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—À Qaa ies ias or 
  
  
  
PHOTOGRAMMETRIC ENGINEERING 
phy was carried out in 1956 on a scale of 
1:20,000. For photo interpretation purposes 
the most important part of the forest area was 
selected; the species are pine, oak, fir and 
cedar. This area covers about 2,500 sq. km. 
The photo interpretation was field checked. 
Timber volume estimates were obtained from 
sample plot records, and for this purpose a 
local volume table for pine was constructed. 
Map compilation was based on the slotted 
templet method. Instructions were given for 
the demarcation of legal forest boundaries, 
with the help of aerial photographs, in order 
to avoid an annual loss of about 500,000 
Syrian pounds by destruction of forested 
land. Use of modified infrared film in the 
future has been suggested to obtain a better 
differentiation between hardwoods and conif- 
erous trees. 
TANGANYIKA 
[Interesting information dealing with the 
application of aerial photography in relation 
to forest inventory problems were obtained 
from an article recently published. It concerns 
the classification of woodland formations 
covering nearly 5095 of the total area in this 
country with a total extent of 460,000 sq. km. 
For this inventory work, aerial photographs 
were used on a scale of 1:30,000. Photographs 
were probably made by a 6" Ross camera in 
combination with a Williamson MBV2 vig- 
netted filter, which is equivalent to Wratten 
No. 8. Ilford hyperpan film was used and 
prints were delivered on double-weight paper 
with usually a glossy dried matt finish. 
Identification of individual tree species on 
the aerial photographs was hardly possible; 
the classification. of type differences was 
mainly based on ecological facts, which were 
easily identifiable on aerial photographs. 
Based on this principle 12 different vegeta- 
tion types could be distinguished on the 
photographs. In addition to other character- 
istics such as tree height, crown size and 
crown form, the estimation of the crown den- 
sity proved to be a very important indicator 
for identifying types. 
In combination with this type-mapping, 
corresponding observations were made in the 
field to obtain more knowledge of the species 
composition within the different areas. In 
most cases the ecological formations inter- 
preted from the air photographs proved to be 
characterized by a particular composition of 
the main tree species. More detailed ground 
enumerations were made in type areas con- 
taining timber species of marketable value. 
A striking agreement was also found to 
exist between the ecological formations and 
20 
their local soil conditions; this enabled con- 
clusions to be drawn on soil types in relation 
to the interpretation of the corresponding 
vegetation types. 
THAILAND 
During the period 1956/57 a national forest 
inventory project was carried out in the 
northern part of this country. This was pri- 
marily to obtain a reliable estimate of the 
total timber volume of Teak wood and its in- 
crement as a basis for more efficient manage- 
ment planning. For this inventory scheme 
aerial photographs could be used; this re- 
sulted in a tremendous reduction in cost and 
üme. Assuming the same results obtained by 
pure terrestrial methods, the time necessary 
for the measurements in the field would have 
been ten times greater. 
The scale of the aerial photographs used 
for this purpose was 1:48,000. Photographs 
were made by an RC5 and an Eagle 9 camera 
with a panchromatic film in combination with 
a yellow filter. By interpretation of these 
photographs 10 different vegetation types 
could be recognized. This photo interpreta- 
tion was based on the tract line sampling de- 
sign which may be still new among photo 
interpreters. For this purpose a special glass 
template is made of size equal to the air 
photo. On this template a 5 cm. square is indi 
cated having millimeter and centimeter divi- 
sions graduated on its four sides. After super- 
imposing this template on one of the stereo- 
pairs, with the aid of the mirror stereoscope, 
the number of millimeters which fall on each 
stratum are noted down in tabular form. The 
numbers falling in each stratum are after 
wards totalled. After treating 4,000 photo 
graphs by this method the percentage of each 
stratum was calculated. 
As the total area to be surveyed could be 
obtained from existing topo maps, the total 
area of each type could be calculated. The 
standard error was for the most important 
type (the mixed deciduous forest); this was 
within 7%, which is acceptable. Taking into 
consideration the large number of photo 
graphs to handle, this method seems the best 
suited in these conditions and far preferable 
to the usual method of type map construction. 
For estimating the timber volume of the 
main species terrestrial sample plots were 
measured. For this purpose circular sample 
plots of 0.05 ha. were used arranged in a spe 
cial cluster system or camp-unit-system. 
UGANDA 
Aerial photographs are used in this country 
for forest type mapping and for the prepara-