间伐对人工林木材质量有重要影响。该文通过对塞罕坝机械林场千层板林场间伐与未间伐的华北落叶松人工林的测定，分析了间伐对华北落叶松人工林出材量的影响。结果表明：间伐能够提高华北落叶松人工林木材规格，增加出材量。

Intermediate cutting plays a very important role on timber quality. The study showed that there was a difference in the timber outturn of Qiancengban forest center in Saihanba for Larix principis-ruppre-chtiiin Mayr plantation between thinned and un-thinned stands,and analysed the thinning effects on timber outturn. The results show that the thinning of Larix principis-rupprechtiiin Mayr plantation can increase timber size and timber outturn.

为了阐明华北落叶松人工林不同林隙大小对更新的影响规律,对木兰围场低效华北落叶松人工林林隙内苗木更新特性进行了研究。结果表明:林隙内更新苗的主要种类有华北落叶松、山杨和油松。华北落叶松和山杨的密度在林隙面积为120~140m2时最大,达到2 411株/hm2;而油松的密度在林隙面积为20~40m2时最大,为196株/hm2。随着林隙面积的增大,华北落叶松和山杨大径级和大高度级更新幼苗数量基本呈现增加的趋势,在林隙面积达到160~180m2时达到最大值;而油松在40~60m2时达到最大,径级大于2cm的更新苗密度为69株/hm2。

Seedling regeneration properties of inef ficient Larix principis-rupprechtii forest in Mulan Weichang were researched in order to clarify gap size on update rules of Larix principis-rupprechtii forest .The results showed renewed seedlings within gaps consist of Larix principis-rupprechtii ,Populus davidiana and Pinus tabulaeformis .Larix principis-rupprechtii and Populus davidiana density in the gap area range from 120 to 140 m2 is maximum ,reaching 2 411 individuals per hectare .But Pinus tabulae f ormis density in the gap area ranging from 20 to 40 m2 is maximum ,with 196 individuals per hectare .With the in-crease of gap size ,the seedling number of Larix principis-rupprechtii ,and Populus davidi-ana of large diameter and height class showed an increasing trend ,reaching the maximum value in the gap area up to 160 to 180 m2 while Pinus tabulaeformis reached the maximum value at 40 to 60 m2 ,with the seedling density of 69 individuals per hectare when diameter at >2 cm .

采用标准地调查和标准木树干解析法调查林龄为31年的华北落叶松人工林,对解析木资料进行综合汇总、计算,绘出华北落叶松树高、胸径、材积的生长曲线图,揭示华北落叶松在六盘山区的生长动态规律.结果表明:华北落叶松的胸径、树高、材积总生长量随着林龄增长,呈明显的上升趋势,胸径、树高连年生长量呈明显的波浪型增长趋势,胸径快速增长主要集中在6—16年;第7年时,胸径生长量达到连年生长量的最高峰.华北落叶松树高快速增长主要集中在6—14年,第12年时,达到连年生长量的最大值;材积连年生长量快速生长期主要集中于12—29年,材积生长量保持在0.007~0.031 m3;第29年时,达到材积生长量的最高峰.材积连年生长量的快速生长期较胸径连年生长量、树高连年生长量迟.第11年、14年时,林分的高生长、胸径生长均有明显下降,可将第11—14年,定为对华北落叶松开展首次抚育间伐的最佳时间段,之后应当按森林经理期5~8年,定期对华北落叶松人工林开展森林抚育间伐措施,以保证其胸径、树高的正常生长.华北落叶松为早期速生型树种,其材积生长率曲线随着林龄的增长呈明显的下降趋势.

