The effects of grazer exclosure duration on soilmicrobial communities on the Qinghai-Tibetan Plateau
The effects of grazer exclosure duration on soilmicrobial communities on the Qinghai-Tibetan Plateau
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DOI：
10.1016/j.scitotenv.2022.156238
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发表时间：
2022-05-29
影响因子：
9.8
通讯作者：
Feng, Qi
中科院分区：
文献类型：
--
作者：
Cao, Jianjun;Jiao, Yumeng;Feng, Qi
虽然确定土壤微生物对放牧者圈闭时间的响应是了解生态系统恢复过程的关键，但很少有研究关注这一问题。微生物多样性是通过Illumina高通量测序16S rRNA基因和内部转录间隔（ITS）来确定的。结果表明，不同放牧期和不同放牧期土壤细菌a-多样性差异不显著，而5年放牧期土壤真菌a-多样性差异显著。放牧13年、22年和39年的土壤微生物群落特征与季节性放牧和5年放牧的土壤微生物群落特征差异显著。简而言之，较长的封闭时间导致多种共营养微生物谱系（如β -变形菌门、根瘤菌门和Frankiales）的相对丰度较高，而几种寡营养微生物谱系（如Chloroflexi、Leotiomycetes和Xylariales）的相对丰度逐渐显著降低。功能预测表明，随着放牧动物封闭时间的延长，固氮菌的相对丰度增加，而植物病原真菌的比例下降。这表明长期放牧可能通过维持植物生长和降低植物病害风险来促进土壤固氮和草地健康。然而，这可能会带来资源成本，因为随着放牧期的延长，植物生产力和土壤有机碳都有所下降。
While determining the response of soil microbes to grazer exclosure duration is critical to understanding ecosystem restoration processes, few studies have focused on this issue. With seasonal grazing as a control, microbes of alpine grassland soils under 5, 13, 22, and 39 years of grazer exclosure situated in the eastern part of the Qinghai-Tibetan Plateau, were examined. Microbial diversity was determined through Illumina high-throughput sequencing of the 16S rRNA gene and an internal transcription spacer (ITS). We found that soil bacterial a-diversity showed insignificant differences between seasonal grazing and grazer exclosure and among the grazer exclosures of different durations, while fungal a-diversity under the 5-year grazer exclosure was significantly different from those under the other treatments. Soil microbial community profiles under the 13-, 22-, and 39-year grazer exclosures were significantly different compared to those under the seasonal grazing or 5-year grazer exclosure. Briefly, longer exclosure durations led to a higher relative abundance of multiple copiotrophic microbial lineages (e.g., beta-Proteobacteria, Rhizobiales, and Frankiales), whereas several oligotrophic microbial lineages (e.g., Chloroflexi, Leotiomycetes, and Xylariales) gradually and significantly decreased. Functional predictions suggest that as grazer exclosure duration was extended, the relative abundance of nitrogen fixers increased, while the proportions of plant pathogenic fungi decreased. This indicates that long-term grazer exclosure duration may contribute to enhanced soil nitrogen fixation and grassland health by maintaining plant growth and decreasing the risk of plant disease. However, this may have a resource cost as plant productivity and soil organic carbon both decreased with the extension of grazer exclosure duration. Therefore, the agroecology effect of grazer exclosure duration on the diversity and abundance of soil nitrogen fixing bacteria and plant pathogen fungi, should be given more attention in the cold and humid portion of the Qinghai-Tibetan Plateau.