Chen Xianjiang, Hou Fujiang, Wu Yanpei, Cheng Yunxiang
Soil Fertilizer and Water-Saving Institute, Gansu Academy of Agricultural SciencesLanzhou, China.
The Ministry of Agriculture in Gansu Province Cultivated Land Conservation and Agricultural Environmental Science Observation Experiment StationsWuwei, China.
Front Microbiol. 2017 Apr 7;8:606. doi: 10.3389/fmicb.2017.00606. eCollection 2017.
The Loess Plateau of China is one of the most fragile ecosystems worldwide; thus, human production activities need to be conducted very cautiously. In this study, MiSeq high-throughput sequencing was applied to assess the relationship between bacterial and fungal community structures and changes in vegetation and soil physical and chemical properties induced by grazing, in four grasslands with different levels of grazing intensity (0, 2.67, 5.33, and 8.67 sheep/ha) in the semiarid region of the Loess Plateau. The relative abundances of the bacterial community in the grasslands with 2.67 and 5.33 sheep/ha were significantly higher than those in grasslands with 0 and 8.67 sheep/ha, and the fungal diversity was significantly lower for grasslands with 2.67 sheep/ha than for the other grasslands. Redundancy analysis (RDA) showed that plant biomass, nitrate, and total nitrogen have significant effects on bacterial community structure, whereas nitrate and total nitrogen also significantly affect fungal community structure. Variation partitioning showed that soil and plant characteristics influence the bacterial and fungal community structures; these characteristics explained 51.9 and 52.9% of the variation, respectively. Thus, bacterial and fungal community structures are very sensitive to grazing activity and change to different extents with different grazing intensities. Based on our findings, a grazing intensity of about 2.67 sheep/ha is considered the most appropriate in semiarid grassland of the Loess Plateau.
中国黄土高原是全球最脆弱的生态系统之一；因此，人类生产活动需极为谨慎地开展。在本研究中，运用MiSeq高通量测序技术，对黄土高原半干旱地区4个不同放牧强度（0、2.67、5.33和8.67只羊/公顷）的草地中，放牧引起的细菌和真菌群落结构与植被及土壤理化性质变化之间的关系进行评估。每公顷2.67只羊和5.33只羊的草地中细菌群落的相对丰度显著高于每公顷0只羊和8.67只羊的草地，且每公顷2.67只羊的草地中真菌多样性显著低于其他草地。冗余分析（RDA）表明，植物生物量、硝酸盐和总氮对细菌群落结构有显著影响，而硝酸盐和总氮对真菌群落结构也有显著影响。变异分解表明，土壤和植物特征影响细菌和真菌群落结构；这些特征分别解释了51.9%和52.9%的变异。因此，细菌和真菌群落结构对放牧活动非常敏感，并随不同放牧强度而发生不同程度的变化。基于我们的研究结果，黄土高原半干旱草地约每公顷2.67只羊的放牧强度被认为是最合适的。
