Silviculture in the City: Urban and Climate Adapted Management Strategies for Forested Natural Areas in the Northeastern U.S.

[photo:] A picture containing a diagram of urban forest types, with additional examples of what an urban forested natural area looks like.Urban forested natural areas, or forest patches, are distinct from street and park trees in how they need to be managed; NRS scientists are developing a formal silvicultural framework for their management, taking into account multiple interacting stressors. Restoring these habitats represents a transformative sweet spot of opportunity to simultaneously address social justice, climate change, and the economy.

Research Issue

The northeastern U.S., stretching from Boston, Mass. to Washington, D.C., is more densely populated than any other region of the United States. Within this region, there are more than 250,000 forests that are larger than 2 acres in size, growing in a matrix of human development, creating what has been described as an overstory of trees with an understory of people.  Many of these small forests are in urban areas, where they may be called forest patches or urban forested natural areas.  These habitats are distinct from street and residential trees both in how they need to be managed and how they are perceived by the surrounding community.

Our station’s science demonstrates that ecologically functional urban forest patches provide outsize benefits by mitigating extreme heat and precipitation and reducing the public health impacts and economic costs associated with extreme events.  These spaces provide biodiversity benefits to birds and pollinators, as well as a place for the majority of our country’s population to experience primary interactions with nature. A conceptual diagram showing knowledge transfer between rural and urban silviculture. Such interactions can lead to reductions in stress, depression, aggression, obesity, and feelings of grief and loss, and improve immune function, eyesight, mental health, and social connectedness. In short, urban woodlands can help improve quality of life for all communities and are particularly important to redressing environmental injustices in our most vulnerable communities.

We are also learning that these urban forest patches are governed by the same patterns and processes as their rural cousins. Regardless of size, forests must remain healthy to fully realize their potential to provide a wide variety of socio-ecological benefits. Our research indicates that these urban forested areas or patches are distinct from street and park trees both in how they need to be managed and how they are perceived by the surrounding community. 

Our Research

[photo:] : A degraded urban forest patch with lots of vines.The number of threats to forest patches is extensive. Many forest patches are threatened by multiple and interacting stressors. They are typically in poor ecological health, threatened by climate change, impacted by pests and disease or overrun with biotic invasives, leading to little understory recruitment -  which means even the presence of trees may not be a given in several decades. Without management, the ecological function and health of these forests will decline, leaving cities ever more vulnerable to compounding climate and ecological stressors. 

The goal of this project is to develop and test adaptive silviculture strategies and tactics that use urban and climate-adapted species to accelerate the restoration of canopy gaps and promote resilience against future biological invasion and climate change driven canopy loss. The management strategies and experimental design that are being used were co-created by urban forest managers and scientists during the Northeast Urban Silviculture Workshop, which took place virtually during December 2020- January 2021. As a result of the workshop, scientists and practitioners across seven cities are working to implement an applied/adaptive-management experiment in upland oak forests located across a latitudinal gradient in the northeastern U.S. Cities involved include: Baltimore, MD, Philadelphia, PA, Somerset, NJ, Westchester County, NY, New York City, NY, New Haven, CT, Hartford, CT, and Springfield, MA.  [diagram:] A map showing urban silviculture network cities and urban heat island severity.

It is notable that the 100-year projected future climate for the northernmost site, Springfield, corresponds with present day temperatures in the southernmost site, Baltimore. Furthermore, the Tree Atlas species projections suggest that future conditions across the region will favor oak and hickory species. These effects may be exacerbated in cities where temperatures are often higher than nearby or adjacent rural sites.  The presence and health of forest patches, which provide a regional cooling effect, is especially important proximate to socio-economically vulnerable neighborhoods where people may lack air conditioning, struggle with the cost of utilities, and have underlying health issues that are exacerbated by extreme heat.

To provide a replicable framework that will be applied in all seven cities, we had managers identify mature, closed-canopy upland oak forests in each city that can accommodate long-term study plots. Broadly characterized as healthy urban forest stands, or “good woods” these stands are especially valuable because of the ecosystem services they provide and access to high quality greenspace by residents. The sites are all dominated by native trees in the canopy and midstory and have minimal invasive species in the understory. These sites typically have limited natural regeneration of native tree species resulting in a dissimilarity between the mature canopy and seedling community compositions. As a result, today’s “good woods” are vulnerable to future disturbance, such as windthrow and pests, and may become tomorrow’s invaded forest gaps. The primary threats, associated impacts, and sociological factors influencing management strategies in forests across the study region include:

  • limited natural regeneration and/or advance regeneration, especially of current canopy dominant species
  • high deer abundance and browse
  • frequent gap creation due to canopy tree loss caused by natural senescence, pests, and storm events
  • current or future risk from pests, pathogens, and plant invasions
  • public perception of tree removal and/or management activities

The project is currently leveraging in-kind resources and planned restoration work in these communities. Additional funding is being sought to support scaling and monitoring over time. Notably, oak forest types are found in all forested regions of the United States and the techniques developed from this project may be broadly applicable to other communities across the country.

Expected Outcomes

This project will advance methods and share social and ecological knowledge across boundaries to apply effective urban- and climate-adapted silvicultural techniques to maintain and restore healthy forest patches.  This knowledge will provide municipalities with a critical life-line in helping to maintain and improve their natural infrastructure, while yielding insights for the National Forest System as to how to deal with similar stressors ahead.  These forest patches can also be key points of connection to urban communities, to not only engage youth and adults alike in formative outdoor learning and experience, but to engage with and demonstrate to the public the importance of climate-adapted silvicultural techniques.

