The problem is scale. Doing a lot of carbon capture with trees doesn't mean you're growing a nice biodiverse forests, it means you're growing vast tree plantations that you periodically chop down and sequester, e.g. with biochar.
A while back I saw a paper in Nature claiming that we could use trees to absorb up to 1 gigaton carbon annually, but more than that and we'd seriously impact biodiversity. There are probably other estimates around, but regardless of the exact threshold, it wouldn't be a bad thing to have technology able to do the same thing with a thousand times less land area. Then we can let the forests grow undisturbed.
To your edit: climate change itself is making species go extinct, so it's not like we can solve the extinction problem without addressing climate change too.
A while back I saw a paper in Nature claiming that we could use trees to absorb up to 1 gigaton carbon annually, but more than that and we'd seriously impact biodiversity. There are probably other estimates around, but regardless of the exact threshold, it wouldn't be a bad thing to have technology able to do the same thing with a thousand times less land area. Then we can let the forests grow undisturbed.
To your edit: climate change itself is making species go extinct, so it's not like we can solve the extinction problem without addressing climate change too.