摘要
Soil-emitted N_(2)O contributes to two-thirds of global N_(2)O emissions,and is sensitive to global change.We used DayCent model to simulate major plant-soil N cycling processes under different global change scenarios in a typical temperate mixed forest in north-eastern China.Simulated scenarios included warming(T),elevated atmospheric CO_(2) concentration([CO_(2)])(C),increased N deposition(N)and precipitation(P),and their full factorial combinations.The responses of plant-soil nitrogen cycling processes including net N mineralization,plant N uptake,gross nitrification,denitrification and soil N_(2)O emission were examined.Concurrent increase of elevated[CO_(2)]and N deposition displayed most strong interactive effects on most fluxes.Using the results from experimental studies for evaluation,simulation uncertainty was highest under elevated[CO_(2)]and increased precipitation among the four global change factors.N deposition had a fundamental impact on soil N cycle and N_(2)O emission in our studied forest.Despite forest soil acting as a N sink for added N,scenarios which included increased N deposition showed higher cumulative soil N_(2)O emissions(summed up from 2001 to 2100).In particular,the scenario which included T,P,and N had the largest cumulative soil N_(2)O emission,which was a 24.4% increase over that under ambient conditions.Our study points to the importance of the interactive effects of global change factors on plant-soil N cycling and the necessity of multi-factor manipulation experiments.
基金
supported by the National Basic Research Program of China(973 program,2014CB954400)
the National Natural Science Foundation of China(41401289).
