Know Before You Go: Information and helpful hints for your next visit
The Morton Arboretum Get tickets
Science

Chicago Region Tree Census

Assessing the state of trees across the seven-county Chicago region

Content Detail

In 2010, The Morton Arboretum, in collaboration with the USDA Forest Service, undertook the first tree census of the regional forest to understand its value and develop a plan to manage and curtail rising threats. It was the largest effort of its kind in the country, producing valuable scientific data about the benefits provided and making clear the challenges to maintaining a healthy tree population.

In 2020, The Morton Arboretum partnered with Davey Resource Group Inc. and the Student Conservation Association to conduct its second tree census, remeasuring 1,576 plots in the city of Chicago and the seven surrounding counties of Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will to gain a comparative snapshot of the regional forest and the benefits it provides.

The 2020 tree census serves as a strategic guide for local and regional stakeholders to understand current trends and make informed decisions about how to protect and improve the forest to benefit residents and communities.

In 2022, Arboretum researchers compiled and analyzed data from each of the seven counties in the Chicago region: Cook (not including the city of Chicago), DuPage, Kane, Kendall, Lake, McHenry, and Will.

Key Findings

  • The trees of the Chicago region provide critical benefits to the environment, ecosystems, human health, and quality of life for 9 million residents in 284 municipalities. The trees that make up the regional forest face many current and impending threats including invasive pests, opportunistic species, climate change, and urban development.
  • There are 172 million trees in the region, an increase from 157 million in 2010. Canopy cover increased overall from 21% to 23%, but decreased in the city of Chicago and McHenry county.
  • The region’s trees provide more than $416 million in crucial ecosystem benefits annually to residents of the seven-county Chicago region, such as pollution removal, carbon storage and sequestration, and energy savings.
  • Invasive European buckthorn (Rhamnus cathartica) is the most common species in the region, accounting for 36% of total trees. Although its population ranges from 4% to 55% in different counties, buckthorn is a serious issue for the region. An estimated 42% of tree species in the region are considered invasive, preventing other species from growing to full maturity to provide the benefits of a larger canopy.
  • The estimated number of standing ash trees decreased 46% from 12.7 million to 6.8 million over the past decade, with an additional 4 million dead or dying. This loss is largely due to the removal of trees killed by the emerald ash borer insect.

What You Can Do

Everyone in the Chicago region can have an impact on the health of the regional forest, even if they don’t have their own trees.

Homeowners and property owners can help by planting the right tree, in the right place, with the right care, ensuring that trees mature to provide the greatest possible benefits. Anyone who doesn’t have the ability to plant a tree might consider helping water trees in city parkways or supporting a local organization, such as The Morton Arboretum, focused on scientifically informed tree planting.

Together, we can build a strong, expansive tree canopy that will provide many benefits to people and communities for years to come.

Resources

2020 Chicago Region Tree Census Report: County Data and Change Analysis: An accompanying report analyzing data by county

Searchable tree and plant profiles: An online tool for selecting the right trees for your location.

The Morton Arboretum Plant Clinic: For information and advice for tree and plant selection and care.

Chicago Region Trees Initiative: A partnership for coordinated action to improve the health, diversity, and equitable distribution of trees in the region.

Healthy Hedges: For help removing and replacing invasive buckthorn with non-invasive trees or shrubs.