海南铜鼓岭鸭脚木种群动态特征研究

Population structure and dynamics of Schefflera octophylla in Tongguling,Hainan Province

鸭脚木(Schefflera octophylla)是海南文昌铜鼓岭国家级自然保护区内滨海森林的优势种,也是海南其他地区热带森林常见伴生种。为深入了解该区滨海森林内鸭脚木种群的生存现状、更新机制以及未来发展的动态变化特点,该研究通过对海南热带滨海森林2.56 hm 2样地中鸭脚木种群的调查,以径级结构代替龄级结构,编制鸭脚木种群静态生命表,并结合种群动态量化指数、生存函数、时间序列预测模型等方法定量分析鸭脚木种群结构和数量动态变化。结果表明:(1)研究区域内共记录鸭脚木数量2814株,按照径级大小共划分为12个龄级,龄级结构呈倒J字型,属于趋向稳定型种群。(2)该区鸭脚木的存活曲线趋于Deevey-Ⅱ型,种群各径级的死亡率相接近。(3)鸭脚木种群的量化指数显示,V pi=30.685>0,V pi′=0.236>0,说明该种群现处增长阶段并且相对稳定。(4)据时间序列模型预测鸭脚木种群在未来的3、6、9 a内各龄级的种群个体数量整体呈现增加的趋势。综上分析认为,该区生境有利于鸭脚木种群的生长且该种群形成了良好的生存策略,其幼龄个体较多且后备资源丰富,能较好地补充各龄级个体自然死亡造成的损失,对森林的天然更新起到一定促进作用。

Schefflera octophylla is the dominant species of coastal forest in Tongguling National Nature Reserve in Wenchang,Hainan,and is also a common associated species of tropical forests in other areas of Hainan.Based on the field investigation of sample plot(2.56 hm 2),the dynamic characteristic changes of S.octophylla population were analyzed.In order to reveal the survival status,renewal mechanism and dynamic change characteristics of S.octophylla population in the coastal forest in this region,the age class was divided according to the diameter class method and the static life table,the dynamic index,survival function and time series analysis of the population was compiled to quantitatively analyze the population dynamic changes.The results were as follows:(1)The total number of S.octophylla population in the study area of coastal forest was 2814,which was divided into 12 age classes according to the diameter class.The age class structure was inverted J-shaped,belonging to the stable population.(2)The survival curve of S.octophylla in this area tended to Deevey-Ⅱtype,and the mortality rate of each diameter class of the population was closed to that of S.octophylla.(3)The quantitative index of the S.octophylla population showed that V pi=30.685>0,V pi′=0.236>0,which indicated that the population was in the growth stage and relatively stable,and the number of young individuals in the population was large,which could better supplement the losses caused by natural death of individuals of all ages and form a good survival strategy.(4)According to the time series model,it is predicted that the number of individuals in each age group will increase in the next 3,6 and 9 years.The results show that the habitat in this area is favorable for the growth of S.octophylla with more young trees,abundant reserve resources and good regeneration state,which is conductive to the natural regeneration of the forest.A good survival strategy is formed,which plays a certain role in promoting the natural renewal of forest,and has great significance in the construction and stability of coastal forest community.