Adopting the method of typical sampling, totally 78 sample plots of 20 m × 20 m of Betula alnoides plantations in Dehong prefecture of Yunnan province were investigated in spring of 2011 and 2012 respectively. Through correlation analysis, it was found that the planting density was significantly correlated with stand age, average DBH, volume, average annual volume growth rate, whereas was not significantly correlated with average tree height. To the regression between stand density and stand age, hyperbolic equation could get the best fitting effect. Calculating with the whole data of 78 sample plots, the regression equation for analyzing the correlation between stand density and stand age was y -1 =0. 014 2-0. 009 6 ×-1 , with the correlation coefficient of r =0. 336 8; considering only the stand of ten years old, the equation for analyzing the correlation between stand density and DBH was y -1 =0. 082 5 -0. 851 6 ×-1 , with the correlation coefficient of r =0. 627 0. The correlation equation between planting density and volume was y -1 =0. 058 3+2. 846 6 ×-1, with the correlation coefficient of r =0. 663 5; the correlation equation between planting density and average annual volume growth was y =0. 582 9 + 28. 465 7 ×-1, with the correlation coefficient of r = 0. 663 5. Analyzing from the change rule of planting density with the increase of stand age, and relevant change of average DBH of stand, three suggestions for management of B. alrwides plantations were proposed as follows: 1) Tending and intermediate cutting of B. alrwides plantations should begin as early as 3 to 5 years old; 2 ) Up to the main cutting time of 20 years old, the proper density should be 900 to 1 050 trees/ha; 3) The suggested initial planting density of B. alrwides plantations was 1 335 to 1 665 trees per ha.%采用“典型抽样”方法,2011年春和2012年春,在德宏州调查了78块20 m×20 m的西南桦人工林样地.通过相关分析,认为林分密度与林分年龄、平均胸径、蓄积量、年平均蓄积生长量显著相关,而与林分平均树高相关不显著.林分密度与林龄等相关指标的回归,以双曲线方程拟合最好.78块西南桦人工林样地的林分密度-林龄回归方程为y-1 =0.014 2-0.009 6 x-1,相关系数r=0.336 8.10年生同龄林分18块样地林分密度-平均胸径的相关系数r =0.627 0,其回归方程为y-1 =0.082 5-0.851 6 x-1；林分密度-蓄积量的相关系数r=0.663 5,其回归方程为y-1 =0.058 3 +2.846 6 x-1;林分密度与年平均蓄积生长量的相关系数与蓄积量同值,其回归方程为y-1 =0.582 9 +28.465 7 x-1.从林分密度随林龄增长的变化规律及与林分平均胸径的相关变化提出,(1)西南桦人工林应提早在3～5年生时进行抚育间伐；(2)采用“低密粗径”的育林方针,以提高西南桦大中径材产出.到20年生主伐时,抚育间伐后的密度则以900～1 050株/hm2最佳；(3)西南桦造林初植密度降到1 665～1 335株/hm2(株行距2m×3 m～2.5 m×3 m)为宜.
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