Abstract:

Temporal and spatial variations of sexual reproduction in a remnant population of the endangered species Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang were investigated based on changes in flowering and fruiting traits with elevation on Guanzhou Island, Zhijiang, China. The impact of cascade water conservancy and hydropower construction projects on the sexual reproduction of remnant populations was analyzed based on the characteristics of water-level fluctuations in the habitat of M. laxiflora. Results showed significant differences in the sexual reproduction of the remnant population at different elevations. Flower branch number per plant, flower number per branch, and flower number per plant of plants at the upper part of the fluctuation zone were 66.09%, 50.14%, and 98.63% higher than those at the middle part, and 79.50%, 283.33%, and 461.05% higher than those at the lower part, respectively. Fruit branch number per plant, fruit number per branch, fruit number per plant, seed number per fruit, and seed germination percentage of plants at the upper part of the fluctuation zone were 60.17%, 25.26%, 88.05%, 6.96%, and 30.69% higher than those at the middle part, and 97.39%, 82.45%, 208.31%, 19.12%, and 45.91% higher than those at the lower part. Correlation analysis showed significant correlations between the flowering and fruiting characteristics and elevation, plant exposure period, soil water content, and temperature. The influence of environmental factors on sexual reproduction was in the order of exposure time, elevation, daily average temperature, and soil moisture content.

摘要：

本文以分布于枝江关洲岛的濒危物种疏花水柏枝（Myricaria laxiflora (Franch.) P. Y. Zhang et Y. J. Zhang）为研究对象，调查其种群开花和结果性状沿高程的变化，分析该残存种群有性繁殖的时空变化规律；同时结合三峡大坝-葛洲坝水利水电工程修建所引起生境地水位消涨节律的变化，分析其对残存种群有性繁殖的影响。结果显示，残存疏花水柏枝种群的有性繁殖在不同高程之间存在显著差异。消涨带上部植株的每株花枝数、每枝花朵数、每株花朵数分别比消涨带中部植株高66.09%、50.14%和98.63%，比消涨带下部植株高79.50%、283.33%和461.05%。消涨带上部植株的每株果枝数、每枝结果数、每株结果数、每果种子数和种子发芽率分别比消涨带中部高60.17%、25.26%、88.05%、6.96%和30.69%，比消涨带下部高97.39%、82.45%、208.31%、19.12%和45.91%。相关性分析结果表明，植株的开花结果特性与高程、出露时期、土壤含水量以及温度变化极显著相关。环境因子对有性繁殖的影响强度依次为出露时间>高程>日均温度>土壤含水量。上游水利水电工程对疏花水柏枝残存种群的有性繁殖具有一定的影响。