Methane flux and regulatory variables in soils of three equal-aged Japanese cypress (Chamaecyparis obtusa) forests in central Japan

Soil fertility controls soil–atmosphere carbon dioxide and methane fluxes in a tropical landscape converted from lowland forest to rubber and oil palm plantations

“…Compared to measurements conducted in Indonesia, our lowland forests had higher soil CO 2 fluxes than a montane forest in Sulawesi at 1000 m elevation with similar spatially replicated and temporally intensive measurements (127 mg C m −2 h −1 ; van Straaten et al, 2011); fluxes were also higher than in the seven partially logged forest sites in Jambi, where measurements were only made once (162 mg C m −2 h −1 ; Ishizuka et al, 2005). While the difference with this last study may be caused by their one-off sampling, the only other study that measured CO 2 fluxes from the same region (which conducted nine measurements spread over 1 year at three plots) reported values that were as low as 33 to 50% of our measured soil CO 2 fluxes (63-94 mg C m −2 h −1 ; Ishizuka et al, 2002).…”

“…High Al 3+ concentrations in the soil solution and higher exchangeable Al in the soil are known to be toxic for plants, the root growth of which may be inhibited (Ma et al, 2001). Dissolved Al 3+ can also be toxic for soil microorganisms, and it has been shown that high dissolved Al concentrations in the soil inhibited CH 4 uptake in a temperate forest soil in Japan (Tamai et al, 2003). We are not aware of any study reporting such a relationship for tropical ecosystems, which is not surprising since in most trace gas studies exchangeable Al in the soil is either not measured or does not reach such high levels as at our sites.…”

“…Seasonal variation in soil CO 2 fluxes from the reference land-use types was driven by changes in soil water content, as suggested by the positive correlation with WFPS in jungle rubber on the loam Acrisol soil (Table 3). Other studies conducted in tropical rainforests have shown that seasonal changes in soil CO 2 fluxes are often caused by changes in soil water content (e.g., Sotta et al, 2007;Koehler et al, 2009;van Straaten et al, 2011), sometimes in combination with a reduction in solar irradiation caused by clouds during the wet season (Schwendenmann et al, 2003). In tropical forest soils, the relationship of soil CO 2 flux with soil water content is curvilinear, with the highest fluxes typically at field capacity (pF ∼ 2 or WFPS between 50 and 55 %; Sotta et al, 2007;Koehler et al, 2009;van Straaten et al, 2011), which explains why WFPS did not show correlation in forests in both landscapes where WFPS (mostly ≥ 60-80 %; Fig.…”

“…Whether net consumption or net emission of CH 4 occurs at the soil surface depends on the balance between production and consumption in the soil. For soil CH 4 fluxes, the proximal controllers are soil moisture, gas diffusivity and temperature, while other distal regulators include microbial activity, N availability and aluminum toxicity Tamai et al, 2003;Bodelier and Laanbroek, 2004;Veldkamp et al, 2013).…”

Effect of nitrogen deposition on CH4uptake in forest soils in Hokkaido, Japan

“…On the other hand, at the Uryu 1 and Teshio 1 sites, the CH 4 uptake rates was low, 41-54 and 32-36 /-Lg CH 4 m-2 h-I , respectively (Table 4). The mean CH 4 uptake rates in the present study ranged from 32 to 157 /-Lg CH 4 m-2 h-I , values were slightly lower than those recorded in central Japan (88-178 /-Lg CH 4 m-2 h-I ) (Tarnai et al 2003). Cumulative CH 4 uptake is presented in Table 4.…”