State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Ecology, Lanzhou University, Lanzhou, China.
Center for Grassland Microbiome, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China.
Appl Environ Microbiol. 2024 Mar 20;90(3):e0007024. doi: 10.1128/aem.00070-24. Epub 2024 Feb 22.
Nitrogen availability limits the net primary productivity in alpine meadows on the Qinghai-Tibetan Plateau, which is regulated by ammonia-oxidizing microorganisms. However, little is known about the elevational patterns of soil ammonia oxidizers in alpine meadows. Here, we investigated the potential nitrification rate (PNR), abundance, and community diversity of soil ammonia-oxidizing microorganisms along the altitudinal gradient between 3,200 and 4,200 m in Qinghai-Tibetan alpine meadows. We found that both PNR and gene abundance declined from 3,400 to 4,200 m but lowered at 3,200 m, possibly due to intense substrate competition and biological nitrification inhibition from grasses. The primary contributors to soil nitrification were ammonia-oxidizing archaea (AOA), and their proportionate share of soil nitrification increased with altitude in comparison to ammonia-oxidizing bacteria (AOB). The alpha diversity of AOA increased by higher temperature and plant richness at low elevations, while decreased by higher moisture and low legume biomass at middle elevations. In contrast, the alpha diversity of AOB increased along elevation. The elevational patterns of AOA and AOB communities were primarily driven by temperature, soil moisture, and vegetation. These findings suggest that elevation-induced climate changes, such as shifts in temperature and water conditions, could potentially alter the soil nitrification process in alpine meadows through changes in vegetation and soil properties, which provide new insights into how soil ammonia oxidizers respond to climate change in alpine meadows.IMPORTANCEThe importance of this study is revealing that elevational patterns and nitrification contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities were primarily driven by temperature, soil moisture, and vegetation. Compared to AOB, the relative contribution of AOA to soil nitrification increased at higher elevations. The research highlights the potential impact of elevation-induced climate change on nitrification processes in alpine meadows, mediated by alterations in vegetation and soil properties. By providing new insights into how ammonia oxidizers respond to climate change, this study contributes valuable knowledge to the field of microbial ecology and helps predict ecological responses to environmental changes in alpine meadows.
青藏高原高寒草甸的净初级生产力受氮供应限制，而氮供应受氨氧化微生物调控。然而，人们对高寒草甸土壤氨氧化微生物的海拔分布模式知之甚少。在此，我们研究了青藏高原高寒草甸海拔 3200-4200 米范围内土壤氨氧化微生物的潜在硝化速率（PNR）、丰度和群落多样性。结果表明，从 3400 米到 4200 米，PNR 和基因丰度都下降了，但在 3200 米时降低了，这可能是由于底物竞争激烈以及草类的生物硝化抑制作用。土壤硝化的主要贡献者是氨氧化古菌（AOA），与氨氧化细菌（AOB）相比，它们在土壤硝化中的比例随着海拔的升高而增加。AOA 的α多样性随着低海拔地区较高的温度和植物丰富度而增加，而在中海拔地区随着较高的湿度和较低的豆科生物量而降低。相比之下，AOB 的α多样性随着海拔的升高而增加。AOA 和 AOB 群落的海拔分布模式主要受温度、土壤湿度和植被的驱动。这些发现表明，海拔引起的气候变化，如温度和水分条件的变化，可能会通过植被和土壤性质的变化，改变高寒草甸的土壤硝化过程，为了解土壤氨氧化微生物对高寒草甸气候变化的响应提供了新的见解。
