Curlycup gumweed (Grindelia squarrosa (Pursh) Dunal [Asteraceae]): a native forb candidate for inclusion in Great Basin greenstrips

Abstract

The introduction and expansion of the alien annual cheatgrass (Bromus tectorum L. [Poaceae]) has led to significant changes in the North American sagebrush biome fire regime. Fires have become larger and more frequent due to the creation of continuous fine fuel load of cheatgrass biomass that fills large expanses of the Intermountain West. In an effort to compartmentalize and slow fire progress, land management agencies continue to install hundreds of kilometers of vegetative greenstrips, largely comprising introduced forage grasses and sub-shrubs. While effective at suppressing fire progress, these greenstrips provide little ecological functionality because of their limited species composition. Curlycup gumweed (Grindelia squarrosa (Pursh) Dunal [Asteraceae]) is a short-lived native perennial forb, which may have potential for inclusion in Intermountain greenstrips to provide a pollen and nectar source without compromising the fire-suppressing capabilities of the greenstrip. We compared flammability traits of curlycup gumweed against 4 commonly utilized greenstrip species and cheatgrass during the summer months of June through September using collections made in southern Idaho. Curlycup gumweed maintained moisture content levels similar to those of forage kochia (Bassia prostrata (L.) A.J. Scott [Chenopodiaceae]). Curlycup gumweed out-performed crested wheatgrass (Agropyron cristatum (L.) Gaertn. [Poaceae]), Siberian wheatgrass (A. fragile (Roth) P. Candargy [Poaceae]), and Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski [Poaceae]) for time to ignition and duration of combustion. Based on these results, curlycup gumweed should be considered for use in Intermountain greenstrip seedings.