Vegetation of Southeast Asia Studies of Forest Types 1963-1965

This is a compilation of survey data, published materials and
field reports on Thailand. It font-Tins a discussion of the general
and comparative geography of Thailand; climate; variations in
rainfall; floods; droughts; water control systems; climatic classification
of the natural vegetation of Thailand; economic classification
of the forests of Thailand; soils and farm-land use of Thailand;
economic background and principal agricultural products of
Thailand; agricultural experiment stations and studies of varieties;
phenology and yield of rice; distribution and production of farm
crops; local field practices; control of crop pests, crop diseasesj
and weeds of Thailand.
Nyyssonen, A. Aerial photographs of tropical ''orests. Unasylva 16
(1). No. 6k. pp. 3-12, 5 figs. 1962.
The sum of the factors of the environment that- influence tree
growth is measurable on aerial photographs to the extent that the
key features of the environment can be recognized. Tree growth
reflects thelocal climate and soil. Local climate and soil moisture,
in turn, are apt to be closely related to the topography. Topographical
data can be classified accurately from the stereoscopic
image.
The following factors are described at sjme length: tree species
identification; classification of forest cover .types; and quantitive
estimation of growing stock. Depending upon the quality
of photographs, such information makes it possible to assess the
value of aerial photographs as a source of practical information
for use in forest survey.
In some cases identification of tree species from aerial photographs
was remarkably successful, but on the whole the results were
not adequate. Several successful experiments, however, showed that
important forest types can be detected from aerial photographs,
although checking and supplementation from the ground is also often
necessary.
Photo-interpretation alone seems adequate for a survey of certain
forest types. Sometimes this can be accomplished by aircrn.it
or nelicopter reconnaissance without photography, ^ut it should
be emphasised that ground work can not be dispensed with in tropical
forest surveys.
The use of eerial photographs has important advantages in forest
surveys. Above all, aerial photographs enable a study of stratification
and arrangement of the ground work to be made in the moct
efficient manner, and are an excellent tool in surface area assessment.
Photographs are also useful in practical survey work, in •
delineating roads, drainage, major topographical features and forest
boundaries. Consequently, combined aerial and ground surveys seem
to be the best procedure to make forest inventorica.
A list of references is included.
Ogawa, H., K. Yoda and T. Kira.
Nature and Life in Southeast Asia.