The photo above may look familiar. In a previous post, data was collected across four paths every 100 feet in a previous blog post. Now, this area is being used to examine tree canopy cover and its monetary benefits and ecological services. As the site exists, trees make up about 35% of the area (taken from a random survey of 100 points).
This an impressive statistic for an urban area. These trees are doing more than just shading the path and adding interest to the landscape. They are also providing important ecological services such as habitat for animals, slowing and soaking up stormwater runoff, and reducing carbon dioxide in the atmosphere. These benefits can be translated into real money. The chart below shows just how much the trees in this area are saving the community as a whole.
The other prominent land covers are roofs, grass, asphalt, concrete, and mulch (in descending order). Roofs take up almost as much as trees at 27%. Roofs often reflect light back into the atmosphere adding to the urban heat island effect. They also allow stormwater to flow quickly over them and create erosion from the speed. Green roofs can solve these problems and even add social and economic benefits to this area. If all the randomly surveyed spots of roof were converted to green roofs, the cover percentages for this area would look like the chart below.
The switch to all green roofs would result in 27% increase in trees and to follow suit, every monetary benefit value has almost doubled. Green roofs also utilize a space often forgotten about. This switch would add a whole new layer to this area. If the green roofs are accessible, they can also be used for social events. This improves the character of a place and often times, its economic success. Green roofs are an attraction. They would also decrease stormwater runoff and the urban heat island effect while reducing heating and cooling costs of the buildings.
While this is a wonderful possibility, it is not entirely feasible. There are few immediate benefits to green roofs and while the ecological services offer plenty reason (both environmentally and monetarily) to make the change, those benefits are not directed to the building owner. The costs of installation and maintenance for a green roof probably means they won’t reach their potential until there is some sort of economic subsidy involved for businesses who decided to implement them.
If there was enough government or private support to implement green roofs all throughout this small area, the end result would definitely be worth it.
However, roofs aren’t the only convertible spaces in the highlighted area. Changes could also be made to parking and road widths to decrease asphalt and increase trees.
Since adding more trees to one small section of Athens has such an effect, it begs the question: what would this experiment look like on a larger scale? In choosing where to plant trees in a city, there are many factors to consider. Where is there space for the trees? Who needs them? How many people can they benefit?
And most importantly, where will these trees offer the most benefit? I-trees Landscape feature, allows the exploration of these priorities and their benefits.
For this area, the locations for tree plantings were chosen using the following criteria:
Below poverty line – 35%
Population Density – 25%
Tree cover per capita – 20%
Tree stocking level – 20%
Urban tree canopy is often a direct indicator of median household income. This makes sense when you consider that trees cost money in their planting and maintenance. However, urban tree canopy can also predict minority populations, educational attainment, and even crime. This begs the question: is tree placement in cities being chosen justly? All people enjoy the benefits trees provide. Why does it seem only the elite are privileged with ample tree canopy?
Using the chart above, it is possible to prioritize certain characteristics of a neighborhood and find out where trees could be most beneficial. The priorities chosen for this site were: percentage below poverty line, population density, existing tree cover per capita, and tree stocking level. These were chosen focusing on the human element of the landscape. The percentage of people below the poverty line was given the most weight due to its influence on other factors such as education and crime. Population density was chosen next because the denser the population, the more people the trees can affect.
Looking at the larger scale, the area east of the Oconee River is the spot best suited for these priorities. This area is mostly residential and not as suited for a shift to green roofs as downtown or another residential or campus area might be. However, there is still plenty of opportunity for an increase in tree canopy. For instance, infill lots could become public parks. The road lanes could be narrowed and a treelined sidewalk introduced. There are many ways to increase tree canopy and many benefits, but the most important thing needed is will power.