In this study we examined the validity of the canopy closure curve as a reference in relation to light conditions and demonstrated the applicability of the curve to different thinning types. An even-aged sugi (Cryptomeria japonica) plantation of 91 years was thinned heavily and transformed to a two-storied stand by underplanting with sugi and hinoki cypress (Chamaecyparis obtusa) seedlings. Three initial sample plots were selected in the stand before thinning. After the conversion, five permanent sample plots were established and both overstory and understory trees were measured up to the age of 118 and 28 years, respectively. The canopy closure curve was estimated from measurements collected in the initial sample plots and crown density (i.e. the ratio of overstory productivity to the maximum stand productivity) was calculated based on the canopy closure curve as a reference. To validate the curve, we derived three time points from the measurements collected in the permanent sample plots: one when the trajectory of stem density and stand volume of the overstory trees intersected the canopy closure curve, one when the relationships between the volume of individual overstory trees and their growth changed, and one point when the growth of understory trees dropped. The first of these time points coincided with the second and third time points. This means that dominant overstory trees suppressed smaller overstory trees and overstory trees constrained the growth of understory trees because of light reduction when the canopy closed. The canopy closure curve was found to be a valid way to assess light controlling the growth of understory trees. Furthermore, we generated virtual thinning data from the measurements taken in the initial sample plots for different thinning types. We obtained the canopy closure curve for these. We plotted the trajectory of stem density and stand volume in relation to the thinning as well as the canopy closure curve to demonstrate the applicability of the canopy closure curve. The thinning simulation showed sufficient effect to demonstrate that there was no need for additional accretion cutting.
Semi-captive Asian elephants (Elephas maximus) engaged in forestry activities in Myanmar account for 20% of all captive and semi-captive Asian elephants in the world, and are important for both forestry and the conservation of Asian elephant populations. Understanding moving behavior of the semi-captive elephants is required to sustain them. Our specific goals are 1) to determine the moving range during free time, and 2) to determine the hourly moving distance during skidding and when off duty. Three elephants were fitted with handheld global navigation satellite systems with the signals of global positioning system to collect data on their movements. The elephants were generally located between 0.534 and 0.875 km from the camp with temporary housing of the elephant handler when not skidding (i.e., free time) and between 1.365 and 1.372 km when skidding (i.e., work time). The hourly moving distance during free time (0.622–0.655 km) and work time (1.522 and 1.629 km) did not differ greatly from the hourly moving distance of wild Asian elephants (0.010–1.500 km). The elephants remained within 0.875 km of the camp of the elephant handler, and some variation in movements among individuals was observed during free time. Thus, the conservation of forest in areas near the camp is important for the well-being of these elephants.