地表覆盖栽培雷竹林植被退化特征分析

Classification of Vegetation Degradation Degree of Phyllostachys praecox Forests under Soil-surface Mulching

为进一步明确不同经营程度地表覆盖雷竹林的退化程度,应用主成分分析法对浙江、江西两地40块雷竹主产区试验林的14项林分调查因子指标进行植被退化等级划分。结果表明:40块不同经营程度的雷竹试验林可以划分为未退化、轻度退化、中度退化和重度退化4大类,退化竹林的比例(90%)显著高于未退化竹林(10%);立竹平均胸径,立竹平均枝下高以及竹笋产量随退化程度的加重基本上呈逐渐降低的趋势;雷竹林退化等级划分存在地域差异,江西省万年县所调查的试验林中,没有重度退化雷竹林,而浙江省太湖源镇中度和重度2种退化程度的雷竹林所占的比例高达67.86%,其中栽植年限10 a及以上的雷竹林占94.74%,覆盖年限达4 a及以上的也高达88.89%,可见栽植年限以及覆盖年限的增加均会引起竹林的退化。

In order to determinate the degradation degree of Phyllostachys praecox forests under various soil-surface mulching managements , a principal component analysis of 14 stand description factors was conducted to classify the vegetation degradation degree of 40 Ph. praecox forests in Zhejiang and Jiangxi Province .The results showed that the 40 test forests were classified into four categories , i.e., heavy degradation , medium degradation , slight degradation and normal .The proportion of degraded forests （ 90%） were significantly higher than that of normal ones （10%） .The average height under the first branch ,average diameter at breast height （ DBH） ,and yield of bamboo shoots decreased gradually with the aggravation of degradation .The degradation degree differed geographically .There were no forests of heavy degradation in Jiangxi province , while the proportion for forests of heavy and medium degradation was high up to 67.86%in Zhejiang province ,where the forests planted more than 10 years accounted for 94 .74%, and the forests mulched more than 4 years accounted for88.89%.Therefore ,the increase of planting years and mulching years may cause degradation of Ph.praecox.