scale of photographs. On larger scale it was for height 5 meters, crown
closure 2 0%, crown diameter 5m, volume in three classes. On smaller
scales the limit for height was 10 meters, crown closure in three classes
and three volume classes.
Aerial photo-interpretation proved very useful in delineating
areas of various resource categories. Areas such as blanks and degraded
type of forests not contributing any growing stock could be separated
easily on 1:40,000 scale, TIWARI ( 10 ). Delineation into height and
crown closure classes indicated various categories of existing resources.
One of the main useful purposes was for volume class stratification a
basic parameter used in designing of forest inventories. This was even
attempted down to scales of 1:60,000 for East Godavary Survey by V.K.
Seth and M.S. Tomar ( 6 ) with significant results. However as a
general experience volume class stratification on scales larger than
1:20, 000 could be done easily with sufficient accuracy, TIWARI ( 8 ) „
One of the objective method where the stratification into volume classes
could be done based on forest type with photo height and crown closure
on 1:40, 000 scale photographs through pilot survey was done by TIWARI
( 10 ) for Karimnagar forest resources survey. Photo stratification into
height and crown closure classes was made and volume per unit area in
each of the types was measured on the ground on predetermined sample
plots. These types were then grouped into three volume classes on the
basis of mean volume and variation by Duncan's multiple range test and
an objective basis was developed for rest of the area whereby the volume
class could be assigned by recognition of forest type. When applied
for broad regional area the stratification was significant and gave saving
in cost and time.
TOMAR and MASLEKAR ( 13 ) have given a comprehensive
classification system to be adopted for forest type classification for
resources survey by photo-interpretation techniques. Their system is
mainly based on their experience in Pre-investment Survey of Forest
Resources where in mostly medium to small scales were used. One of
the main draw backs of the system is that they have used undue weight
to the scale of the photographs and recognition possibilities of various
parameters which may overshadow the entire objectives of the survey.
Aerial photographs are tools to achieve a classification and any such
system which is based on tools cannot serve the purpose and be a
standard. Further they do not distinguish between various intensities of
resource survey and therefore are one sided approach. It is well to be
seen that it is very difficult to make a standard classification as the
objectives of the survey are a prime consideration which differ from
survey to survey. Any attempt to generalize may not cater to all the
requirements. However the approach and broad categories applicable to
Indian conditions can be given which may serve the purpose in the
initial stage and later on the inventory designer may give final shape to
the classification to be adopted in a particular survey. To this end in
view, the methodology adopted in Pre-investment Survey organisation has
been a sound one.
Wherever the important species could be recognised, they were
separated out and on larger scales division into percentage classes was
also given.