They take up a lot of space at scale though.

Most tree planting efforts fail, as they ignore a lot of implementation/maintenance details and result in lots of dead trees.

Mass tree planting is like doing a massive, massive migration. You can't just stick seedlings in the ground arbitrarily and expect a stand of trees to sustain itself 'cause "nature"... the successful processes like the Miyawaki method require planning, community investment, sustained work for ~5 years, etc.

https://daily.jstor.org/the-miyawaki-method-a-better-way-to-...

Planting is just the first step as I see it.

After the trees have grown, you need to harvest them and - somehow - make sure they don't rot and return the CO2 to the atmosphere.

Finding space for that is what I mean by "take up space at scale".