|Budget Amount *help
¥2,000,000 (Direct Cost : ¥2,000,000)
Fiscal Year 1995 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1994 : ¥1,100,000 (Direct Cost : ¥1,100,000)
The carbon dioxide release from mineral soil layr was measured by using alkali solution in young Cryptomeria japonica stands. The CO_2 release changed seasonally in accordance with the fluctuation in soil temperature, being around 2.2 the Q_<10> values. The amount of CO_2 release largely differed with measurement places, where root biomass and root composition with its diameter in mineral soil layr at each place had a great influence. The linear multiple regression model, R=a_0+a_1w_1+a_2w_2+a_3w_3, was quite useful to divide the total CO_2 release (R) into those from mineral soil and root systems. Here w_1 to w_3 in the equation stand for root weights for different diameter classes. The respiratory amount by root system was estimated to occupy more than 60% of the total CO_2 release.
The respiration by root system was investigated in relation to growth and respiration of the above-ground organs in seedings of three coniferous species, Pinus densiflora, Lalix leptolepis, and Cryptomeria
japonica. The linear relationship was recognized in each species between above-ground and under-ground respirations through various growth stages. Gradient of the regression line, implying ratio of above-ground respiration against under-ground one, was significantly higher in C.japonica and lower inP.densiflora. These differences were considered to result from specific properties with respect to internal development of root tissues. Although additional works are needed to clarify that simple relationships are observed in more developed stages in individual growth, the results obtained here are very suggestive in examining much better estimation methods of the under-ground respiration in forest stand level.