Differential influence of water and early vegetation on desert soil microbiome abundance and interaction

Frequent droughts driven by variable precipitation, depleted soil moisture, and water-use pressure limit tree establishment in dryland restoration. We examined microbiome trajectories in desert soil during a 4-month field trial under four treatments: non-vegetated non-watered soil (SN), non-vegetated watered soil (SW), vegetated non-watered soil (VN), and vegetated watered soil (VW). By combining 16S rRNA and ITS2 amplicon sequencing with generalized Lotka-Volterra modeling, we observed that vegetation was the primary filter for microbial diversity, whereas watering adjusted the interaction strength. Phylum-level patterns remained stable, but vegetation input caused pronounced, condition-specific shifts at the genus level. Intrinsic growth rates revealed drought-resilient persistence in bare non-watered soil, opportunism in bare watered soil, vegetation-induced antagonism in vegetated non-watered soil, and cooperative expansion in vegetated watered soil. Network connectivity in the vegetated-watered soil increased by 31% and mutualistic links tripled relative to drought soils. In contrast, vegetation alone led to a rise in antagonism and competition exceeding 9%. The results suggest that aligning water application with practices that induce microbe-microbe synergy and plant-microbe mutualism may enhance early seedling survival and establishment in arid soils.