Alpine meadows at different levels of degradation in the Beiluhe Basin of Tibetan Plateau Characteristics of soil respiration

Soil respiration is one of the most important components of the carbon cycle in terrestrial ecosystems. The widely distributed degradation of the alpine meadows on the Tibetan Plateau will impact the soil respiration and carbon cycle. In order to further explore the effects of degradation on the soil respiration of alpine meadows, we measured the soil respiration and related factors of alpine meadows under different levels of degradation in the Beiluhe area, and the relationships between soil respiration and biomass, belowground net primary productivity (BNPP) and soil temperature was analyzed . Our results showed that: 1) Soil respiration of alpine meadows at different levels of degradation showed similar dynamic characteristics during the growing season. Soil respiration increased first and then decreased along the degradation gradient, which reached the maximum under moderate degradation and significantly changed in the middle of the growing season (P < 0.05); 2) There was a significant positive linear correlation between the soil respiration and the aboveground biomass, belowground biomass, and BNPP (P < 0.05); 3) The soil respiration is exponentially correlated with the soil temperature. The temperature sensitivity of the soil respiration changed with the degradation. The Q₁₀ under slight (Q₁₀ = 3.26) and moderate degradation (Q₁₀ = 3.22) was higher than that under non-degraded soils (Q₁₀ = 2.66); however, under severe (Q₁₀ = 2.49) and extreme degradation (Q₁₀ = 1.96), this was lower than that under no degradation. The change in the temperature sensitivity is mainly caused by differences in the soil temperature, belowground biomass, and soil organic carbon content under different degradation levels. The results of this study will help further the understanding of the carbon cycle process of degraded grasslands.