Tree aren't great for carbon capture. They take up land space, which then has to be reserved for those trees. Then, they eventually die, and decompose, which means a new tree has to grow to re-capture the carbon that is released when the tree decomposes. Better to put the excess carbon back underground, where it came from.

The term is “sequestration”. You are correct that trees are a temporary capture, and even then- only when you plant woodlands that did not previously exist. Given enough time, the trees that are planted will decompose or burn in a forest fire to become net neutral. Trees buy time, but they aren’t a clean up plan.

Trees decomposing and being consumed by other trees is literally how it's worked for untold millions of years, so doesn't seem like a problem to me ...

Forests also provide local cooling, improve the water cycle, and aid biodiversity. A world with forests is a healthier world.

Trees dying and not decomposing is how we got all that coal that we're now turning back to CO2.

It's also how we got all the carbon in our top soils. A 6 inch or more covering of carbon (mixed with minerals etc) covering huge parts of the earth's surface.

Planting trees, harvesting them, and turning them by pyrolysis into biochar/charcoal and then burying it can partially restore these soils and sequester carbon at the same time.

Yep, but it is a nontrivial amount of work to produce approximately as much biochar as we have burnt coal.

Oh, absolutely. It would take generations. But taking forestry waste and turning it into a soil amendment is a worthwhile endeavour even from the POV of improving food production.

Also, as we're seeing in the US west or Siberian forests; they cascade co2 release quickly with forest fires.

A recent thought on carbon credit scheme with trees. If you grow a tree and build a house with it, then that carbon is captured until the house burns down.