Su Junhu, Ji Weihong, Sun Xiaomei, Wang Haifang, Kang Yukun, Yao Baohui
College of Grassland Science, Key Laboratory of Grassland Ecosystem (Ministry of Education), Gansu Agricultural University, Lanzhou, 730070, China; Gansu Agricultural University-Massey University Research Centre for Grassland Biodiversity, Gansu Agricultural University, Lanzhou, 730070, China; Gansu Qilianshan Grassland Ecosystem Observation and Research Station, Wuwei, 733200, China.
Gansu Agricultural University-Massey University Research Centre for Grassland Biodiversity, Gansu Agricultural University, Lanzhou, 730070, China; Institute of Natural and Mathematical Sciences, Massey University, Private Bag, North Shore Mail Centre 0632, Auckland, 102 904rad, New Zealand.
J Environ Manage. 2023 Feb 1;327:116859. doi: 10.1016/j.jenvman.2022.116859. Epub 2022 Nov 28.
Management practices, such as grazing exclusion and reseeding, have been implemented to mitigate the degradation of grassland. Low grazing intensities and reseeding increase grass production. Nevertheless, few studies have investigated the effects of these measures on the soil microbial community structure and function in the Qinghai Tibetan Plateau (QTP). To reveal the effects of management practices on soil microbes and give a reference to assess and improve ecosystems functions, we here evaluated the impact of various types of grazing (exclusion, seasonal, and traditional), reseeding (annual oat (Avena fatua) grassland (RO) and perennial artificial grassland cultivated >10 y), and integrated restoration (weed control and no-tillage reseeding) measures on soil microbial community structure and function in the QTP. The Shannon-Wiener diversity indices were highest for prokaryotes under RO and for fungi under integrated grassland restoration. Relative Actinobacteria abundance was higher under seasonal grazing than that under integrated grassland restoration. The latter had relatively higher abundances of Betaproteobacteria, Alphaproteobacteria, and Deltaproteobacteria and comparatively lower abundance of Thermoleophilia. There were significantly higher abundances of plant pathogens under seasonal grazing than those under other managements. There were significantly high proportions of pathotrophs and saprotrophs (10.0%) under seasonal and traditional grazing, respectively. The proportion of pathotrophs under integrated restoration (10.0%) was about seven-fold greater than that under grazing exclusion (1.5%). The relative differences among treatments in terms of soil water content, plant biomass, and soil C:N partially explained the differences in their prokaryotic community compositions. Increases in soil organic carbon and C:N may explain the observed changes in the soil fungal communities. The management practices affected soil microorganisms mainly by altering the soil nutrient profile. Grazing attracted specific pathotrophs and saprotrophs while repelling certain plant pathogens. Hence, modulations in soil microbial community structure and function must be considered in the process of planning for the implementation of grassland degradation management measures.
为减轻草地退化，已实施了诸如禁牧和重新播种等管理措施。低放牧强度和重新播种可提高牧草产量。然而，很少有研究调查这些措施对青藏高原土壤微生物群落结构和功能的影响。为揭示管理措施对土壤微生物的影响，并为评估和改善生态系统功能提供参考，我们在此评估了不同类型放牧（禁牧、季节性放牧和传统放牧）、重新播种（一年生燕麦（野燕麦）草地（RO）和种植超过10年的多年生人工草地）以及综合恢复（杂草控制和免耕重新播种）措施对青藏高原土壤微生物群落结构和功能的影响。RO处理下原核生物的香农-威纳多样性指数最高，而综合草地恢复处理下真菌的该指数最高。季节性放牧下放线菌的相对丰度高于综合草地恢复处理。后者的β-变形菌纲、α-变形菌纲和δ-变形菌纲的丰度相对较高，嗜热菌的丰度相对较低。季节性放牧下植物病原体的丰度显著高于其他管理方式。季节性放牧和传统放牧下致病营养型和腐生营养型的比例分别显著较高（10.0%）。综合恢复处理下致病营养型的比例（10.0%）约为禁牧处理下（1.5%）的7倍。各处理间土壤含水量、植物生物量和土壤碳氮比的相对差异部分解释了其原核生物群落组成的差异。土壤有机碳和碳氮比的增加可能解释了土壤真菌群落的观察变化。管理措施主要通过改变土壤养分状况影响土壤微生物。放牧吸引了特定的致病营养型和腐生营养型，同时排斥了某些植物病原体。因此，在规划实施草地退化管理措施的过程中，必须考虑土壤微生物群落结构和功能的调节。
