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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2 m×3 m～2.5 m×3 m)为宜。
Using the “typical sampling” method, 78 20 m × 20 m forests of Betula alnoides were surveyed in Dehong Prefecture in Spring 2011 and Spring 2012. Through correlation analysis, it is concluded that stand density is significantly related to stand age, average DBH, stock volume and annual average stock volume growth, but not significant with mean stand height. Stand density and age and other related indicators of regression, hyperbolic equation fitting best. The stand density of 78 Southwest Betula platyphylla plantations showed that the regression equation was y-1 = 0.014 2-0.009 6 x-1, and the correlation coefficient was r = 0.336 8. - the correlation coefficient of mean DBH was 0.627 0, the regression equation was y-1 = 0.082 5-0.851 6 x-1; the correlation coefficient of stand density-stock volume was 0.663 5, the regression equation was y-1 = 0.058 3 +2.846 6 x-1. The correlation coefficient and stock volume of stand density and annual average stock volume were the same, the regression equation was y-1 = 0.582 9 + 28.465 7 x-1. (1) The Betula alnoides plantation should be tending and thinning at 3 ~ 5 years old earlier than others; (2) Using “Low Density Crude Diameter ”of the forest policy, in order to improve the output of Southwest birch diameter timber. The density after tending thinning was 900 ~ 1050 plants / hm2 at the time of 20-year-old cutting. (3) The initial planting density of Betula alnoides decreased to 1 665-1 335 plants / hm2 (plant spacing 2 m × 3 m ~ 2.5 m × 3 m) is appropriate.