长白山云冷杉针阔混交林年龄结构研究

Age structure of Picea-Abies coniferous & broadleaves forests in Changbai Mountains

保证幼苗幼树的林下更新是森林可持续发展的必要条件之一,了解和确定幼树幼苗的更新株数标准是很有必要的,这就需要了解林分从幼树幼苗到大径阶林木完整的林分结构。用1988年调查的4块长白山云冷杉针阔混交林皆伐标准地的幼树幼苗数据和大于检尺径阶林木数据,对林分的年龄结构进行了研究。比较了只用大于检尺林木数据建立的年龄分布与所有林木数据建立的年龄分布之间的区别,并用负指数分布、Weibull分布和幂函数对年龄结构进行了拟合。用胸径≥7 cm的林木数据得到的长白山云冷杉针阔混交林年龄结构呈偏左正态分布,用所有林木数据得到的年龄结构呈反J型分布,龄级35 a以后两者的分布形状相似。通过拟合时的R2和预估值的χ2检验结果发现,Weibull分布对林分结构的拟合效果最好,其次是幂函数,负指数分布最差。但Weibull分布也不是最理想的分布函数,虽然R2达到了0.996,但χ2=297.24大于χ20.05=42.557,这可能和数据数量的多少有关。

Enough seedlings and saplings regeneration is one of the necessary conditions for sustainable forest development, understanding and confirming the standard number of updating trees seedlings and saplings are necessary, which requires understanding of the stand structure from seedling and sapling stage to large diameter trees. The age structure of spruce-fir coniferous ＆ broadleaves forests in Changbai Mountains was studied based on all the tree data from four clearing-cut plots in 1988. The distinctions between two age distributions using all the tree data and tree data larger than the location-foot diameter class were observed. Web the negative exponential distribution, Weibull distribution and power functions were fitted to the age structure. The age structure of spruce-fir coniferous ＆ broadleaves forest in Changbai Mountains was left normal distribution with the data from trees whose diameter at breast height ≥ 7 cm, while that was inverse J-distribution using all the tree data. The distribution of shape was similarity between the two distributions after 35 age class. By R2 derived fitting and X2 evaluating the estimated value showed that, Weibull distribution of stand structure fitted best, followed by a power function, negative exponential distribution fitted worst. However, the Weibull distribution was not ideal, although R2 had reached 0.996, but X2 = 297.24 was greater than X^2 0.05 = 42.557, which might be related to the magnitude of data. Key words ： spruce-fir; coniferous ＆ broadleaves forests ; age structure ; Weibull distribution ; regeneration