Blackbrush (Coleogyne ramosissima: ROSACEAE) natural regeneration following fire in the Great Basin - Mojave Transition Zone

Abstract

Abstract Blackbrush (Coleogyne ramosissima) has rarely been observed naturally regenerating following fire. It was historically considered a paleoendemic species because it did not recolonize following disturbance. In 2008, the Fossil and Jacob fires burned 241 ha of blackbrush in Basin and Range National Monument, Lincoln County, Nevada, USA in the Mojave-Great Basin Desert transition zone. These sites are at the northern boundary of the species range near the top of its current elevational band. Eighteen 5 x 30 m plots within the burned areas were monitored in 2009–2011 and 2018–2022 to assess plant foliar cover and woody plant density. Another 18 plots in adjacent unburned areas were monitored in 2022. Blackbrush seedlings emerged within the first year following fire at higher densities in the burned areas compared to adjacent unburned areas. After an initial flush of seedlings in 2009, there was high seedling mortality in 2010. By 2011, density in the burned areas was 0.35 blackbrush per m2 (46% of density in adjacent unburned areas), but individuals were small and had less than 1% total cover. Upon returning in 2018, the blackbrush that established early following fire had grown, and showed a significant increase in cover to 5.83–10.80%. Cover continued to increase through 2020 peaking at a mean of 12.9% before slighting declining with drought in 2021–2022. The area now has nearly two-thirds the blackbrush density and one-third the cover that adjacent unburned areas have. Blackbrush redominated these burned areas in under 10 years following fire and continues to increase.