The problem, in my mind, is that activities of this sort are ultimately meaningless, since a) it's a good chance a lot of said trees don't survive very long, and b) even if they do, quite often the species chosen are not native to the area, sometimes even to the continent.
And most of all, tree-planting is an activity that is hugely overshadowed by the logging and paper industries, who mow down forests as fast as they can, with most of us not knowing about it until the deed is done. (All we can do is "tsk-tsk," and plant a few more baby trees, that won't achieve full growth for anywhere from 50 to 300 years from now.)
And have you been paying attention to the fungal/viral problems that are facing particular species, such as ash and oak? Millions and millions of these trees are being wiped out yearly, in Britain, Europe, Asia, and North America.
Along with that, there's the warming of the northern forests, allowing Pine bark beetles to decimate more millions of pine and spruce, and massive forest fires that are taking out thousands, even hundreds of thousands of acres (while rich idiots build their extravagant houses in the forested foothills, so when the firefighters DO come to do their job, they have to waste inordinate amounts of time and resources trying to save these houses, rather than the much more valuable forests around them.)
And don't get me started on genetic engineering. I mean, who the hell do we think we are? We will never be smarter than Mother Nature! We will never be able to anticipate the full effects of our self-centered meddling on plants, animals, ecosystems and, inevitably, ourselves.
Lastly and, what seems to me saddest of all, it's all done to make rich people richer. The rest of us sit around being angry or oblivious, but we don't stop them, either.
So the upshot of this rant is that I'm going to be concentrating on finding stories about people and organizations that are doing something, ANYTHING, to try and give some relief to the suffering and possible extirpation of thousands of species of animals, plants and us.