三峡库区消落带不同水位高程植被和土壤特征差异

植被和土壤是消落带生态系统的重要组成部分.本研究选择三峡库区腹地忠县境内的3个地质地貌和土地利用历史相似的近自然消落带,对不同水位高程(160 m和170 m)植被群落和土壤特征进行研究,结果表明:一年生草本在消落带植物物种数中比例高达72.4%,而多年生草本仅为27.6%;不同水位高程植被物种组成完全相同,且盖度、生物量、生物多样性指数均没有显著差异;随着水位高程变化,群落优势物种存在一定差异,即160 m高程优势种为多年生狗牙根(Cynodon dactylon),而170 m高程为一年生白酒草(Conyza japonica);土壤容重、含水量、pH、有机质、总氮、总磷在160 m和170 m水位高程间均没有显著差异.因此,160 m和170 m水位高程在淹水时间和深度上的差异造成群落优势种的不同,而对当前植被和土壤特征并没有显著影响.

Differences in vegetation and soil characteristics at different water-level altitudes in the drawdown areas of Three Gorges Reservoir area

Vegetation and soil are the key components of the drawdown area of Three Gorges Reservoir.To investigate characteristics of vegetation and soil from water-level altitude of 160 m and 170 m,three drawdown areas with similar geological environment and history of land-use in Zhongxian County were chosen.Results indicated that percent of annual and perennial herbaceous species in drawdown area were 72.4% and 27.6%,respectively.There were no significant differences in species composition,coverage,biomass and biodiversity index between 160 m and 170 m.With water-level altitude changing,the dominant species of plant community varied.Cynodon dactylon was the dominant species at 160 m,while Conyza japonica at 170 m.Soil bulk density,water content,pH,SOM,TN and TP at 160 m and 170 m did not differ significantly.Therefore,it seems reasonable to suggest that their different dominant species resulted from the different inundation period and water depth in those areas between 160 m and 170 m,which did not play a significant role in current vegetation and soil development.