Chicago Plans to Inventory Urban Forest Canopy in 2020

Photo: Morton Arboretum

The Chicago Department of Streets and Sanitation plans to conduct a comprehensive inventory of the city’s urban forest canopy next year.

While the stated objective of the audit is to help create a more effective tree trimming schedule, information gathered should also be of great interest to arborists and tree care professionals, as well as businesses dedicated to urban wood utilization.

In a Sept. 27 letter to Inspector General Joseph Ferguson, John Tully, DOS commissioner, writes, “To continue to improve tree trimming operations, in the upcoming 2020 budget year, the Bureau of Forestry will work to develop a comprehensive tree inventory of the entire City canopy, which currently does not exist. This will provide valuable information regarding the number and location of trees as well as size and species. It will also provide information about electric wire interference within the canopy helping to inform the daily scheduling process for tree trimming and removals as well as the Department’s response to weather-related events.”

In an Oct. 30 press release, Ferguson called the tree canopy inventory a “step in the direction.” He added, however, “But (this) is only a starting point for an urgently needed generational re-assessment of the management of the City’s dwindling urban forest whose canopy is substantially smaller than many cities nationally. We strongly encourage DSS to re-evaluate the Monitor Group report the City invested in a decade ago, and work towards seriously implementing the recommendations for a grid-based approach to tree trimming. The benefits of more horticulturally precise and cost-effective tree trimming are substantial for the City and its potential for cost savings, optimized use of taxpayer-funded resources, and preventable liabilities. A thriving and healthy urban forest is critical to mitigating ever-mounting climate change concerns like the urban heat island effect and excessive storm water runoff, and recent studies have revealed stark differences across City neighborhoods that generally correlate with tree canopy percentages.”The Monitor Group report referenced by Ferguson found that DSS has largely used a reactive 311 caller request-based approach to identify trees for trimming. As a result of scheduling tree trimming on a case-by-case basis, city crews spend an inordinate amount of their time traveling to tree trimming sites, resulting in backlogs, allowing for many trees to go untrimmed for than a decade and some wards of the city receiving less tree trimming service than others.

According to the press release, OIG recommended that DSS employ suggestions found in Monitor Group’s report, which details the benefits of switching from the current reactive request system to a grid-based approach. This new approach (previously used by the City and commonplace for most municipal urban forestry programs) would make the Bureau of Forestry much more efficient, reducing the average crew’s travel time by 35% and the average cost per tree trim by 60%. It would also result in arborists determining how best to manage the urban forest rather than safety-driven resident calls, which constitutes an important added level of input to proper holistic management. In response, DSS stated that it will work to develop a comprehensive tree inventory of the entire City canopy within the next year, which will provide valuable information regarding the number and location of trees as well as size and species. However, DSS did not commit to switching to a grid-based approach, stating that it would require 15-20 additional crews to transition to this system, on a cycle of 7-10 years.