[akafred]

Land owners can generally chop down trees as they wish; with some exceptions, which mostly don't apply in these photos. I think there are three main reasons for the increase in woodland: 1. Less cultivated land; including less land used for grazing (eg. by sheep). 2. Other sources of heating (mostly electricity, some oil, and still some wood, but usually not taken from just outside the door; there is very little use of gas in Norway). 3. Milder climate has raised the tree line. Which of these is most significant probably varies.