Stratum 
mid-point 
in m. 
Diameter 
estimate 
in cm. 
Precision 
in 
per cent 
24 . 5 
42 
0. 9 
29. 5 
48 
1. 0 
34. 5 
63 
0. 9 
39. 5 
87 
1. 5 
Table 12. 
Estimated diameters and precision for 2471 trees 
The average diameter of the 2471 trees is 48 cm which corresponds with the 
29. 5 metres canopy stratus. 
In the Surinam rain forest timbers in the middle diameter classes are the most 
important from a utilization point of view. The heavier timbers tend to be over 
mature and have many defects, while the smaller trees are not very interesting 
because of their size. In the above table the middle diameters are represented 
in the second highest stratum with an estimated diameter of 63 cm. This value 
may be compared with the average diameter of the enumerated trees which were 
grouped in 10 cm. classes from 55 to 85 cm. and with the average diameter of 
the trees in these classes which could be located on the aerial photographs. In 
both cases this average was 67 cm. , a value which also corresponds with the 
second highest stratum. 
Thus it appears that the number of trees counted in the second highest 5 metre 
stratum may give an indication of the potential timber value of the forest. 
REFERENCES 
HEINSDIJK, D. 
LOETSCH, F. and 
HALLER, K. E. 
NOPSUVAN, P. 
SARDAR, M. G. 
SWELLENGREBEL, E.J.G. 
The upper storey of tropical forests. 
Tropical Woods, 1957/1958. 
Forest Inventory, Volume I. BLV Miinchen, 
Basel, Wien, 1964. 
Large scale aerial photography with various 
emulsions. Thesis submitted for a M. Sc. 
degree, ITC, 1972. 
Applicability of large scale narrow angle 
aerial photography. Thesis submitted for 
aM.Sc. degree, ITC, 1973. 
On the value of large scale aerial photographs 
in British Guyana. Empire Forestry Review, 
Vol. 38.