More science on the regenerative powers of wildfire

Fire is good for birds, frogs, even spiders

For tens of thousands of years, fire had been a natural part of the ecosystems of western forests and other portions of North America. Usually sparked by summertime lighting strikes, low-intensity fires consumed leaf litter, fallen dead branches, and other organic material of the forest floors. With few exceptions, mature trees easily withstood the blazes. Examining scars of these older trees and using other evidence, fire experts found that fires could recur as often as every seven years in the western forests of the continent. Trees and other plants evolved strategies around this fire regime. Some pines only release seeds from their cones when heat from a wildfire warms them, as Giant Sequoias of the Sierra Nevada do.

European settlers upset that balance. Vast areas of eastern hardwood forests were clearcut, some areas repeatedly, which robbed hills and valleys of the characteristics and ecology of old growth forests. Europeans also started putting out fires. This led to forests filled with dense understories of smaller trees and shade-tolerant trees, such as oaks.

We know that trees and other plants benefit from naturally recurring fires. But what of other species? Some recent scientific papers found promising results on this topic.

Birds benefit from wildfire

A team of researchers from The Institute for Bird Populations found that bird species benefit from wildfire. After the destruction of a fire, it would be easy to assume that bird populations would recover slowly, but the team found quite the opposite. Bird populations rapidly increased in burned areas following fires. And their populations in burned areas exceeded that of unburned forested areas, even after 35 years.

Using previously gathered bird counts and fire records going back to 1984, the scientists conducted their studies in Sequoia and Kings Canyon, two remarkable national parks in California’s most southerly reaches of the Sierra Nevada mountain range.

Another surprising result is that bird populations rebounded rapidly even in areas that were severely burned. In all, their study included 129,761 individual birds of 159 species.

The response to fire differed among individual species. For example, populations of acorn woodpeckers, American robins, and dark-eyed juncos flourished after fires then decreased to some degree in post-fire years, while flycatcher and mountain chickadee populations increased with time after a fire. The results of this study were published in Fire Ecology in October.

Fire helps frogs

Another study was also published in Fire Ecology, going back to April of this year. From 2006 to 2022, a team of researchers from Virginia Tech monitored areas along streams in Elgin Air Force Base for the Florida bog frog. Listed as Vulnerable by the International Union For the Conservation of Nature (IUCN), Florida bog frogs occupy a limited range of Florida’s western panhandle, where they live in shallow spring seeps, pond edges, and sluggish bends in streams. Habitat loss threatens their survival.

Although fighter jets take off and land on great tarmacs at the base, Elgin is noteworthy for having hundreds of acres of preserved and restored open spaces that serve as habitat for a wide range of species, including rare and endangered species. Besides the bog frog, Elgin is home to IUCN Red Listed gopher tortoises and red-cockaded woodpeckers.

Under the direction of the Air Force’s Wildland Fire Branch, Elgin conducts regular prescribed burns that recreate the natural fire regime of the panhandle before the introduction of fire suppression.

The scientists found that, even though this small, yellowish frog lives in and along aquatic environments, it thrives when its environment experiences frequent fires. Sites that received prescribed burns every two years were twice as likely to have bog frogs than sites that burned once every 10 years in that time period. The team also found that frogs were more likely to colonize areas adjacent to a burned site.

Even spiders benefit from fire

Researchers from Hungary and the Czech Republic looked at prescribed burns, this time in grasslands of the Dunajovice Hills National Nature Monument in the Czech Republic. They found that burns enhanced populations of spiders. Of the 107 spider species they monitored, those that prefer hot, dry environments thrived in open burned patches, while shade-tolerant spiders that prefer a more moist environment thrived in burned patches that were shaded by common hawthorn, an invasive plant that is the target of removal by prescribed burning.

The team suggested that prescribed burning could be part of enhancing the biodiversity of spiders that live in temperate, dry grasslands. Although the hawthorns are invasive, a scattering of them should be retained during these burns to benefit the full spectrum of arthropods living in the grasslands. Unburned areas should also be retained, as the research team found that a number of beetle species were more prevalent in these areas. This paper was published this month, once again in Fire Ecology.

Flowers and bumblebees in Ohio

Briefly, researchers from Marshall University, my alma mater, looked into prescribed burns and their effects on bumblebees. They did not detect any difference in bumblebee counts between areas that received prescribed burns and areas that did not. But they did find that burned areas had more abundance of the flowers that native bumblebees like to pollinate. As the saying goes, more research needs to be done.

Please check out a previous Green Dispatch on the subject of wildfire:

And check out the new Substack that

Robert Crespin

and I are publishing, Two Old Guys, Two Bikes, and A Lot of Electrons.