长白山阔叶红松林林隙大小结构研究

Size structure of canopy gaps in broadleaved Korean pine forests in the Changbai Mountains

该文应用高斯分布、对数正态分布和二阶对数分布模型对长白山阔叶红松林林隙大小结构进行研究,分析了模型的模拟效果,并对模型的拟合优度进行分析和评价.结果表明:长白山阔叶红松林主要以中小型林隙为主,大林隙极少出现.林冠空隙总面积占调查样地总面积的12.5%,扩展林隙总面积占调查样地总面积的28.8%;冠空隙面积在20～100m2之间的林隙占林隙总数的80.7%,扩展林隙面积在80～240m2之间的林隙占林隙总数的81.8%.冠空隙和扩展林隙的大小结构都呈峰值左偏的偏山状分布.冠空隙大小结构服从高斯分布,扩展林隙大小结构可以用高斯分布、对数正态分布和二阶对数分布进行理论描述;根据复相关系数、决定系数、校正决定系数、回归标准误、预测残差平方以及模型拟合度(α=0.05)对模型拟合优度进行评价的结果一致,模型拟合优度顺序为:对数正态分布>二阶对数分布>高斯分布.该文所采用的单峰分布模型能够从数学及生态学上对长白山阔叶红松林林隙大小结构进行较好的解释.

Three kinds of models, which were used to simulate the size distribution of forest gaps of broadleaved Korean pine forests in the Changbai Mountains, were discussed in this paper. The effect of fitting was analyzed and goodness of fit of the models was evaluated. The results showed that most of the gaps consisted of small and medium-sized gaps with the occasional occurrence of large-sized gaps. According to our field survey data, areas of canopy gaps and expanded gaps in broadleaved Korean pine forests in Changbai Mountains accounted for 12.5% and 28.8% of total survey areas, among which gaps with canopy gap area of 20 - 100 m^2 and expanded gap area of 80 - 240 m^2 made up of 80.7 % and 81.8 % of the totals respectively. The size structure of canopy gaps and expanded canopy gaps could be fitted by different unimodal functions with a peak skewed to the left. For the category of the canopy gap area distribution, only the Gaussian Model could be fitted, while for the expanded gap area distribution, all three models, ie the Log Normal Model, the 2nd Order Logarith mic Model and the Gaussian Model could be fitted. In order to evaluate goodness of fit of the models, R, R2 , R2adj, the standard error of the estimate, PRESS, the power of the performed test at a = 0.05 and goodness of fit were calculated. The entire evaluation process reached the same conclusion, ie the order of fitting the best model in descending order was the Log Normal Model, the 2nd Order Logarithmic Model and the Gaussian Model. The models fitted were all unimodal functions with a peak skewed to the left. Both Mathematically and ecologically, this skewness was explained by the fact that small and medium-sized gaps predominate in the broadleaved Korean pine forests.