Monocultures of any kind are always fragile, you need diversity to have a resilient ecosystem. These projects should benefit from an understanding of permaculture, which is a discipline that aims to create the right conditions for healthy systems. Everything from succession (pioneer leguminous species that can fix nitrogen and improve soil, slowly replaced by other species), trying to slow down and catch water where it falls to prevent soil erosion and runoff and much more. I've heard (unsubstantiated) claims that initiatives in China have already started to take these into account and have succeeded where other monoculture forests failed.

A side effect is that you can end up with productive species. Imagine forests where many trees bear fruits, others have acorns that pigs can feed on, fruit vines and understory herbs that animals can graze on, large lakes with edible fish. This is the future I'd be excited for and it's all currently possible with the right policies.