Wiregrass (Aristida beyrichiana) survival and reproduction after fire in a long-unburned pine savanna

PLoS One. 2021 Feb 17;16(2):e0247159. doi: 10.1371/journal.pone.0247159. eCollection 2021.

Abstract

Restoring fire regimes is a major goal of biodiversity conservation efforts in fire-prone ecosystems from which fire has been excluded. In the southeastern U.S.A., nearly a century of fire exclusion in pine savannas has led to significant biodiversity declines in one of the most species-rich ecosystems of North America. In these savannas, frequent fires that support biodiversity are driven by vegetation-fire feedbacks. Understory grasses are key components of these feedbacks, fueling the spread of fires that keep tree density low and maintain a high-light environment. When fire is reintroduced to long-unburned sites, however, remnant populations of bunchgrasses might experience high mortality from fuel accumulation during periods of fire exclusion. Our objective was to quantify fire effects on wiregrass (Aristida beyrichiana), a key component of vegetation-fire feedbacks, following 16 years without fire in a dry pine savanna typically considered to burn every 1-3 years. We examined how wiregrass size and fuel (duff depth and presence of pinecones) affected post-fire survival, inflorescence and seed production, and seed germination. Wiregrass exhibited high survival regardless of size or fuels. Probability of flowering and inflorescence number per plant were unaffected by fuel treatments but increased significantly with plant size (p = 0.016). Germination of filled seeds was consistent (29-43%) regardless of fuels, although plants in low duff produced the greatest proportion of filled seeds. The ability of bunchgrasses to persist and reproduce following fire exclusion could jumpstart efforts to reinstate frequent-fire regimes and facilitate biodiversity restoration where remnant bunchgrass populations remain.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biodiversity
  • Ecosystem
  • Germination / physiology
  • Grassland
  • Poaceae / physiology*
  • Seeds / physiology

Grants and funding

This research was supported by USDA National Institute of Food and Agriculture, Agriculture and Food Research Initiative, Foundational and Applied Science Program Award #2018-07356 (to RMC), USDA AFRI Education and Workforce Development Award #2018-08049 (to JMF), McIntire-Stennis Project #FLA-FOR-005759 (to RMC), and University of Florida, Institute of Food and Agricultural Sciences Ordway Swisher Biological Station Jumpstart Award (to RMC). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.