Landing your parachute in trees is relatively unlikely to kill you compared with flying into trees in your aeroplane.
It would be relatively simple to just say
Code:
If parachute then
trees = not deadly
else
trees = deadly
end if
Personally I think that the immersion factor would be greatly improved if we had hedges, power lines, phone lines, plough furrows and crops to contend with when attempting forced landings. At the moment, field selection is pretty much just anything approximately flat and not water = good...
Livestock would also make things interesting (even if it was static). I'm told that cows like to lick the dope from fabric covered aeroplanes, so the sim could add a few extra % damage points to aeroplanes which landed in fields with livestock... Of course, hitting a cow at 70 knots would do neither it nor the aeroplane much good either, and if you land in the same field as a bull then loss of doped fabric might well be the least of your worries!