Penn Park: A Study of Ecological Health in an Urban Environment

Penn Park (PP) was built in 2011 serving a vital need for the University of Pennsylvania’s athletic programs, faculty, staff, and students. This space has had many different land uses over time from agriculture to railyard use and, more recently, as a parking lot. PP covers 24 acres that include two multipurpose fields, 12 outdoor tennis courts, a softball stadium, six acres of native grass meadow, and over 550 trees. This project created corridors that were previously unavailable for people who live and work in the area. Upon completion of the structural engineering, storm water controls and athletic field designs, an ecological community was created to surround and soften the architectural elements. Assessment of the current ecological conditions of PP revealed overall successful growth of the tree canopy and efficient performance of the hydrologic system. However, invasive plants have taken hold in the native grass meadows and turf grass areas requiring more focused management and a re-evaluation of current management guidelines. Carbon sequestration rates for turf grass and native meadow areas are estimated at over 2 million g of C/m2/year and for trees at over 180 million kg of carbon dioxide. Over 20’ of compacted fill deposited over 200 years of assorted land use inhibited ground water recharge and required designers to capture storm water runoff through a variety of drainage systems while controlling water flow to meet required discharge rates. The irrigation system primarily uses captured rainwater from an underground cistern that can hold over 200,000 gallons of water. This system is estimated to provide between 50-70% of PP irrigation needs. Soil tests showed that PP soils consist of greater than 90% sand and have low nutrient status and cation exchange capacity which could contribute to the abundance and diversity of invasive weeds. This condition has led to management strategies that reduce turf lawn areas and increase native meadow plantings which are more drought tolerant, require less nutrients, and may compete with invasive weeds