Disruption from wildfires reaches all the things that lives in or around a burning field or forest — including microbes — giving researchers a greater understanding of how microbial communities change and grow after a fireplace. Can help predict how bacteria and fungi will reply to environmental changes.
A study published this week suggests that dispersal—by wind or rain, for instance—plays a very important role in microbial succession after a catastrophic fire. Researchers on the University of California, Irvine, spent a 12 months tracking how bacterial and fungal communities return to leaf litter in a burned field. They found that the microbial communities emerging within the soil surface modified with the seasons and the reappearance of vegetation, and that the assembly of those communities was largely driven by dispersal.
The risk and extent of major environmental disturbances akin to forest fires have been increasing over the past few a long time.
“We know that with climate change and human activity we are increasingly disturbing our ecosystems,” said Kristen Barber, lead creator of the brand new study and a Ph.D. student on the University of California, Irvine. “Microbes, especially those in surface soils, carry out many important ecological processes such as carbon and nitrogen cycling.” Bacteria and fungi, he said, break down dead and decaying plant matter on the sphere or forest floor.
Barber originally set out to review microbial diffusion within the context of drought, but her plans modified when an unplanned wildfire burned a field site in Loma Ridge near Irvine. What gave the look of a setback changed into a possibility. “We wanted to take advantage of this problem, especially since wildfires are becoming more common in many parts of the world,” Barbour said.
Extreme heat generated during wildfires alters the chemical composition of leaf litter, where microbes live, and might shift microbial communities across ecosystems.
The researchers checked out 2 ecosystems that were affected by fire: a semi-arid grassland and a coastal sage scrub. To study the movement of microbes, they used 4 configurations of dispersed bags. First, they used burnt leaf litter to fill small porous sacs that allowed microbes to maneuver out and in. For one other, a control group, they sealed the leaf litter in bags that didn't allow in or out. The third configuration was a porous bag stuffed with glass slides, wherein to gather the microbes as they moved, and the fourth, one other control group, consisted of sealed bags with glass slides.
Five times in the course of the 12 months after the hearth, Barber and his colleagues collected dispersal bags from each sites and identified bacteria and fungi on the leaf litter. They found that the effect of diffusion differed within the two environments, suggesting that microbial responses depend upon their environment. “That hurts our ability to make general statements,” Barber said.
They noticed some recurring patterns. Overall, wind dispersal contributed probably the most to microbes entering the soil surface — 34% for bacteria and 42% for fungi. They also found that in the primary few months after fire, before vegetation reappeared, bulk soil (the soil beneath the leaf litter) explained the most important fraction of migrating bacteria.
Studying how microbes move through the environment is an emerging field of research, Barber said, but one which is closely related to the larger problem of how large-scale disturbances change the environment.
“There's a lot of exciting work being done right now, looking at diffusion and microbial communities in the environment,” he said.