by Connie Carroll-Cunningham
The Northern White Cedar (Thuja occidentalis) is a state threatened tree found naturally in northeastern Illinois. It has been cultivated as a landscape tree, but the planted trees tend not to spread into natural areas.
During botanical surveys for the Jane Addams Memorial Tollway Rebuilding and Widening Project, we found populations in wetlands at 2 adjacent properties: Trout Park and Chicago Junior School (CJS). The population at Trout Park had 299 trees, 82 of which were dead, whereas the CJS population had 568 trees.
To understand the differences between populations, we, in partnership with the INHS Plant Ecology Lab, compared seeds and soil characteristics. Because the sites are near a heavily used tollway, we hypothesized that salt spray used to deice pavement might impact plant germination and growth.