三峡库区新生城市湖泊岸带初冬植物群落构成及多样性初步研究——以开县汉丰湖为例

Preliminary Study on Floristic Composition and Plant Community Diversity around Shore Zones of Newly Formed Urban Lakes in the Three Gorges Reservoir Area in the Early Winter——A Case Study of Hanfeng Lake in Kai County

通过对重庆开县汉丰湖岸带植被样方调查,研究初冬三峡水库高水位蓄水后该区域的植物群落构成与多样性的空间分布,为库区湿地公园生态恢复与重建提供科学依据。采用简化重要值取代传统方法,在调查时记录植物的盖度和高度,通过植物所占的体积来计算该物种的重要值。研究结果表明,调查样地共有维管植物41种,分别隶属于22科39属,其中,以菊科(Asteraceae)和禾本科(Poaceae)种数最多,优势科、1属1种现象明显;植被生活型组成多样,175 m水位线以下以一年生草本植物占优势;而其上以多年生草本植物占主导,并出现经济树种与园林绿化树种;植物分布区系共12种,类型多样,热带分布物种占属总数的47.5%,具有显著优势,其次是温带分布物种占32.5%,说明该区植物区系具有从暖温带向热带过渡的亚热带地带性特点;随着距湖岸线距离的增加,群落优势种从湿生过渡到中生,单因素方差分析表明,汉丰湖岸带植物群落的丰富度、多样性和优势度在距湖岸线距离梯度上的差异达到显著水平(p<0.05),群落物种的丰富度、多样性和均匀度都是在最高水位线175 m之后达到峰值。水文机制是干扰该区域植物群落分布格局的主导因素。建议在进行湖岸带生态恢复时,应根据不同高程的水文条件选择具有相应生活史特征的植物。

In order to provide evidence-based advices on the future restoration of lake shore zone and environ- ment within and around the water fluctuation zone of the Three Gorges Reservoir, this preliminary research in- vestigated floristic composition and plant community diversity along a shoreline elevation gradient in Han- feng Lake Wetland Park, Kai County, Chongqing Municipality. This study was carried out during the early winter in 2012 （high water condition） after a full cycle of water level fluctuation. Simplified importance value （SIV） was used to describe the characteristics of plant communities by recording plant coverage and height and calculating the volume they occupied in 1 m x 1 m sample quadrats laid out contiguously on transects from 173-180 m above sea level. The results showed that a total of 41 vascular plant species belonging to 39 genera and 22 families were identified. The dominant families were Asteraceae and Poaceae and almost all the genera were represented by only one species. A diverse range of plant life forms included annual herbs domi- nating below the water level of 175 m, while above this were more perennial herbs. Some economic and ame- nity woody plants, such as Eriobotrya japonica, Prunus persica, and Ligustrum lucidum, were also found above the water level of 175 m. There were 12 bioclimatic types of plant genera presented. Tropical types predomi- nate and account for 47.5% of the genera, followed by temperate types with 32.5%. It revealed that the plant communities of the study area were distinctively transitional between tropical and temperate floras. With in- creasing distance （elevation） from the lake shore line, the dominant species transition from wetland plants to mesophytes. The results of one-way ANOVA analysis demonstrated that variation in species richness, commu- nity diversity, and dominance along the distance gradient was significant （p〈0.05）. Species richness, communi- ty diversity and evenness represented the pattern of gradually increasing and then declining, and reached the peak after the 175 m water level. The habitats at different elevations within the Three Gorges Reservoir experi- enced anti-natural and varying inundation periods and depths. These hydrological conditions appeared to be the main driver of plant composition and community structure. Choosing suitable plant species for vegetation restoration of the water fluctuation zone and lake shore environment must take account of the regional biocli- matic conditions, and plants＇ life history strategies in response to the specific hydrological conditions at differ- ent elevations.