Abstract: Uncovering the change of soil microbial community composition and its interaction with soil nutrients and enzyme activities is the precondition for better understanding the shortterm effects of fencing on the recovery of ecosystem function in Ulmus pumila scattered woodland. In this study, 16S rRNA gene and ITS gene high-throughput sequencing technology was used to examine microbial community composition in response to shortterm fencing and continued grazing in Ulmus pumila scattered woodland of Horqin Sandy Land. The correlation between microbial community composition and soil nutrient concentrations was analyzed. The results showed that the dominant bacteria belonged to Actinobacteria in phylum level, with a proportion of 40.63% and 43.02% in fencing lands and grazing lands, respectively. The dominant fungi belonged to Ascomycota, with a proportion of 76.19% and 66.42% in fencing lands and grazing lands, respectively. Fencing shifted community composition of bacteria from slow growing bacteria to fast growing bacteria. Fencing significantly increased the number of OTUs of soil bacteria and fungi, but reduced the soil bacteria/fungi ratio. Fencing significantly increased α-diversity and relative abundance of soil fungi by 77.89% and 70.78% compared to grazing lands. This result indicated that fencing improved the habitat environment of the fungi and thus is beneficial to their growth. Soil bacterial and fungal community composition were positively correlated with soil nutrients and enzyme activities in fencing lands, indicating that short-term fencing could affect soil microbial community composition.

Key words: fencing, Ulmus pumila scattered woodland, microbial diversity, microbial ecology, high-throughput sequencing.