This paper is based on the calculation of data of sample trees by means of plot investigation and stem analysis the growing curves of tree height, diameter of breast height (DBH) and volume of timber were drawn to determine the characteristics of the stand growth of 31 a Larix principis-rupprechtii plantation in LiuPan Mountains.The results show that:The growth of tree height, DBH and volume of Larix principis-rupprechtii increased significantly with the age of plantation. The growing curves fluctuated in the processes of increase in tree height, DBH. Growth of DBH was quickly at age of 6-16a, and reached its peak of annual growth at age of 7a. In similar, growth of tree height was quickly at age of 6-14a, and reached its peak of annual growth at age of 12a. However, growth of volume of timber was quickly at age of 12-29a, then kept annual growth with 0.007~0.031 m3, and reached its peak of annual growth at age of 29a. The quick growth of volume of timber was delayed compared

通过研究择伐面积以及人工更新不同树种对华北落叶松低效林的土壤有机碳含量和碳密度的影响,为低效林的改造提供参考。2007年在华北落叶松低效林内进行3种不同面积的择伐,即0.02、0.03和0.05 hm2,并在择伐孔内人工更新白桦和华北落叶松2种树种,2012年测其土壤有机含碳量和碳密度。结果表明:同一择伐面积下,人工更新华北落叶松的土壤含碳量和碳密度均比白桦高,即异龄纯林比针阔混交林高;人工更新白桦的各择伐孔内土壤有机碳含量和碳密度表现为0.02 hm20.03 hm20.05 hm2,栽植华北落叶松时表现为0.05hm20.02 hm20.03 hm2;同一择伐孔内,土壤含碳量和碳密度均随着土层深度的增加而降低;对于0~30cm土层来讲,更新树种的影响比择伐面积的影响大。

The purposeof this study is to provide references for transformation of low efifciency stands by research the influences on soil carbon content and carbon density aboutLarix principis-rupprechtii low efifciency stands which were treated with the selective cutting and artiifcial regeneration. The selective cuttings of three different areas were conducted inL.principis-rupprechtiilow function forest in 2007, which were 0.02 hm2, 0.03 hm2 and 0.05 hm2 respectively,Betula platyphylla andL. principis-rupprechtii seedlings were planted in the artiifcial regeneration zones of selective cutting areas. The soil organic carbon content and carbon density were determined in 2012. The results show that within the same selective cutting area, the soil organic carbon content and carbon density of artiifcial L. principis-rupprechtii were both higher than that ofBetula platyphylla, this means that the carbon content and density of uneven-agedpure stands were higher than those of mixed broadleaf-conifer

以燕山地区华北落叶松人工林为研究对象，在收集大量临时样地和解析木资料的基础上，筛选出合适的数据，根据承德市隆化县林管局、木兰林管局和塞罕坝机械林场3个地方的地区特征引入哑变量的概念，利用非线性回归的方法对华北落叶松人工林胸径、树高、材积生长过程进行拟合，结果显示3个地区华北落叶松人工林的胸径、树高、材积生长量没有显著差异。基于哑变量建立了3个地区华北落叶松人工林的胸径、树高、材积生长模型。结果表明：含有哑变量的Schumacher模型对华北落叶松人工林胸径、树高生长过程的拟合效果最好，决定系数R2分别达到了0．9941和0．9929，残差平方和分别为4．7339和6．8849；含有哑变量的二次函数对华北落叶松人工林的材积生长过程拟合最好，决定系数R2为0．9928，残差平方和为0．0023。通过对所建立生长模型的适应性检验，结果表明残差分布比较均匀，预估精度都达到95％以上，说明模型的预估效果比较好。

Larix principis-rupprechtii plantations were selected as study example in Yanshan region .On the basis of mass data about temporary sample plots and analytical trees , screened appropriate data , the concept of dummy variable was introduced ac-cording to the different areas character of Longhua County , Weichang County and Saihanba Machine Forest Farm .Nonlin-ear regression was used to simulate the models of DBH , tree height and volume of L.principis-rupprechtii plantations .The increments of DBH , tree height and volume with dummy variable of Larix principis-rpu prechtii plantations had no significant difference in the three regions .The growth models of DBH ,tree height and volume were established based on dummy varia -ble.The dummy variable Schumacher equation was the best model of the DBH and tree height , the determination coeffi-cient R2 , respectively, achieved 0.994 1 and 0.992 9, the residual sum of squares achieved 4.733 9 and 6.884 9, the dum-my variable quadratic