Jim,
What if you created a raster line representation of the border
then used that as a mask.
Run r.stats -z (no zeros since their non hits) on the clumped
vege map and pipe that thru an awk reformater and on into
r.reclass setting them equal to themselves. Then remove the mask
Something like:
r.stats -z vege_clump | awk '{print $1 = $1}' | r.reclass input=vege_clump
output=border_vege
Mark Johnson - USACERL