Students in the M.P.A. in Environmental Science and Policy (MPA-ESP) program recently embarked on a field trip through the Bronx to explore urban rivers, wetlands and forests. Led by senior lecturer Matthew Palmer, this immersive experience gave me and my cohort an opportunity to understand the role these ecosystems play in cities, the unique challenges they face due to urbanization, and the vital services they provide to residents.

The Bronx River: A vital urban waterway

The Bronx River was once heavily altered by industrial activity and has been the subject of significant restoration efforts to improve its ecological health and connectivity. One major project is the construction of a fish passage at the East 182nd Street Dam, which aims to improve aquatic species migration and enhance the ecological functioning of the river. By facilitating the movement of fish that had previously been blocked by the dam, this project would promote a healthier aquatic ecosystem.

The river’s restoration efforts also include addressing water quality issues, primarily due to stormwater runoff, sewage overflows and invasive species that affect native fish and plant life. This restoration is vital for maintaining biodiversity and supporting the river’s ecosystem services, such as water filtration and flood control. These efforts also play an essential role in improving the river’s ability to manage stormwater, mitigate flooding and create a more resilient environment for local communities. However, as urbanization continues, there are challenges to maintaining water quality and ensuring long-term sustainability, requiring both scientific innovation and community engagement.

Green infrastructure and flood mitigation: A solution for urban stormwater

During the field trip, we explored the concept of green infrastructure, particularly in the form of “rain gardens” designed to mitigate urban flooding. These green spaces, consisting of permeable soils and native plants, are strategically placed in urban areas to capture and filter stormwater before it enters the sewer system. As climate change accelerates, resulting in more frequent and intense rainfall events, rain gardens are seen as a key solution to reducing the burden on aging urban infrastructure, which is often ill-equipped to handle extreme weather events.

While rain gardens are an important part of the flood mitigation strategy in vulnerable neighborhoods, they do not directly address the challenges facing the Bronx River. Still, the idea of green infrastructure represents a broader commitment to using nature-based solutions to solve urban problems. In the Bronx, communities have embraced these solutions as part of a larger environmental justice effort—creating green spaces in neighborhoods that are disproportionately impacted by flooding, pollution and a lack of access to nature.

Urban forests: Overcoming challenges for long-term resilience

At Pelham Bay Park, we learned about the benefits of urban forests, from reducing the urban heat-island effect to improving air quality and supporting biodiversity. However, these forests face significant pressures, including pollution, invasive species and soil degradation, all of which hinder their ability to deliver the full range of ecosystem services.

One of the most pressing issues in urban forests is the impact of invasive species, particularly the emerald ash borer, which threatens the ash trees that have the highest concentration in the world in New York State (around 1 billion). These pests have led to widespread damage, and efforts are underway to protect the ash trees from further devastation. For example, researchers have identified that the color purple attracts the emerald ash borer the most, so purple traps are being used to monitor the presence of these pests. Although these traps are helpful for tracking, the financial burden of managing infected trees is significant. Infected ash trees are often removed due to safety concerns, as falling branches pose risks to the public, especially when trees are close to buildings and roads.

There is a critical gap in the circular economy for dealing with the wood waste from these trees. While ash trees are used to make baseball bats, there is no comprehensive project to recycle or repurpose the wood from infected trees. As the city works on developing a breeding program for ash trees that survive the infection, the need for sustainable solutions and more efficient ways to use the wood remains pressing.

Another important challenge in urban forests is the alteration of the nitrogen cycle. Urban environments, with their high concentration of pollutants, significantly alter nitrogen levels, which can negatively impact soil health and tree growth. Nitrogen pollution, mainly from vehicle emissions and industrial activity, can disrupt the natural nitrogen cycle, leading to soil acidification and nutrient imbalances in urban forests. These changes further stress tree species that are already struggling with urban conditions, making forest restoration even more difficult. Understanding and mitigating these disruptions is crucial to maintaining healthy urban forests.

Disease transmission: The role of wildlife in urban health

As part of the field trip, we also learned about the role of habitat connectivity and how wildlife movement in urban areas can influence the spread of diseases. For instance, ticks, which are known to transmit diseases such as Lyme disease, can thrive in urban forests and wetlands, impacting human health. Scientists are using habitat connectivity modeling to predict how wildlife, including ticks, is distributed across urban landscapes. Using camera traps, researchers can better understand how ticks and other disease vectors spread across urban areas.

For monitoring tick populations, 1×1 meter whiteboard traps are used to capture ticks and gather data on their distribution. This research allows scientists to predict how certain wildlife species might influence the presence of ticks in urban areas. Understanding these dynamics is crucial because as animals move through urban environments, they can introduce and spread pathogens that affect human health. Maintaining healthy urban forests and wetlands is not just about environmental restoration but also public health protection. By improving habitat connectivity, we can reduce the spread of diseases and improve urban resilience.

Wetlands: the unsung heroes of urban ecosystems

Wetlands, often seen as peripheral in urban landscapes, are critical to maintaining water quality, controlling floods and supporting biodiversity. But as Chris Haight, wetland division project manager at NYC Parks, noted, wetlands are under constant threat from urban development, pollution and invasive species. Managing and restoring these ecosystems requires balancing ecological priorities with the demands of urban growth.

In addition to managing pollutants and altered water flow, urban wetlands face the challenge of rising sea levels, a direct consequence of climate change. The fragmented nature of wetland habitats in urban environments also limits biodiversity and reduces their ability to function properly. However, wetlands are also incredibly resilient, and through well-planned restoration efforts, they can continue to provide invaluable ecosystem services.

The restoration of urban wetlands also offers an opportunity for community engagement and environmental justice. As we saw with the work of the NYC Parks team, wetland restoration efforts are increasingly being funded through innovative strategies such as “mitigation banks,” where developers purchase credits to offset their environmental impact. By restoring wetlands and maintaining these critical ecosystems, we can ensure that they continue to support urban biodiversity and offer flood protection, particularly for vulnerable communities.

Citizen participation: The key to real change

The importance of citizen involvement in the restoration and preservation of urban ecosystems cannot be overstated. As urban environments are inherently complex, with competing priorities and limited resources, the role of the community in advocating for green infrastructure, supporting restoration efforts and participating in decision-making is critical. The field trip emphasized that urban ecosystems must be seen as a shared resource, with citizens playing a central role in their stewardship. Whether through supporting green infrastructure projects, advocating for better environmental policies or participating in local restoration initiatives, community engagement is essential for achieving real, lasting change.

The field trip to the Bronx highlighted the significant challenges and opportunities associated with restoring urban rivers, wetlands and forests. These ecosystems are not only essential for environmental health; they provide invaluable services that enhance the well-being of urban communities.

Achieving sustainable urban ecosystems requires collaboration between scientists, policymakers and, crucially, citizens. By engaging in decision-making processes, advocating for green infrastructure and supporting urban ecosystem restoration efforts, citizens can help shape a more resilient, sustainable future for our cities.