退化人工林不同恢复类型对土壤微生物群落功能多样性的影响

为了评价华南退化人工林生态系统的不同恢复类型,本研究以土壤微生物群落功能多样性为对象,探讨恢复林土壤微生物功能多样性的差异及影响因子.在研究区内选取代表性的近自然经营杉木林(CF)和毛竹林(MB),以天然次生林(NF)为对照,采集表层土壤样品.运用Biolog-Eco微平板技术,对3种林分的土壤微生物群落功能多样性进行研究.结果表明: 不同恢复林分的植物多样性差异显著,NF植物多样性指数显著高于MB和CF,而MB的植物多样性指数显著高于CF;不同林分类型的土壤pH和容重差异显著,其他土壤理化性质差异不显著;不同林分类型土壤微生物的平均颜色变化率(AWCD)为NF＞MB＞CF,不同林分对6种类型碳源底物的利用也有相似规律;NF的土壤微生物群落Shannon多样性指数、Shannon丰富度指数、Simpson优势度指数和McIntosh指数最高,MB次之,CF最低;主成分分析表明,从31种碳源类型提取的主成分1和主成分2分别能解释变量方差的60.0%和12.4%,在主成分分异中起主要贡献作用的是羧酸类、碳水化合物类和氨基酸类碳源;相关性分析表明,植物物种丰富度和多样性指数、土壤容重与土壤微生物群落多样性指数之间存在显著相关关系,对土壤微生物群落功能多样性具有重要影响.NF土壤微生物的碳源利用效率高于人工林,而MB土壤微生物碳源利用效率高于CF.从植被多样性及土壤微生物群落功能多样性来看,近自然经营的MB人工林更有利于退化人工林生态系统功能的恢复与提升.

Effects of stand type of artificial forests on soil microbial functional diversity

We explored the changes of soil microbial biodiversity in response to forest ecological restoration. Soil samples were collected from the close-to nature managed Chinese fir plantation (CF), Moso bamboo plantation (MB), and natural secondary forest (NF). Soil microbial community diversity was analyzed by Biolog-Eco micro-plate technique. The results showed that plant diversity was significantly different among the three stands. Plant diversity of NF was significantly higher than MB and CF, and MB was higher than CF. Soil pH and bulk density showed a great difference, while there was no difference of other soil physiochemical properties among the three stands. Avera-ge well color development (AWCD) of soil in various stands followed the order of NF＞MB＞CF, consistent with the changes of utilization of six types of carbon sources. Shannon index of NF was the highest, and the index of MB was significantly higher than that of CF. Soil physical and chemical properties in different stands were not significantly different, except soil pH and bulk density. The Shannon diversity index (H), Shannon species richness index (S), Simpson dominance index (D) and McIntosh index (U) were the highest in NF, second in MB, and the lowest in CF. Results from principal component analysis (PCA) showed that two factors from 31 carbon sources could explain 60.0% and 12.4% of the variation and that carboxylic acids, carbohydrates and its derivatives, amino acids were the main carbon sources of the two principal component factors. Correlation analysis indicated that plant species richness and Shannon diversity indexes, soil bulk density were significantly correlated to soil microbial community diversity. The microbial community of NF was more efficient in carbon utilization than that in MB and CF, while that in MB was more efficient than that of CF. Based on plant diversity and soil microbial carbon utilization, MB is much better than CF in the artificial forest restoration and improvement in South China.