光皮桦天然林分生长与结构对间伐强度的响应

The Stand Growth and Structure of Betula luminifera Natural Forest:Response to the Thinning Intensity

针对光皮桦天然次生林分抚育经营管理技术薄弱、林分生产力低的问题,开展光皮桦天然次生林不同强度的抚育间伐试验,旨在掌握抚育间伐对其生长的影响。在光皮桦天然次生林内,设置0%(CK)、10%、20%和30%4个间伐强度,分析不同间伐强度对林分的胸径、树高、单株材积、蓄积等林分生长及直径分布特征、空间优势度等林分结构的影响。结果表明:(1)在间伐强度≤30%时,光皮桦林分平均胸径、树高、单株材积与蓄积的生长量随间伐强度增加而增加。其中30%强度间伐对林分生长最显著,分别高于CK林分133.0%、67.6%、67.3%、89.5%。(2)间伐有利于林木向大径级发展,随间伐强度的增加,林分胸径在4~10 cm的林木所占比例低于CK林分2.46、8.19、13.69个百分点;间伐显著改善林分空间优势度,其中,30%间伐强度最高为0.366。在光皮桦次生林经营管理过程中,基于改善林分结构,促进林分生长,对平均年龄为13年、林木密度为2500~2900株/hm^(2)的光皮桦次生林林分建议采用30%间伐强度。

Aiming at the problems of weak tending management technology and low stand productivity of natural secondary forest of Betula luminifera, the experiments of tending and thinning at different intensities were carried out to master the influence of tending and thinning on the stand growth. Four thinning intensities:0%(CK), 10%, 20% and 30% were set in the natural secondary forest of Betula luminifera. The influence of different thinning intensities on the stand structure such as average DBH, tree height, individual plant volume,accumulation and other stand growth, diameter distribution characteristics and spatial dominance were analyzed. The results show that:(1) when the thinning intensity is less than or equal to 30%, the average diameter at breast height, tree height, and the volume and accumulation of individual plant growth of B.luminifera forest increased with the increase of thinning intensity, among them, 30% intensity thinning has the most significant effect on stand growth, and the increase is 133.0%, 67.6%, 67.3%, and 89.5%, respectively,compared with those of CK;(2) thinning is beneficial to the growth of trees into large diameter, with the increase of thinning intensity, the proportion of trees with DBH of 4-10 cm in thinning stands of the 3 intensities is lower than that of CK stand by 2.46, 8.19, and 13.69 percentage points;thinning significantly improves the spatial dominance of stand, and the highest intensity of thinning at 30% is 0.366. In the management process of B. luminifera secondary forest, based on improving stand structure and promoting stand growth, it is suggested that 30% thinning intensity is the best for B. luminifera secondary forest with an average age of 13 years and a tree density of 2500-2900 plants/hm^(2).