小果紫薇林近自然种群结构及动态特征

通过对西藏墨脱近自然分布的小果紫薇种群展开样地调查,编制小果紫薇种群静态生命表,绘制小果紫薇存活曲线、生存函数曲线以及死亡率和消失率曲线,同时利用时间序列模型和种群动态量化方法进行预测,以揭示近自然分布的小果紫薇种群结构和动态特征。结果表明:小果紫薇种群属于增长型,整个种群数量变化动态指数值Vpi与V'pi(考虑外界干扰时)均大于零,但对外界干扰敏感性较高;存活曲线趋于Deevey-Ⅱ型,说明小果紫薇各龄级有相近的死亡率;死亡率和损失率曲线变化趋势基本相同;时间序列预测分析表明,在未来2、4、6、8龄级时间后小树、中树和大树个体数量都将得到增多。小果紫薇种群若能维持现有生境,并适当进行轻微的人为干扰,将具有较好的自我更新能力,有利于维持种群延续发展。

Structure and dynamic characteristics of Lagerstroemia minuticarpa near-natural population

Base on the field survey data of Lagerstroemia minuticarpa Debberm. ex P. C. Kanjilal population under near-natural condition in Motuo,Tibet, the static life table, survival curve, survival function curve, mortality rate and killing power curve were analyzed.And the population structure and dynamic characteristics of L.minuticarpa were predicted by the adoption of the time sequence model and quantitative method of population dynamics in this paper.Results showed that: the population of L.minuticarpa fit in with the growing type, Vpi andV′pi was greater than zero when taking external interference into consideration, but sensitive to external disturbance.The survival curve trended to Deevey-Ⅱ type which indicated that the mortality rate in different age-classes was similar.The changing trend of the curve of mortality rate was the same as the killing power curve.Time sequence model suggested that the number of small, medium and big trees would increase in the age-classes of 2, 4, 6 and 8 in the future.With appropriate minor human disturbance, the existing habitat of L.minuticarpa population would be maintained completely and the population will go developing with self-renewal ability.