Suburban and small metropolitan areas have grown more quickly than their urban and rural counterparts. Approximately 46 million Americans live in rural counties, 98 million in urban core counties, and 175 million in city suburbs and small metropolitan areas. Expansion into suburban areas goes hand in hand with increased development, mainly in housing, and ultimately leads to the loss of ecosystem services. Ecosystem services, by definition, provide the many life-sustaining benefits we receive from nature and are important to the well-being of human health and to the health of the environment, yet they are often taken for granted. Expansion of new housing developments in West Goshen Township (WGT) has resulted in loss of forests and pollinator habitats, two important ecosystem services, of which there are many. Moreover, the value (in U.S. dollars) of ecosystem services that are provided in any community can be quantified. For example, treed neighborhoods can reduce the heat index, and therefore conserve energy, providing a cost benefit to residents. Trees also provide a monetary benefit to municipalities by decreasing the amount of stormwater runoff and pollutants that reach local waters. The presence of trees in streetscapes, communities and neighborhoods have myriad more ecosystem services including reduction in noise and air pollution, shield children from ultraviolet radiation, reduce violence, beautify space, and increase property values, just to name a fraction of services provided.
Parks and their associated trees are important to both public and planetary health, especially for those who might only be able to experience treed environments in public parks. Park design, however, is usually planned from an economic perspective (e.g., mowing up to a streams edge as opposed to maintaining a riparian buffer). Park design should be directed to achieve specific goals, such as heat mitigation and/or to provide green spaces to residents that are beneficial and attractive to different demographics. Much research in the last decade has focused on tree canopy cover and tree ecosystems services in urban communities, with very few studies that focus on suburban or exurban (the bridge between suburban and rural that are quickly becoming suburban) environments. Towards this end, WGT, most of which is classified as suburban, conducted a tree canopy survey, and calculated the monetary value provided by park trees in all 12 WGT parks. Tree canopy cover is the layer of leaves, branches, and stems of trees that cover the ground when viewed from above. Economic valuation provides real time monetary values for ecosystem services.
The US Forest Service has created a web-based Urban Tree Cover (UTC) assessment tool for public use: i-TREE Canopy (http://canopy.itreetools.org). i-TREE Canopy is a photointerpretation method that uses a point sampling protocol that is incorporated into a Google Maps™ interface, allowing users to view different land cover types across a delineated area and to calculate the percentage of predetermined land cover types. We estimated tree canopy cover percentages using random sampling statistics in the i-TREE Canopy application. We chose seven different cover classifications: tree/shrub, grass/herbaceous, impervious buildings, impervious road, impervious other, soil/bare ground, and water.
West Goshen Township includes 12 parks ranging in acreage from 0.5 to 32, and in tree canopy cover from 0.01% to 86.4 %. The US Forest Service suggests 30% to 40% as a minimum tree canopy cover estimate. Six of the 12 parks surveyed have achieved more than 40% tree canopy cover, yet all 12 parks surveyed have significant grass cover (e.g., Fresh Meadows Park is 99.9% grass). You may be wondering why grass, while green, is not desirable. It is, of course, more desirable than concrete, but green lawns have a host of negatives. Grass lawns are expensive and unsustainable, especially if you employ fertilizers and herbicides, etc. Maintaining grass lawns increases greenhouse gases, pollutes ecosystems, wastes water, diminishes biodiversity, and decreases native pollinator populations. While the amount of carbon collectively stored in some of WGT parks maintains the U.S. Forest Service cover of 30% to 40%, a subset of parks surveyed clearly need a substantial investment in tree plantings to ensure the health and well-being of WGT residents and the environment, especially given recent upticks in climate change related heat waves.
We found that WGT park trees sequester 83.5 metric tons of carbon each year, for a total of 2,096.4 metric tons of carbon stored. The average US citizen emits approximately 3.9 metric tons of carbon per year. The population of WGT as of the 2021 census was 22,940, and roughly emits nearly 92,000 metric tons of carbon each year, suggesting that WGT could help to mitigate climate change by enhancing existing parks with trees and encouraging its citizens to plant trees or pollinator habitat in lieu of grass. Lastly, the amount of carbon stored in WGT park trees is equivalent to a value of $399,230.00, indicating that the township would suffer significantly greater economic costs due to a changing climate without its current tree cover, but also could save more by investing in greater tree cover throughout WGT.