Understanding how nitrogen（N） availability interacts with soil acidity and phosphorus（P） availability to affect soil-atmosphere exchanges in CO_2, CH_4 and N_2O in forest ecosystems is important for understanding ...Understanding how nitrogen（N） availability interacts with soil acidity and phosphorus（P） availability to affect soil-atmosphere exchanges in CO_2, CH_4 and N_2O in forest ecosystems is important for understanding the mechanisms driving ecosystem responses to enhanced N deposition. Here, we conducted an experiment with N, P and acid（H） addition in a mixed forest in subtropical China to investigate how acid and P addition affects CO_2, CH_4 and N_2O exchange under N addition. Our results showed that soil NH4^＋-N and NO3^--N increased after N addition, but CO_2 emissions in N addition plots remained unaffected. CH_4 uptake in N–, P–, NP–, NH– and NPH–addition plots were reduced by 21.1%, 15.7%, 39.1%, 26.6%, and 28.4%, respectively. CH_4 uptake in NP–addition plots were lower compared to N–addition and P–addition plots, indicating that N and P addition had an additive effect on inhibiting CH_4 uptake. N_2O emission in N–, NP–, NH– and NPH–addition plots increased by 158.6%, 176.0%, 117.2%, and 91.8%, respectively. N_2O emissions in NPH–addition plots were lower compared to NP–addition plots while showed no difference between N–addition and NH–addition plots. This suggests that only under P rich conditions, acid addition would greatly mitigate N_2O emissions under N addition. Our results demonstrate that for N and P co-limited forest ecosystems with acidic soils, low P availability constrains the inhibition of soil CH_4 uptake by N deposition. When P availability is low, a weak soil acidation induced by N deposition may have less influence on the stimulation of N_2O emissions by N deposition.展开更多
基金Natural Sciences Foundation of China(No.31290221)
文摘Understanding how nitrogen（N） availability interacts with soil acidity and phosphorus（P） availability to affect soil-atmosphere exchanges in CO_2, CH_4 and N_2O in forest ecosystems is important for understanding the mechanisms driving ecosystem responses to enhanced N deposition. Here, we conducted an experiment with N, P and acid（H） addition in a mixed forest in subtropical China to investigate how acid and P addition affects CO_2, CH_4 and N_2O exchange under N addition. Our results showed that soil NH4^＋-N and NO3^--N increased after N addition, but CO_2 emissions in N addition plots remained unaffected. CH_4 uptake in N–, P–, NP–, NH– and NPH–addition plots were reduced by 21.1%, 15.7%, 39.1%, 26.6%, and 28.4%, respectively. CH_4 uptake in NP–addition plots were lower compared to N–addition and P–addition plots, indicating that N and P addition had an additive effect on inhibiting CH_4 uptake. N_2O emission in N–, NP–, NH– and NPH–addition plots increased by 158.6%, 176.0%, 117.2%, and 91.8%, respectively. N_2O emissions in NPH–addition plots were lower compared to NP–addition plots while showed no difference between N–addition and NH–addition plots. This suggests that only under P rich conditions, acid addition would greatly mitigate N_2O emissions under N addition. Our results demonstrate that for N and P co-limited forest ecosystems with acidic soils, low P availability constrains the inhibition of soil CH_4 uptake by N deposition. When P availability is low, a weak soil acidation induced by N deposition may have less influence on the stimulation of N_2O emissions by N deposition.
