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 (538Kb)
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10,585,000 Yen (FY1995; 3,954,000 Yen)
The flow rates and amounts of soil carbon were measured simultaneously with soil environmental condition, periodically during the growing seasons from 1994 to 1995 at the two plots (Plot A: drier soil condition, B: wetter condition) in a black spruce forest stand in the Candle Lake area, Saskatchewan, Canada. The seasonal trend of litterfall and accumulation of Ao layer were not observed while the total and mineral soil respiration rates changed seasonally with soil temperature. There was no significant relationship between soil moisture content and any flow rates or accumulations of soil. Soil respiration and loss of litter might ceased during the winter because of the frozen soil. The annual soil carbon cycling was analyzed by a compartment model, based on the data obtained in this study. The relative decomposition rate of Ao layer and humus in the mineral soil were estimated at 0.0616 and 0.0039 y-1 for Plot A, and 0.0275 and 0.0017 y-1 for Plot B, respectively. These values indicate that the cycling of soil carbon in Plot A was twice as fast as in Plot B. The slower cycling in Plot B might be caused by the lower soil temperature and per-humid soil condition due to higher ground water level in Plot B. The soil in both plots function as the sink of CO2 in atmosphere(O.1-0.2 tC ha-1 y-1). The soil carbon cycling in the boreal forest stand was slower than those reported in the cool- and warm-temperate forests owing to the lower soil temperature in the former than in the latter. The cycling in the boreal forest was conducted concentrately in or on the surface of mineral soil, suggesting that the decomposition of soil organic matter in the boreal forest will be facilitated strongly more than in forests developed in any other climate zone under global warming.
Boreal forest, Carbon balance, Carbon cycling, Missing sink