When doing research into local biomarkers, I couldn’t help but notice the obvious amount of non-native plants populating the area. For example, my own apartment complex is populated by palm trees, flowering bushes, and thick, green grass that is clearly not native to a desert environment. Since humans are clearly having such a large influence on the biology of the local area, I thought it might be interesting to attempt to use local bio-indicators to determine information about the people (both the actual residents of an area and the results of personal presence, such as irrigation and infrastructure).
While this was just a preliminary review, I have found that the amount and type of “greenery” in certain parts of the city can be a direct bio-indicator of the wealth of that community and/or the history/irrigation system of that area.
Below: median square foot price for Phoenix homes, circa 2008 (http://www.arizonarealestatenotebook.com/phoenix-az-map-of-median-home-price-per-square-foot/)
As we can see (assuming relative home prices have stayed close to what they were in 2008), it appears that homes are most expensive in northeast Phoenix (Scottsdale), cheapest in southwest Phoenix, and mixed in other areas. If my premise that “greater wealth = more greenery” is correct, we will find residential areas of Scottsdale to be the most green, while southwest Phoenix will have notably less plant life.
(Note: because I am trying to get data from around the city, I am using Google images in order to get larger and better amounts of data, as opposed to riding my bike around and photographing random houses, which is more likely to produce skewed and questionable results).
Within Scottsdale there is green diversity:
Paradise Valley, Scottsdale
Paradise Hills, Scottsdale
Notably, the region of Arcadia appears to have lots of houses with grass or green lawns, whereas in Paradise Valley only some of the houses have lawns, but most have a large number of trees or shade. Paradise Hills appears to have even more sparse greenery, though they apparently are willing to put in the effort to keep maintaining a GOLFCOURSE in the middle of the desert.
A brief history of the region reveals the fact that Arcadia was originally developed as orchards, and thus has an effective irrigation system in place. This likely explains why the Arcadia area of Scottsdale is much greener than the similarly priced Paradise Valley and Paradise Hills area of Scottsdale.
In contrast, other areas of the city have much less greenery. This is likely the result of areas that were not initially irrigated, less willingness to invest in the care and upkeep of plants, and smaller lot sizes which lead to less space to plant trees, bushes, etc.
Notably, these neighborhoods in southwest Phoenix likely are not suffering from a lack of available irrigation, as many of the neighborhoods are located right next to farmland, and the communities were likely built on top of what once was irrigated land.
This raises the question, how does one access water to keep a yard green? Phoenix’s Salt River Project (SRP), is in charge of distributing and regulating the use of water in Phoenix, and provides a nifty guide to getting yourself irrigated. For obvious reasons (so that each household isn’t in charge of picking up it’s own water), they suggest working through neighborhood associations when ordering/paying for water. (http://www.srpnet.com/water/irrigation/overview.aspx). Since these decisions are made neighborhood by neighborhood, it explains some presence of greenery like in this snapshot from southwest Phoenix:
Of course, acquiring water won’t help if an irrigation system isn’t already in place, so for many neighborhoods it is unclear if they do not want to purchase water, or were built in areas that had not been properly irrigated previously (presumably because the area had not previously been used for agriculture). For a close to home example, there is a notable decrease in greenery in the neighborhoods west of campus after the first couple of blocks. I have been told this is because of lack of irrigation:
Overall, while the presence of grass and trees does not always point to a specific cause, it does seem that we can find clues towards previous agricultural endeavors and the wealth of the current inhabitants by studying the amount of greenery that has been able to flourish in this desert environment.