Challenges in alpine meadow recovery: The minor effect of grass restoration on microbial resource limitation

Microorganisms play a vital role in restoring soil multifunctionality and rejuvenating degraded meadows. The availability of microbial resources, such as carbon, nitrogen, and phosphorus, often hinders this process. However, there is limited information on whether grass restoration can alleviate microbial resource limitations in damaged slopes of high-altitude regions. This study focused on alpine bare land impacted by engineering activities, with the goal of using grass seeds to improve soil resource availability and multifunctionality. High-throughput sequencing and enzyme stoichiometry (vector analyses) were employed to analyze microbial community composition and assess resource limitations. Our findings suggested that soil carbon, nitrogen, and phosphorus contents were low, ranging from 7.67 to 12.6 g kg⁻¹for carbon, 0.61 to 0.98 g kg⁻¹,for nitrogen, and 0.65 to 0.78 g kg⁻¹for phosphorus. Nevertheless, the standardized scores for high yield and resource acquisition strategies remained at 0.26 and 1.36 in the four groups, which were lower than those of the stress tolerance strategy. Microorganisms primarily employed the stress tolerance strategy, focusing on repairing injured cells rather than promoting cell growth, which suggests that microbial growth and metabolism were only marginally enhanced. Because of this strategy's limited impact on enhancing microbial community diversity and fostering a co-occurrence network, the resultant levels remained comparable to those observed in degraded meadows. In this case, microbial resource limitations persisted, with phosphorus remaining a constraint. Consequently, grass restoration alone offered limited relief for microbial resource limitations in alpine meadows, underscoring the challenges of solely relying on grass seeds to recover damaged alpine ecosystems.