摘要
上海城郊人工林普遍存在林分密度高、林相结构简单、个体生长分化严重等现象，合理调控森林的密度结构成为城市森林建设亟待解决的关键问题。本研究以上海宝山区建植于2001年、初植密度为4600株·hm^-2的香樟人工林为对象，在生长3a后将林分密度分别调控为1000株·hm^-2（P1）、1300株·hm^-2（P2）和1600株·hm^-2（P3）的3个不同样地，于2012年各设置1个50mX50m典型样地，细分成4个25m×25m样方，调查测定林木的测树因子、空间结构和树芯结构，分析林木生长过程和空间分布格局。结果表明，随着密度增加，林木枯死率升高，林木分化程度增强；P1、P2、P3样方个体最大径级分别达25．7、28．6cm和23．9cm，变异系数分别为0．11、0．13和0．17。在4～25m空间尺度上，P1、P2样方个体呈随机分布，P3样方个体呈聚集分布和随机分布交替现象。各龄级林木胸径生长呈先增加后减少趋势，密度越高林木径向生长量越小，而现存生物量以P2样方最高，达17392．21kg·hm^-2。因此，上海地区10a左右的香樟幼林合理密度约为1300株·hm^-2，采用动态密度管理机制，使林分达到最佳生长状态。
How to regulate to the reasonable density of urban forest has become a key issue in Shanghai due to the current status of high tree density, simple community structure and serious growth differentiation. The tree measurement factors, spatial structure and tree-ring structure in each 50 mN 50 m plot of Cinna- momum camphora forest with different densities of 1 000 （Pl）, 1 300 （P2）, 1 600 trees ·hm^-2（P3） in Boshan District of Shanghai were studied. These plots were planted in 2001 with density of 4 600 trees/ hm2 and regulated to the designed density 3 years later. The results indicated that the death rates and tree differentiation degrees increased with the increase of tree density. The maximum diameter classes and dif- ferential coefficients in the sampling plots of Pl, P2, and P3 were 25.7 cm and 0.11, 28.6 cm and 0.13, and 23.9 cm and 0.17, respectively. At the special ranges of 4--25 m scale, the distribution patterns of P1 and P2 were random, while both clump and random distributions were observed in P3. The radial growth of each DBH-size class presented an increased trend firstand then a decreased trend, and the growth was the minimum in the highest density plot. The biomass of P2 was the largest which reached to 17 392.21 kg·hm^-2. Thus, the reasonable density of 10-year Cinnamomum camphora plantation was about 1 300 trees ·hm^-2 in Shanghai area.
出处
《西北林学院学报》
CSCD
北大核心
2014年第2期20-25,共6页
Journal of Northwest Forestry University
基金
国家"十二五"科技支撑项目(2011BAD38B03)
上海市宝山区科技发展基金项目(11-A-5)
关键词
香樟人工林
密度调控
林木分化
空间格局
生长过程
生物量
Cinnamomun camphora ecological forest
density regulation
tree differentiation
spatial distri-bution pattern
growth process
biomass
