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理解土壤可利用性氮(N)如何与土壤酸化和可利用性磷(P)共同作用影响土壤-大气界面CO_2、CH_4和N_2O气体交换,对于揭示生态系统对氮沉降增加的响应机制尤为重要。本研究在中国亚热带地区混交林中设置了N、P和酸添加实验以理清在N添加下酸和P添加如何影响CO_2、CH_4和N_2O气体交换。结果表明,(1)N添加显著增加了土壤铵态氮和硝态氮,对CO_2释放无影响;(2)N、P、N+P和N+P+酸分别降低了21.1%、15.7%、39.1%、26.6%和28.4%的CH_4;相比于N、P单独添加,NP共同添加降低了CH_4吸收,表明N添加和P添加在抑制CH_4吸收上具有加和效应;(3)N、N+P、N+酸和N+P+酸分别增加了158.6%、176.0%、117.2%和91.8%的N_2O释放;N_2O释放在N+P+酸处理中显著低于N+P处理,与N添加和N+酸添加无显著差异,表明在N添加下,仅P丰富的条件下,酸添加才能够缓解N_2O释放。我们的结果证实,在N和P共同限制的酸性土壤森林生态系统,低P将会抑制N沉降引起的土壤CH_4吸收。低P时,N沉降引起的土壤酸化与其引发的N_2O释放无关。
Understanding how soil availability nitrogen (N) interacts with soil acidification and availability of phosphorus (P) affects the CO_2, CH_4 and N_2O gas exchange at the soil-atmosphere interface is particularly important in revealing the ecosystem response to increased nitrogen deposition. In this study, N, P and acid addition experiments were set up in mixed forests in subtropical regions of China to find out how the acid and P addition affected the CO 2, CH 4 and N 2 O gas exchange under N addition. The results showed that: (1) N addition significantly increased soil ammonium nitrogen and nitrate nitrogen, but had no effect on CO 2 release; (2) N, P, N + P and N + P + acids decreased by 21.1% and 15.7% 39.1%, 26.6% and 28.4% of CH_4, respectively. Compared with N and P alone, the addition of NP reduced CH_4 absorption, indicating that N addition and P addition had an additive effect on the inhibition of CH_4 absorption. (3) N + P, N + acid and N + P + increased 158.6%, 176.0%, 117.2% and 91.8% of N 2 O release, respectively. N 2 O release was significantly lower than N + P treatment in N + There was no significant difference in acid addition, indicating that under the addition of N, acid addition can alleviate N2O release only under P-rich conditions. Our results confirm that low P will inhibit the soil CH 4 uptake by N deposition in the acidic soil forest ecosystems with N and P constraints. At low P, soil acidification caused by N deposition had nothing to do with the release of N 2 O.