Abstract：
The altitude distribution patterns of soil microorganisms and their driving mechanisms are crucial for understanding the consequences of climate change on terrestrial ecosystems. There is an obvious altitude difference in Datong River Basin in the Qilian Mountains. Two spatial scale transections were set up along the mountain slope (with altitude spanning 1 000 m) and the mainstream direction (with altitude spanning 300-500 m), respectively. The distribution characteristics of the soil bacterial community structure and diversity along the altitude gradients were examined using high-throughput sequencing technology. Based on the FAPROTAX database, the altitude distribution patterns of nitrogen cycling functional groups were analyzed to investigate the major environmental factors influencing the altitude distribution patterns of soil bacterial communities. The findings revealed that:① Soil physicochemical characteristics varied significantly with altitude. The content of total nitrogen (TN) and nitrate nitrogen (NO3-) were positively correlated with the altitude (P < 0.01), whereas the soil bulk density and pH were negatively connected (P < 0.001). ② The abundance of OTU increased significantly along the altitude (P < 0.01), and the richness and diversity indices increased along the altitude, although the trend was not statistically significant (P > 0.05). ③ The predominant bacterial communities were Acidobacteria, Proteobacteria, and Bacteroidetes, and as altitude climbed, their relative abundances varied between increasing, decreasing, and slightly decreasing, respectively. ④ The nitrogen cycling processes involved 13 functional groups, primarily nitrification, aerobic ammonia oxidation, aerobic nitrite oxidation, etc. As the altitude increased, the response law changed, with an increase in the abundance of nitrobacteria (P < 0.01), a slight increase in the abundance of aerobic ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, and a hump-back tendency in bacteria abundance for nitrogen respiration. ⑤ Redundancy analysis revealed that the key determinants influencing soil bacterial populations at the phylum level were altitude, pH, and the content of NH4+. Mantel analysis showed that the dominant groups of soil bacterial nitrogen cycling were all statistically and significantly driven by altitude (P < 0.01). ⑥ The α-diversity of the bacterial community with increasing altitude were both increased along the mountain slope and the mainstream direction, but the soil properties, the abundance of N-cycling functional groups, and the main environmental factors differed. Therefore, it is of great significance to explore the altitude distribution pattern of soil microorganisms at different spatial scales.
摘要：
土壤微生物的海拔分布模式及其驱动机制对于理解气候变化对陆地生态系统的影响至关重要。祁连山大通河流域存在明显的海拔差异。沿山坡（海拔1000m）和主流方向（海拔300-500m）设置了两个空间尺度横断面，分别。利用高通量测序技术研究了土壤细菌群落结构和多样性沿海拔梯度的分布特征。基于FAPROTAX数据库，分析了氮循环功能群的海拔分布规律，探讨了影响土壤细菌群落海拔分布规律的主要环境因子。结果表明:①土壤理化特性随海拔高度的变化而显著变化。全氮(TN)和硝态氮(NO3-)含量与海拔高度呈正相关(P<0.01),而土壤容重和pH呈负相关(P<0.001)。②OTU丰度沿海拔高度显著增加(P<0.01),丰富度和多样性指数沿海拔高度增加，虽然趋势无统计学意义(P>0.05)。③主要细菌群落为酸性细菌，变形杆菌,和拟杆菌,随着海拔的攀升，它们的相对丰度在增加之间变化，递减,略有下降，分别。④氮循环过程涉及13个官能团，主要是硝化，好氧氨氧化,好氧亚硝酸盐氧化，等。随着海拔高度的增加,应对法改变了，随着硝化细菌丰度的增加(P<0.01)，需氧氨氧化细菌和亚硝酸盐氧化细菌的丰度略有增加，以及细菌丰度对氮呼吸的驼峰趋势。⑤冗余分析表明，在门水平上影响土壤细菌种群的关键决定因素是海拔，pH值,和NH4+的含量。Mantel分析表明，土壤细菌氮循环的优势类群均受海拔驱动，具有统计学意义（P＆lt;0.01）。⑥随着海拔的增加，细菌群落的α-多样性沿山坡和主流方向均增加，但是土壤的特性，丰富的N循环官能团，主要环境因素不同。因此,探索不同空间尺度土壤微生物的海拔分布规律具有重要意义。
