May 7, 2013
Decline In Snowfall Has Negative Impact On Plants, Animals
Lee Rannals for redOrbit.com — Your Universe Online
Plants and animals that thrive in deep snowfall seasons are having a tough time in recent years as less and less snow drops down its blanket.
Scientists writing in the journal Frontiers in Ecology and the Environment say the gradual decay of the Northern Hemisphere's snowfall is having an impact on life that depends on it. The seasonal microenvironment that relies on snowfall, known as "subnivium," has an effect on everything from microbes to bears.
"Underneath that homogenous blanket of snow is an incredibly stable refuge where the vast majority of organisms persist through the winter," explains Jonathan Pauli, a University of Wisconsin-Madison professor of forest and wildlife ecology and a co-author of the new report. "The snow holds in heat radiating from the ground, plants photosynthesize, and it's a haven for insects, reptiles, amphibians and many other organisms."
Snow cover in the Northern Hemisphere has dropped by as much as 1.2 million square miles over the past 40 years. The researchers said maximum snow cover has shifted from February to January, and spring melt has accelerated by nearly two weeks.
"The winter ecology of Wisconsin and the Upper Midwest is changing," says Benjamin Zuckerberg, a UW-Madison professor of forest and wildlife ecology. "There is concern these winter ecosystems could change dramatically over the next several years."
Reptiles and amphibians are also being put at risk by the fluctuating temperatures because it puts them prematurely out of their winter torpor, only to be lashed by late spring storms or big drops in temperature. Insects in the area undergo phases of freeze tolerance and the migrating birds that depend on invertebrates for nutrition go on with an empty stomach when the protective snow cover goes missing.
"There are thresholds beyond which some organisms just won't be able to make a living," says Pauli. "The subnivium provides a stable environment, but it is also extremely delicate. Once that snow melts, things can change radically."
Zuckerberg said the greatest effects on the subnivium will occur on the margins of the Earth's terrestrial cryosphere, which is the parts of the world that get cold enough to support snow and ice.
"The effects will be especially profound along the trailing edge of the cryosphere in regions that experience significant, but seasonal snow cover," the scientists wrote in their report. "Decay of the subnivium will affect species differently, but be especially consequential for those that lack the plasticity to cope with the loss of the subnivium or that possess insufficient dispersal power to track the retreating range boundary of the subnivium."
The researchers say as snow cover retreats, land managers need to start paying attention to the changes and the resulting loss of habitat for a variety of plants and animals.
"Snow cover is becoming shorter, thinner and less predictable," says Pauli. "We're seeing a trend. The subnivium is in retreat."
A climate model created by National Oceanic and Atmospheric Administration (NOAA) predicts there will be less snowfall in most areas of the world over the next 100 years due to rising carbon dioxide (CO2) levels. The AOS/GFDL model revealed that the mountainous regions of the western part of North America and the northeastern coast will be the hardest hit, with snowfall levels dropping to less than half of their current levels.
The NOAA model did show not everywhere on Earth would be seeing less snowfall. In fact, it says the very cold regions of the globe will see more snowfall, including the Arctic and Antarctica areas.