Carbon and nitrogen status of decomposing roots in three adjacent coniferous plantations

Abstract

Abstract. This study evaluated the carbon (C) and nitrogen (N) status of decomposing roots in three adjacent plantations consisting of one deciduous (larch: Larix leptolepis) and two evergreen (red pine: Pinus densiflora; rigitaeda pine: P. rigitaeda) species planted in the same year (1963) under similar site conditions. The mass loss rates and C and N status of three diameter classes of roots (UF < 2 mm, F 2-5 mm, CF 5-10 mm in diameter) were examined in the upper 15 cm of the mineral soil using in situ buried root bags for 496 days. The remaining mass of decomposing roots was significantly higher for larch (69.0%) than for red pine (59.6%) or rigitaeda pine (59.1%) over 496 days. The mass loss rates of decomposing roots did not differ significantly among the three root diameter classes, but the C and N status of decomposing roots was affected by the tree species. The larch roots showed low C concentrations but high N concentrations, C and N remaining compared to the pine roots over the study period. The results indicate that the substrate quality indicators of roots were not attributed to the mass loss rates, C and N status of decomposing roots in three coniferous tree species grown under similar environmental conditions.

Comparsion of soil CO2 efflux rates in Larix leptolepis, Pinus densiflora and P. rigitaeda plantations in southern Korea

“…Mean stand densities, diameters at breast height (DBH), and basal areas of the three plantations are shown in Table 1. More information about the soil conditions, understory vegetation, and nutrient dynamics in relation to litter fall and root decomposition of this study site can be found elsewhere Kim et al, 2013;Jeong & Kim, 2014).…”

“…Root decomposition rates were estimated using the in situ buried root decay bag technique, which has been the most common approach for comparisons of root decay rates (Silver & Miya, 2001;Jeong & Kim, 2014), employing 15 cm × 15 cm nylon bags with < 0.5 mm mesh size. Fresh roots from each plantation were collected from a sampling point located randomly in each plot at approximately 15 cm mineral soil depth on July 15, 2006.…”

“…Collected bags were oven-dried at 65°C for 48 hours, cleaned by gentle brushing with a soft paintbrush to remove mineral soil and weighed to determine root mass loss rates. Information about the C and nitrogen dynamics in fine root decomposition processes of this study site can be found elsewhere (Jeong & Kim, 2014). The exponential regressions between the soil CO 2 efflux rates and soil temperature were calculated as follows:…”

“…Quantitative evaluation of soil CO 2 efflux rates among different tree species is key to understanding the C cycling in forest ecosystems because tree species can have a significant influence on soil CO 2 efflux rates (Pangle & Seiler 2002;Lee & Jose 2003;Lee et al, 2010) due to their different nutrient requirements (Dijkstra et al, 2009), litter fall fluxes (Vesterdal et al, 2012), litter decomposition mechanisms (Davidson & Janssens, 2006), fine root production (Valverde-Barrantes, 2007) and decomposition (Jeong & Kim, 2014). However, it is difficult to compare the soil CO 2 efflux rates of different tree species due to the potentially confounding effects of site macroclimatic and forest management fac-tors (Kim et al, 2009).…”