FAIRBANKS -- A rusty brown substance is covering snow melting in Fairbanks, and foresters say it's good news for people with allergies.
The substance is a massive crop of birch seeds, produced by trees growing in ideal conditions since last summer.
Fairbanks birch trees pouring their energy into seeds instead of catkins should mean less pollen, which has been heavy in recent springs, the Fairbanks Daily News-Miner reported. Catkins are the cylindrical flower clusters named for their resemblance to cats' tails.
Jan Dawe, an assistant professor of forest science at the University of Alaska Fairbanks, said anecdotal reports and limited sampling seems to verify an uncommonly strong birch seed crop.
Dawe last week examined branches from several trees and noted they were loaded with the seed-filled remnants of female flowers. Male catkins create pollen but were either underdeveloped or absent on the branches she reviewed.
Dawe said the pattern began early last summer. Warmth and moisture were ideal for birch trees.
"Energetically, it's a lot more costly to make seeds," Dawe said. "But when the conditions are right, you want to make a bumper crop."
The trend has provided abundant food for chickadees, grouse, and most significantly, redpolls. Alaska Department of Fish and Game wildlife biologist Mark Ross estimates Fairbanks has seen the biggest influx of March redpolls in seven to 10 years.
"That's the primary thing they feed on this time of year," Ross said. "I've seen them actually make short tunnels through the snow to get to the different layers."
Birch trees were considered a possible loser with climate warming. Retired UAF forestry professor Glenn Juday said two years ago the birch population was in "terrible shape" after hot, dry summers and the recent migration north of birch leaf miner insects.
Warmer weather, however, has also has lengthened the growing season by about 45 percent in the past century, giving surviving birch trees a boost when conditions are good. Some 4-year-old birch trees at a UAF test plot already are producing seeds. That would normally be expected after 12 or more years among wild trees, Dawe said.