Effect of weeding frequency, slope aspect and initial tree density on the mortality and accidental cutting of planted sugi (Cryptomeria Japonica) trees: A case study in the Kagoshima University Research Forest, southwestern Japan
2017
Fukumoto, K. (Kyushu University, Fukuoka (Japan). Graduate School of Bioresource and Bioenvironment Scinece) | Ota, T. | Mizoue, N. | Iwanaga, F. | Yoshida, S. | Teraoka, Y. | Kajisa, T.
This study investigated the effects of weeding frequency, slope aspect and initial tree density on the mortality and accidental cutting of planted Sugi (Cryptomeria japonica) in southern Kyushu. To predict the probability of mortality and accidental cutting, we used the multinomial logistic regression model using weeding frequency, slope aspect and initial tree density. The highest mortality on north- and south-facing slopes was found in non-weeding plot (33.3%) and every-year weeding plot (16.9%), respectively. Accidental cutting of planted Sugi was found in 3 or 4 times weeding plots. Multinomial logistic regression model showed that mortality was affected by slope aspect and initial tree density. Mortality decreased with the increase of weeding frequency on north facing slope, while mortality was invariable regardless of weeding frequency on south-facing slope. Accidental cutting rate was invariables regardless of weeding frequency on both slopes. The mortality rate and accidental cutting rate under the 1,500 trees/ha density was higher than that under the 3,000 trees/ha. These results suggest that weeding frequency should be determined according to slope aspect and initial tree density.
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