How can we maximize urban park benefits?
Large Parks, Minimal Edges
Realizing there is minimal space for parks in an urbanized Seattle, I sought to find out if certain aspects of park design contributed more to native plant biodiversity. I found that large parks with minimal edges held more biodiversity than smaller parks with higher edge ratios. Below is my proposed layout for a new, larger park in Montlake that takes all of this into account:
Image Courtesy of Google Maps
Green indicates proposed link between existing parks. Black lines indicate areas in need of edge protection.
Realizing there is minimal space for parks in an urbanized Seattle, I sought to find out if certain aspects of park design contributed more to native plant biodiversity. I found that large parks with minimal edges held more biodiversity than smaller parks with higher edge ratios. Below is my proposed layout for a new, larger park in Montlake that takes all of this into account:
Image Courtesy of Google Maps
Green indicates proposed link between existing parks. Black lines indicate areas in need of edge protection.
How To Best Preserve Biodiversity
To understand how to best maintain native species biodiversity in parks, I looked at data from five different parks in Seattle. A reasonable judgment of the parks’ biodiversity was made by recording the alpha- and beta-diversity pairwise average [29]. α-diversity is simply the total number of different species present. Ideally, α-diversity values would be high, showing high species richness (a good indication of overall biodiversity). β-diversity pairwise average is essentially the average difference between a given park and the parks it is compared to (the higher the value, the more unique that park’s species combination is). With the five parks investigated, high β-diversity pairwise average would indicate either exceptionally few species (making it very unique from other parks in that it has so little diversity), or far more species (making it very unique in that it is extremely diverse).
Calculated from data collected in accordance with the general field protocol for
Conservation Biology 476 (Tewksbury 2009).
To understand how to best maintain native species biodiversity in parks, I looked at data from five different parks in Seattle. A reasonable judgment of the parks’ biodiversity was made by recording the alpha- and beta-diversity pairwise average [29]. α-diversity is simply the total number of different species present. Ideally, α-diversity values would be high, showing high species richness (a good indication of overall biodiversity). β-diversity pairwise average is essentially the average difference between a given park and the parks it is compared to (the higher the value, the more unique that park’s species combination is). With the five parks investigated, high β-diversity pairwise average would indicate either exceptionally few species (making it very unique from other parks in that it has so little diversity), or far more species (making it very unique in that it is extremely diverse).
Calculated from data collected in accordance with the general field protocol for
Conservation Biology 476 (Tewksbury 2009).
Discovery Park had both the highest α-diversity and β-diversity pairwise average, which is a strong indicator that Discovery Park has the greatest biodiversity. Once these measurements of biodiversity were calculated, I recorded the parks’ sizes in acres. Then I took a ratio of the parks’ overall size in acres to trail length in miles (the higher the ratio, the less trail there was). I also took the ratio of plots with man-made edges within 50 meters to plots with no man-made edges within 50 meters (the higher the ratio, the fewer man-made edges there were). I then looked to see if there was any noticeable correlation between diversity and trail or edge ratio [31-35].
With the above data, I found that β-diversity pairwise average has little to no correlation with all the variables investigated. However, the α-diversity showed much more correlation between higher diversity and more overall area, less trail, and less edge area (note that by throwing out the biggest outlier in the Trail Ratio vs Alpha Diversity, r=0.79). This strongly supports the idea that diversity increases with fewer man-made intrusions (edges or paths) and overall size. This suggests we should strive to construct our parks with minimal edges, moderate levels of paths, and larger size when possible to better preserve biodiversity.
My proposed example of a park in the Seattle area is one that could undergo minimal changes to gain a lot of connected acreage. Over time, my results would indicate the α-diversity would increase. There would be a lot of edges in this proposed park, however, with the increase in connectivity, edge thickness, and overall area, I believe it would ultimately be successful in maintaining or increasing biodiversity.
My proposed example of a park in the Seattle area is one that could undergo minimal changes to gain a lot of connected acreage. Over time, my results would indicate the α-diversity would increase. There would be a lot of edges in this proposed park, however, with the increase in connectivity, edge thickness, and overall area, I believe it would ultimately be successful in maintaining or increasing biodiversity.
Primary Sources
30. Tewksbury, 2009. On file with the Seattle Parks.
Secondary Sources
29. Harrison, Susan, and Jim Quinn. "The Importance of Beta-Diversity." Principles of Conservation Biology. 3rd ed. Sunderland: Sinauer, 2006. 44-45. Print.
31. "Carkeek Park." Seattle Parks & Recreation:. N.p., n.d. Web. 12 Feb. 2014. <https://www.seattle.gov/parks/environment/carkeek.htm>.
32. "Discovery Park." Seattle Parks & Recreation:. N.p., n.d. Web. 12 Feb. 2014. <https://www.seattle.gov/parks/environment/discovery.htm>.
33. "Interlaken Park." Seattle.gov Home Page. N.p., n.d. Web. 12 Feb. 2014. <http://www.seattle.gov/parks/park_detail.asp?ID=3023>.
34. "Ravenna Park." Seattle.gov Home Page. N.p., n.d. Web. 12 Feb. 2014. <https://www.seattle.gov/parks/park_detail.asp?ID=391>.
35. "Seward Park." Seattle.gov. Seattle Parks and Recreation, n.d. Web. 12 Feb. 2014. <https://www.seattle.gov/parks/environment/seward.htm>.