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I have a student (final year BSc) who is writing a dissertation
related to the identification of changes and the revision of woodland
and forests on topographic maps.
 
He is particularly interested in:
 
1.  Discovering how mapping agencies around the world identify,
classify and map woodland and forests.  How is the basic data
acquired?
 
2.  How often is this feature up-dated on topographic maps?  Is it
cyclic, periodic or on demand?
 
3.  What techniques are used to identify changes?
 
We would be very greatful for any indication of either references,
policies or personal experience and would like to spread this as
widely as possible across the world.
 
In anticipation, very many thanks for your cooperation.
 
Bob