- 1908 - 
It is better to prepare à type of land use map with the emphasis on 
shifting cultivation and to classify the forest types according to 
suitability for agriculture. Practical knewledge about shifting 
cultivation systems in use and the soil types is required for making 
such a map. 
In forest type mapping shifting cultivation areas can be delineated 
according to the following practical system: 
& — Clearcut fields, including fields 1n preperation for agriculture, with 
crops and recently abandoned, . 
b — Secondary forest (sub-delineation into age classes). 
c - Grass land with "pseudo-gallery" forest. 
a = Clearcut fields 
The area of clearcut fields for one family is of the order of 0.2 ha to 
1.0 ha, large enough to produce crops for the family during a year. Fields 
larger than 2 ha can be a sign that families are working together or that the 
fields are of young secondary forest. The form ef the fields are generally 
in straight lines;an exception are the circular plots of indian tribes in 
the Colombian Amazon. 
Depending on local custum, the fields may be separated by strips of uncut 
forest or are linked together. Occasionally trees are left standing because 
they are too large, or the wood is too hard or they give fruits or nuts, 
specially palms are left as they produce material for roof construction and 
edible fruits. 
Even in the field the differentiation between abandoned field and secondary 
forest is not sharply defined. In the second year fast growing trees can 
grow between the cassava and banana stems. To include such fields on aerial 
photographs in the clearcut class depemds on personal decisions by the 
interpreter and the scale of the photograph; for a small scale (1:50,000) 
the tendency is to include them in the clearcut class and for a larger 
scale (1:25,000) in the class of secondary forest. 
b - Secondary forest 
A trained interpreter will be generally able to differentiate secondary 
forest from low forest types like mangrove, swamp forest, streamlet forest 
and "wet savanna" forest. 
The differentiation between creeper forest and secondary forest is, even 
for a well trained interpreter, a difficult task. If the terrain is flat 
and drainage is not visible, the location away from the streamlet can be