|Budget Amount *help
¥5,300,000 (Direct Cost : ¥5,300,000)
Fiscal Year 1993 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1992 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1991 : ¥3,500,000 (Direct Cost : ¥3,500,000)
The whole-tree CO_2 gas-exchange was measured on five sample trees in a 19-year-old hinoki (Chamaecyparis obtusa) stand, using an open gas-exchange system. The measurement for each sample tree was kept on a 10-day run a month.
The annual gross photosynthetic production by a tree, p, decreased with decreasing stem volume, v. The relationship was successfully expressed in the following generalized power function :
where g, h, and v_<min> are coefficients. Equation 1 implies that p decreases abruptly near the critical tree size, v_<min>, below which trees can not survive. In the light of the fact that the value of the exponent h was about 2/3, p is approximately proportional to the surface area in larger-sized trees.
On the other hand, the annual respiratory consumption by a tree, r, was proportional to p, i.e.,
where the proportional constant k of 0.38 meant that r accounts for about 40% of p, regardless of tree size.
Assuming Eqs.1 and 2 results in the following equation :
where g' is equal to k^.g. The observed data were well fitted with Eq.3.