Plant rhizospheres selectively recruit microorganisms to enhance environmental adaptability and nutrient acquisition. Yet, the mechanisms that drive this trade-off between these functions under environmental stress, especially in fragile alpine ecosystems, remain poorly understood. Here, we investigated microbial community dynamics across four ecosystems (desert-grassland, grassland, shrubland, and meadow) in the Ngari region of the western Qinghai-Tibet Plateau (4200 m elevation). By integrating differential abundance analysis (DESeq2) of bulk and rhizosphere soils with network modeling, we identified key microbial taxa driving community assembly and evaluated their roles in balancing stability and nutrient acquisition. Our findings revealed distinct microbial community compositions across vegetation types, with meadows exhibiting the highest diversity and a pronounced enrichment of copiotrophic taxa (e.g., Proteobacteria, Firmicutes). Notably, recruitment strategies shifted with environmental stress: desert-grassland rhizospheres selected for oligotrophic taxa to maintain stability, whereas meadow rhizospheres enriched copiotrophic taxa to accelerate nutrient cycling. Network analysis demonstrated that key taxa increased community complexity (per-ASV mean increase: 0.006147%), yet reduced network robustness (per-ASV mean reduction: 0.144092%). Crucially, this reveals a divergent strategy: plants in harsh environments prioritize microbial network stability, whereas those in resource-rich patches trade network robustness for targeted nutrient mobilization. This study provides novel insights into how plants leverage rhizosphere microbiomes to navigatethe trade-off between ecosystem stability and functional efficiency in extreme environments, offering a framework for understanding microbial resilience in alpine ecosystems under global change.