杉木短周期小径材培育模式的林分直径结构及经营要素预测

以6~14年生杉木短周期小径材人工林为研究对象,对其直径结构进行统计分布检验,采用Weibull生长方程对林分直径累积分布进行模拟,并通过动态预测分析立地、林分密度、主伐年龄对培育目标的影响。结果表明:88.3%的样地其林分直径分布为左偏,林分直径分布峭度为负值的样地占所有样地的81.7%,林分平均直径对应的植株数量累积分布率为55.1%,直径结构为Weibull分布的林分占86.7%;两参数Weibull生长方程对各林分直径分布具有较好的适合度(R2>0.99),参数b、c具有明显生物学意义,分别与林分平均直径和直径变异系数呈紧密线性关系(R2=0.986 7、0.885 7)。采用回归法建立直径曲线1-1/e和拐点处参数回收方程,关键点处直径与林分平均直径呈紧密幂函数关系(R2≥0.95),由此构建的林分直径预测系统K-S检验通过率为85%。通过建立林分平均直径与年龄、立地指数和林分密度的多元非线性关系,在对不同关键要素组合模式下林分不同径级立木植株数量动态预测的基础上,比较分析不同要素对培育目标的影响,提出了杉木短周期小径材培育模式关键技术的理论参数。

Stand Diameter Structure and Management Factor Prediction of Chinese Fir Short-cycle Cultivation Model

The diameter structure of 6-14 year old Chinese fir short-cycle plantation for small-sized timber was studied for statistical distribution. The Weibull growth equation was used to simulate the cumulative distribution of stand diameter and the influence of site, stand density and cutting age on the cultivation target was analyzed through dynamic prediction. The stands with the distribution of stand diameter to the left accounted for 88.3% of all the stands and the stands with the negative kurtosis of stand diameter distribution accounted for 81.7%. The cumulative distribution rate of plant number corresponding to the mean diameter of stand was 55.1%, and the stands with Weibull distribution in diameter structure accounted for 86.7%. Two-parameter Weibull growthequation with had good fitness for the distribution of stand diameters(R~2>0.99), and the parameters b and c had obvious biological significance, showing a close linear relationship with stand mean diameter and diameter variation coefficient, respectively(R~2=0.986 7 and 0.885 7). The regression method was used to establish the parameter recovery equation of 1-1/e of the diameter curve and the inflection point. The diameter at the key point was in a tight power function relation with the average diameter of the stand(R~2≥0.95). Through the establishment of forest stand average diameter and age, site index and stand density of multivariate nonlinear relationship, the number of standing trees with different diameters was predicted dynamically under different key combination modes and the influence of different factors on cultivating target was analyzed. The theoretical parameters of the key techniques in the cultivation mode of Chinese fir short-cycle small path timber were proposed finally.