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Project ID:

25-1-01-10

Year:

2025

Date Started:

09/15/2025

Date Completed:

Title:

Impacts of Anomalously Short Interval Wildfires on Understory Vegetation Recovery in Rocky Mountain Subalpine Forests

Project Proposal Abstract:

1. Proposal Purpose and Objectives: High-severity wildfires are increasing in frequency across western North America, threatening forest ecosystems’ ability to regenerate. As the intervals between wildfires shrink to a time period shorter than dominant species require for maturation, changes in fire regimes can interact with vegetation to determine postfire forest recovery. Yet few studies have examined the mechanisms underlying how increasingly short-interval fires affect understory vascular plant recovery despite these communities’ crucial role in ecosystem function and future fire activity. Wildfire can affect forest regeneration through several mechanisms, including soil nutrient dynamics, tree regeneration, fuel loading, and changes in local environmental conditions. Specifically, wildfire releases elements such nitrogen, alters stand structure and future fuels via tree mortality and consumption of potential seed sources, and influences soil moisture, temperature, and canopy cover. Together these factors ultimately determine the long-term trajectory of vegetation community composition as well as pollination services, elemental pools, and the fuel for subsequent fires. However, we know remarkably little about the direct and indirect effects of wildfire on understory vegetation recovery, limiting our ability to predict postfire ecosystem response. To help anticipate wildfire-driven vegetation shifts, we will use a demographic modeling framework to assess via which environmental effects wildfire restructures understory vegetation and which life stages are most vulnerable. A mechanistic understanding of how changes in fire intervals affect important demographic stages will allow us to identify the processes that contribute to vegetation recovery post wildfire and make targeted management recommendations in burned landscapes.
2. Activities to be Performed: This research focuses on addressing gaps in our knowledge of how lodgepole pine forest understory vegetation recovery is affected by short-interval wildfire and indirectly by wildfire’s potential effects on nutrient cycling, stand structure and future fuels, and microenvironment conditions. We will achieve this by assessing how vital rates of the dominant understory vegetation in forests that have burned at least twice in the past 30 years (a) respond to wildfire and (b) contribute to landscape-scale population growth. Specifically, this research will allow us to investigate (1) which vital rates matter most for population growth, (2) which local conditions affect population trajectories, and (3) how population-level demographic outcomes scale up to affect species composition and vegetation cover across a landscape experiencing rapidly changing fire regimes.
3. Expected Deliverables: Our findings will be communicated via a research brief and webinar hosted by the Northern Rockies Fire Science Network targeting the broader fire ecology community, as well as a presentation at the Missoula Fire Sciences Laboratory in collaboration with the Rocky Mountain Research Station targeting land managers. The data produced from this work will be integrated into curated datasets and ecological models for use by the Montana Natural Heritage Program (MTNHP), where the models will be used to make decisions about National Vegetation Classification System designations, update species conservation status rankings and develop habitat suitability models in a region with no existing data in the Montana Field Guide. MTNHP supported data and models are publicly accessible and used by private landowners, local and state conservation agencies, the Forest Service, and the Bureau of Land Management. This work will also culminate in a peer-reviewed journal article.
4. Benefits: The proposed work will contribute to a better understanding of fire effects on lodgepole pine forests understory composition. The findings of this project will inform management goals related to forest resilience as described*

Principal Investigator:

Meredith Zettlemoyer

Agency/Organization:

University of Montana

Branch or Dept:

Division of Biological Sciences

Other Project Collaborators

Type	Name	Agency/Organization	Branch or Dept
Agreements Contact	Dari Quirk	University of Montana	Office of Research and Sponsored Programs
Budget Contact	Dari Quirk	University of Montana	Office of Research and Sponsored Programs
Student Investigator	Dalton Brantley	University of Montana	Division of Biological Sciences