长白山濒危植物牛皮杜鹃(Rhododendron chrysanthum)种群数量特征与动态分析

Quantitative characteristics and dynamic analysis of the endangered species Rhododendron chrysanthum population in Changbai Mountain

牛皮杜鹃为国家Ⅲ级重点保护植物,种群数量有限,处于濒危状态。本文运用种群静态生命表、存活曲线、个体数量动态预测等方法分析了长白山高山苔原带不同海拔牛皮杜鹃种群数量特征及动态发展趋势。结果表明:1)牛皮杜鹃种群大小级结构呈纺锤形,属衰退型种群;2)随海拔升高,种群增长潜力逐渐减小,非完全随机干扰下,种群增长潜力有限,低海拔的Vpi″接近于0;3)种群存活曲线趋于DeeveyⅢ型,高海拔出现较高的死亡率和致死力,种群退化明显;4)在经历1、2、4个龄级后,Ⅳ龄级个体数量会不同程度增加,种群在生长后期个体数量得到补充;5)牛皮杜鹃种群数量主要靠自身匍匐生根形成分株来维持。整个种群向大龄级个体集中,高海拔面临较强的环境胁迫,会比中低海拔更早进入衰退期。导致其濒危的可能原因是牛皮杜鹃的生物学特性及人为干扰。

Rhododendron chrysanthum is listed as one of the national protected plants at third category in Chinese Plant Red Book.Its population size is very small,being on the verge of extinction.Based on the methods of population static life table,survival curve,and individual amount dynamic prediction,the quantitative characteristics and dynamic trend of R.chrysanthum population at different altitudes of alpine tundra in Changbai Mountain were studied.The results were as follows：（1） The spindle-shaped size class structure suggested that R.chrysanthum population exhibited a declined pattern.（2） The growth potential of population decreased gradually with the rising altitude.Under incomplete random disturbance,the growth potential of the population was limited,and the Vpi″ of low altitude was close to 0.（3） The survival curve of population exhibited as the Deevey-Ⅲ type,which had higher death rate and lethal force with obvious degradation at the higher altitude.（4） After 1,2,and 4 age classes,the individual number at age class 4 would increase to varying degree.The individual number was supplemented in the later growth stage.（5） The population size of R.chrysanthum was maintained mainly by ramets reproducing from reptant roots.The possible factors leading to the species being endangered might be its biological characteristics and the disturbances from human activities.