A lot of the trees being cut down are old growth forests, there are nearly no old growth forests left on the whole continent and some animals specifically need old forests with their diversity of species and with different ages of trees throughout. Things grow back differently when you clear cut a section than when an old tree died and falls here and there or is harvested sparingly without destroying the surrounding trees and underbrush, so the lack of selectivity when harvesting is also harmful. Cutting down everything and replanting one species that grows ok in a clear cut area doesn’t restore the forest. Look at longleaf pine forests, for example. Nearly the entire southern US used to be longleaf pine and now it only exists in 3% of its former range. The southern US is still covered in pine, but it mostly got replaced with loblolly pines. You can replant some trees, but you can’t replant a whole complex forest ecosystem, and many of the trees people replant are ones they think they can personally profit from like the fast growing loblolly pines rather than slow growing species that need special care and land management practices to maintain good growing conditions.
Mountain lion only describes one type of habitat cougars live in, they have the widest distribution of all the big cats and live in a variety of habitats, including the Everglades swamp in Florida, in canyons, and in areas with a lot of scrubby brush they can ambush from.