三峡库区香溪河消落带植物群落构成及物种多样性

Floristic Composition and Plant Community Diversity of Water-Level Fluctuation Zone Along Xiangxi River,Three Gorges Reservoir Area

通过对三峡库区香溪河消落带145~175m范围内植物群落的调查,研究了三峡水库低水位运行期间消落带植物群落构成和物种多样性.采用以植物所占体积（盖度乘以高度）表示的简化重要值（SIV）代替传统方法计算物种多样性.结果表明：调查共记录维管植物23科49属50种,以禾本科种类最多,菊科次之,为消落带优势科,绝大部分是1属1种的草本植物;一年生草本植物为消落带优势生活型,一年生草本植物狗尾草、稗、苍耳、鬼针草和多年生草本植物狗牙根、香附子等是三峡库区消落带优势物种;单因素方差分析表明,香溪河消落带植物群落的丰富度、多样性、均匀度和优势度在各水位梯度带上差异显著（p〈0.05）,植物群落物种多样性沿水位高程梯度145~175m呈先增加后降低的抛物线状变化;水文机制是影响消落带植物群落组成的重要因素.

Based on the vegetation survey of water-level fluctuation zone along the Xiangxi River of the Three Gorges Reservoir,the floristic composition and plant community diversity were reported.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 1m×1msample quadrats laid out contiguously on transects from 145-175 mabove sea level.The result showed that there were 50 vascular plant species belonging to 49 genera and 23 families in the water-level fluctuation zone.The dominant families were Gramineae and Compositae and almost all the genera were represented by only one species;Therophytes were the most abundant life form;Setaria viridis,Echinochloa crusgalli,Xanthium sibiricum,Bidens pilosa,Cynodon dactylon,Cyperus rotundus were the dominant vascular plants.The results of one-way ANOVA analysis demonstrated that variation in species richness,community diversity,evenness and dominance along the distance gradient was significant（p〈0.05）.Species richness,community diversity,evenness and dominance represented the pattern of gradually increasing and then declining.The hydrological conditions appeared to be the important reasons of vegetation composition.