近自然经营间伐对黔中马尾松天然次生纯林生长的初期效应

以黔中地区2013年实施近自然经营间伐的2个龄级马尾松Pinus massioniana天然次生纯林为研究对象，通过对8个固定样地与8个临时样地（100~400 m2）胸径、树高、材积、蓄积以及林下植被各生长因子的调查，对比近自然经营间伐林分与相应对照林分各生长因子的差异，评价近自然经营间伐实施4 a的初期效果，为建立贵州省森林可持续经营技术体系提供理论参考。结果表明:①间伐增加了马尾松林分大径级林木的株数比例，对照的中龄林和近熟林胸径分别在8~14和10~14 cm的株数比例最大，间伐在12~18和22~26 cm的株数比例最大。②间伐提高了林木胸径与材积的生长量，间伐的平均木、目标树、非目标树胸径与材积生长量均达到对照的1.15倍以上，最高在中龄林目标树中可达对照的1.65倍。③间伐提高了林分蓄积的生长率，间伐林分蓄积的生长量在小于对照林分的情况下，生长率却在中龄林和近熟林中分别比对照林分高出了4.13%和1.03%。④间伐不能有效促进林分树高生长及林下植被生长。树高及林下植被各生长因子在间伐与对照林分中没有表现出显著的差异性（P>0.05）。

Initial effects of close-to-nature thinning on a natural secondary Pinus massoniana pure forest in central Guizhou

In 2013, close-to-nature thinning was implemented in two, age-grade Pinus massoniana natural secondary pure forests in the middle of Guizhou Province. To evaluate the growth initial effects of the close-to-nature thinned forests for 4 years and to provide references for sustainable forest management of Guizhou Province, through the investigation of the diameter of breast height(DBH), tree height, volume, accumulated and understory vegetation of 8 fixed plots and 8 temporary plots (100-400 m2), compare the difference between the growth of thinned forests and control stands. Results showed that:(1) Thinning was conducive to the production of large-diameter timber. For middle-aged forests and near-mature forests, the ratio of the number of plants with DBH of 8-14 cm and 10-14 cm for the control medium was largest. Whereas, with DBH of 12-18 cm and 22-26 cm, the thinned medium was largest. (2) Thinning promoted growth of DBH and volume of the trees. The annual growth of DBH and volume of the average tree, target tree, and non-target tree in the thinning reached 1.15 times higher of the control, and the highest in the target tree of the middle-aged forest reached 1.65 times of the control. (3) Thinning increased the accumulated growth rate of the stands. In thinned stands, the accumulated growth was less than the control stands, but the accumulated growth rate was higher than the control stands in the middle (by 4.13%) and near mature forests (by 1.03%). (4) The effect of thinning on height growth and the growth of understory vegetation was not obvious, the growth factors of tree height and understory vegetation did not show significant differences in thinning and control stands (P>0.05).