This open article in PLOS ONE mentions tree canopy targets in several cities.
Increasing UTC [urban tree canopy] has become a widespread goal, often incorporated into municipal sustainability plans. It has been proposed as a way to mitigate impacts from human-dominated systems on the immediate (e.g. shade and cooling) and global (e.g. carbon capture) environment. Sacramento Tree Foundation has pledged to plant five million trees by the year 2025, an effort that would double the region’s tree canopy cover. Philadelphia has established a goal of increasing tree canopy cover to 30% by the year 2025 (www.phila.gov/green/trees). New York City, Baltimore, and Los Angeles have also announced extensive tree planting initiatives (www.milliontreesnyc.org, www.baltimorecity.gov, www.milliontreesla.org). In addition to regional efforts, there are national and global efforts to bring more awareness to the benefits of UTC cover (Urban Environmental Accord 2005, www.sfenvironment.org/downloads/library/accords.pdf; http://www.plant-for-the-planet-billiontreecampaign.org/Partners/VariousPartners/TreePlanting.aspx). One of the implications of embedding tree canopy goals in sustainability plans is that environmental justice is frequently included as an objective of the plans, and sometimes explicitly linked to UTC. For example, Philadelphia’s 2009 GreenWorks Plan includes goals of increasing tree canopy cover in all neighborhoods highlighting the desire for the equitable distribution of UTC cover (www.phila.gov/green/greenworks/2009-greenworks-report.html).
Incidentally, I lived on a beautiful tree-lined block in Philadelphia until a year ago, when the city cut them all down to replace a major sewer line. I suppose it couldn’t be helped, and they are promising to replant.
Here are a bunch of other articles I’ve stumbled across lately on urban tree benefits:
- The Case for More Urban Trees, from Atlantic CityLab
- New evidence that city trees reduce crime, from Natural Resources Defense Council
- Tree planting in D.C.’s less-green neighborhoods, from Washington Post
The last is slightly negative. There are people who don’t like trees. Most of their beliefs are erroneous, but some are based on nuggets of fact. Some species of trees will invade sewer lines, particularly if they are starved of water and nutrients because they are under sealed pavement. And trees do kill a small, but nonzero, number of people each year. I believe the tree haters are a tiny but highly vocal minority. It’s not worth spending any effort trying to reason with them. The best thing to do is put a tree everywhere but in front of their house. Maybe they will see how nice it is and eventually come around. If they don’t, well, you still have more trees than you had before.