Or, you know, pay locals a consistent salary, thus helping the environment and also mitigating extreme poverty (<$1.25 a day) - which is what they are doing.
More importantly, these green spaces are sustainable. So even if you run out of budget in 5 years, the people no longer need you to pay them as they now get everything they need from the work you paid them to do in the past and so they can live without subsidy. Or if you do have budget you can move to some other village and pay them to become sustainable.