News Release 

Invasive grasses and fire regimes in the United States

Proceedings of the National Academy of Sciences

A study explores how invasive grasses alter fire regimes across the United States. Non-native invasive grasses have the potential to alter fire regimes by increasing fuel loads and fuel continuity. However, the regional-scale effect of invasive grasses on fire regimes has not been assessed for most species. Emily Fusco and colleagues calculated the differences in fire occurrence, size, and frequency between invaded and uninvaded landscapes for 12 invasive grass species across the United States. Eight of the 12 species were associated with significant increases in fire occurrence, with occurrence up to 230% greater in invaded areas than in uninvaded areas. Six species were associated with significant increases in fire frequency, with fires up to 150% more frequent in invaded areas than in uninvaded areas. Species with significant effects spanned multiple ecoregions, from the Great Basin and the desert Southwest to eastern temperate deciduous forests and southern pine savannah and rocklands. The results suggest that many ecosystems may be vulnerable to increased fire occurrence and frequency caused by invasive grasses. According to the authors, fire management plans should account for the contribution of invasive grass to fire regimes.


Article #19-08253: "Invasive grasses increase fire occurrence and frequency across US ecoregions," by Emily J. Fusco, John T. Finn, Jennifer K. Balch, R. Chelsea Nagy, and Bethany A. Bradley.

MEDIA CONTACT: Emily J. Fusco, University of Massachusetts Amherst, MA; tel: 828-301-7274; e-mail:; Bethany A. Bradley, University of Massachusetts, Amherst, MA; tel: 401-440-9660; e-mail:

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