Soil respiration and its autotrophic and heterotrophic components in response to nitrogen addition among different degraded temperate grasslands

摘要: Abstract Atmospheric nitrogen (N) deposition greatly affects grassland soil respiration (Rs) and its components. However, whether there exists a similar pattern in the response of Rs components to N among grasslands with varying degradation status remains unclear. We established 3-year field experiment six addition levels on three sites (non-degraded, moderately degraded severely degraded) measured autotrophic (Ra), heterotrophic (Rh), their influencing factors, including abiotic biotic variables. Our results showed that Ra had an increasing tendency, whereas Rh decreasing tendencies, non-degraded grasslands. In grassland, Ra, exhibited tendencies under lower higher levels. mainly affected by directly Rh. Conversely, tended indirectly affect through increased aboveground biomass. was influenced increase The findings this research highlight importance considering level when assessing carbon emissions scenarios.