Tim de Chant is a journalist who has also studied the effects of urbanisation on California’s oak woodlands. So he knows a bit about trees.
Tim recently made a visual connection on Google Earth and wrote about this on his blog site (Per Square Mile). Tim wondered if it was possible to use Google Earth to check the thesis that there is a “tight relationship between per capita income and forest cover”. Showing examples from cities in the USA, Brazil and China he discovered that it is possible.
I then wondered: can I see something similar in the city in which until recently I had spent 30 years of my life – Christchurch, New Zealand? Here is the evidence. The first snapshot is of the suburb of Aranui, one of the poorest in Christchurch. The second snapshot is of Fendalton, a suburb on quite the opposite end of the wealth spectrum in Christchurch. I’d say glaring, but make your own mind up.
|Aranui, Christchurch. Source: Google Earth|
|Fendalton, Christchurch. Source: Google Earth|
Is this as far as it goes though? Nothing more than a recognition that richer suburbs have more trees, poorer suburbs less trees. Well, no, there is more. The contribution of trees to the oxygen-carbon dioxide cycle is well known and hence the contribution of trees to the well-being of humans. Most of us also know of the usefulness of trees in the conservation of energy, in reducing the impact of storm-water and providing shade. But what may be less well known are the contributions that trees make to other areas including better births and lessening crime.
A study published in 2010 (Geoffrey Donovan et al) found that “greater tree-canopy cover within 50m of a house… (was) associated with (reduced risk of poor birth outcomes)”. The Portland, Oregon study did acknowledge that the results had some limitations and that further research was needed.
Another Portland study found “that trees in the public right of way are associated with lower crime rates”. Not just any tree though. It was larger trees that had this effect, not smaller view-obstructing trees that can be associated with crime.
Although both studies suggest that the effects of trees are slight, the presence of trees are useful in a multitude of ways and each slight gain adds up to a significant benefit. And now too, there seems to be a way of seeing social inequality from the air.