Changes in the stand structure during a 12-year period in a natural fir-hemlock [Abies firma-Tsuga sieboldii] forest in mountain regions of Kyushu [Japan]
1999
Okano, T. (Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture) | Aragami, K.
A permanent plot (0.25ha) was established in a Fir-Hemlock forest in mountain regions of Kyushu, south west Japan, to clear the dynamics of the forest. Changes in stand structure were analyzed based on species composition, size distribution, stratification and behavior of trees during a 12-year period (1983-1995). Number of tree species was decreased and species diversity evaluated by H' was declined. In the size distribution, there were two evident tendencies that Fir trees in upper layer were recruited into larger classes and number of broad-leaved shrubs in smaller classes was decreased. In addition to them, it was recognized that Hemlock trees and broad-leaved trees were recruited into higher classes in height distribution. The stratification of the stand in both survey years was composed of four layers indicated in H-h diagram that was drawn using mean tree height1t and individual tree height. In all layers, number of individuals and number of tree species were decreased, and survival rate was lower in understory. It was considered that the light environment under the fourth layer was not suitable for survival or growth of regenerated trees. and that attack by wild deer influenced disappearance of trees. Behavior of trees was different among layers, for example, more than half number of trees in second layer were exchanged with trees from other layers. Analyzing the behavior of individuals based on stratification was an effective method to clear the temporal change
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