1 Xinjiang Key Laboratory of Desert Plant Roots Ecology and Vegetation Restoration, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, 848300, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address: waqarislam@ms.xjb.ac.cn.
2 Xinjiang Key Laboratory of Desert Plant Roots Ecology and Vegetation Restoration, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Cele, 848300, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address: zengfj@ms.xjb.ac.cn.
3 Department of Building, Civil and Environmental Engineering, Concordia University, 1455 de Maisonneuve Blvd. W. Montreal, Quebec H3G1M8, Canada.
4 Yele School of Environment, New Haven, CT, 06511, USA.

The underground community of soil organisms, known as soil biota, plays a critical role in terrestrial ecosystems. Different ecosystems exhibit varied responses of soil organisms to soil physical and chemical properties (SPCPs). However, our understanding of how soil biota react to different soil depths in naturally established population of salinity tolerant Tamarix ramosissima in desert ecosystems, remains limited. To address this, we employed High-Throughput Illumina HiSeq Sequencing to examine the population dynamics of soil bacteria, fungi, archaea, protists, and metazoa at six different soil depths (0-100 cm) in the naturally occurring T. ramosissima dominant zone within the Taklimakan desert of China. Our observations reveal that the alpha diversity of bacteria, fungi, metazoa, and protists displayed a linear decrease with the increase of soil depth, whereas archaea exhibited an inverse pattern. The beta diversity of soil biota, particularly metazoa, bacteria, and protists, demonstrated noteworthy associations with soil depths through Non-Metric Dimensional Scaling analysis. Among the most abundant classes of soil organisms, we observed Actinobacteria, Sordariomycetes, Halobacteria, Spirotrichea, and Nematoda for bacteria, fungi, archaea, protists, and metazoa, respectively. Additionally, we identified associations between the vertical distribution of dominant biotic communities and SPCPs. Bacterial changes were mainly influenced by total potassium, available phosphorus (AP), and soil water content (SWC), while fungi were impacted by nitrate (NO₃-) and available potassium (AK). Archaea showed correlations with total carbon (TC) and AK thus suggesting their role in methanogenesis and methane oxidation, protists with AP and SWC, and metazoa with AP and pH. These correlations underscore potential connections to nutrient cycling and the production and consumption of greenhouse gases (GhGs). This insight establishes a solid foundation for devising strategies to mitigate nutrient cycling and GHG emissions in desert soils, thereby playing a pivotal role in the advancement of comprehensive approaches to sustainable desert ecosystem management.