Research Results & Related Resources

Piana, M. R., Hallett, R. A.; Aronson,M. F. J.; Conway, E.; Handel, S. N. 2021. Natural regeneration in urban forests is limited by early-establishment dynamics: implications for management. Ecological Applications 31(2):e02255 doi/10.1002/eap.2255

Sonti, Nancy Falxa; Griffin, Kevin L.; Hallett, Richard A.; Sullivan, Joe H. 2021. Photosynthesis, fluorescence, and biomass responses of white oak seedlings to urban soil and air temperature effects. Physiologia Plantarum. 15 p.

Zukswert, J. M.; Hallett, R.; Bailey, S. W.; Sonti, N. F. 2021. Urban Forestry & Urban Greening Using regional forest nutrition data to inform urban tree management in the northeastern United States. Urban Forestry & Urban Greening, 57(November 2020).

Sonti, N. F.; Hallett, R. A.; Griffin, K. L.; Sullivan, J. H. 2020. White oak and red maple foliar chemistry of urban and reference forests of the eastern US ver 1. Environmental Data Initiative.

Smith, Jason; Hallett, Richard; Groffman, Peter M. 2020. The state factor model and urban forest restoration. Journal of Urban Ecology. 6(1): 254-.

Sonti, N.F.; Hallett, R.A.; Griffin, K.L; Sullivan, J.H. 2020. White oak and red maple tree cores from urban forest patches and reference sites. Dendroecological Network.

Pregitzer, C. C.; Ashton, M. S.; Charlop-Powers, S.; D’Amato, A. W.; Frey, B. R..; Gunther, B.; Hallett, R. A.; Pregitzer, K.;S.; Woodall, C. W.; Bradford, M. A. 2019. Defining and Assessing Urban Forests to Inform Management and Policy. Environmental Research Letters, 14(8), 1–9.

Hallett, R.; Piana, M.; Pregitzer, C. 2019. Silviculture in the city : Can traditional silvicultural practices inform urban forest management? IUFRO World Congress, 72.

Sonti, Nancy F.; Hallett, Richard A.; Griffin, Kevin L.; Sullivan, Joe H. 2019. White oak and red maple tree ring analysis reveals enhanced productivity in urban forest patches. Forest Ecology and Management. 453: 117626. 11 p.

Pregitzer, Clara C.; Charlop-Powers, Sarah; Bibbo, Silvia; Forgione, Helen M.; Gunther, Bram; Hallett, Richard A.; Bradford, Mark A. 2019. A city-scale assessment reveals that native forest types and overstory species dominate New York City forests. Ecological Applications. 29(1): e01819. 12 p.

Johnson, Michelle L.; Novem Auyeung, D.S.; Sonti, Nancy F.; Pregitzer, Clara C.; McMillen, Heather L.; Hallett, Richard; Campbell, Lindsay K.; Forgione, Helen M.; Kim, Mina; Charlop-Powers, Sarah; Svendsen, Erika S. 2019. Social-ecological research in urban natural areas: an emergent process for integration. Urban Ecosystems. 22: 77-90. doi:10.1007/s11252-018-0763-9.

Doroski, Danica A.; Felson, Alexander J.; Bradford, Mark A.; Ashton, Mark P.; Oldfield, Emily E.; Hallett, Richard A.; Kuebbing, Sara E. 2018. Factors driving natural regeneration beneath a planted urban forest. Urban Forestry & Urban Greening. 29: 238-247.

Pregitzer, Clara C.; Sonti, Nancy F.; Hallett, Richard A. 2016. Variability in urban soils influences the health and growth of native tree seedlings. Ecological Restoration. 34(2): 106-116.

Piana, M. R.; Aronson, M. F.; Pickett, S. T.; Handel, S. N. 2019. Plants in the city: understanding recruitment dynamics in urban landscapes. Frontiers in Ecology and the Environment, 455–463.

Ward, E. B.; Pregitzer, C. C.; Kuebbing, S. E.; Bradford, M. A. 2019. Invasive lianas are drivers of and passengers to altered soil nutrient availability in urban forests. Biological Invasions, 2.

Swanston, Christopher W.; Janowiak, Maria K.; Brandt, Leslie A.; Butler, Patricia R.; Handler, Stephen D.; Shannon, P. Danielle; Derby Lewis, Abigail; Hall, Kimberly; Fahey, Robert T.; Scott, Lydia; Kerber, Angela; Miesbauer, Jason W.; Darling, Lindsay; Parker, Linda; St. Pierre, Matt. 2016. Forest Adaptation Resources: climate change tools and approaches for land managers, 2nd ed. Gen. Tech. Rep. NRS-GTR-87-2. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 161 p.

Research Participants

Principal Investigators

  • Richard Hallett, Northern Research Station, USDA Forest Service, Research Ecologist
  • Max Piana, Northern Research Station, USDA Forest Service, Post-doctoral Research Ecologist
  • Nancy Sonti, Northern Research Station, USDA Forest Service, Research Ecologist
  • Leslie Brandt, Northern Research Station and Eastern Region, USDA Forest Service, Climate Change Specialist

Research Partners

  • Last modified: February 3, 2022