An excellent article about Toronto's urban forest by
We're not just growing plants, we're growing soils and the biota who live there. This is especially important in urban and suburban areas where so much of our soil-life has been heavily disturbed and destroyed. In past few years we've started to clue-in to the necessary role of mycorrhiza fungi in tree health. Check out Mycorrhizae: Unsung Heros of Forest Health from the Ontario Arborist.