中亚热带5种类型森林土壤微生物群落特征

采用PLFA(phospholipid fatty acids,磷脂脂肪酸)分析法研究江西省九连山国家级自然保护区杉木纯林、马尾松纯林、杉木阔叶混交林、马尾松阔叶混交林与天然常绿阔叶林的土壤微生物群落结构特征,探讨植被特征和土壤理化特征对土壤微生物群落的影响.结果表明:1杉木阔叶混交林土壤细菌、放线菌和总微生物生物量最高,分别为7.77、1.74和18.21 nmolg,而马尾松纯林均最低.2针阔混交显著提高了土壤微生物生物量及其丰富度.土壤微生物生物量及其丰富度均与土壤含水率、w(AN)(AN为有效氮)、w(TC)、w(TN)呈显著正相关(R为0.426~0.701),而与CN〔w(TC)w(TN)〕呈显著负相关(R分别为-0.447、-0.518).3w(AN)对土壤微生物群落结构的解释率达55.8%.尽管林下灌木、草本层生物量对土壤微生物生物量影响不大,但对微生物群落结构有一定影响,解释率分别为5.5%和6.3%.灌草层丰富度与土壤微生物生物量及其丰富度呈显著正相关(R为0.369~0.452).可见,阔叶树种和林下灌草层能够显著影响土壤微生物群落组成.

Characteristics of Soil Microbial Community in Five Forest Types in Mid-Subtropical China

Abstract: Using phospholipid fatty acid (PLFA) analysis, the characteristics of soil microbial community and its response to soil and vegetation were studied in five forest types, including pure and mixed Chinese fir (Cunninghamia lanceolata) plantations, pure and mixed Masson pine (Pinus massoniana) plantations and natural evergreen broad-leaved forest in Jiulianshan National Nature Reserve in Jiangxi Province. The results showed that:1) The mixed Chinese fir plantation had the highest biomass of bacteria (7.77 nmol/g), actinomycetes (1.74 nmol/g) and total microbes (18.21 nmol/g), while the pure Masson pine plantation had the lowest values. 2) The mixed forests significantly enhanced the forest soil microbe biomass and richness, which were positively correlated with soil physio-chemical factors including water content, available nitrogen, total carbon and total nitrogen (R ranged from 0.426 to 0.701), but were negatively correlated with soil C/N (R were -0.447 and -0.518). 3) The soil available nitrogen explained 55.8% of the variability of soil microbial community composition. Understory shrub and herb biomass had no significant effects on soil microbial biomass, but significantly affected the soil microbial community composition and explained 5.5% and 6.3% of variability, respectively. In addition, shrub and herb richness were positively correlated with soil microbe biomass and richness (R ranged from 0.369 to 0.452). These results suggest that broad-leaved trees, understory shrubs and herbs in subtropical forest ecosystems all have important effects on the soil microbial community.