以胸径、树高、材积为数量评价指标,结合干形、冠高比和分枝粗细形质指标,采用5株优势木对比法开展了西南桦人工林的优树选择技术研究.通过对西南桦人工林10～21年生不同林龄阶段的优树选择标准的总结,提出了优树选择标准,即优树胸径、树高、单株材积分别大于5株对比优势木平均值的9％～l1％、5％～7％、26％～31％以上,形质指标综合得分大于7.5,共选择出西南桦优树37株,入选率为33.9％.西南桦优树的选择标准在实际应用中可根据林分状况适当调整,选优即要考虑其生长性状,同时注意材性、抗性的选择以保证西南桦育种群体的遗传多样性.%Based on quantity indexes ( DBH, tree height and individual volume) in combination with quality indexes ( stem form, crown/height ratio and branch size) , the selection criterion of Betula alnoides superior trees was established using a method of five-dominant-trees. By analyzing the superior tree selection criteria for B. alnoides plantation during different age stages ranged from 10 to 21 years, it was proposed that the strategy of superior tree selection for this species involved as follows: the DBH, tree height, and individual volume of superior tree were respectively 9%-11% , 5%-7% and 26%-31% greater than that of five-dominant-trees, and the multiple shape score was higher than 7.5, Thirty seven in 109 candidate trees were selected according to this criterion and the selected ratio was 33.9%. The superior tree selection criterion should be modified in the practice according to different stand conditions. Since the B. alnoides plantations were managed for large-size timber production, the growth index should be regarded as the principal factor for selection of superior trees so as to obtain high genetic gain. On the other hand, the wood property and resistance should also be considered to insure the genetic diversity of B. alnoides breeding population.
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