PS 8-81
Large difference of inhibitive effect of nitrogen deposition on soil methane oxidation between plantations with N-fixing tree species and non-N-fixing tree species

Monday, August 5, 2013
Exhibit Hall B, Minneapolis Convention Center
Wei Zhang, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Xiaomin Zhu, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Lei Liu, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Shenglei Fu, South China Botanical Garden, Guangzhou, China
Hao Chen, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Juan Huang, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Xiankai Lu, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Zhanfeng Liu, South China Botanical Garden, Chinese Academy of Sciences
Jiangming Mo, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
Background/Question/Methods

The responses of soil methane (CH4) net fluxes to nitrogen (N) addition in a N-fixing tree species (Acacia auriculiformis, AA) and a non-N-fixing tree species (Eucalyptus citriodora, EU) plantation were studied in southern China. Treatments were conducted at each plantation with three N levels (0, 50, 100 kg N ha-1 yr-1 for Control, Medium-N, and High-N treatment, respectively, abbreviated as C, MN, and HN). From August 2010 to July 2011, CH4 flux was measured bi-weekly using a static chamber and gas chromatography technique. 

Results/Conclusions

The soils of the two plantations were all net sink of atmospheric CH4. The CH4 uptake rate in control of the AA site (36.3 ± 3.2 µg CH4-C m-2 h-1) was greater than that of the EU plantation (29.9 ± 0.9 µg CH4-C m-2 h-1). In the AA plantation, the averaged rates of CH4 uptake for the MN (28.6 ± 2.3 µg CH4-C m-2 h-1) and HN treatment (23.8 ± 2.8 µg CH4-C m-2 h-1) were decreased by 21% and 35%, respectively, compared to the control. However, there was no change of soil CH4 uptake between N treated plots and the controls in the EU site.  Alterations in CH4 uptake might be resulted from N addition-induced changes in soil available N contents (NH4+, NO3-) and pH value, which affected the activities of bacteria responsible for CH4 oxidation. The results indicated that there might be large difference of inhibitive effect of N deposition on soil CH4 oxidation between the AA and EU plantations. As far as we known, our study is among the first to investigate the effect of N deposition on soil CH4 fluxes between reforestation with N-fixing species and non-N-fixing species. Our results implied that the projected increase of N deposition would potentially decrease the capacity of AA plantation as a sink of atmospheric CH4 considering the large area of AA plantation in tropical/subtropical regions.

See more of: Biogeochemistry: Atmospheric N Deposition Effects
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