Key points:
- Following a wildfire, dispersal from wind or rain explains the return of most fungal species, while air dispersal contributs most to the microbes entering the soil surface.
- Understanding how microbes move and re-establish communities is a key research area that can help scientists understand how big disturbances change the environment.
As the environment undergoes major changes, researchers need to understand and predict how microbial communities change and grow. A new study, published in mSystems, reveals that dispersal through either air or rain plays a role in microbial succession after a destructive fire.
“We know with climate change and human activity we’re disturbing our ecosystems more and more,” said lead author Kristin Barbour of the University of California, Irvine. “Microbes, especially those in the surface soil, perform a number of really key ecosystem processes.”
The intense heat from wildfires alters leaf litter chemical composition, which can shift the microbial communities present in the ecosystem. Researchers spent a year tracking how bacterial and fungal communities returned to leaf litter in a burned field. They focused on two ecosystems affected by a wildfire—a semi-arid grassland and a coastal sage scrub.
To study the movement of microbes, they used four configurations of dispersal bags. First, they used burned leaf litter to fill small porous pouches that allowed microbes to pass in and out. A second control configuration utilized sealed leaf litter bags that prevented movement. The third configuration was a porous bag filled with glass slides to collect microbes, while the final one was another control closed bag filled with glass slides. At five times during the year after the fire, the research team collected all dispersal bags and identified the bacteria and fungi present on the leaf litter.
The assembly of these microbial and fungi communities was driven by dispersal, which differed in the two ecosystems. In general, dispersal from wind or rain explained the return of most fungal species, while air dispersal contributed most to microbes entering the soil surface. Additionally, in the first few months following the fire, before plants re-emerged, the soil beneath the leaf litter contained the largest share of immigrating bacteria.
Determining how microbes move through the environment to re-establish communities is emerging as a key research area. Dispersal in microbe communities is one part of a bigger picture concerning how big disturbances change the environment.