三峡水库忠县至秭归县段消落带植被群落特征研究

为了研究三峡水库周期性的水位调节对消落带植被群落特征的影响，选择重庆忠县至宜昌秭归段的消落带植被群落进行研究，运用重要值和多样性指数分析不同高程的植物种类组成、生活型分布特征及物种多样性。结果表明：（1）研究区域统计植物共32科70属73种，禾本科、菊科和豆科是3个优势科，单种、属现象明显；狗牙根、苍耳、鬼针草、苘麻、鳢肠、酸模叶蓼、莲子草是3个高程的共存种，其中，狗牙根和苍耳在3个高程均为优势物种。（2）研究区域共统计11种植物生活型，在消落带下部和中部，一年生草本植物占绝对优势；在消落带上部，多年生草本植物成为优势生活型，生活型类型多样化，蕨类、藤本、灌木以及乔木植物开始出现。（3）消落带植物群落的丰富度、多样性、均匀度指数均随海拔变化表现出显著差异，并且随海拔升高呈现上升趋势。由此可见，水位变化对植物群落结构和物种多样性产生很大影响，在低海拔区段，消落带物种组成简单化，耐水淹和繁衍能力强的植物成为优势物种；随着海拔上升，水淹胁迫减弱，出现更多适应水位变化的植物种类，使植物群落沿海拔变化形成不同的分布特征。这些研究结果对三峡库区消落带生态修复植物的筛选，以及物种多样性的提高具有参考价值。

Characteristics of Plant Community in the Hydro-fluctuation Belt of the Three Gorges Reservoir at the Zhong to Zigui section

To study the impact of periodic water level adjustments on the characteristics of plant community in the hydro-fluctuation belt of the Three Gorges Reservoir, Zhong to Zigui section were selected for research. The plant species composition, distribution characteristics of life form and species diversity at different elevations were analyzed using important values and diversity indices. The results showed that: (1) There were 73 species in 32 families and 70 genera in the study area. Poaceae, Asteraceae, and Leguminosae were 3 dominant families, and the single species and genera were obvious. Cynodon dactylon, Xanthium sibiricum, Bidens Pilosa, Abutilon theophrasti, Eclipta prostrata, Polygonum lapathifolium, Alternanthera sessilis were co-existing species at three elevations. Among them, Cynodon dactylon and Xanthium sibiricum were dominant species at three elevations. (2) A total of 11 plant life forms were determined in the study area. In the lower and middle parts of the hydro-fluctuation belt, annual herbaceous plants occupied a great dominant position; in the upper parts, perennial herbaceous plants became dominant life form, and the plant life forms were more diverse. Ferns, vines, shrubs, and trees were beginning to appear. (3) The richness, diversity, and evenness index of the plant community in the hydro-fluctuation belt showed significant differences with changes in altitude, and showed an upward trend with increasing altitude. Therefore, the change of water level had a great impact on the plant community structure and species diversity. In the low-altitude section, the species composition was simplified, and plants with strong flood tolerance and reproduction ability became dominant species. The flooding stress weakened as the altitude rose, and more plant species that adapt to changes in water level appeared, causing plant communities to form different distribution characteristics along altitude changes. These results are of reference value for the selection of ecological restoration plants and the improvement of species diversity in the water-level fluctuation zone of the Three Gorges Reservoir.