2.1. Site selection and description
The study was carried out from May 2001 to May 2003 in rural
areas of southern Cambodia, northeast Thailand and northern Vietnam
(Table 1). In the study area, the climate is tropical with an average daily
temperature of 27 °C and an average annual precipitation of 1500 mm,
about 75% of which occurs in the monsoon season (May to October).
Rice is the dominant agricultural crop. Cambodia has the lowest
population density of the three countries, about half that of Thailand
and less than a quarter that of Vietnam. Cambodia is also the poorest
country in terms of per capita GDP and the proportion of the
population that is undernourished. Thailand boasts by far the highest
per capita GDP, but a greater proportion of undernourished people
than Vietnam. The countries thus offer great contrast in terms of
population density and development indicators. Rice farming dominates
the landscapes of all study areas. The intensity of rice farming as
indicated by yields and degree of irrigation development is lowest in
Cambodia, intermediate in Thailand and very high on Vietnam