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SCIENCE & conservation

Dynamics of forested ecosystems - Current projects

Emma measure tree

For each project, a brief description is given with the names of lead staff members and collaborators. Names with no institutional affiliation indicate Arboretum staff; names of external collaborators have their affiliations in parentheses.

Forest resiliency
Forests and climate change
Oak woodlands
Forest restoration



Evaluating forest response and resiliency to disturbance. As forests face threats from invasive pests and climate change, it is vital to understand how they respond to disturbances such as insect damage or moderate-scale tree dieoffs and determine how these disturbances affect the services they provide to environments and people. The goal of this project is to assess the role of understory tree community compositional differences in promoting resilience of carbon uptake in the system. This work is a component of a Department of Energy FASET project focused on assessing the impact of a simulated moderate-severity disturbance (girdling of ~30% of canopy—similar to an insect defoliation event) on carbon sequestration and ecosystem functioning. R. Fahey; C. Gough, E. Goodrich- Stuart (Virginia Commonwealth University); P. Curtis (Ohio State University); C. Vogel (University of Michigan)

Impact of forest canopy complexity on forest productivity and resilience. The canopies of old-growth forests tend to be more complex than canopies in younger stands. Old-growth forest canopies are made up of trees of different sizes and ages, standing dead trees, lianas, and other elements that create a diverse array of microclimates and support other organisms. Structural complexity can affect energy, water, and nutrient cycles; productivity; and community assembly. This work investigates drivers of canopy structural complexity in old-growth hemlock-hardwood forests and the impact of this complexity on productivity and resilience in these forests. It combines long-term plot data from Duke University’s Experimental Forest near Durham, North Carolina, and the Huron Mountain Club in the Upper Peninsula of Michigan, with measurements of canopy structural complexity made with a below-canopy LiDAR system. This project will help understand the type of canopy characteristics to encourage in younger, developing forests if they are to provide the same benefits and ecosystem functions as old-growth forests. R. Fahey; K. Woods (Bennington College); C. Webster (Michigan Technological University); P. Curtis(OSU); C. Gough (VCU); A. Fotis (OSU); A. D’Amato (University of Minnesota); C. Kern, B. Palik (USDA Forest Service Northern Research Station)


Responsiveness of woody plant leaf-out and flowering timing to climatic variation. The response of woody plant phenology to climatic variation (e.g., timing of spring warming) will have major implications for the growth and viability of these plants under forecasted future climatic conditions. Inter- and intraspecific variation in response (along with information on species and individual origin, traits, and phylogeny) could indicate mechanisms for responsiveness and help predict which species and individuals are likely to deal with future climates most effectively. R. Fahey, E. Hedborn; Z. Panchen (Carleton University); R. Primack (Boston University); B. Nordt (Freie Universität Berlin); E. Ellwood (Florida State University); A. Stevens (Freie Universität Berlin); S. Renner (University of Munich); C. Willis (Harvard University); A. Whittemore (US National Arboretum); Y. Du (Chinese Academy of Sciences); C. Davis (Harvard University)

Tracking tree response to recent climate fluctuations. In partnership with the Illinois Natural History Survey, tree growth responses are being monitored from Illinois Natural Areas Inventory sites throughout Illinois. The Illinois Natural Areas Inventory (INAI) systematically surveys the state to identify and describe natural areas that are significant for maintaining statewide populations of plants and animals or that have significant natural features. Increment tree cores are collected from INAI-designated sites, processed, analyzed, and connected with plot data in partnership with the Illinois Natural History Survey. Data are being used to analyze recent tree growth responses to climate fluctuations at a statewide level. R. Fahey, M. Bowles


Developing strategies to maintain oak dominance in Chicago-region woodlands. The dominant presettlement vegetation of the Chicago region was a mosaic of prairie, oak savannas, and oak woodlands. This project is focused on developing and assessing management strategies to maintain oak (Quercus) dominance in the urban natural areas of the region. It makes use of a large-scale, replicated experimental management treatment that is being implemented by the Lake County Forest Preserve District and The Morton Arboretum. We are studying the response of a variety of organisms and communities, including oak seedlings, ground-layer plants, amphibians, birds, mammals, and invertebrates. The project will be essential as a source of scientific data, management best practices, and demonstration/outreach for oak woodland restoration in the region. R. Fahey, K. Dreisilker; D. Maurer, J. Anderson (Lake County Forest Preserve District); S. Menke, J. Pastick (Lake Forest College); D. Goldblum, M. Moses (Northern Illinois University)

