Warming and altered precipitation frequently co-occur and jointly influence key carbon cycling processes in alpine ecosystems. However, the interactive effects of these two global change factors on ecosystem respiration (Re) and methane (CH₄) fluxes remain unclear. To address this gap, a long-term field experiment was conducted in an alpine meadow on the Qinghai-Tibet Plateau, combining warming (+2°C) and increased precipitation (+20%). Warming significantly reduced Re by 14.2%, concurrent with a shift from fungal to bacterial dominance. In contrast, increased precipitation enhanced Re by 34.1%, driven by improved soil moisture and greater plant carbon inputs. CH₄ uptake increased under warming (+31.0%) but decreased under increased precipitation (−26.3%), linked to the change in methane-oxidizing bacterial communities. Candidatus Methylumidiphilus, Methylococcus, and Methylomagnum were identified as key predictors. Combined warming and increased precipitation enhanced Re while suppressing CH₄ uptake, indicating that future warming-wetting conditions may intensify carbon losses and weaken the carbon sink capacity of alpine meadows. These findings underscore the necessity of integrating microbial ecological responses into ecosystem models to better predict carbon-climate feedbacks under multifactorial global change.

Nitrogen (N) enrichment is expected to induce a greater phosphorus (P) limitation, despite the acceleration of soil P cycling. However, the changing patterns in plant P and soil available P after N enrichment, and their regulatory mechanisms, remain poorly understood in alpine meadows. Here, we conducted a field experiment with four N addition rates (0, 5, 10, and 15 g N m^–2 yr^–1) in an alpine meadow, and investigated the P in plants, microorganisms, and soil to determine their patterns of change after short-term N addition. Our results showed that N addition significantly increased plant biomass, and the plant P pool showed a non-linear response to the N addition gradient. Soil available P initially increased and then declined with increasing N addition, whereas the occluded inorganic P decreased markedly. The critical factors for soil available P varied with different N addition rates. At lower N addition levels (0 and 5 g N m^–2 yr^–1), soil acidification facilitated the mobilization of occluded inorganic P to increase soil available P. Conversely, at higher N addition levels (10 and 15 g N m^–2 yr^–1), the elevated soil microbial biomass P intensified the competition with plants for soil P, leading to a decline in soil available P. This study highlights the non-linear responses of the plant P pool and soil available P concentration to N addition rates. These responses suggest the need for developing ecosystem models to assess different effects of increasing N rates, which would enable more accurate predictions of the plant P supply and soil P cycling under N enrichment.