ミャンマー・バゴー山地におけるカレン焼畑土地利用の地図化 (<特集>ミャンマー少数民族地域における生態資源利用と社会変容)

Abstract

We conducted a field survey in S village, in a Karen Area of the Bago Mountains of Myanmar. Through GPS mapping, interviews, and observation, we examined the present state of shifting cultivation in this area by focusing on the vegetation in fallow lands and fallow period lengths. In 2002, 59 households (HHs) opened 60 plots for shifting cultivation. The village itself covered an area of 4973.94ha (A). The 60 plots covered 161.46 ha (B1), corresponding to an average plot size of 2.69 ha. In 2003, 62 HHs opened 66 plots for shifting cultivation, with an aggregate area of 141.15 ha (B2) and an average plot size of 2.17 ha. In 2004, 74 HHs opened 75 plots for shifting cultivation, with an aggregate area of 179.91 ha (B3) and an average plot size of 2.40 ha. In 2005, 63 HHs opened 73 plots for shifting cultivation, with an aggregate area of 196.88 ha (B4) and an average plot size of 2.70 ha. In 2006, 54 HHs opened 56 plots for shifting cultivation, with an aggregate area of 96.06 ha (B5) and an average plot size of 1.72 ha. Based on these figures, the potential maximum numbers of fallow years were 30.8(A/B1) for 2002, 35.3 (A/B2) for 2003, 27.8 (A/B3) for 2004, 23.7 (A/B4) for 2005, and 50.9 (A/B5) for 2006. During the first fallow year, the land was covered with Chromolaena odoratum, which was replaced by bamboo (Bambusa polymorpha and Bambusa tulda) over several years. After 12 years, tree species such as Xylia xylocarpa gradually dominated the fallow lands. Despite the potential length of fallow periods, the actual fallow periods were only 17.9 years in 2002, 15.1 years in 2003, 12.8 years in 2004, 13.0 years in 2005, and 11.9 years in 2006. This difference may have occurred because lands left fallow for 12 to 18 years become covered with trees and bamboo. These can be easily cleared and provide good burning material for shifting cultivation.