Carbon sequestration in soil in a semi-natural Miscanthus sinensis grassland and Cryptomeria japonica forest plantation in Aso, Kumamoto, Japan

Yo Toma, Kevin Armstrong, J. Ryan Stewart, Toshihiko Yamada, Aya Nishiwaki, Fabián G. Fernández
2012 GCB Bioenergy  
Although Miscanthus sinensis grasslands (Misc-GL) and Cryptomeria japonica forest plantations (Cryp-FP) are proposed bioenergy feedstock systems, their relative capacity to sequester C may be an important factor in determining their potential for sustainable bioenergy production. Therefore, our objective was to quantify changes in C accumulation rates 47 years after a Misc-GL was converted to a Cryp-FP. The study was conducted on adjacent Misc-GL and Cryp-FP located on Mt. Aso, Kumamoto, Japan.
more » ... o, Kumamoto, Japan. After Cryp-FP establishment, only the Misc-GL continued to be managed by annual burning. Mass C and N, δ 13 C, and δ 15 N at 0 to 30 cm depth were measured in 5 cm increments. Carbon and N concentrations, C:N ratio, δ 13 C, and δ 15 N were measured in litter and/or ash, and rhizomes or roots. Although C input in Misc-GL by M. sinensis was approximately 36% of that in Cryp-FP by C. japonica, C accumulation rate in soil in Misc-GL (503 kg C ha -1 yr -1 ) was higher than that in Cryp-FP (284 kg C ha -1 yr -1 ). This was likely the result of larger C input from litter to soil, C quality (C:N ratio and lignin concentration in litter) and possibly more recalcitrant C (charcoal) inputs by annual burning. The difference in soil δ 15 N between sites indicated that N was better preserved and had greater cycling between plant, microbes, and soil in Misc-GL than in Cryp-FP. Our data indicate that in terms of soil C sequestration, biomass production with Misc-GL may be more advantageous than with Cryp-FP in Aso, Japan. 13 C/ 12 C or 15 N/ 14 N ratio of the PDB or atmospheric N 2 standards, respectively. Proportion of C (X C ) of C. japonica-derived C in the soil was calculated as follows using the method by Hansen et al. (2004) and Clifton-Brown et al. (2007): X C = (δ 13 C new-cryp -δ 13 C old ) / (δ 13 C cryp -δ 13 C old )
doi:10.1111/j.1757-1707.2012.01160.x fatcat:irlvs42gxjeqfbyfckw3plqq6e