>Others ask: Why plant at all, when we can often simply leave the land for nearby forests to seed and recolonize?

Because we continue to seek ways to profit from climate change, and re-wilding land is not profitable. The tree planting push is an example of the status quo attempting to maintain itself in the face of increased awareness of the consequences of it continuing. The recent fad of 'swipe your credit card here and we'll sequester carbon for you!' is another example. These attempts will probably get increasingly desperate over time. I would lend the tree-planting movement a lot more credibility if we were talking about re-wilding significant areas of developed land, and rendering them inaccessible to any possibility of profit. What you actually find is a large intent to expand the logging industries of various nations. A lot of it is obscured 'we don't have data on that' type stuff, but take a look at whether natives and re-wilding are on the cards or if it's about planting profitable species, and the reality is quite different from the spin.

"It is difficult to get a man to understand something when his salary depends upon his not understanding it." - Upton Sinclair

The longer we limit our thinking to solutions within the entrenched, centuries-old economic/social system which gave rise to the problem in the first place, the longer the problem will perpetuate unchecked before effective action is taken to mitigate and reverse it. If we're even in a state capable of such action by the time we realize that's what it's going to take.

>It was a good reminder that nature knows what it is doing

Couching natural processes in this language implies there is some level of knowledge humans could attain which would enable us to become a better steward than nature herself. Again, looking for solutions within the box that created the problem is folly when stepping outside of it is necessary to resolve matters. Nature has no idea what it's doing, it doesn't 'know' a damned thing, and this is it's inherent strength which we will never successfully emulate. Nature is chaotic and constitutes an incredibly complex ongoing battle of wills played out over at least 3.5 billion years of competition, death, birth, selection pressures and evolution. Misplaced hubris alone accounts for our belief we can somehow do better than nature with the power of knowledge.

"When you are new at sheep-raising and your ewe has a lamb, your impulse is to stay there and help it nurse and see to it and all. After a while, you know that the best thing you can do is walk out of the barn." - Wendell Berry

We have the capability, knowledge, and power to restore balance to our environment but our only hope of success is to work with existing natural systems, not against them. The solution certainly lies in our ability to augment, complement, and enhance them. Anyone asking why we can't just settle other plantes or geo-engineer earth in a way that's beneficial to us hasn't thougt things through enough - We're already ON spaceship earth and it is capable, with cautious collective caretaking that our intelligence and knowledge affords us, of carrying us through and into the stars in perpetuity. If we don't completely fuck it beforehand.

"For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons." - Douglas Adams

I believe that if we as a species were to develop enough knowledge and attempt to effect a superior replacement for nature, what we would have invented at the end of it would look an awful lot like a natural ecosystem, probably just with some sticky-tape (technology) holding things up behind the scenes. So in the end surely it's better to ruthlessly preserve the ecosystem we already have than allow it to die and have to try and re-create it or adapt to whatever the hell emerges in the void it leaves.

“I used to think that top environmental problems were biodiversity loss, ecosystem collapse and climate change. I thought that thirty years of good science could address these problems. I was wrong. The top environmental problems are selfishness, greed and apathy, and to deal with these we need a cultural and spiritual transformation.” – Gus Speth, founder Natural Resources Defense Council