自然疏伐,自然间苗;
The 5-year study indicates that the optimal thinning treatment for 20~ 30-year-old natural birch stands is to maintain a stand density of 1 100 stems · hm-2 and the pruning intensity should not exceed 1/ 2 tree height.
5a的研究结果表明,林龄20~30a的白桦天然林最适林分密度为1100株·hm-2,修枝强度不应超过1/2树高。
The study on the relation between thinning intensity and seed production of the natural Scotch pine seed forest
樟子松天然母树林疏伐强度与种子产量的关系
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