A precise, unified method for estimating carbon storage in cool-temperate deciduous forest ecosystems

Abstract Accurate estimation of the storage and spatial distribution of carbon in forest ecosystems is essential when studying the role of these ecosystems in global warming. Appropriate methods and reliable data are thus necessary. In this study, we developed a precise, unifying estimation method and assessed seven components of carbon storage in a cool-temperate deciduous forest ecosystem in central Japan. This method is based on detailed dividing of carbon pools in forest ecosystem, unifying, and systemic survey and estimate for each divided carbon component using precise and suitable methods, respectively. Data and methods used include tree census and allometry method between diameter at breast height (DBH)–biomass for tree, spectral reflectance measurement using a handy-type spectroradiometer for floor vegetation ( Sasa ), standing dead tree census (diameter at breast height and tree height) and allometry method between DBH–biomass and geometric calculation, detailed dry weight surveys for litter and coarse woody debris, detailed soil profile survey using profile digging and profile sampler measurement. The total carbon storage in the ecosystem equaled 440.6 t C ha −1 . Of the aboveground mass, 71.4 t C ha −1 was stored in living trees, 5.3 t in standing dead trees, and 2.8 t in Sasa senanensis (the understory vegetation). Of the belowground mass, 19.6 t C ha −1 was stored in living roots, 1.8 t in the roots of the standing dead tree, 15.3 t in plant litter, 6.1 t in coarse woody debris, and 318.3 t in the mineral soil. Carbon was stored unevenly throughout the ecosystem, and storage varied as a function of topography. The minimum and maximum amounts of stored carbon were 125.1 and 726.9 t C ha −1 , respectively; the highest and lowest amounts were found in a valley (average, 556.7 t C ha −1 ) and on a west-facing slope (average, 381.3 t C ha −1 ), respectively. Compared with other ecosystems, carbon storage in this forest ecosystem was higher in the soil and lower in the vegetation. The results also demonstrate the importance of gravels and stones in the soil and of standardizing the soil sampling depth.