texturing a cylinder is not so complicated ... the "trick" is putting Blender into the correct "view"
before using "Smart projections"
Make sure your cylinder is perfectly upright and that you are looking at it in your 3D window "side on" ... with it pointing upwards ...then hit "Smart Projections"
This method will even map the top and base of the cylinder correctly ...

- cylinder.jpg (195.83 KiB) Viewed 3925 times
this method would work for your trees too ... (by the way, its better to texture your object BEFORE you place it in it's "final resting place" in the scene). The more "square on" in Blender it is ...the better the UV mapping (usually!)
If you make a new tree like the cylinder in the screenshot (perfectly upright) ...then texture it ...
then you can 'bend' and twist and "deform" the tree trunk to make it look more natural. This usually produces better results than "fine modelling" the tree trunk and THEN trying to apply the UV map.
when it comes to Age creation ... "DOH" seems to be my middle name...