马尾松人工同龄纯林自然稀疏规律研究

通过对马尾松4~20年生不同密度的人工同龄纯林生长资料的分析表明:第1次树高生长分化高峰期在4~7年生,第2次在11~14年生,幼林郁闭后林木直径分化状态比较稳定。中幼林期抚育间伐主要采伐劣等木,进入近熟林期后除采伐劣等木外,还可采伐一部分中等木。间伐施工应以留优去劣为主,适当照顾均匀。总稀疏强度与密度呈正相关性,出现稀疏的时间随密度增大而提前;连年稀疏强度高峰期出现在林分郁闭后的一段时间内。根据总稀疏强度与稀疏时间同密度的关系可确定不同密度林分的间伐强度与时间。利用马尾松人工林观测资料拟合出与立地条件、现存株数密度、林龄三因子相关的自然稀疏模型,从而可推算出不同立地条件的自然稀疏表,为马尾松人工林密度调控提供科学依据。

Study on the Natural Thinning of Even-aged Pure Masson Pine Plantation

Based on the growth analysis of 4-20 year-old Pinua massoniana even-aged pure plantations,it showed that the first tree height growth differentiation peak appeared during the 4-7 year,the second peak appeared during the 11-14 year,and the diameter differentiation became stable after the young plantation close.In junior and middle aged plantation,the tending focused on cutting inferior trees,but part of intermediate tree could also be cut for near-mature plantation.Thinning should retain the dominant trees while properly keep the homogeneous density.The natural thinning density was positive correlated to the stand density.The denser the density,the early the thinning,and the heavier the natural thinning.The peak period of successive annual natural thinning intensity emerged soon after the stand closed.The self-thinning intensity and time for stands with different density could be determined by the relationship between thinning intensity and time.According to the observation data,the natural thinning model related to site condition,existing tree number and stand age could be fitted,from which the natural thinning table for different site conditions could be calculated.