武夷山不同海拔植被带土壤微生物PLFA分析

Phospholipid Fatty Acid Analysis of Soil Microbes at Different Elevation of Wuyi Mountains

运用磷脂脂肪酸标记法(PLFA)研究武夷山不同海拔植被带(常绿阔叶林EBF、针叶林CF、亚高山矮林SDF、高山草甸AM)土壤微生物群落结构特征。结果表明:从不同海拔土壤中共检测到25种PLFA生物标记,EBF土壤微生物PLFA生物标记种类和总量明显高于其他植被类型,随着海拔的升高,土壤微生物种类和含量逐渐下降。4个海拔土壤中含量最高的PLFA生物标记是18:1ω9c,16:1ω7c,16:00和cy17:0。3种特征微生物相对生物量在不同海拔土壤中分布不同,细菌分布量最大,其次是真菌,放线菌分布量最小。不同海拔植被带土壤微生物群落多样性用不同指数表示,均呈现相似规律,即EBF>CF>SDF>AM。主成分分析表明:与土壤微生物PLFA群落多样性相关的2个主成分分别解释变量方差的59.23%和35.46%,基本能够区分不同海拔土壤微生物群落特征。对第1主成分起主要作用的磷脂脂肪酸为16:1ω9c,a17:0,18:1ω9c和16:1ω7c,对第2主成分起主要作用的为i17:0,16:1ω5c和cy17:0。不同海拔土壤细菌、真菌、放线菌、原生动物各总PLFA与土壤理化性质和酶活性之间存在相关性,总有机碳、全氮和过氧化氢酶对细菌、放线菌和原生动物总PLFA呈极显著正相关。土壤微生物群落多样性随着海拔上升、土层加深而逐渐下降的原因,可能是生物量、林分凋落物、土壤养分、微小动物、植物根系等多种因素共同作用的结果。

In this study, experimental sites were respectively set in evergreen broadleaf forest（EBF） , coniferous forest （CF） , subalpine dwarf forest（SDF） and alpine meadow （AM） along an elevational in the national natural reserve of Wuyi Mountains, and the phospholipid fatty acid analysis（PLFA） was used to examine variations in soil microbial community diversity and its influencing factors. The results showed that： There existed 25 PLFAs that were significantly different in the soil samples from different elevations. The EBF soil exhibited richer PLFAs distribution both in type and amount than the other vegetation types. The microbial activity and functional diversity were decreased with increasing elevation, and in an order of EFB 〉 CF 〉 SDF 〉 AM. The PLFAs biomarkers of three species with the highest contents were 18 ： 1ωgc, 16 ： 1ω7e, 16：00 and cyl7：0. The bacterium had the richest distribution, followed by fungus and actinomycetes at different elevations. The Simpson index, Shannon-Wiener index, Brillouin index and McIntosh index of EBF were holistically higher than those of AM. Component analysis （PCA） identified 2 principal component factors in relation to microbial community diversity, explaining 59.23% and 35.46% of the variation, respectively. The PLFAs, which play a major role on first principal component, are 16：1ω9c,alT：0,18：19c and 16：1ω7c, and, which play a major role on second principal component, are i17：0,16：1ω5c and cyl7：0. The PLFAs of different microbial groups were closely correlated to the soil physicochemical property and enzyme activities, and the TOC, TN and catalase were positively correlated with the PLFAs of bacteria, actinomycete and protozoon. The soil microbial community diversity was decreased along the elevation in Wuyi Mountain, and vegetative biomass, forest litter, soil nutrient, microzoon and plant roots might be the major factors controlling soil microbial community diversity.