CO2 isn't the only reason to take care of forests. If we replace a naturally grown forests with newly planted one we destroy an existing thriving habitat and replace it, in most cases, with a monoculture. This has tragic impact on biodiversity.

Here's a good article you might want to read. It also says that natural forests are actually better at capturing CO2.

https://www.nature.com/articles/d41586-019-01026-8