Heavy grazing weakened linkage between phoD harboring bacteria and organic phosphorus in two steppes of Inner Mongolia

文献类型： 外文期刊

第一作者： Zhang, Mei

作者： Zhang, Mei;Chu, Guixin;Zhang, Mei;Zhang, Ruixi

作者机构：

关键词： Grassland; Phosphorus; phoD community; Organic P fractions; Grazing intensity

期刊名称：CATENA （ 影响因子：5.7； 五年影响因子：6.3 ）

ISSN： 0341-8162

年卷期： 2025 年 254 卷

页码：

收录情况： SCI

摘要： Organic phosphorus (Po) is the dominant phosphorus (P) fraction in grassland soils, which plays a pivotal role in maintaining P fertility. The mineralization of Po is mainly mediated by phoD-harboring bacteria through secreting alkaline phosphatase (ALP). However, the responses of organic P fractions and phoD community to different grazing intensities have not been well-documented. Herein, an investigation was conducted in two contrasting steppes in Inner Mongolia, four sheep grazing intensities were established: no grazing (UG), light grazing (LG), moderate grazing (MG), and heavy grazing (HG). Various Po fractions; ALP activity; and the diversity, composition, and abundance of phoD-harboring bacterial community were analyzed. In the typical steppe, compared with the UG treatment, integrated phosphorus availability index, NaOH-Po, and total Po decreased by 41.6-51.4 %, 7.6-10.4 %, and 5.0-17.7 %, respectively, under the treatments of HG and MG. Similar observations were noted in the desert steppe. Moreover, in the typical steppe, the influences of four grazing intensities on ALP activity, phoD gene copies, and alpha-diversity of phoD-harboring bacterial community followed the order: LG > UG > MG > HG. In the desert steppe, heavy grazing decreased soil ALP activity and phoD gene copies, but did not significantly influence alpha-diversity of phoD-harboring bacterial community. The network complexity of phoD community decreased with increasing grazing intensity, heavy grazing obviously weakened the interconnections between phoD species and different Po fractions in both typical and desert steppes. Additionally, Variibacter and Hartmannibacter were identified as the keystone bacteria genera involved in Po transformation. Taken together, our findings suggested that overgrazing decreased P availability, which was closely associated with the adverse effects of heavy grazing on ALP activity and the composition, abundance and co-occurrence networks of phoD-harboring bacterial community.

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