This summer, students in Columbia University’s Master of Public Administration in Environmental Science and PolicyMPA-ESP) program participated in an sponsored urban ecology field trip. Matthew PalmerSenior Lecturer in the Department of Ecology, Evolution, and Environmental Biology at Columbia University. The group visited three major locations in New York City: Randall’s Island, River Park, and Bronx Park East. Each served as a living laboratory, allowing students to explore the intersection of natural ecosystems and urban environments. Through hands-on learning and first-hand observation, students gained an understanding of the critical role urban ecology plays in fostering sustainable and resilient communities.
First stop: Randall Island
The trip began at Randalls Island, where the students met with Ann Wilson, director of planning for the Randalls Island Park Alliance (RIPA). Wilson explained how RIPA, a nonprofit public-private partnership founded in 1998, manages the park by securing both private and public funding. This approach allows RIPA to efficiently enhance the park and support facilities such as waterfront trails, courts and fields that attract nearly 4 million visitors each year.
Next, RIPA biologist Olivia Smith described Little Hell Gate Salt Marsh, one of the first restored salt marshes in New York County. Named after a treacherous body of water that once caused a shipwreck, the wetland has higher plant and animal growth per square foot than a rainforest and is an important nursery for fish. Tall Spartina grasses filter sediment and “sweat” salts, and mussels contribute to nutrient cycling. However, the wetland’s limited roaming space and small size leave it vulnerable to frequent hurricanes, highlighting the need for further restoration efforts. On the island, restoration focuses primarily on plant management as animals naturally move into these new habitats.
Mr. Palmer gave students an overview of Randall Island’s hydrological challenges and restoration efforts. Originally two small islands surrounded by salt marshes, Randall Island has undergone major changes due to urbanization, leading to changes in river flow and problems with shallow groundwater runoff. To address these, nature-based solutions such as wetland construction are being introduced to help manage stormwater and improve water quality. Currently, most of the island’s rainwater is collected in pipes designed to filter trash and slow the buildup of sediment, and the island’s topography and soil microbes play a key role in rainwater treatment. Heavy metals are not broken down but are fixed in the soil and absorbed by plants, while hydrocarbons are broken down by microorganisms.
Second stop: River Park
At River Park in the Bronx, participants learned about wetland restoration efforts led by the New York City Parks Natural Resources Group team. The Bronx River is influenced by the tides near its southern tip, supporting a dynamic ecosystem such as oysters that filter water and create habitat for marine life. However, poor water quality and excessive sedimentation impede oyster reef growth. The Billion Oyster Project addresses this problem by collecting oyster shells from restaurants and depositing them in rivers, providing a hard substrate for coral reef formation.
Students also investigated the role of anadromous fish, such as river herring, which migrate upstream to reproduce. First built in the 1600s, dams stopped herring migration for centuries. However, construction of fish ladders and the introduction of herring from other locations into the upper Bronx River have restored their breeding patterns. Herring imprints the chemical composition of the river early in its life, allowing it to recognize it and return to the same location to spawn as an adult.
The discussion then turned to green infrastructure in the Bronx. Students learned how roofs and impermeable surfaces contribute to the rapid flow of water into sewers, causing contamination and potential fines in New York City. The city is currently investing in green infrastructure solutions such as green roofs, bioswales, and rain gardens to absorb rainwater, reduce sewage overflows, and promote groundwater recharge.
Ending point: Bronx Park East
The final stop was Bronx Park East, where urban ecology teaching assistant Ayanna Butler discussed the relationship between streams and forest health. She explained that hurricanes can cause large amounts of nitrate to be lost from forests, impacting the nitrogen cycle, a process important for both plant and animal life. Butler detailed the processes of mineralization, nitrification, and nitrogen fixation, highlighting in particular the role of black locust trees in converting atmospheric nitrogen into a form that plants can use.
At Bronx Park East, students also learned about the challenges of invasive species management, focusing on knotweed. Originally introduced as an ornamental plant, knotweed has become one of the most aggressive invasive species in urban environments. Its rapid growth creates dense thickets that compete with native vegetation, reducing biodiversity and threatening local wildlife. Additionally, these dense brush can create secluded areas that can impede visibility and attract unwanted activity, making them a concern for law enforcement as well. Japanese knotweed is particularly difficult to control because it grows in disturbed soils common in urban areas. Their shallow root systems also make them less effective at stabilizing soil, which can worsen erosion in floodplain areas. However, natural shade from tall trees and plants has proven to be an effective way to control its growth. By reducing the amount of sunlight reaching the ground, we can limit the spread of native woody knotweed, providing a more sustainable approach to managing this persistent invader.
Together, these three stops provide Columbia University’s MPA-ESP students with valuable hands-on experience that demonstrates the complex balance required to maintain and restore the natural environment within a dynamic urban environment. I was able to get it. From salt marsh restoration efforts on Randall Island to the role of oysters and green infrastructure along the Bronx River to the critical link between forest health and urban rivers in Bronx Park East, students bring classroom knowledge to life. I was able to connect directly to the world. Environmental challenges.
