There is some evidence that foliage on pedestrian streets does increase a sense of well being, lower blood pressure, and so forth. There was an article a while

There is some evidence that foliage on pedestrian streets does increase a sense of well being, lower blood pressure, and so forth. There was an article a while back that showed greater health benefits to walking around trees than walking along a concrete suburban sprawl. Another thing that front yards help with is reducing the amount of rain runoff that makes its way into storm drains. This is actually becoming a big problem in SF, which has an antiquated combined storm and sewage system. http://www.sfweekly.com/sanfrancisco/news-san-francisco-sewers-floods-el-nino-sfpuc-wastewater-cayuga-mission-district/Content?oid=4160430 http://www.sfweekly.com/sanfrancisco/news-san-francisco-sewe... That doesn't mean lawns are needed, of course, but unfortunately a lot of my neighbors (south of 280), as well as residents in the outer sunset and a few other neighborhoods, are paving over their front yards for extra parking. I find the whole thing pretty depressing, and it is causing infrastructure problems. http://www.sfgate.com/bayarea/article/Paved-over-S-F-yards-raise-concerns-4218247.php http://www.sfgate.com/bayarea/article/Paved-over-S-F-yards-r... http://www.surfrider.org/coastal-blog/entry/surfrider-un-paving-san-francisco http://www.surfrider.org/coastal-blog/entry/surfrider-un-pav... It's actually illegal, but this is San Francisco, so you know.