基于林分结构和竹笋产量的有机材料覆盖雷竹林退化程度评价

为建立有机材料覆盖雷竹Phyllostachys praecox林退化程度评价体系，在浙江省临安市雷竹栽培区设置15个样点，在林分结构和竹笋产量等14项因子调查的基础上，进行主成分分析。研究表明，立竹年龄结构、立竹胸径和竹笋产量可作为雷竹林退化程度评价的主要指标；试验区有机材料覆盖雷竹林退化程度可分为4类6级：重度退化（Ⅰ级）、中度退化（Ⅱ，Ⅲ级）、轻度退化（Ⅳ，Ⅴ级）和正常（Ⅵ级）。重度、中度、轻度退化雷竹林所占比例分别为13.34%，26.66%，46.67%，未退化雷竹林仅占13.33%。有机材料覆盖易造成雷竹林立竹年龄结构不合理，立竹胸径减小，立竹整齐度、分布均匀度降低，竹林出现退化，竹笋产量显著下降。表5参20

Stand structure and bamboo shoot number production based assessment of degradation degree of Phyllostachys praecox covered with organic materials

A principal component analysis of 14 factors including the stand structure and bamboo shoot number in multiple plots was conducted to establish an assessment system of degradation degree of Phyl-lostachys praecox covered with organic materials. The 15 experiment points were set in P. Praecox cultivation region of Lin'an City. The results indicated that the age structure, average diameter of breast height (DBH) and bamboo shoot output were important indexes in assessing the degradation degree of P. Praecox. The test area were classified into six grades and four categories in terms of the degradation degree of P. Praecox, namely, heavy degradation (grade Ⅰ), medium degradation (grades Ⅱ and Ⅲ), slight degra-dation (grade Ⅳ,Ⅴ) and normal (Ⅵ). Percentage of the four categories was 13.34%, 26.66%, 46.67% and 13.33% respectively. P. Praecox covered with organic materials would lead to improper age structure, decrease in DBH, uniformity and evenness, degradation of forest and decreased bamboo shoot yield.