Headline is a false dichotomy. Some of the content is good - certainly natural regrowth is vital. So is planting trees. Replacing cement and buildings in concrete jungles with trees puts the trees exactly where they are the most needed.
Visible on google maps here https://www.google.com.au/maps/@-34.9279778,138.6043731,3461...
Probably more interestingly, I am skeptical about the premise. Obviously, cities need parks and trees. Largely they have parks and trees.
I see a lot of newer areas designed with mini-lawns and I always shake my head - in an urban environment, the name of the game is density and accessibility. Don't put a bush between the sidewalk and your shop: the shops are supposed to be on the sidewalk. Half of the time, these shops seem to be hiding their main entrance in the back, next to a parking lot, because it's actually a suburb with some apartments over a dentist office, not a real attempt at an urban environment.
So if we're talking about clearcutting, we ideally want to back up a step and make rules about the topology of a clearcut (not just shape, but holes as well).
If it's a forest fire, we may want to know how far natural reforestation can be 'stretched', and replant areas that are outside of that range, accounting for how fast the artificial forest will spread.
I don't understand; the perimeter of a square and a rectangle are the same? The amount of "edge" to spread out from should be the same?
The perimeter of a rectangle with the same area as a square is larger, so there is more edge for the surrounding forest to encroach upon at the same time.
The worst shape, from a 'fill from the edges' standpoint, would be a circle. (Although I suspect that a square turns into a roughly circular hole within a few years, since the forest encroaches on the corners from two directions at once)