Benchmarking Pre-Settlement Forest Vulnerability
Historical forest cover in the US was more extensive prior to this settlement period. For example, only 17% of the original forested area remains in the Chicago region. As forests provide critical habitat and sequester a substantial amount of carbon each year, conservation groups are focused on continuing to increase and protect the amount of forested land to ensure these ecosystems remain on the landscape.
In an effort to create healthy and sustainable forest ecosystems, managers often use pre-settlement forest conditions as a target for current management efforts. However, it is difficult to assess how resilient these past ecosystems were or if modern forests themselves are likely to survive the projected future changes to the climate system.
In collaboration with the Morton Arboretum and the Chicago Region Trees Initiative, I am investigating pre-settlement forest conditions through tree rings. We are using a combination of remnant living trees from the extensive preserve system in the region and the Witness trees that were used by the original land survey crews to map the region. A challenge to this work is the availability of old trees on the landscape. Between being cleared for agriculture and normal tree mortality old trees are rare on the landscape. However, many pre-settlement era trees are preserved in historical buildings such as barns, taverns, and storehouses. We can sample the beams and supports of these buildings to collect tree rings that can help us better understand these past ecosystems.
Through this mix of remnant trees, witness trees, and historical structures, we can assess how susceptible past forests were to changes in growing conditions and how quickly they recovered after large-scale disturbance events. We can then compare the responses of these older trees to modern forests to determine how much current ecosystems resemble these past forests and how well these modern trees might do under projected climate changes.