五台山华北落叶松水源涵养林密度结构与生长动态

 为探索华北落叶松水源涵养林的立地适应性和密度合理性,在山西省五台山水源涵养林区,利用标准木树干解析法,对10年生华北落叶松2种密度(2600和3500株.hm-2)的人工林生长过程和直径分布进行研究。结果表明:1)2种林分树高生长量基本相同,几乎不受密度变化的影响;林木直径和立木材积生长过程差别较大;低密度林分的生长状况和密度结构优于高密度林分。2)2种林分直径分布的偏度系数(Sk)差别较大;低密度林分Sk=0.01,接近正态分布,密度结构基本合理;高密度林分Sk=0.45,偏离正态分布,林木密度偏大。2种林分直径分布的峰度系数(K)相差不大(分别为-0.64和-0.74),密度因素对林木分化的作用较小。3)低密度林分的林木胸径、单株材积和干材蓄积生长量逐年增加,没有受到密度的影响;高密度林分的林木胸径、单株材积和干材蓄积生长量从6年生开始明显下降。4)华北落叶松人工林的林龄为10年生时,合理密度约2600株.hm-2;若不考虑10年生之前的间伐利用,可以作为人工造林合理的初植密度。

Density structure and growth dynamics of Larix Principis-rupprechtii stand for water resource conservation in Wutai Mountain region in Shanxi Province

To search after the adaptability on site and suitability on density of Larix Principis-rupprechtii Mayr.stand for water resource conservation,the growth process and diameter distribution characteristic of Larix Principis-rupprechtii Plantation in 10 years old were studied using stem analysis method of sample tree,which had two density structures(one was 2 600 per hm2,the other was 3 500 per hm2) in water conservation forest region of Wutai Mountain in Shanxi Province.The results showed that: 1) The tree height growth of two kind of forests were the same basically,and it was almost not affected by density.But the growth process of diameter and timber volume had great distinction.The growth status and its density structure of low density forests were superior to the high density forests.2) The S_kewness(S_k) of diameter distribution had great distinction.The S_k(was 0.01) of low density forests approached to normal distribution,the density structure was reasonable,while the S_k(was 0.45) of high density forest was partial to normal distribution,the density structure was on the high side.The kurtosis(K) of two forests(one was-0.64,the other was-0.74) had little distinction and the density factor had little function to forest polarization.3) The growth of diameter at breast height,timber volume and trunk stock of low density forests increased year after year without effect of density.But the growth of high density forests had declined from since 6 years old,which was restricted by high density.4) The reasonable density of Larix Principis-rupprechtii Plantation about 10 years old was 2 600 per hm2,if the utilization of double cutting was not considered,it is also the reasonable planting density.