Abstract
This study aimed to reveal the above and below-ground carbon pool trade-off of alpine meadow plants in response to litter inputs. The following methods were used: a moderately degraded alpine meadow ungrazed for 4 years was selected as the research object. In 2024, simulated litter input experiments were conducted, and four level gradients were set: T0 (0 g C/m2), T1 (1.39 g C/m2), T2 (3.48 g C/m2) and T3 (6.97 g C/m2), and the effects of litter inputs on the above and below-ground carbon pools, and the carbon pools trade-offs of alpine meadow plants were analyzed. The results showed that: (1) litter input had a positive effect on the Shannon-Wiener index and Pielou index of plants; (2) the levels of S-β-XYS, S-β-GC, S-FDA, S-DHA, CBH, \({\text{NH}}_{4}^{ + }\) -N, \({\text{NO}}_{3}^{ - }\) -N, MBC and MBN showed a positive correlation with the input of litter, and their peak values were reached at T3, with maximum values of 10.28, 29.74, 2793.31, 15.81, 9.82 U/g, 18.48, 0.54, 512.44, and 55.11 mg/kg, respectively; (3) AB, AC, ACP, RB, RC and RCP all had maximum values at T3 with values of 213.35 g/m2, 368.41 g/kg, 78.57 g/m2, 118.52 g/m2, 300.05 g/kg and 35.66 g/m2. (4) Mantel test analysis showed that ACP and RCP each paired with \({\text{NO}}_{3}^{ - }\) -N showed significant positive correlation (P < 0.05) with S-FDA, GOD, S-β-GC, S-β-XYS and MBC. (5) The results of trade-off analysis showed that the trade-off relationship between ACP and RCP under different levels of litter treatments was in the following order: T0 (0.0178) > T2 (0.0127) > T1 (0.0002) > T3 (0.0001). Propensity analysis indicated that the trade-off of carbon pools in alpine meadows was more in favor of ACP under T0 and T2. (6) Structural equation modeling indicated that plant diversity, enzyme activity and carbon pools correlated positively with the ACP-RCP trade-off. This study contributes to the scientific management of alpine meadows and the development of rational grazing systems.
