Soil life survived the Mojave Dome Fire ^{CEFR B2}

The Dome Fire of 2020 swept the Mojave Desert, killing an estimated one million Eastern Joshua trees and burning roughly 43,000 acres. Scientists initially feared that the blaze, which began with lightning, had also erased the underground partners—mycorrhizal fungi—that help Joshua tree roots take up water and nutrients.

New research led by UC Riverside, published in the journal Fire Ecology, tracked soils in burned and unburned plots from just over two weeks after the fire through three years. Teams repeatedly sampled the same locations and report no detectable declines in fungal biomass, microbial richness, or the overall abundance of bacteria and fungi. In some cases mycorrhizal fungal and bacterial diversity rose slightly. "The existing community of microbes stayed, and some fire specialists even joined the party," says UC Riverside fungal ecologist Sydney Glassman, the study's senior author.

Aboveground change was stark: many trees initially showed green leaves, yet survivorship fell to about 50% after one year and to 20% at the three-year mark in burn plots. Dead trees became covered by a bright-coloured, fire-loving fungus called Neurospora discreta. The authors attribute many delayed deaths to compound stresses—initial fire damage, followed by drought and rodent activity. "The trees were already mortally wounded, then drought and rodents helped finish them off," says UCR research ecologist Lynn Sweet.

The study suggests one reason soil life persisted: low plant density across much of the Mojave likely limited heat penetration into the soil during the fire and so spared underground organisms. For restoration this is important: because mycorrhizal fungi remained, costly soil amendments to replace those partners may not be necessary. Nevertheless, recovery will be slow, as Joshua trees grow slowly and seedlings are often eaten by desert herbivores where vegetation has burned away.