Research
Urban forest cover can be an index of the function of vegetation in densely populated human areas. The effects of environmental factors such as air pollution mitigation and carbon dioxide sequestration can be better understood by analyzing the relationship between the natural landscape and the human landscape (Nowak et al., pg. 49). Quantification of urban forestry is therefore a useful tool for urban planning, offering an opportunity to improve quality and function of a urban landscaping and building within a city. With a better depiction of the role of landscaping in our environment, we can continue to reduce environmental impact from within cities, while continuously improving the quality of life for those whom the city is a place of residency.
To properly analyze the data gathered for this project, it is necessary to first analyze what sort of results one would expect from the environment given preexisting conditions. There are two main influencing factors that determine the pattern of distribution of vegetation in an urban environment. The first is the surrounding natural environment, and the second is the land use of the region (Nowak et al., pg. 54). In the case of Los Angeles, the biome most dominant in the area is chaparral, and therefore characterized by shrubs that are drought and fire resistant (Keeley et al., pg 1609). The land use of the area is primarily commercial and residential, leaving very little open space and natural vegetation.
Therefore, due to the limitations of land use and the surrounding natural environment, the pattern and distribution of vegetation in the Los Angeles area is negatively affected. The UCLA campus is no exception, baring scars of years of construction and rebuilding. Since the establishment of the school, development in and around the campus has not ceased, and this is more than evident when reviewing the historical images. Although some deterioration of the quantity and quality of landscaping is to be expected in such an urban setting that is expected to house over 40,000 individuals, it is still our responsibility to retain greenery on campus for environmental, economic, and aesthetic purposes. That is why the natural preserves on campus, both Sage Hill and the Mildred E. Mathias Botanical Gardens, are of particular importance.
Sage Hill is a four acre parcel located on the northwestern corner of campus and provides a sanctuary for 50 native plant species, 7 native mammals, several amphibians and reptiles, 17 butterfly species, and 30 resident or migratory birds (Mattoni). This site is utilized for educational and research purposes, offering the unique opportunity for students to study natural vegetation without leaving the UCLA campus. The Midlred E. Mathias Botanical Gardens located on the southwestern corner of the campus are named for the original director of the Botanical Gardens. Mathias’ original collection focused on Eucalyptus and Ficus species, as well as more tropical plants. Slowly the garden was diversified as future directors introduced flowering species as well as coastal shrubs more typical of the natural chaparral environment (History of the UCLA Midred E. Mathias Botanical Gardens). Although not all species are native, the garden still serves an important role as an educational environment for students.
Results
As stated above, the final results of the analysis of greenness of UCLA from the 1920s to the 2000s should be understood in light of change of the surrounding environment and particular land use. When examined in this context, it is apparent that UCLA has followed a pattern of decreasing greenness throughout the decades. While unable to quantify or display in the satellite analysis software, the biggest growth in urbanization, and therefore the largest decrease in greenness seems to occur between the 1940s and the 1960s. However, attempts to increase greenness of UCLA are not unavailing. Small increases in greenness are visible in the satellite images from year to year in certain areas, most notably the botanical gardens, IM sports fields, and sculpture gardens. Yet a decrease in greenness is still a general pattern as UCLA has progressively deceased in many areas, especially in south campus from 1975 to 2005.
Limitations
Collecting the imagery and analyzing the greenness of the UCLA campus since the 1920s to the present is no easy task and is constrained by a few limitations. One major limitation is that there are no satellite images from before the 1970s, there are only a very limited supply of aerial photographs to be used. This makes it difficult to analyze and compare images of UCLA before the 1970s. It can be very challenging to analyze greenness from black and white photographs that are taken at different angles and obliquity. Even the more recent satellite imagery is limited. We can only use what is available to the general public and that which is free thus making it hard to achieve an exact decadal time series. Additionally, such available imagery is often displayed in a high resolution, making it difficult to analyze small areas, like UCLA, because the pixel size is so large comparatively. High-resolution images are available, but come at a high cost and scun technology has not been in place for very long, thus it is not useful for looking for analyses spanning a long period of time. Since we are limited by what imagery is available to us, it also was not always possible to find satellite images from the same month. This becomes an issue when comparing the greenness of the UCLA campus over time because the amount of greenness can vary depending on the month the image was taken. The vegetation is naturally going to fluctuate throughout the different seasons so the ideal situation would be to have all the satellite imagery from the same month for the most accurate results.
Future Research
A complete time series history of UCLA that analyzes how vegetation has changed on campus since the establishment of the university until the present day has never been done before. Our project has created a great starting point for future research to expand and build upon. If more research is to be accomplished on this topic, it would be beneficial to purchase high resolution satellite imagery that would provide much more accurate results. It would also be advantageous to acquire all images from the same satellite and from the same month to make comparison between decades more precise. Future research may also want to obtain multiple images from each decade, perhaps from each year, to get a further detailed look at how greenness has been changing at UCLA.
