焼畑移動耕作と休閑期間短期化の要因分析

―ラオス中部地域を事例として―

抄録

It has been pointed out, in quite a few surveys, that the main factors of deforestation are not commercial logging, illegal logging, and wars, but are “the intensive slash and burn cultivation” or “a short period of fallow”. However, few have tried to explain as to why people engage in intensive slash and burn cultivation, and also as to why people tend to shorten fallow period.

This paper, therefore, tries quantitive analysis of the factors of both “intensive slash and burn cultivation” and “a shortening of fallow period”. Three factors are assumed; (1) substitutional factors, (2) property factors, and (3) household characteristics factors. In the substitutional factors, it is supposed that the more paddy lands people have or the more a rice production is possible, the less people prefer both “intensive slash and burn cultivation” and “a short fallow period”. In Property factors, it is assumed out that the more property such as cash income and livestock people have, the less people prefer “intensive slash and burn cultivation” and “a short fallow period”. In the household characteristics factors, several factors, such as ethnics or the number of family, would be taken into consideration. Although it is supposed that they put some effects on people's choice of cultivation form, an elaborate correlation can not be introduced before the analysis.

Finally, the main resultsts are as follow. First, it is found that property factors affect negatively both of “intensive slash and burn cultivation” and “a shortening of fallow period”. Especially, the estimated parameters of the income from livestock, salary, and wage are quite lager than other factors, and it is expected that there are more negative effect of “intensive slash and burn cultivation” and short fallow period. Secondly, It is also pointed out that ethnics do not influence people to engage in slash and burn cultivation, but to shorten fallow period positively. Thirdly, it is not found that the number of family affects “intensive slash and burn cultivation”, but it affects “a shortening of fallow period.”