Structure and Composition of a Teak-bearing Forest under the Myanmar Selection System (<Special Issue>Ecological Resource Use and Social Change in the Minority Regions of Myanmar)

Abstract

The impact of selective logging on a natural teak-bearing forest was examined in the Kabaung Reserve Forest, Bago Division, Myanmar. The examined forest was under selective logging from 2001 to 2002. In the area, a bamboo, Cephalostachyum pergracile, flowered in 2002 and then died back in 2003. Thirty-seven circular plots of 20 m radius (4.65 ha in total) were set in the forest and 837 tree stems (DBH ≥ 10 cm) and 1809 bamboo clumps were enumerated in the plots. The average basal area density was 30.2 m2 ha–1, and bamboo accounted for 33% of the basal area. Trees with a DBH ≥ 10 cm and 60 cm were 180 ha–1 and 10.1 ha–1, respectively. The 37 plots were classified into four stand types, Tectona grandis type, Xylia xylocarpa type, Bambusa polymorpha type, and Dipterocarpus alatus type. The felling operation was conducted only in 10 of the 37 plots sampled and 11.7% of the basal area of trees over 10 cm DBH was removed during the logging. The percentage of extracted basal area (%-extracted) varied from 6.9 to 51.0% among the 10 plots. The highest %-extracted was recorded in D. alatus stands (38.7–51.0%), while the %-extracted in the other stand types was rather smaller (6.9–36.5%). As a result, the impact of harvesting was minimal except in the case of D. alatus stands. Teak was most abundant in the sapling layer (427 ha–1). The combination of the logging operation and bamboo dieback enabled the sapling bank to accelerate height growth and to enter the pole size class, while logging or bamboo dieback alone had no significant effect. In the bamboo dieback sites with the logging operation, 84–96% of tree saplings overtopped bamboo seedlings, but the value decreased to between 53 and 56% in non-logged stands. The combination of logging operations and bamboo flowering thus had remarkable effects on the sapling banks of tree species and enhanced recruitment of pole-size trees.