Fluxes of dissolved organic carbon and nitrogen throughout Andisol, Spodosol and Inceptisol profiles under forest in Japan

Abstract

Leaching of dissolved organic matter (DOM) is an important process in the translocation and stabilization of organic carbon (C) and in influencing nitrogen (N) availability in forest soils. The roles of DOM in soil carbon and nitrogen cycles were evaluated by quantifying the fluxes of dissolved organic carbon (DOC) and nitrogen (DON) entering and leaving the organic (O), A and B horizons. In Spodosol and Inceptisol soils, DOC fluxes were highest in the O horizon (149 to 344 kg C ha À1 yr À1 ), decreasing in the A and B horizons. In Andisol soils, DOC fluxes were low throughout the profile because of low DOC production in the O horizon (53 kg C ha À1 yr À1) and the high adsorption capacity of amorphous aluminum (Al) and iron (Fe) (hydr)oxides in the mineral horizons. In Spodosol soil, DOC from the O horizon represented a large proportion of C input into the mineral soil, whereas this contribution appeared to be small in Andisol soil. The DOM was enriched in nitrogen during decomposition and humification of the foliar litter, but DON was a small proportion (5-31%) of total dissolved nitrogen (TDN) in surface soil solutions. The narrow DOC/DON and DON/TDN ratios were attributable to the low C/N ratios of the foliar litter (33-40). It was quantitatively shown that the importance of DOM in C and N cycles in forest soils varied depending on soil types and litter C/N ratio.

Dissolved organic carbon (DOC) input to the soil: DOC fluxes and their partitions during the growing season in a cool‐temperate broad‐leaved deciduous forest, central Japan

“…In general terms, the increase in DOC concentration from precipitation to throughfall is almost certainly due to leaf leaching and microbial metabolites (biodegradable and hydrophilic neutral carbohydrates) that wash from the canopy during this process (Guggenberger and Zech 1994;Michalzik et al 2001;Levia et al 2012). In this study site, the mean concentration of DOC in throughfall (6.84 ± 0.45 mg C L À1 ) consistent with previous reports (3-35 mg C L À1 , Michalzik et al 2001;Fujii et al 2011a), while the mean concentration of DOC in the precipitation (2.98 ± 0.45 mg C L À1 ) was a little higher than that reported in other studies (1.8-2.7 mg C L À1 ; Currie et al 1996;Michalzik and Matzner 1999;Moreno et al 2001;Solinger et al 2001). Contrary to expectations, the DOC concentration in throughfall below the dwarf bamboo (7.08 ± 0.42 mg C L À1 ) was not notably different from that in throughfall above the dwarf bamboo (6.84 ± 0.45 mg C L À1 ) ( Table 2), which indicates that the bamboo canopy had little effect on the DOC concentration.…”

“…The growing season DOC flux was 311.5 kg ha À1 7 months À1 at the study site, which was in the upper range of those reported in other temperate forest ecosystems (100-400 kg C ha À1 year À1 , Michalzik et al 2001) and much higher than that reported in another deciduous forest in Steigerwald, Germany (85.9-208.2 kg C ha À1 year À1 ; Solinger et al 2001) and in Japan (52.6-343.6 kg C ha À1 year À1 ; Fujii et al 2011a). The magnitude of the DOC flux might be explained by several factors.…”

“…In Asia, the unique climatic and other environmental characteristics that distinguish the region from the relatively well-studied forests of Europe and the USA (Fujii et al 2011a), several studies about DOC flux have been conducted in subtropical forest (Liu and Sheu 2003;Xu et al 2005) or tropical forest (Fujii et al 2011b). To date, most of studies about DOC dynamics were focus on forested catchment or in soil profile (Kawasaki et al 2002(Kawasaki et al , 2005Kawahigashi 2011;Fujii et al 2011a). The investigations of linking the DOC fluxes in temperate forest ecosystems to the soil organic carbon in Japan were limited (Shibata et al 2001).…”

Soil-vegetation-water interactions controlling solute flow and transport in volcanic ash soils of the high Andes

“…Besides cushion plants in the A horizon, mean DOC concentrations in our study (3.1 -4.0 mg L -1 ) are close to the range of values measured in Andosols grasslands: 4.7 mg L -1 (by wick samplers, Pesántez et al, 2018) and 5 -7 mg L -1 (by lysimeters, Ugolini et al, 1988). DOC concentrations present a larger range when measured in soil solutions collected by lysimeters for Andosols under other vegetation covers (2 -28 mg L -1 , Aran et al, 2001;Chen et al, 2017;Fujii et al, 2011).…”

Underestimation of boreal forest soil carbon stocks related to soil classification and drainage

“…All three conditions are characteristics of a large portion of the Norwegian forest soils. In Japan, DOC flux rates from the O horizon were measured to 6-9 g C·m −2 ·year −1 , and of this flux, 0.9-2.8 g C·m −2 ·year −1 percolated into the B horizon (Fujii et al 2011). In the Fichtelgebirge, Bavaria, Germany, it was found that 2-5.5 kg C·m −2 (19%-50% of soil organic C) was sorbed, stabilized DOC in the soil profile (Kaiser and Kalbitz 2012;Kalbitz and Kaiser 2008).…”