case, the upper level paddy fields are much less productive
than the lower ones, it is possible that the value of the goods
and services that the trees provide to the farmers may to some
extent offset whatever reduction they may cause in rice yields.
Availability of natural forest resources also tends to covary together with history of land development and topographical position. Old paddies (48.2 % of all the cells
containing old paddy fields in our sample) are usually
located in flat bottoms or lower terraces in villages which
are also located far from natural forests. On the other hand,
newly developed paddies are usually located on middle or
high terraces (88.4 % of all the cells containing new paddy fields in our sample) in villages that are located closer to
the mountainous areas where most of remaining natural
forests in Northeast Thailand are found. Consequently,
differences in the availability of natural forest resources
may to a considerable degree simply be a reflection of
differences in topographical position rather than being an
important determinant of variations in tree density in its
own right.