Fire and Invasive Plants

Research Issue

The use of prescribed fire to sustain oak forests has increased rapidly in the last decade as the threat of poor regeneration and increased dominance of shade-tolerant and or fire-sensitive tree species. While prescribed fire can favor oak regeneration, it may also increase the invasion and expansion of non-native invasive plant species (NNIS). Unlike the western US where much is known about the impacts of fire on NNIS, little is known in eastern US forests. The majority of knowledge regarding the response of NNIS is anecdotal as managers have reported the expansion of invasives such as tree-of-heaven(Ailanthus altissima) and princess tree(Paulownia tomentosa) following prescribed fires. Before managers can adopt proactive and integrated NNIS control strategies into forest management programs, we need to conduct empirical studies on the direct impacts of prescribed fire on individual non-native species. 

Our Research

Since 2008, we have been studying the impacts of prescribed fire and other forest management practices on Ailanthus altissima (tree-of-heaven), a shade-intolerant tree that is widely distributed in the eastern U.S. and can be highly invasive. The research was initially funded through a Joint Fire Science Program to focus on the interaction of fire and non-native invasive species in East. Using a systematic grid of sample plots, we identified key factors related to the presence and abundance of Ailanthus across the landscape.  The direct effect of prescribed fire on Ailanthus populations with and without the pre-burn application of herbicide was studied. This is the first field study that documented the direct effects of fire on Ailanthus. ODNR Division of Forestry will continue collaboration to implement a second prescribed burn in 2016. This will allow us to study the effects of multiple burns on Ailanthus populations and subsequent regeneration.

Expected Outcomes

Given the fact that prescribed fire is being used more extensively in the East, developing new knowledge about the effects of fire on Ailanthus and other non-native plants populations and also tools to detect and mitigate their expansion in the landscape would clearly benefit forest management.  Results have already been used to help develop the Wayne National Forest Land and Resources Management Plan and the Ohio Division of Forestry prescribed fire program. 

Research Results

Although the project is still ongoing, we have found to date:

• Based on Random Forest and CART modeling, we found that prescribed fire was not a significant predictor of Ailanthus presence. The most important predictor of Ailanthus presence was a timber harvest within the last 25 years. 
• After one dormant springburn, we determined that pre-burn herbicide application was highly effective killing large saplings and trees with no sprouting after three growing seasons. Small Ailanthus saplings and seedlings increased in the season immediately after the burn with and without herbicide treatment, but did not persist. Ailanthus germinants and sprouts from top-killed saplings and trees were poor competitors with faster-growing post-fire woody regeneration as forest floor shading increased over time. 
• Aerial mapping of Ailanthus populations- we developed an effective tool to aerially map infestations of Ailanthus and Paulownia across large forested landscapes at a cost of about $1 per acre. With this geo-referenced information in hand, managers can develop treatment target areas for ecological restoration. This tool is being used for adaptive management priorities and strategies for future silvicultural treatments such as fire and timber harvesting on the Wayne National Forest. Having these geo-referenced data aids in the development of short-term and long-term plans to target treatments to minimize the spread of NNIS.

Rebbeck, J; Hutchinson, T; Iverson, L; Peters, M; Yaussy, D; Bowden, M; Guess, G; Kloss, A.  Ailanthusand prescribed fire, is it a volatile combination?  2014.  Waldrop, Thomas, ed. Wildland Fire in the Appalachians. Gen. Tech. Report SRS- 199, Asheville, NC. USDA Forest Service, Southern Research Station, p. 48-52.

Rebbeck, J. 2012. Fire management and woody invasive plants in oak ecosystems. Proceedings of the 4th Fire in Eastern Oak Forests Conference, Springfield Missouri, USDA Forest Service GTR-NRS-P-102, p. 142-155.

Research Participants 

• Joanne Rebbeck, Plant Physiologist, USFS Northern Research Station

Research Partners

• Todd Hutchinson, Ecologist, USFS Northern Research Station 
• Dan Yaussy, Supervisory Research Forester, USFS Northern Research Station
• Louis Iverson, Landscape Ecologist, USFS Northern Research Station
• Matt Peters, GIS Technician, USFS Northern Research Station
• Robert Boyles, Ohio Division of Forestry
• Aaron Kloss, Ohio Division of Forestry
• Sierra Patterson, USFS Wayne National Forest

For further details log on website :
https://www.nrs.fs.fed.us/disturbance/invasive_species/fire_plants/