the local people’s reason for leaving the area alone was wrong unless it was specifically understood that it was a reservoir for biodiversity
It was understood as the sacred source of life. People by and large aren't stupid, just because not everything is coated in a veneer of materialist jargon doesn't mean that interrelations aren't understood. It's a specifically western trait to be so adamant about that distinction, making it a hard delineation people don't want to think across, want to keep separate, and that has something to do with the church retreating to matters of the spirit when science figured out how to explain the material world better than Aristotle. That left a deep scar in our collective psychology and frameworks that's still not even remotely healed.
Consider psychosomatics: It's a discipline all of its own only because people first decided to make a harsh distinction between psyche and body and analyse them independently of each other, the more reductive the better, while in truth it's a deep interrelationship, so now we need a third thing to somehow connect them up again. The same is true about cultures and the places they live: In reality, there's no boundary between the two, so you get ecology to somehow connect them up again. The difference between that tribe and us isn't the level of understanding about what's happening, but them not having had the hare-brained idea to see themselves apart from nature in the first place.
As to ecologists communing with spirits: If you talk to an animist, yes they very much are. Doesn't matter what the scientists believe they're doing, they're still doing communing with spirits stuff. If you don't think so then you're using another idea of "spirit", that's all.