戴云山不同海拔黄山松群落的高度级结构研究

Height class structure of a Pinus taiwanensis community growing at different elevations on Daiyun Mountain

采用级间失稳率、群落高度级分享度和Whittaker指数分析戴云山黄山松群落高度级结构随海拔梯度变化的特征。结果表明,随高度级增加,群落个体数和物种数均呈下降趋势。沿海拔梯度上升,黄山松群落整体失稳率大致呈上升趋势,且均为正值。黄山松种群的Ⅰ~Ⅱ、Ⅱ~Ⅲ级间失稳率多为负值,而Ⅲ~Ⅳ、Ⅳ~Ⅴ和Ⅴ~Ⅵ为正值,种群优势地位明显。总体上,优势种对第Ⅰ高度级分享度最大,随高度级增加,种对高度级的分享度不断降低。黄山松群落高度级随海拔梯度变化其物种替代速率存在差异,Whittaker指数(βw)大多分布在0.4左右,高度级间物种变化幅度相对平稳。戴云山黄山松群落在垂直空间上物种分布连续性良好,处于稳定发展阶段,更新能力强。目前黄山松种群优势地位显著,高海拔区域优势地位更明显。黄山松在混交群落竞争中偏向K对策,以较多的成年大树来增强其在群落的优势地位。

The height class structure characteristics of a Pinus taiwanensis community growing at different elevations on Daiyun Mountain were analyzed using the inter-stage failure rate,community height sharing,and the Whittaker index.The results were as follows.As tree height increased,the number of individuals and species decreased.As altitude increased,the overall instability rate for the P.taiwanensis community generally showed an increasing and positive trend.TheⅠ-ⅡandⅡ-Ⅲheight classes for the P.taiwanensis population were mostly negative,whereas theⅢ-Ⅳ,Ⅳ-Ⅴ,andⅤ-Ⅵclasses were positive and the dominant position was obvious.On the whole,the sharing degree of the dominant species was largest for the first height classes,but it decreased as the height classes increased;and there was a difference in the species turnover rates between the height classes of the P.taiwanensis community along the elevation gradients.The Whittaker index(βw)was mostly around 0.4,and the species variation range between the height classes was relatively stable.The results show that the species distribution of the P.taiwanensis community in vertical space was continuous.Furthermore,the P.taiwanensis community was at a stable development stage and had a strong natural regeneration ability on Daiyun Mountain,and the dominant position of the P.taiwanensis population was significant and more obvious in the high elevation area.The P.taiwanensis population tended to adjust its K strategy when subjected to community competition,and the more mature trees were used to strengthen its dominant position in the community.