Adding to what gRomoZeka said about painting tree trunks: when I lived on a military base in Okinawa, some of the trees were painted this way, although the Okinawan climate is sub-tropical, so the winter/spring temperature change isn't the issue.


Apparently, in hot climates, it's done mostly to protect the bark of young trees from sunburn. This is especially important if you have trees planted far apart from each other along a road, since the trees don't get shade from each other's leaves. Also, along a road, the white paint makes the trees more reflective to vehicle headlights! (Border stones may be painted white for the same reason: so they're easier to see at night.)