COMMISSION VII: INTERPRETATION OF VEGETATION 
tion of topographic maps necessary for forest 
management. For this purpose 110 sq. miles 
have been photographed from the air. Photo- 
graphs were made on a scale of 1:25,000 to 
1:30,000. No special filters were used for this 
purpose. Camera type used was RC5a. Iden- 
tification of different forest types could be 
based on differences in tone, texture and aver- 
age crown size. Interpretation is checked in 
the field, usually in combination with enumer- 
ations by random sampling. Stratification of 
samples is based on the interpretation. 
For the transfer of detail the Hilger & 
Watts Plotter was found to give quite satis- 
factory results. The Zeiss Sketchmaster was 
used for well-mapped flat areas. No volume 
estimations have been made so far on aerial 
photographs. À research scheme has been 
initiated to study the correlation between 
crown-size and stem-diameter on large-scale 
(1:5,000) photographs of selected forest areas 
under natural growing conditions. The object 
is to extrapolate sample plot data on a field 
scale for forest management purposes. 
Aerial photographs are further used in the 
field to assist in road lay-out and for the loca- 
tion of forest boundaries. By making com- 
parative studies of aerial photographs of the 
same forest region made with a time interval 
of several years, it was possible to observe 
severe destruction of riparian forests and gen- 
eral National Park. Also a 
study of grassland conditions was possible in 
tree cover in a 
protected areas to determine hippo grazing 
intensities. 
VENEZUELA 
Aerial photographs have been secured on 
scales varying between 1:10,000 and 1:40,000. 
1:40,000 1:35,000, 
for cartographic and geologic 
The majority are and 
particularly 
purposes. Special flights for forestry purposes 
have not been made so far. The best season 
for photography falls between December and 
the end of February, but flying conditions are 
the best in December and the first 
January as at that time the visibility is not 
part of 
yet reduced by dust and smoke. 
Based on the interpretation of aerial photo- 
maps have been made. 
250,000. All informa- 
tion has been assembled together into a gen- 
graphs, vegetation 
The scale is mainly 1 
eral vegetation map of the whole country, on 
a scale 1:4 million. On these mostly the main 
vegetation types are indicated. Boundary 
location of the different types is obtained by 
interpretation in combination with 
field check. In the low lands the 
following types were distinguished: Tropical 
Deciduous Gallery 
photo 
occasional 
Forest, 
Rain Forest, 
Forest, Thorn Woodland and Chaparral, 
whereas in the mountainous regions of the 
Andes the following types were differentiated: 
Sub Montane Forest, Montane Forest and 
Mossy Forest. 
A sub-differentiation according to tree 
species composition proved to be almostim- 
possible due to the difficulty of detecting in- 
dividual tree species on the photographs. By 
observations from a small airplane flying at a 
low altitude, however, it was possible to 
identify about 12 different species with a high 
degree of certainty. Observations were made 
above a deciduous forest tract in the State of 
Barinas in Central Venezuela. As the same 
forest tract had already been surveyed by 
terrestrial methods, the composition of the 
main species was known. 
NEW ZEALAND 
From the report dealing with the National 
Forest Survey published in 1957 the following 
information could be obtained: 
The majority of the Forest area of New 
Zealand has been covered by air photography. 
The total extent of surveyed forest area was 
7.1 million million have been 
mapped. The technique applied was based on 
Scandinavian and North-American methods. 
Photographs were made by N.Z. Aerial Map- 
ping Ltd. under contract to the N.Z. Dept. of 
Lands and Survey. Camera focus: 81", size of 
prints: 7 X9", flying heights adjusted to give 
an average photo-scale of 4" to 1 mile 
(1:15,840). Flight lines; E/W to cross main 
Mountain ranges. 
Forest type boundaries were marked on 
photos and checked during the field work, the 
final revision being made after completion of 
all field work. Cover types were sub-divided 
into volume per acre and in condition classes. 
Minimum area delineated on photographs 
was 5-20 acres. Ground control points were 
located in the field and pin-pricked on the 
photographs during field work. 
Timber volume estimates were obtained by 
sampling in the field. Survey lines run parallel 
to flight lines with plots at regular intervals, 
varying from 1 to 4 miles between lines, and 
t or 3 mile between plots, according to the 
productivity of the forest. At least 20 to 30 
plots were measured for each type. Plots were 
5 by 2 chains or 1 acre. The following data 
were collected: D.B.H. and merchantable 
height of all merchantable trees with deduc- 
tions for visible defects and stem irregularity. 
Distances of merchantable trees to centre 
acres: 35.5 
lines were chained. For low potential forest, 
techniques varied from a walking reconnais- 
sance to random and systematic sampling 
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