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Project ID:

25-2-03-15

Year:

2025

Date Started:

10/01/2025

Date Completed:

Title:

Assessing the interactive impacts of cogongrass and invasive woody plants on fire regimes of the southeastern USA

Project Proposal Abstract:

Purpose and Objectives: Invasive species can cause large departures from historical fire regimes that have knock-on effects for fire risk, ecological function, and natural resources. Fuel models do not often consider the presence or abundance of invasive species and are often the basis for fire risk assessments, management decision support tools, and fire management decisions. Invasive species’ impacts on fuel parameters that inform fire behavior models have not been well studied. This project aims to address this gap by developing new fuel models that incorporate the impacts of cogongrass and invasive woody plants on fire behavior.
Our objectives are to 1) determine temporally-explicit impacts of cogongrass, invasive woody plants, and their interaction on fire behavior, 2) develop new fuel models that incorporate impacts of interacting invasive plant species on fire behavior, 3) use these fuel models in concert with available location data for invasive species to update the Southern Wildfire Risk Explorer such that it includes risk associated with invasive species and how that risk changes through time, and 4) determine if previous and current invasions have had impacts on fire regimes of the southeastern USA at a broader scale. We hypothesize that 1) cogongrass alone will increase fireline intensity, flame length, rate of spread, and burn probability, but the magnitude of these impacts will depend on fuel moisture conditions of cogongrass 2) woody plants alone will reduce fire behavior metrics because they have less flammable litter structure 3) fire behavior impacts in areas where cogongrass and woody invasive plants co-occur will be speciesspecific, but will generally be amplified relative to cogongrass alone during dryer conditions and dampened when fuel moisture is high, and 4) broad fire regime changes will be driven more by cogongrass occurrence than invasive woody plants or their interactions with cogongrass.
Activities to be Performed: The project will involve collecting temporally explicit field data on fuel parameters associated with different levels of cogongrass and woody plant invasion from two locations within the Gulf Coast region. These data will inform custom fuel models used to parameterize fire behavior models. Fire behavior will be measured in sampling plots to calibrate the models. Available data on invasive species occurrence and wildfires will be collected to assess changes in fire regimes. A framework will be developed to update the Southern Wildfire Risk Explorer with new fuel models and occurrence data.
Expected Deliverables: The project will produce new fuel models that can be integrated into fire risk assessment tools, making them robust to wildfire risk associated with invasive species. Deliverables include invasive-species-specific fuel models, updates to the Southern Wildfire Risk Explorer, journal manuscripts reporting findings relative to our major hypotheses, webinars, final report to JFSP, and a publicly accessible data repository. These products will provide state and federal fire managers with accurate decision support tools for predicting and preparing for prescribed and wildfire outcomes in areas with invasive species.
Benefits: This study will provide new fuel models that can be used in concert with available invasive species occurrence data to update the Southern Wildfire Risk Explorer, making it robust to wildfire risk associated with invasive species. This will provide the opportunity to assess change in risk associated with invasive species and their treatment so that state and federal government fire managers can more accurately predict and prepare for outcomes of both wildfire and fuels management in areas with interacting invasive species. Moreover, it will provide community planners with accurate decision support tools for pinpointing where fuels and invasive species management might be most necessary to reduce fire risk, reducing the costs associated with these activities.

Principal Investigator:

Carissa L. Wonkka

Agency/Organization:

University of Florida

Branch or Dept:

Office of Research

Other Project Collaborators

Type	Name	Agency/Organization	Branch or Dept
Agreements Contact	Stephanie L Gray	University of Florida	Office of Research
Budget Contact	Stephanie L Gray	University of Florida	Office of Research
Co-Principal Investigator	Jonathan Pitchford	Mississippi State University	Wildlife, Fisheries, and Aquaculture
Co-Principal Investigator	Victoria M. Donovan	University of Florida	Agronomy Department