I’ve been thinking a little bit about urban greenery recently. I am lucky enough to have always lived near trees. My last home was next to a gorgeous bush block which made up for (sort of) the fact that trees where pretty much completely removed from the rest of the housing development. My new home is on a beautiful tree lined street. Its an older neighbourhood so there are plenty of beautiful large trees. It’s been especially great during autumn when there was a beautiful carpet of leaves to run/dance through.

Street Trees Victoria Park, Western Australia. Taken by Chris @lolroy

So trees in urban areas don’t just look pretty, they support community health, happiness and well-being, provide habitat and reduce heat, amongst other things.

I just read a great blog post by Kaid Benfield of the US Natural Resources Defence Council entitled “What trees mean to communities: more than you may think.” Particularly interesting was the crowd sourced inventory of street trees in San Diego.

He lists a few community benefits of trees;

• “The net cooling effect of single, young healthy tree is equivalent to 10 room-sized air conditioners, running for 20 hours a day. 10 air conditioners, a single tree!!
• A tree planted today on the west side of your house will result in a 3% energy savings in the five years time, 12% savings in fifteen years.
• A single stand of trees reduces particulate pollution 9-13%, with the amount of dust reaching the ground beneath those trees 27-42%, versus in an open area.
• If you have trees on your property near your home it accounts for 10-23% of your home value.
• In urban areas, assuming the cost of planting and maintaining a tree for three years at $250-600, it will return $90,000 in direct benefits over its lifetime (apart from beautification, etc.).” Summary by Treehugger.

One of the most awful things I see day to day as a planner are the words “clear, fill and drain” meaning get everything off the land, fill it up with sand, add those lovely limestone retaining walls to even out all the blocks and give that Mediterranean feel, and connect it all up to the storm water drainage system to get rid of all the water. From that an ecosystem will never recover.

Trees are a bit difficult to protect in the current planning system. If its not native its not protected, if its not considered a “significant” tree, its not protected (in normal areas, not near the river, bush forever etc. which have much better protection). The problem is we don’t have a universally recognised definition of what is considered to be “significant”. Each local government and agency have different ideas and what matters to the community might not be captured by either of them.

For example, if you lived next to a gorgeous Ghost Gum (Corymbia aparreinja, native to central Australia) which provided a lovely view and shade for your backyard but was in your neighbours property there is nothing you could do to prevent it from being removed if the owner decided to.

I believe that there are many trees which are not native that are worthy of protection, many of my fellow enviros would disagree because these “weeds” do not further our mission to support endemic biodiversity. The huge Norfolk Pine trees at Cottesloe, for example. Not native but they are significant not just in terms of shade and habitat but for place.

Some Local Governments have considered a “Significant Tree Register” but because of the amount of work involved in setting it up and the legal ramifications they have  been mostly put aside in the “too hard” pile. You hit problems listing anything on a private property as “significant” because you enter the realm of property rights. So any trees on private property would need to be volunteered by the property owner in order to be on the protected list.

Perhaps a crowd sourced database of those “significant” trees, important to the community, is a way forward. How, I wonder, would that work given that many people have a bit of a fear of having trees above their houses. It would be interesting to see which trees had the most communal love. I would wager that local governments would get a good understanding of how important street trees and shady parks are.