FOCUS ON FIRE
IN THE FOREST
FUNCTION OF FIRE
A GRASP ON SMOKE
BEYOND THE BLAZES
By Caroline Kurtz
When fires scorch the landscape it can seem as though nothing survives. However, ongoing research into how plants and animals recolonize burned areas shows that organisms evolving with fire as a regular disturbance are quick to take advantage of the opportunities such landscapes present.
Many kinds of bugs and birds thrive in blackened forests. Moose, elk and deer benefit from the flush of new plant growth that follows a burn. Fire can even provide a boon to fish in the form of new deadfall for hiding and increased nutrients that support a burgeoning insect population. Now another piece of the picture is coming into focus from research involving boreal toads and their response to fire.
Intrigued by observations of sharp increases in boreal toad numbers at breeding sites within burned areas, forestry Assistant Professor Lisa Eby and graduate student Greg Guscio spent the summer of 2004 catching as many toads as they could find at locations within the Robert Fire near Lake McDonald in Glacier National Park. Guscio used Velcro to fasten tiny radio collars around the toads’ waists — just in front of their hind legs — and then tracked where the toads went after mating season.
Although all the collared toads had the option of moving from mating ponds into unburned or mildly scorched areas, all stayed within burned areas, most within the high-severity burns.
“Why did they do this?” Eby asks. “Is populating burned areas costly or beneficial to toads? What do they get out of it?”
Boreal toads are greenish-brown and about the size of a tennis ball. They hide during the heat of the day and come out at night to hunt for their insect dinners. They breed in late May and early June in small ponds or at the edges of larger ponds and lakes — generally in warm shallow water without much cover. The tadpoles hatch and turn into toads by late summer. Eby says not much is known about what happens after they become adults.
Eby and Guscio developed the tracking project in close collaboration with Steve Corn and Blake Hossack at the UM-based Aldo Leopold Wilderness Institute. The institute’s statewide survey of boreal toad breeding sites, and specifically of those within the 2001 Moose Fire near Camas Creek in Glacier National Park, originally prompted them to look more closely at the association between the toads and fire.
It appears that toads benefit from the warmer nighttime temperatures of severely burned areas, which presents the cold-blooded creatures with conditions more conducive to moving around to find and digest food than those of unburned areas. During the daytime, the higher temperatures of burned areas mean potentially greater water loss for the toads, but inside burrows or under logs — where toads typically retreat during the day —the temperatures are about the same between burned and unburned sites.
“So toads are able to protect themselves during the day in burned areas and reap the benefits at night,” Eby explains.
Eby was surprised at how quickly toads responded to fire, but she says, “Toads have lived with fire on the landscape for a very long time.”
Follow-up observations by Corn and Hossack within the 2001 Moose Fire show that toads no longer use those breeding sites that were so populated a few years ago.
“It suggests there may be a finite window during which toads make use of burned areas for breeding,” she says.
For more information, e-mail Eby at firstname.lastname@example.org.