By Dr. Brice Hanberry, USDA Forest Service Rocky Mountain Research Station
Presented on February 7, 2023
Abstract: Open forests of savannas and woodlands, along with grasslands, historically were widespread in the United States. Open forests are characterized by simple internal stand structure consisting of a single layer of overstory trees and limited midstory, with a co-existing ground layer. Surface fires maintained open forests by providing a unique and important process that removes small trees, allowing growing space for herbaceous vegetation. Following Euro-American settlement, fires were excluded and historical accounts document rapid growth of trees. Replacement of open forests by current forests resulted in decreases in associated plants and animals, including species that are considered early successional. Historical forests offer different options for ecology and management, including better support of biodiversity and preparation for a warming climate with expected increases in severe fires, drought, and insect outbreaks. For this seminar, I will define open forest composition and structure along with probable extent, in comparison to current forest structure and composition in the eastern United States. I also will illustrate several lines of evidence indicating that factors other than fire and fire exclusion, such as herbivory and precipitation, do not appear to be influential on forest composition and structure at landscape scales. Based on historical ecosystems shaped by fire, I will propose a few alternatives to central tenets of modern ecology, such as limited importance of succession and tree diversity. Then we can discuss how fire ecology is different than classical ecology presented in textbooks and conventional academic settings. Although classical ecology may suit the novel ecosystems that exist today, classical ecology has impeded development of fire ecology.
