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采用固定标准地定位观测和临时标准地调查点面结合的方法 ,在立地分类的基础上[1] ,研究了天然杨桦林林分的经营密度 ,确定杨桦林最佳经营密度为 0 .70 .根据各立地级林分平均胸径的生长进程规律、林分的经营密度模型以及林分胸径与小头直径的相关关系 ,提出了杨桦林大、中径材用材林定向培育技术 .结果表明 ,采用该项技术 ,山杨林和白桦林林分单位面积生长量分别可提高 9.5 0 %～ 2 4.5 2 % ,2 7.6 3% .
Based on the site classification [1], the management density of natural birch forest was studied, and the best management density of birch forest was determined to be 0.70. According to the method of fixed point observation and temporary standard, According to the law of growth of mean DBH at stand-level, the management density model of stand and the correlation between stand DBH and head diameter, the directional cultivation technology of large and medium diameter timber stands of poplar was proposed. The results showed that with this technology, The stand growth per unit area of Populus euphratica and Betula platyphylla can be increased by 9.5 0% -2 4.52% and 2 7.63% respectively.