, rallidaes, and so on. During the high-water-level period of the Hanfeng Lake in winter (December, at the water level of 174.50m), the avian Shannon-Wiener index and Pielou index were the lowest, and the herbivorous birds were the main feeding functional group; however the number of birds was the largest due to the presence of open water with single type of habitat in this period, and the open water was favorable for the ducks clustering to overwinter. During the water-releasing period in winter (at the water level of 170.01m), a decline in water level resulted in the changes in the habitat structure of the Hanfeng Lake leading to a decline in the number and richness of wintering birds, according to which their spatial distribution patterns changed at the same time. Birds are important components of the biodiversity of the Three Gorges Reservoir. To protect and promote the biodiversity of this reservoir as well as to restore and rebuild the avian habitats, we should create ecological designs to satisfy the functional needs of breeding birds and wintering waterfowls.