沙坡头地区凋落物分解及其对土壤微生物群落的影响

以腾格里沙漠东南缘沙坡头人工固沙植被区典型植物种凋落物(小画眉草、藓类、油蒿叶片)为对象,运用凋落物分解袋法和高通量测序技术,分析了3种植物凋落物分解特征及其对土壤微生物群落的影响。结果表明: 分解时间和凋落物类型均显著影响分解速率,藓类分解最慢,13个月后质量损失比仅为15.4%,油蒿叶片和小画眉草的平均分解速率分别是藓类的4.9和3.4倍。经过11个月的分解,细菌群落的优势菌门为放线菌门和变形菌门,真菌群落的优势菌门是子囊菌门;藓类分解过程中,拟杆菌门和绿弯菌门的相对丰度显著增加,担子菌门的相对丰度显著降低。凋落物分解后,细菌和真菌群落物种多样性和丰富度显著增加,细菌群落组成在凋落物间变化不显著,真菌群落变化显著。凋落物的分解速率与细菌和真菌群落多样性及丰富度均呈负线性变化。植物多糖、全磷和土壤pH、微生物生物量氮、铵态氮含量是影响微生物群落结构的主要因子。凋落物分解改变了土壤微生物群落物种组成和种间相似性,显著增加了土壤中微生物群落的多样性和丰富度,促进了土壤生境的恢复。

Litter decomposition and its effects on soil microbial community in Shapotou area,China

We investigated the decomposition characteristics of Eragrostis minor, mosses, and leaves of Artemisia ordosica with litterbag method in the sand-binding revegetation area, southeastern edge of the Tengger Desert, and further examined their effects on soil microbial communities using the Illumina MiSeq sequencing method. The results showed that the decomposition duration and litter types significantly affected litter decomposition rate. Mosses had the lowest decomposition rate, with a mass loss ratio of only 15.4% after decomposition for 13 months. The average decomposition rates of E. minor and leaves of A. ordosica were 4.9 and 3.4-fold of that of mosses, respectively. During decomposition for 11 months, the dominant bacterial phyla were Actinomycota and Proteobacteria, while that of the fungal community was Ascomycota. Moss decomposition significantly increased the relative abundance of Bacteroidetes and Chloroflexi, but remarkedly decreased the abundance of Basidiomycetes. The diversity and richness of bacterial and fungal communities significantly increased after litter decomposition. The compositional changes of fungal community were significant among litters, but that of bacterial community was not. There was a negative correlation between decomposition rate and the diversity and richness of bacterial and fungal communities. Plant polysaccharides, total phosphorus, soil pH, microbial biomass nitrogen, and soil ammonium content were the main factors affecting microbial community structure. Litter decomposition changed the composition and interspecific similarity within microbial communities, as well as increased the diversity and richness of soil microbial communities, and thus would promote the restoration of soil habitat.