小兴安岭阔叶红松混交林林隙特征

Gap characteristics in the mixed broad-leaved Korean pine forest in Xiaoxing' an Mountains

对小兴安岭阔叶红松混交林林隙基本特征进行了研究。结果表明:林隙的线状密度为31.78个/km,冠空隙和扩展林隙所占的面积比例分别为15.71%和30.78%;冠空隙的年干扰频率为0.46%,干扰轮回期约为434.8a。冠空隙的大小变化在42.12—372.52m2之间,平均为153.37m2;扩展林隙的大小变化在98.65m2—633.10m2之间,平均为300.44m2。冠空隙和扩展林隙面积分布格局均符合Weibull分布。林隙形成方式主要为干基折断,占总形成木总数的35.29%,其次为掘根风倒,占28.43%。平均每个林隙的形成木为4.98株,由红松、白桦、枫桦、冷杉形成,径级在20—30 cm之间,高度在15—30 m之间。冠空隙的直径与高度比值的相对频率的分布呈单峰型曲线,当比值为0.30—0.45时,出现峰值;而扩展林隙的直径与高度比值的相对频率的分布呈双峰型曲线,当比值分别为0.75—0.90和1.05—1.15时,出现峰值。林隙边缘木胸径级的多度分布和高度级多度分布符合Weibull分布,但不符合正态分布。约13.41%的边缘木未出现偏冠现象,偏冠率在0.5—0.7之间的边缘木占70.49%。

Gap characteristics were studied in the mixed broad-leaved Korean pine forest in Xiaoxing＇an Mountains. The results showed that the linear gap density in the forest was 31.78 gaps/kin. The canopy gaps and expanded gaps occupied 15.71% , and 30.78% of total investigated area, respectively. The yearly gap disturbance frequency was 0.46% and the disturbance rotation was 434.8 years. Canopy gaps varied from 42.12 to 372.52 m2 and average area of canopy gaps was 153.37m2. Expanded gaps varied from 98.65m2 to 633. 10m2 and average area of expanded gaps was 300.44mz. The distribution pattern in both canopy gap area and expanded gap area followed Weibull model. The major means of gap formation was breakage at base（35.29% of the total）, and the second was uprooting （28.43%）. The average number of gap makers was 4.98 per gap. Major gap makers were Pinus koraiensis, Betula platyphylla, Abies nephrolepis, Betula costata, of which the diameter at breast height （DBH） were between 20--30 cm and the height ranged from 15 to 30 m. For canopy gaps, their distribution in relative frequency of the ratio of their diameter to the height of forest gap （ dcc/H） presented single peak curve, the peak value occurred when the ratio of dcc/H was between O. 30--0.45, but for expanded gap, their distribution exhibited double peak curves, the peak value came when the ratio of dcc/H was between O. 75--0. 90 and between 1.05--1.15, respectively, in the mixed broad-leaved Korean pine forest in Xiaoxing＇an Mountains. The distribution of DBH classes and tree height classes of gap border trees followed Weibull distribution model but they did not follow the normal distribution model. About 13.41% of GBT had regular crowns, the GBT, of which the ratios of crown inclination （RCI） ranged from 0.5 to 0.7, comprised about 70.49% of total GBT.