三峡水库消落区不同生活史类型植物群落的空间分布格局

为探究三峡水库消落区不同生活史植物群落随海拔梯度及水库干流沿程的空间分布规律,于2017年8月至2017年9月对三峡水库干流消落区植被进行了调查。研究结果表明:(1)三峡水库消落区植被的植物物种丰富度随距大坝里程距离的缩短而呈现逐渐减小的趋势。(2)三峡水库消落区不同生活史类型植被群落盖度对水淹梯度胁迫的响应呈现相反的变化规律:随着消落区高程的升高,一年生植物对消落区植被覆盖度的贡献逐渐增加,而多年生植物对植被群落覆盖度的贡献逐渐降低。但是,在消落区的任一高程区域,多年生植物物种盖度均要大于一年生植物物种盖度。(3)采用TWINSPAN植被分类方法可对9个样地607个样方的三峡水库消落区植被划分为25个组,其中苍耳+狗牙根群落Ass.Xanthiumsibiricum+Cynodon dactylon(含213个样方)、狗牙根群落Ass.Cynodon dactylon(包含137个样方)、狗牙根+香附子群落Ass.Cynodon dactylon+Cyperus rotundus(含55个样方)、狗牙根+酸模叶蓼群落Ass.Cynodon dactylon+Polygonum lapathifolium(40个样方)、苍耳+藿香蓟群落Ass.Xanthiumsibiricum+Ageratum conyzoides(38个样方)等为消落区的优势植物群落,群落特征明显表现出对水位涨落及小生境差异的适应。

Spatial distribution of plant communities composed of different life history species in the water-level-fluctuating-zone of Three Gorges Reservoir

In order to explore the spatial distribution pattern of vegetation, which is composed of different life-history plants, along the river in the mainstream and bank elevation gradient at the water-level-fluctuating-zone of Three Gorges Reservoir, we investigated the vegetation in water-level-fluctuating-zone of the mainstream of Three Gorges Reservoir from August to September 2017. We found that (1) the plant species richness of vegetation in the Three Gorges Reservoir area decreased with the decrease of the distance from the dam. (2) The response of vegetation coverage of different life history species to water flooding gradient stress at water-level-fluctuating-zone of the Three Gorges Reservoir showed the opposite change rule: with the elevation increasing, the contribution of annual plants to the vegetation coverage gradually increased, while the contribution of perennial plants to the vegetation coverage gradually decreased. However, the species coverage of perennial plants was higher than that of annual plants in any elevation in water-level-fluctuating-zone of the Three Gorges Reservoir. (3) Using TWINSPAN vegetation classification method, the vegetation in water-level-fluctuating-zone of the Three Gorges Reservoir can be divided into 25 groups, in which the dominant plant communities are Ass. Xanthiumsibiricum+Cynodon dactylon (including 213 samples), Ass. Cynodon dactylon (including 213 samples), Ass. Cynodon dactylon+Cyperus rotundus (including 55 samples), Ass.Cynodon dactylon+ Polygonum lapathifolium (including 40 samples), Ass. Xanthiumsibiricum +Ageratum conyzoides (including 38 samples). The community characteristics showed obvious adaptation to the fluctuation of water level of the Three Gorges Reservoir and ecological niche differences.