Soil Net N Mineralization Potential and Its Temperature Sensitivity Along a North-South Forest Transect in the Eastern China

Soil net nitrogen (N) mineralization potential (R_min) is a key indicator for predicting the capacity of available N supply for plant growth and ecosystem productivity. Thus, it is crucial to understand the spatial pattern and regulatory mechanisms of forest R_min and its temperature sensitivity (Q₁₀) under current global change scenarios. In this study, we determined the R_min and its Q₁₀ value of soil samples collected from 18 forest ecosystems along a 5200-km-long north-south forest transect in eastern China. We found significant differences in R_min and its Q₁₀ values among different forest types. Tropical and subtropical forests had significantly higher R_min values than temperate forests and cold temperate forests. In contrast, tropical and subtropical forests had the lowest Q₁₀ values followed by temperate forests and cold temperate forests. R_min varied with mean annual precipitation, soil total carbon (C) and N, microbial biomass carbon (MBC) and the MBC to the microbial biomass nitrogen (MBN) ratio. The Q₁₀ value varied with the mean annual temperature (MAT), the MBC/MBN ratio, and aridity index. Overall, our results indicate that the Q₁₀ value of the R_min is generally lower in warmer or wetter areas than in colder or drier areas along the north-south forest transect in eastern China. Our results imply that the predicted global change may narrow the gaps in the R_min between high- and low-latitude forests or among forests with different humidity levels.