不同生境内濒危植物长喙毛茛泽泻种群数量动态比较

湖南茶陵自然种群动态在一年内表现为春季数量下降，以后振荡变化。在以莼菜为主的样方中，种群在夏季以后一直呈增加趋势，至冬季末数量下降；在杂草拥挤的样方内，种群基本呈下降趋势。湖北武汉，网室中迁地保护的种群生长在理想条件下，单一种群呈逻辑斯缔（Ｌｏｇｉｓｔｉｃ）增长，方程为Ｎ（株／ｍ２）＝８４０１＋ｅ４．４７７－０．２６４ｔ。江西东乡回归原产地的种群在回归当年经过精心照顾，种群呈增加趋势，次年随着杂草茂盛生长，种群数量迅速下降，种群具消失的危险。长喙毛茛泽泻种群数量的变动很大程度上受水位变化和杂草干扰的影响。实验结果表明，长喙毛茛泽泻种群能成功地实施迁地保护。

POPULATION DYNAMICS OF RANALISMA ROSTRATUM ,AN ENDANGERED SPECIES GROWING IN DIFFERENT HABITATS

In Chaling county of Hunan Province,the natural population density was declining in spring and fluctuating later in all the following growth seasons.In those quadrats where Brasenia schreberi was the dominant,population density was increasing from summer to autumm and declining in winter.In the quadrats with a lot of grasses,however,population density showed a decline.In Wuhan University,the logistic growth cquation of the cultivated population grown under good conditions was N =8401 e 4.47-0.264 t (In/m 2) In Dongxiang County of Jiangxi Province,the restored population grew well in the first year if the weed was cut,but in the second year when weeds grew vigorously,the population declined rapidly and confronted to extinction.Water level and neighbouring species had great effect on the increase of the popula tion.The ex situ conservation of R.rostratum population was carried out successfully.