Just make it take a good minute and several actions to (depending on your atrributes and logging ability of course) to chop a tree down. It takes me longer to drink water from a river than it does for someone to chop a tree down and cut it into logs.
Increasing the number of trees, and adding actual forests wouldn't hurt either. You should not be able to see the sky very well in certain areas.
If trees will be so few in number and so easy to chop down, then yes, respawn them every 2 days please.