摘要
为克服结构参数的均值或单一分布在描述林分空间结构的局限性,更准确有效地探讨择伐对林分空间结构的影响,以混交度、大小比数和角尺度的二元分布为切入点,以杉阔混交人工林为对象,对比分析不同强度择伐(中度择伐34.4%、强度择伐47.1%、极强度择伐69.5%)下林分空间结构的变化。从混交度—大小比数二元分布来看:中度择伐3 a后,林分中处于劣势且混交较差的林木有所降低,不存在绝对劣势且零度混交的林木;强度择伐3 a后,不同竞争态势呈中强度混交的林木比例下降;极强度择伐3 a后,处于优势的林木单种聚集现象明显。从混交度—角尺度二元分布来看:不同强度择伐后,二元分布的频率最大值仍集中在很不均匀分布上;中度择伐3 a后,林分中处于均匀分布且混交良好的频率值增加,团状且零度混交的林木株数减少;强度择伐后有更多林木处于团状分布且混交较差状态;极强度择伐后团状分布的林木中呈强度和极强度混交的林木减少,且处于零度混交的株数显著增加。从大小比数—角尺度二元分布来看:不同强度择伐后,林木处于优势且均匀分布比例与伐前相比都有所增加,但极强度择伐后有更多林木处于绝对劣势且很不均匀分布。综合来看,中度择伐后林分空间结构趋于合理,建议采用中度择伐作为调整杉阔混交人工林空间结构的采伐强度。
To overcome the limitation of parameters univariate distribution or mean in describing stand spatial structure, we take the bivariate distribution of mingling, dominance degree and uniform angle index as an effective method to analyze the influence of selective logging on stand spatial structure of Cunninghamia lanceolata-broadleaved mixed plantation. The stand were harvested by selective cutting of different intensities （medium intensity of 34.4% , high intensity of 47.1% and over-high intensity of 69.5% ）. In terms of the bivariate distribution of mingling and dominance degree, the results showed that fewer trees were in a state of low mingling and inferior, and no in absolute inferiority or only surrounded by the same species under medium intensity cutting. Over- high intensity cutting showed opposite result. The number of tree of medium and high mingling reduced under high intensity cutting. The results of the bivariate distribution of mingling degree and uniform angle index indicated that most of trees were still in absolute asymmetrical pattern after selective cutting. More trees were in a randomly distributed and surrouded by more then two different species under medium intensity cutting. However, more trees were asymmetrical and low mingling in high intensity cutting stand, and it was worse in over-high cutting stand. In terms of the bivariate distribution of uniform angle index and dominance degree, more trees were in the state of relative superior and random pattern after selective cutting. Over-high intensity cutting resulted in increased numbers of trees under situation of absolute inferiority and reunion distribution. Generally, the stand under medium intensity cutting presented more ideal structure, and we suggest take medium intensity as an effective method to optimize spatial structure of C. lanceolata-broadleaved mixed plantation.
出处
《森林与环境学报》
CSCD
北大核心
2015年第4期337-342,共6页
Journal of Forest and Environment
基金
国家自然科学基金项目(30972359)
福建省林业厅科学基金项目(闽林科[2012]2号K8512001)
福建省中青年教师教育科研A类科技项目(JA14124)
福建农林大学高水平大学建设项目(113-612014018)
福建农林大学部级创新平台项目(ptjh13002)
关键词
杉木
择伐
空间结构
二元分布
Cunninghamia lanceolata （Lamb.） Hook
selective intensity
spatial structure
bivariate distribution
