> it doesn't seem likely that wellbeing causes trees Why not? Maybe people who feel well are more likely to care about their environment, and e.g. organize pro

> it doesn't seem likely that wellbeing causes trees Why not? Maybe people who feel well are more likely to care about their environment, and e.g. organize protests when someone wants to remove trees from their neighborhood. Meanwhile, depressed people will watch their environment deteriorate, and do nothing about it. (I am not saying this is how it is, just proposing a possible causal mechanism.) A possible common-cause explanation could be that some places are designed "for people to feel happy", and those contain trees, but also other things (parks? accessible sidewalk? or perhaps those are simply places where many nice people live?) which make people happy.