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Unimodal Response of Soil Methane Consumption to Increasing Nitrogen Additions
- Peng, Yunfeng, Wang, Guanqin, Li, Fei, Yang, Guibiao, Fang, Kai, Liu, Li, Qin, Shuqi, Zhang, Dianye, Zhou, Guoying, Fang, Huajun, Liu, Xuejun, Liu, Chunyan, Yang, Yuanhe
- Environmental science & technology 2019 v.53 no.8 pp. 4150-4160
- biogeochemistry, ecosystems, field experimentation, highlands, meta-analysis, methane, models, nitrogen, prediction, soil, steppes, China
- Nitrogen (N) status has a great impact on methane (CH₄) consumption by soils. Modeling studies predicting soil CH₄ consumption assume a linear relationship between CH₄ uptake and N addition rate. Here, we present evidence that a nonlinear relationship may better characterize changes in soil CH₄ uptake with increasing N additions. By conducting a field experiment with eight N-input levels in a Tibetan alpine steppe, we observed a unimodal relationship; CH₄ uptake increased at low to medium N levels but declined at high N levels. Environmental and microbial properties jointly determined this response pattern. The generality of the unimodal trend was further validated by two independent analyses: (i) we examined soil CH₄ uptake across at least five N-input levels in upland ecosystems across China. A unimodal CH₄ uptake-N addition rate relationship was observed in 3 out of 4 cases; and (ii) we performed a meta-analysis to explore the N-induced changes in soil CH₄ uptake with increasing N additions across global upland ecosystems. Results showed that the changes in CH₄ uptake exhibited a quadratic correlation with N addition rate. Overall, we suggest that the unimodal relationship should be considered in biogeochemistry models for accurately predicting soil CH₄ consumption under global N enrichment.