抚育对粗枝云杉人工林生长和空间结构的影响

森林抚育是实现人工林科学、高效、可持续经营的基本要求。以甘肃省沙滩国家森林公园云杉（Picea asperata）人工林为研究对象,设置幼龄林和中龄林两个试验区,对5种抚育方式后的林分生长情况和空间结构特征进行6 a连续调查分析。结果表明,封禁（FJ）、卫生伐（WF）、机械疏伐 隔一伐一（JF1）、隔二伐一（JF2）]、生态疏伐（SF）后,幼龄林林分的平均胸径、单株材积和蓄积6 a生长量均较对照显著增加,平均胸径分别比对照高-0.3、0.2、2.1、4.5、2.3 cm,单株材积6 a生长量分别是对照的1.2、1.1、4.0、7.8、10.2倍,蓄积6 a生长量分别是对照的1.5、1.4、1.8、8.1、10.4倍。中龄林阶段,FJ、WF、JF1、JF2、SF实施6 a后平均胸径分别比对照高0.2、0.3、2.8、2.6、1.6 cm;抚育明显地增加了林分的蓄积量生长量,除JF1为负增长-16.8 m³/hm²外,FJ、WF、JF2、SF分别是对照的2.1、2.6、11.7、18.2倍,且SF最有利于增加林分蓄积。抚育对林木隔离程度作用效果不显著,对林木大小分化程度影响较小,林分平均角尺度值显著减小,左侧频率之和大于右侧接近正态分布,林分空间格局调整为随机分布或均匀分布;抚育对中龄林林分大小比和角尺度的调节作用优于幼龄林。综合分析得出,云杉人工林高效抚育方式为：密度为4 500~4 800株/hm²幼龄林采用SF、JF2均可,经营密度宜为3 200~3 500 株/hm²;密度为1 630~ 2 151株/hm²的中龄林只能采用SF以加快胸径、蓄积生长,留存密度以1 500株/hm²左右为宜。

Effects of Tending on Stand Growth and Spatial Structure in Picea asperata Plantation

Forest tending is the basic requirement of scientific, efficient and sustainable management of forests. Taking two experimental areas of young and middle-aged Picea asperata plantation in Shatan National Forest Park, Gansu as the research objectives, the spatial structure, non-spatial structure of forest after five different adjustment measures and a no-optimizing (control) treatment were investigated and analyzed continuously in six years. The five kinds of tending methods were forsook, sanitary cutting, mechanical thinning (cut one row every one other row, cut one row every two other rows), and ecological thinning measures, hereinafter referred as FJ, WF, JF1, JF2 and SF. In the young forest, we found that forest tending significantly influenced the average DBH of the stand, height, diameter, individual volume and volume growth. After six years, the average stand DBHs tended by FJ , WF, JF1 , JF2 and SF were -0.3, 0.2, 2.1, 4.5 and 2.3 cm higher than that of control trees, respectively. The volume of individual tree tended by FJ , WF, JF1, JF2 , and SF tending measures were 1.2, 1.1, 4.0, 7.8 and 10.2 times higher than that of control trees, and volume growth were 1.5, 1.4, 1.8, 8.1 and 10.4 times higher than that of control trees. In the middle-aged forest, we found that forest tending significantly increased not only the average stand DBH but also the stand volume growth. After six years, the average stand DBHs of trees tended by FJ, WF, JF1, JF2 , and SF were 0.2, 0.3, 2.8, 2.6 and 1.6 cm higher than that of control trees, respectively. The stand volume of trees tended by FJ, WF, JF2 and SF were 2.1, 2.6, 11.7 and 18.2 times higher than that of control trees, respectively, except the stand volume of trees tended by JF1 which increased -16.8 m³/hm². In addition, the tending measures of SF was the most favorable one in improving the stand volume. The forest tending did not significantly increased the degree of spatial separation, which had less influence on the size differentiation of trees, but it significantly decreased the forest uniform angle index. It was near normal distribution that the left side of the frequency is greater than the right side, and the spatial distribution of stand was adjusted to random distribution or uniform distribution. The results of our comprehensive analysis show that the most effective forest tending measures for Picea asperata plantation is SF and JF2 in young forests whose stand density was 4 500-4 800 trees per hectare, but only SF can used in middle-aged forests whose stand density was 1 630-2 151 trees per hectare. However, to achieve an increase in stand DBH and total volume growth, the stand density should be 3 200-3 500 trees per hectare in young forests and around 1 500 trees per hectare in middle-aged forests.