(Q1)
Forests throughout the world are shrinking because lots of things need wood to be made and or work. To get wood for needed or necessary things, people have to cut the trees down.
(Q2)
I think that we could have a few days out of the year where almost everyone/everyone who wants to attend can go around and plant some trees. This would help because the seeds would grow and create more trees so we could have a never ending cycle of growing trees.
Hope this helped!
For continental U.S. the answer is never. Since the earth's rotation axis is tilted 23.5 degrees with respect to its orbital motion around the su, one would have to be less than 23.5 degrees above or below the equator to have the sun pass direclty overhead
