Scientists from the USDA Forest Service have predicted that the native tree species in a 7-million-acre area in the Chicagoland region may decline — leaving invasive species to thrive in their place. The researchers conducted an assessment of the region’s vulnerability to climate change, and they determined that 17 percent of tree species currently present have either “moderate-high or high vulnerability to climate change, and 77 percent of individual trees with low vulnerability are invasive species,” according to the Forest Service’s Northern Research Station.

A summary of the report states, “In the past century, the Chicago region has warmed by about 1 degree F and has experienced a significant increase in precipitation, as much as 3 inches during the summer. Climate modeling for the region projects that:

  • By the end of the century, temperatures and precipitation will be more erratic.
  • The mean annual temperature will increase by 2.3 to 8.2 degrees F, with temperature increases across all seasons.
  • Precipitation will increase in winter and spring over the 21st century, but climate models disagree about how precipitation may change in summer and fall.
  • Heavy precipitation events have been increasing in number and intensity and are projected to continue to increase further, which could increase runoff and local f looding from stormwater.
  • Extreme and exceptional droughts may increase in duration, frequency and spatial extent compared to the end of the 20th century.
  • Increased temperatures will lead to longer growing seasons and shifts in plant hardiness and heat zones.”

The assessment was led by the Forest Service’s Northern Institute of Applied Climate Science. In addition for Forest Service researchers, contributors to the report include staff from Chicago Wilderness, Chicago Region Trees Initiative, the Field Museum, The Morton Arboretum, DuPage County, Chicago Botanic Garden, Davey Institute and the University of California Davis Arboretum and Public Garden.