I read somewhere that trees help seed clouds, thus causing rain (or maybe just moisture in the air? I forget), though it seems like it's also a vicious cycle - the areas not in drought continue to not be in drought, whereas areas that are lose trees that could've seeded clouds, and thus rain.
That said, I agree with the points made in the article. "Trees are good" is a pretty uncontroversial stance. Should be, anyway.
I do wonder, if the biophilia thing is real, and it seems reasonable that it is - are some trees better at creating this effect than others, even if the same size? If so, does it vary by region, cultural/ethnic background, etc., and what do those trees that are unusually biophilia-inducing have in common?
I have no idea what the answers to those questions are, and there's a lot of speculation before you need to ask it, but it seems like <i>some</i> university or government or something should be researching those questions right now, what with all the plans to make cities greener.