间伐强度对塞罕坝华北落叶松人工林生长进程和生物量的影响

根据塞罕坝机械林场总场阴河林场生产经营现有的间伐强度(24.0%、25.9%、38.6%),设置标准地9块并制作解析木9株,对不同间伐强度条件下的华北落叶松(Larix principis-rupprechtii Mayr.)人工林生长状况、生物量及生产力进行了调查研究。结果表明:随着间伐强度的增加,胸径、树高、材积生长量均有明显增加;相同龄组不同间伐强度条件下,林木树干、树皮、树枝、树叶、树根生物量及总生物量有随间伐强度增大而增加的趋势。间伐强度为38.6%的林分树干的含碳量为48.20 t.hm-2,比间伐强度24.0%、25.9%的林分分别大2.81、1.08 t.hm-2,林木碳储量的积累主要在树干部分,大约占总碳储量的50%左右。从生产实际来说间伐强度为38.6%条件下林分平均生产力比24.0%、25.9%间伐林分分别高出4%、5%。针对林场生产经营现有的3种间伐措施来讲,最适间伐强度为38.6%。

Effects of Thinning Intensity on the Growth and Biomass of Larix principis-rupprechtii Plantation in Saihanba,Hebei Province

Nine sample plots were set up in Larix principis-rupprechtii plantations in Saihanba State-owned Forest Farm based on the existing thinning intensities(24.0%,25.9% and 38.6%).One analytic tree was selected in each sample plot(3 repeated trials for every thinning intensity) to study the effects of various thinning intensities on the growth,biomass and productivity of L.principis-rupprechtii plantations.Results showed that diameter at breast height,tree height and wood volume were positively affected by the increase of thinning intensity.Biomasses of tree trunks,bark,branches,leaves,roots and the total biomass of L.principis-rupprechtii plantations in the same age group showed an increasing trend with increasing thinning intensity.The carbon content in trunks was highest(48.20 t·hm-2) under thinning intensity of 38.6%,which was 2.81 and 1.08 t·hm-2 higher than that of the other two thinning intensity treatments(24.0%,25.9%),respectively.Forest carbon storage was mainly accumulated in the trunks(50% of the total carbon storage).Similarly,plantation productivity was highest(5.2 t·hm-2·a-1) under the thinning intensity of 38.6%,which was 4% and 5% higher than that of the other two treatments,respectively.For the existing thinning measures,the optimal thinning intensity was 38.6%.