What would dry winter mean for Utah's forests?
A lurking drought this winter could leave Utah's forests primed for fires or new waves of beetle-driven die-offs next summer.
It's too early to count out the annual snowpack witness this past weekend's storm but a record dry December followed by a kindling-dry January forecast has state firefighters starting to talk.
"The further that we get into this winter season and the lower we get on snowpack totals, the more concerned we get," said Jason Curry of the Utah Division of Forestry, Fire & State Lands. "Anytime we have a year like this we usually end up with a more severe fire season."
AccuWeather forecasting service reported that the nation's snow coverage for Jan. 4 22 percent was the lowest for that date in an eight-year analysis it conducted. The next lowest was in 2007, at 27 percent. The Intermountain West and Sierra Nevadas, in particular, look historically bare, according to the report.
For now, mountain evergreens are snug in a winter slumber, effectively hibernating before they will need significant moisture to resume growth after the thaw.
At that point, if soil moisture is fleeting from a continued lack of snow, the trees could struggle to nourish themselves for the seasonal fight against insect infestation.
"The real worry is if low snow levels persist and the high country dries out early, then you are more likely to get summer drought conditions that could stress native trees," said Mike Kuhns, Utah State University Extension forester.
Bark beetles, which have overrun pines throughout the West and spruce in Utah in an outbreak dating to the 1990s, are most effective when attacking trees weakened by drought. The trees defend themselves with pitch a saplike toxic compound and are unable to make much of it during droughts.
The good news, according to Kuhns, is that the trees entered winter well-fortified after a couple of wet years.
"They're in better shape from a nutritional standpoint to withstand attacks," he said. "But that'll fade pretty quickly if we have a dry year. They're not able to bank food and certainly not water for the future."
Conditions could be much worse, as they were during successive dry years early in the previous decade. Drought then led to 876 Utah wildfires in 2002, 10 of which were larger than 5,000 acres, according to state records. Nearly 270,000 acres burned that year, compared with 38,000 last year, when a deep snowpack may have helped suppress the number of fires to 675. Only one fire last year topped 5,000 acres.
Soil moisture from those 2010-11 snows also held up nicely heading into this winter, according to the U.S. Natural Resources Conservation Service (NRCS). The agencies soil monitors in the mountain ranges around Utah show an average saturation rate of 43 percent. The Jordan River-Great Salt Lake Basin, which surrounds the Salt Lake Valley, is at 48 percent saturation.
That's a little off the mean moisture reading since the agency installed the last of its soil monitors in 2005, but better than the driest January since then. In January 2010, before the first of two good snow years, the state average was 38 percent and the Salt Lake basin was at 29 percent.
"We're on the lower end of what we've seen over the last five to 10 years," NRCS hydrologist Beau Uriona said, "but certainly we're not the lowest."
There's plenty of time for Mother Nature to ensure decent soil moisture for next summer, Uriona said. Even in low-snow years, there's often enough melt percolating into the ground to bridge the gap until spring rains. It's the runoff into streams and reservoirs that suffers first and that's less of a concern this year because of what last winter did to recharge regional water storage.
Soil moisture is unique by basin, though, and even by slope. Southwest-facing slopes likely will reach spring drier than northeastern faces, Kuhns said, so a tree's health this summer may depend on its location.
January soil moisture, statewide and by basin
Statewide average saturation • 43 percent
Low average since measurements began in 2005 • 38 percent
Bear River Basin • 49 percent
Weber River-Ogden Basin • 48 percent
Jordan River-Great Salt Lake • 48 percent
Uinta Basin-Green River Basin • 44 percent
Carbon-Emery-Wayne Basin • 45 percent
Sevier-Beaver Basin • 46 percent
Garfield-Kane Basin • 42 percent