南京仙林地区次生林马尾松种群结构分析

【目的】更好地了解城市边缘马尾松种群的结构与现状。【方法】在样方调查数据的基础上,利用静态生命表、种群数量动态变化量化指数、时间序列预测模型等方法,对南京仙林地区马尾松种群进行了研究。【结果】结果表明,马尾松种群径级结构为纺锤形,幼树幼苗少,中间径级立木成维持种群发展的核心部分。生命表数据表明死亡率(qx)在Ⅵ径级前基本为负值,说明大量的幼树幼苗在前期死亡;目前,该马尾松种群的Deevey存活曲线为Ⅲ型,说明在生活史的各个时期,种群的存活率相差很大。存活率曲线、死亡曲线和致死率曲线均有较大幅度的变化,种群自然更新过程存在明显的周期性。种群结构动态指数在有干扰和无干扰情况下分别为0.264和0.300,偏离0的程度低。【结论】虽然目前依靠中等径级立木维持稳定的种群结构,但结合时间序列预测数据考虑,该种群为衰退种群。马尾松作为亚热带次生林的过渡种群,其种群的衰退与被其他物种替代,为正常现象;但地处城市边缘人为强烈干扰的存在,使得这一进程加速。

Analysis of the Population Structure of Pinus massoniana Secondary Forest in Xianlin District of Nanjing City

【Objective】 To understand the structure and status of Pinus massoniana Lamb population in Xianlin district of Nanjing.【Method】 Based on plot investigation,static life table,quantitative dynamics of population and forecasting model of time series were used to study the P.massoniana population.【Results】 The size class structure ratio of P.massoniana was spindle-shape,indicating that seedlings and saplings were few and mid-class stumpage was the core of the whole population.Life table showed that mortality rate(qx) was minus value above Ⅵ size class,implying that lots of seedlings died in the earlier life stage.Current survival curve was Deevey-Ⅲ,suggesting that population survival rates were different at each period of life history.There were dramatic changes in survival curve,death curve and killing curve,indicating that an obvious periodic fluctuation was in the process of natural regeneration.The values of population dynamic index were 0.264 and 0.300,respectively,under disturbance and not-disturbance and it deviated from 0 slightly.【Conclusion】 Although the population structure was steady based on the mid-class stumpage,taking the time sequence model into consideration it was still a declining population.As a transition population in the subtropic secondary forest,it was a normal phenomenon that the population is substituted or declining.However,this process might be accelerated because of the strong artificial disturbance in edge of the city.