Distribution and transportation of dissolved organic carbon in the soil of Chinese fir plantations.
Yu, Yuanchun*,1, Wang, Geoff 2, 1 Faculty of Forest Resources and Environmental Sceince, Nanjing, China2 Department of Forestry and Natural Resources, Clemson, SC, USA
ABSTRACT- Leaching of dissolved organic carbon (DOC) and the associated nutrient elements can be a significant form of loss from Chinese fir (Cunninghamia lanceolata) plantations due to intensive cultural treatments. We studied the distribution and transportation of DOC in soils and soil percolating water in recently planted, young, and mature Chinese fir stands in southeastern China. Soil samples were collected from 0-20, 20-40 and 40-60 cm in each stand. Soil percolating water was collected with non-suction lysimeters installed at the mid-slope in a line perpendicular to the slope at the depth of 20, 40, and 60 cm. DOC concentrations in the soils ranged from 16.4 to 92.6 mg kg-1 (mean = 46.2 mg kg-1), with recently planted > mature > young stands. DOC concentrations decreased with increasing soil depth and were strongly correlated with soil bulk density (r2 =0.711) and concentrations of total organic matter (r2 = 0.569), total N (r2 = 0.602), and available P (r2 =0.711) in soils. DOC concentrations in soil percolating water ranged from 6.08 to 21.05 mg L-1 (mean = 12.76 mg L-1), decreasing with increasing soil depth. The DOC concentration of the young stand remained the lowest regardless of measuring time. However, the DOC concentration of the recently planted stand was the greatest in May while the DOC concentration of the mature stand was greatest in July when compared to other plantations. DOC concentrations were highly correlated with total nitrogen (r2 = 0.369) and free iron (r2 = 0.598) concentrations while the amounts of DOC were closely related to the amounts of organic carbon (r2 = 0.829), N (r2 = 0.721), and P (r2 = 0.377), suggesting the important influence of DOC on the transportation of other elements, especially nutrient elements, in the soil.
Key words: Forest soil, DOC, Cunninghamia lanceolata, Lysimeter
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