COMPARISON OF GROWTH HABITS UNDER VARIOUS LIGHT CONDITIONS BETWEEN 2 CLIMAX SPECIES, CASTANOPSIS-SIEBOLDII AND CASTANOPSIS-CUSPIDATA, WITH SPECIAL REFERENCE TO THEIR SHADE TOLERANCE

Two experiments were conducted to examine the difference in shade tole rance between two climax species, Castanopsis sieboldii and Castanopsi s cuspidata, in Aichi Prefecture in the warm-temperate climate of Japa n. In the growth experiment, the seedlings of the two species were rai sed under five light conditions, 100%, 30%, 10%, 3% and 1% relative li ght intensity (RLI). The growth of C. sieboldii highly exceeded that o f C. cuspidata, particularly under higher light conditions. In the hea vy shading experiment, the seedlings of the two species were grown und er three light conditions (0, 0.15 and 0.3% RLI). While all seedlings of C. sieboldii died within 2 years under 0.15 and 0.3% RLI, about hal f of the seedlings of C. cuspidata survived more than 2 years under 0. 15% RLI, and about 70% survived more than 4 years under 0.3% RLI. It w as concluded that C. cuspidata was more shade tolerant than C. siebold ii, and the possibility that C. sieboldii might be more tolerant of th e drought stress than C. cuspidata was discussed.