But it's not just planting the tree, right? It's taking land that currently has no tree, reserving it for the tree, and guaranteeing that the land & tree will remain intact for a nominal period of time, possibly indefinitely?
Trees are cheap. Fertile tree-growing land not currently used for trees: not so much.
Here in the (western) US, millions (billions?) of trees are burning up every year due to forest fires.
So to add to your list, we also need a way to facilitate healthy forests without completely destroying them and re-releasing nearly all of their stored carbon back into the atmosphere within a couple of weeks. Controlled burns is one way, but that requires an investment in firefighters and other specialists.. who are currently all preoccupied fighting uncontrolled fires.
Trees are cheap. Fertile tree-growing land not currently used for trees: not so much.