Ecological and Physiological Studies on the Vegetation of Mt. Shimagare
V. Intraspecific Competition and Productivity Difference among Tree Classes in the Abies Stand
1960 Volume 73 Issue 863 Pages 165-174
Details
1960 Volume 73 Issue 863 Pages 165-174
Intraspecific competition for weight growth was analysed in constituent Abies trees within a 20-year-old A. Mariesii and A. Veitchii mixed stand of Forest Unit V on Mt. Shimagare.
1. Annual dry matter increments in needles, branches, trunk and roots of each of trees, which were classified into the dominant, codominant, intermediate and suppressed, were estimated by the mathematical analyses of tree measures. Annual net production, the sum total of these increments per tree, increased with rise in gradation of the tree weight class. Also the relative productivity (net production/tree weight), the net assimilation rate and the relative growth rate indicated the same trend.
2. The inner and outer factors concerned with the dry matter production were discussed. The somewhat high proportion of needles for the total dry weight and the high light intensity received by needles were responsible for the high productivity in the dominant class.
3. Annual gross production per tree was calculated in each tree weight class by combining photosynthetic activity and light factor received by each canopy, with correction by seasonal temperature changes. Annual respiration loss was also calculated.
4. The difference between the annual gross production and the annual respiration loss gave the net production per tree. This value was in accord with the annual net production determined by the analyses of tree measures, in each class. The accordance may prove the soundness of the calculations.
5. The suppressed tree made relatively small gross production under weak illumination, but high respiration loss comparing with its dry weight. So the growth rate of the suppressed became very low. The reverse was seen in the dominant. Such difference in matter production between the dominant and other tree classes should cause marked growth difference with the lapse of time.
