It’s silly specifically because there are other options meaning you still need to verify a tree not cut down on this block chain hasn’t also been not cut down in some other agreement. Blockchains therefore can’t actually prevent a double spend as it were.

All we have to do is pass a law mandating that my blockchain is the only one allowed to track tree cutting. I’m very generous, so I host it for free and only charge a nominal fee per transaction. If you want to reduce the number of trees chopped, I can always raise the fee for that later.