Biomass Exhibited Greater Sensitivity to Degradation Than Community Structure in an Alpine Meadow

Clarifying the temporal sequence of productivity loss and community structure alteration is critical for developing effective grassland restoration strategies. However, the relative timing of declines in plant productivity and community structure during grassland degradation remains poorly resolved. To address this gap, we conducted a field survey in an alpine meadow in Potatso National Park, southeastern Qinghai-Tibetan Plateau (QTP), to quantify plant biomass and community structure. Based on the collected data, four degradation levels (DL1-DL4) were identified, representing a progressive gradient of degradation intensity. Results indicated that both aboveground biomass (AGB) and belowground biomass (BGB) declined significantly, whereas the root-to-shoot (R:S) ratio increased with increasing degradation severity (p < 0.05). In contrast, most community structural metrics-including species richness, Pielou's evenness index, and the coefficients of variation (CV) for plant cover and height-changed insignificantly (p > 0.05). Similarly, the composition of plant functional groups exhibited no significant shifts across degradation levels (p > 0.05). Species composition, including dominant species, displayed gradual transitions along the degradation gradient. These findings suggest that plant community structure is more resistant than productivity to degradation processes, providing mechanistic insight for prioritizing structural and functional targets in the restoration of alpine meadows in Potatso National Park.