Beneath the Surface: Investigating soil microbial and metazoa communities at various depths in a natural desert ecosystem inhabited by Karelinia caspia

Abstract

Soil organisms play a pivotal role in terrestrial ecosystems, sparking growing curiosity about the comprehensive diversity of subterranean biota across large ecological levels. Soil inhabitants’ exhibit varied responses to soil physicochemical properties (SPPs) across desert ecosystem. Yet, the knowledge of their population dynamics across different soil depths (SDs) in the indigenous natural dominant zone of Karelinia caspia, a primary desert shrub in China, remains limited. This study employed advanced illumina sequencing to assess soil bacteria, fungi, archaea, protist, and metazoa populations across six distinct SDs (0 to 100 cm) within the K. caspia desert landscape. Our findings indicate a descending alpha diversity pattern in bacteria, archaea, and protists as soil depth increases, contrary to fungi and metazoa, which exhibit the opposite trend. SDs significantly shape soil biota beta diversity, notably impacting bacteria, protists, and fungi, as revealed by Non-Metric Dimensional Scaling. Prominent classes include Actinobacteria, Sordariomycetes, Nitrososphaeria, Spirotrichea, and Nematoda for soil bacteria, fungi, archaea, protists, and metazoa, respectively. Correlation analysis between predominant biotic communities' vertical distribution and SPPs variations revealed total potassium (TK) and pH's pronounced influence on bacteria, while fungi were affected by total nitrogen (TN) and soil water content (SWC). Archaea exhibit sensitivity to SWC, available potassium (AK), and available phosphorus (AP); protists respond to C/N-Ratio, nitrate (NO3), and total phosphorus (TP); metazoa correlate with SWC, pH, and NO3. Overall, these findings offer valuable insights regarding population fluctuations of soil biota within naturally established K. caspia across vertical soil strata within China's desert ecosystem.