中亚热带森林转换对土壤微生物群落结构的影响

Effects of forest conversion on soil microbial community structure

森林转换是土地利用变化的重要方式,通过改变森林植被类型,从而改变土壤生态系统;土壤微生物是土壤生态系统的重要组成部分,其变化与土壤肥力的改善密切相关.采用磷脂脂肪酸法对南平市顺昌县武坊林场的常绿阔叶天然次生林和杉木人工林的土壤微生物群落结构、土壤养分及其之间的相互关系进行研究.结果表明,常绿阔叶天然次生林土壤的总碳含量、全磷含量、铵态氮、微生物量碳以及碳氮比(C/N)均显著高于杉木人工林(P <0.05),而2个林分间土壤的总氮含量、有效磷含量差异无显著差异(P> 0.05).常绿阔叶天然次生林的革兰氏阳性菌、真菌、总磷脂脂肪酸(总PLFAs)、革兰氏阳性菌革兰氏阴性菌比(G^+:G^-)、细菌真菌比(F:B)显著高于杉木人工林.皮尔森相关分析结果表明细菌、真菌、总磷脂脂肪酸与总碳、全磷、铵态氮、微生物量碳含量显著相关,总磷脂脂肪酸与酸碱度(pH)显著相关(P> 0.05).主成分分析表明第1主成分与第2主成分共同解释了微生物群落结构变化的97.86%,表明森林转换后不同林分的土壤微生物群落结构存在显著差异.冗余分析结果表明第一轴和第二轴分别解释了89.9%和6.7%,土壤全磷、铵态氮、硝态氮对土壤微生物群落结构的影响最大.本研究结果表明森林转换下土壤微生物群落结构与土壤养分含量具有显著相关性,这对于提高土壤肥力,营造可持续发展的杉木人工林有着重要参考价值.

Forest conversion is an important way of land-use change, which changes soil ecosystem by changing forest vegetation type. Soil microorganisms are an important component of soil ecosystem, and its change is closely related to the improvement of soil fertility. In this study, the phospholipid fatty acid method was used to determine the soil microcommunity structure, soil nutrients, and the relationship between the evergreen broad-leaved natural secondary forest and Chinese fir plantation in Wufang forest farm in Shunchang County, Nanping City. The results showed that the total carbon content, total phosphorus content, ammonium nitrogen, microbial biomass carbon, and C/N ratio of the evergreen broad-leaved natural secondary forest were significantly higher than those of the Chinese fir plantation(P < 0.05), but no significant difference was observed in the total nitrogen content and available phosphorus content between the two stands(P > 0.05). The grampositive bacteria, fungus, total phospholipid fatty acid(total PLFAs), gram-positive/gram-negative bacterial ratio(G+:G-) and fungal/bacterial(F:B) ratio of evergreen broad-leaved natural secondary forest were significantly higher than that of Chinese fir plantation. A Pearson correlation analysis showed that bacteria, fungi, and total PLFAs were significantly correlated with total carbon, total phosphorus, ammonium nitrogen and microbial biomass carbon content, and total phospholipid fatty acids were significantly correlated with pH(P > 0.05). A principal component analysis showed that the first and second principal components together explained 97.86% of the changes in microbial community structure, indicating significant differences in soil microbial community structure among different forest stands after forest conversion. A redundancy analysis showed that the first and second axes explained 89.9% and 6.7% respectively. Soil total phosphorus, ammonium nitrogen, and nitrate nitrogen had the greatest impact on soil microbial community structure. The results showed a significant correlation between soil microbial community structure and soil nutrient content under forest conversion, which was of important reference value for improving soil fertility and building sustainable Chinese fir plantation.