不同密度和立地因子对密云县橡树次生林生长的影响

根据北京云蒙山林场的3块不同密度的标准地资料,分析橡树次生林不同林分密度分别与其平均胸径、平均树高、平均单木蓄积之间的关系,并建立了相应的回归方程,相关系数均在0.88以上。另根据云蒙山林场2009年二类清查资料,对20个小班采用方差分析的统计方法,利用其平均优势木四十年生时的树高,按单项立地因子实际分布区间进行分组,计算其差异显著水平,分析各立地因子对林木生长的影响。结果表明,橡树次生林密度与林分的平均胸径、林木单株蓄积之间呈负相关关系,密度对于评价林分的树高影响程度不如对胸径大;云蒙山林场四十年生橡树次生林的密度应控制在1 570株.hm-2以下;通过分析橡树次生林生长与立地因子的关系,初步确定了其适宜的立地条件为：高海拔,有效土层厚度在≥30 cm,坡度大于25°时树高生长差异不显著。

Effects of Different Densities and Site Conditions on Growth of Oak Secondary Forest in Miyun County

Based on the data of 3 stand sites of oak secondary forest in Miyun county Beijing,the relationship a mong its different forest density respectively with its DBH, the average tree height, single-tree volume,and the regression equations were established, the relevant coefficients were all above 0.88. Based on 20 stand sites of 2009 forest resource inventory data in Miyun county, using its dominant height of forty-year-old secondary forest, the actual distribution area of single site factor was divided into groups to obtain the changing regularity of each factor by variance analysis. The results showed that oak secondary density and its DBH, single-tree volume has negative correlation,while for the average tree height, the influence was not so apparent. Densities of oak secondary should be controlled below 1 570 trees,hm 2. The suitable site factors for oak secondary were initially determined as follows：high altitude,the thickness of effective soil layer more than 30 cm,slope more than 25%, on the conditions, it has no significant difference for tree height growth.