Matthew Kling

WILDFIRE BIOGEOGRAPHY

[PUBLICATION] Biogeography of fire regimes in western U.S. conifer forests: A trait-based approach

Diagram of fire resistance of conifer species

Overview

This research, published in Global Ecology and Biogeography (2020), uses the concept of “functional trait biogeography” to better understand how fire regimes shape the distribution of conifer species across the western United States. As a co-author on this paper headed by Jens Stevens, I led the spatial data analysis and visualization parts of the project.

Research Approach

We developed a trait-based, quantitative ranking of fire resistance (adult tree survival) in 29 North American conifer species by:

  1. Compiling six traits for each species: three related to tree morphology (bark thickness, maximum height, and degree of self-pruning) and three related to litter flammability (flame length, percentage consumption, and flame duration)
  2. Combining these traits into a single “fire resistance score” (FRS)
  3. Using community-weighted averaging with species distribution and relative abundance data to map forest community fire resistance across the western United States

Key Findings

Our analysis revealed that:

  • Species associated historically with frequent fire (e.g., Pinus ponderosa) have high fire resistance scores, reflected by thick bark, tall crowns, and flammable litter
  • Species in subalpine or arid conditions (e.g., Picea engelmannii and Pinus edulis) have low fire resistance scores, with thin bark, short stature, poor self-pruning, and low litter flammability
  • The spatial distribution of community-level fire resistance aligns well with independent assessments of historical fire regimes
  • We identified areas where community-wide species traits might be mismatched with historical fire regimes, suggesting either past high-severity fire or infilling by fire-sensitive species due to fire exclusion

Implications

This work demonstrates how functional trait biogeography can be used to understand ecosystem processes at broad spatial scales. By providing a direct link between ecosystem disturbance and community resistance, this research helps evaluate the long-term resilience of different forest types under dynamic fire regimes, especially in the context of climate change and changing land management practices.

Map of forest community fire resistance across western U.S.

Citation: Stevens, J.T., Kling, M.M., Schwilk, D.W., Varner, J.M., & Kane, J.M. (2020). Biogeography of fire regimes in western U.S. conifer forests: A trait-based approach. Global Ecology and Biogeography, 29(944-955). https://doi.org/10.1111/geb.13079