江西省生态公益林典型林分土壤肥力状况研究

Variations in soil fertility of typical non-commercial forest types in Jiangxi Province of eastern China

【目的】生态公益林是以发挥生态效益和社会效益为主要目标的森林类型,土壤肥力状况是土壤的基本属性和本质特征,探讨生态公益林不同林分类型的土壤肥力状况,旨在为森林土壤资源的科学管理与评价及生态公益林管理提供理论参考。【方法】本文从江西省生态公益林监测样地中选取6种处于发育中期阶段的典型林分类型(常绿阔叶林、马尾松林、毛竹林、杉木林、湿地松和针阔混交林) 33块样地,测定其土壤化学性质,并用方差分析(ANOVA)探索林分类型和土壤层次对土壤肥力的影响,同时比较同一林分类型内不同土壤层次和同一土壤层次不同森林类型的土壤化学性质差异,利用主成分分析(PCA)对土壤指标进行降维,计算各林分类型的PCA综合得分进而排序土壤肥力状况。【结果】研究结果表明:随着土壤深度的增加,土壤有机碳、全钾、速效氮、有效磷和速效钾含量均逐渐降低,而p H值、全氮和全磷均无显著变化。同样,除常绿阔叶林A层的有效磷和针阔混交林A层的速效钾分别显著地高于杉木林和马尾松林外,其余同一土壤层次不同林分类型间土壤养分含量无显著性差异。主成分分析显示,第1主轴(35.9%)主要代表速效养分含量和有机碳含量的变化,其中速效氮、速效钾和有机碳的因子载荷值较大;第2主轴(15.4%)主要代表全量养分和p H值的变化;土壤肥力状况排序为:毛竹林>常绿阔叶林>针阔混交林>马尾松林>杉木林>湿地松林。【结论】从保育土壤的角度来看,不同林分类型的肥力状况将为生态公益林差异化补偿提供数据支持和理论参考;此外,相对于人工针叶纯林,常绿阔叶林和针阔混交林有利于土壤养分的积累,因而建议针对人工针叶林进行补植改造,朝向针阔混交林和常绿阔叶林方向转变,从而提升生态公益林的生态和社会效益。

[Objective]Non-commercial forest is a kind of forest,which is focus on promoting the ecological and social benefits.Soil fertility is the basic property and essential characteristics of soil.This study tries to assess the situation of soil fertility under different stand types of non-commercial forest, which is helpful for scientific management and evaluation of forest soil resources and provides the theoretical reference for the management of non-commercial forest.[Method]33sample plots,middleaged forests under six representative stand types were sampled from the monitoring plots of non- commercial forest in Jiangxi Province of eastern China.Soil chemical properties were examined in these plots.The effects of stand types and soil layers on the variations of soil properties were analyzed by two- way ANOVA.Moreover,the variations of soil chemical properties among different soil layers within a same stand and different stand types in the same soil layer were analyzed by one-way ANOVA. Dimensionality reduction of soil chemical properties was applied by principal component analysis (PCA) and the rank of soil fertility was ordered through the comprehensive scores of PCA for different stand types.[Result]The results showed that organic matter,total potassium,available nitrogen,available phosphorus,available potassium decreased with the increasing soil depth,whereas pH,total nitrogen and total phosphorus were not changed with the soil depth.Most of soil chemical parameters were not significantly changed,expect for available phosphorus of top soil layer in broadleaved evergreen forest and available potassium of top soil layer in coniferous and broadleaved mixed forest 'were respectively significantly higher than Chinese fir plantation and Masson pine plantation.The results of PCA showed that the first axis represented for the available nutrient content and organic carbon content,the factor loading values of available nitrogen,available potassium and organic carbon were larger than other parameters.The second axis represented for the total nutrient content and pH.The descending order of soil fertility was bamboo forest,broadleaved evergreen forest,coniferous broadleaved mixed forest, Masson pine plantation,Chinese fir plantation and slash pine plantation.[Conclusion ]This result would provide data supporting and theoretical reference for the differential compensation of noncommercial forest from the view of soil conservation.Furthermore,our result reveals that broadleaved evergreen forest and coniferous broadleaved mixed forest are more helpful for soil nutrient accumulation than artificial plantations.Therefore,we are looking forward to converting the stand structure from coniferous plantation to coniferous broadleaved mixed forest,even broadleaved evergreen forest by replanting and transformation,then promoting the ecological and social benefits of non-commercial forest.