In 2020, the lightning-caused Dome Fire burned ~43,000 acres in the Mojave Desert (Mojave National Preserve, California), killing around 1 million Eastern Joshua trees (Yucca brevifolia), turning dense stands into blackened skeletons.

Scientists expected the underground microbial community—especially mycorrhizal fungi that partner with Joshua tree roots to help absorb water and nutrients in harsh desert soil—to be devastated too. Instead:

• Soil sampling (from just over two weeks post-fire through three years later) showed no major declines in fungal biomass, microbial richness, or overall bacteria/fungi abundance.
• In some cases, mycorrhizal fungal and bacterial diversity even increased slightly.
• The existing microbial community persisted, and some “fire-loving” (pyrophilous) specialists, like the bright orange Neurospora discreta that grew on charred tree bark, joined in. news.ucr.edu

Aboveground, tree death was slow: Many initially retained green leaves, but survival dropped to ~50% after one year and ~20% after three, likely due to compounded stresses like drought and rodents rather than immediate fire kill.

There is the full title of the open-access scientific paper published in Fire Ecology (2026) by lead author Arik Joukhajian and colleagues, including senior author Sydney Glassman from UC Riverside.

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Mojave Desert microbial communities show high resistance and resilience over three years despite widespread plant mortality following the Dome Fire

The 2020 Dome Fire (lightning-caused) burned ~43,273 acres (~17,500 ha) in Mojave National Preserve, California, killing roughly 1 million Eastern Joshua trees (Yucca jaegeriana). Researchers set up 9 plots (6 burned, 3 unburned controls) and sampled soils and vegetation at 5 time points: from ~2 weeks to 3 years post-fire.

They analyzed:

• Plant mortality and richness.
• Soil chemistry (including ash depth as a burn severity proxy).
• Microbial biomass (via qPCR).
• Microbial diversity and composition (via Illumina MiSeq sequencing of bacterial 16S and fungal ITS2 regions).

Key Results

Aboveground (Plants):

• ~80% mortality of Eastern Joshua trees in burned plots over three years.
• Overall plant richness decreased, though annual herbs boomed around 1 year post-fire.
• Many trees initially kept some green leaves, but survival dropped sharply (to ~50% at 1 year, ~20% at 3 years), likely due to compounded stresses like drought and herbivory.

Belowground (Microbes):

• Extremely high diversity: 25,444 bacterial, 269 archaeal, and 6,683 fungal amplicon sequence variants (ASVs).
• No significant declines in microbial biomass, overall bacterial/fungal abundance, or richness at any time point.
• Microbial communities showed high resistance (little change) and resilience.
• Small but significant shifts: Enrichment of “pyrophilous” (fire-loving) taxa, including bacteria like Tumebacillus, Massilia, and Noviherbaspirillum, and fungi like Pseudotricharina, Penicillium, Coniochaeta, and Naganishia.
• Notably, mycorrhizal fungi (key partners for Joshua trees) were largely unaffected.

The bright orange Neurospora discreta (or similar) fungus prominently colonized charred Joshua tree bark post-fire.

The sparse vegetation in this Mojave Desert area (plants spaced far apart) meant the fire was relatively low-intensity in terms of soil heating compared to dense forests or shrublands. Heat didn’t penetrate deeply, protecting the underground microbiome—similar to responses seen in low-intensity grassland fires.

Implications

• Soil fungi and microbes are not the missing link preventing Joshua tree recovery. Restoration efforts don’t need expensive mycorrhizal inoculations; the partners are still there if seedlings can establish.
• Joshua tree regeneration remains difficult due to slow growth, seedling predation, drought, and climate trends increasing megafire risk.
• This is one of the first detailed above- and below-ground studies of a major desert wildfire, including Archaea, Bacteria, and Fungi.

Restoration context for the Cima Dome area (post-Dome Fire) and broader Joshua tree efforts centers on active intervention by the National Park Service (NPS) at Mojave National Preserve, combined with research on barriers like drought, herbivory, invasive grasses, and slow natural recovery. The microbial resilience findings (mycorrhizal fungi largely intact) are encouraging but don’t solve the main bottlenecks.

Restoration is labor-intensive, costly, and has mixed short-term success due to climate pressures, but it’s viewed as essential to maintain seed sources and biodiversity in refugia like Cima Dome. The microbial paper is positive—it shifts focus from “missing partners underground” to aboveground and landscape-scale issues.

This study highlights desert microbiome toughness but doesn’t mean “no problem” for Joshua trees overall. The bottleneck remains aboveground establishment, not missing fungi.

Published: Springer Link

DOI: 10.1186/s42408-025-00435-7

Provided: University of California – Riverside

Preprint (bioRxiv): Available for earlier version.

Authors: Arik Joukhajian, 
M. Fabiola Pulido Barriga, 
Melanie J. Davis, 
Lynn C. Sweet & 
Sydney I. Glassman

Abstract

Background

High severity desert fires are uncommon but typically chart a new successional trajectory altering plant communities for at least 65 years.

These aboveground vegetation shifts can have large implications for belowground microbial communities that maintain soil structure and nutrient cycling.

High severity wildfires in forests or shrublands can severely reduce microbial species richness and biomass and alter microbiomes for decades but impacts on desert soil microbiomes are virtually unknown.

The 2020 Mojave Desert Dome Fire burned 43,273 acres of Eastern Joshua tree (Yucca jaegeriana) habitat, burning roughly 1 million trees. To track aboveground and belowground impacts of the Dome Fire, we established 9 plots (6 burned; 3 unburned) and sampled 4 subsamples per plot for 5 time points ranging from 2 weeks to 3 years post-fire.

We measured initial ash depth as a proxy of soil burn severity and assessed plant mortality, plant richness, soil chemical characteristics, estimated soil microbial biomass with qPCR, and microbial richness and composition with Illumina MiSeq of 16S and ITS2 amplicons.