Fire management and its impacts to the belowground ecosystem. Soil properties are very influential in determining the health and success of trees. Prescribed burning is a common management tool in oak (Quercus) woodlands. However, the effects of these low-severity forest-floor burns on soil and the below-ground ecosystem are unknown. This research is quantifying those effects in long-term burn plots in The Morton Arboretum East Woods. Results will be used to develop management practices that provide favorable soil conditions for trees and forests. B. Scharenbroch, M. Bowles, R. Fahey, K. Dreisilker

Understanding the fire ecology of oak savanna. The oak savanna ecosystem that once covered a significant portion of the Midwest is in decline due to post-European settlement fire protection. Lightning strikes and Native Americans caused regular fires to burn oak-savanna ecosystems, producing their characteristic structure and maintaining plant community diversity. This work examines the chronology of fire, its effects on long-term changes in woody and herbaceous vegetation in oak savanna ecosystems, and its relationships with soils in fire-managed sand savannas in northeastern Illinois and northwestern Indiana. Understanding historical fire frequency and vegetation communities will help to restore natural areas so they can harbor and protect maximum animal and plant diversity. M. Bowles, B. Scharenbroch; M. Jones (Christopher Burke Engineering); A. Haney (University of Wisconsin-Stevens Point); S. Apfelbaum (Applied Ecological Services)

Canopy and soil as factors in oak regeneration. The exclusion of fire in the post-settlement landscape has resulted in closed-canopy woodlands and hardwood forests in the Midwestern United States. This structure limits light penetration to the forest floor, reducing regeneration of shade-intolerant oaks (Quercus).Current restoration practices involve canopy manipulation and controlled burning to increase available light. This research examines the effects of canopy and understory manipulation on microclimate, soils, and oak regeneration. Study plots are in The Morton Arboretum’s East Woods.Results will be used to make management recommendations that encourage oak regeneration in Midwestern forests and woodlands. B. Scharenbroch, M. Bowles, R. Fahey, K. Dreisilker

Soil properties investigated for their effect on oak (Quercus) woodland structure. Soils are an important control on oak (Quercus) woodland dynamics. This bottom-up control, arising from the bottom of the food web, has been shown to influence local-scale plant distributions and affect tree establishment and growth, and understory development. This research examines variation in soil properties and herbaceous, shrub, and canopy vegetation characteristics in oak woodland plots throughout the Chicago region. Understanding how soil conditions shape woodland structure and change can help managers create favorable soil conditions for tree populations in urban and natural areas. B. Scharenbroch, R. Fahey


Ecology and restoration of mixed pine-hemlock-hardwood forests. Over the past 150 years, various pines (Pinus spp.) have been lost from much of the mesic hemlock-hardwood forest of the Great Lakes region. This study investigates the mechanisms of establishment and persistence and the ecological role of early-successional pine species in late-successional forest landscapes and potential management strategies for restoring these species to the landscape. R. Fahey; C. Lorimer (University of Wisconsin-Madison)

Tracking long-term changes in Chicago-region old-growth forests. As a result of fire protection, Chicago-region old-growth forests are undergoing canopy replacement of oaks by shade-tolerant species and loss of understory vegetation. We maintain a long-term vegetation and tree-ring database from 30 old-growth stands and continually collect new samples from across the region. Analysis of this database will facilitate our understanding of long-term changes in these stands and help understand how best to manage these forests in the future. M. Bowles, R. Fahey; M. Jones (Christopher Burke Engineering)

Long-term deer-browsing effects on woody forest-understory plants. Eastern white-tailed deer populations are greater in the eastern United States today than in presettlement times. At the same time, forest habitat has been significantly reduced. Deer have greatly altered understory vegetation in eastern forests, in some cases arresting turnover of tree populations due to heavy browsing of seedlings and saplings. This long-term study uses exclosures in replicated stands to examine the influence of canopy cover, precipitation, and deer browsing on woody understory composition and structure. This work will help shape management recommendations for woodlands that encourage healthy age structure for sustainable tree and woody plant populations. M. Bowles; M. Jones (Christopher Burke Engineering); T. Bell (Chicago State University)

Assessing the invasive capacity and ecosystem impacts of non-native tree species. Non-native species are commonly planted as ornamentals and street trees in the northeastern United States. However, their invasive capacities and potential effects on natural forests and ecosystem functioning are often unknown. This research focuses on a set of commonly planted street trees and ornamentals: Norway maple (Acer platanoides), amur corktree (Phellodendron amurense), Siberian elm (Ulmus pumila), princess tree (Paulownia tomentosa), and tree-of-heaven (Ailanthus altissima).Their invasive capacity, current distributions, and potential effects on native vegetation communities and ecosystem functions will be assessed. This work will help understand how these species affect urban ecosystems as well as plant communities of nearby natural areas. R. Fahey