AlaskaDenise
In Memoriam
Explanation for reduced migratory bird population. They fly to very flyway in the world. If their habitat is degraded, it would impact their health by competition for available food and overcrowding increasing diease.
http://www.adn.com/news/environment/story/8334961p-8231059c.html
4-YEAR STUDY: Fifty percent of ponds in subarctic boreal regions have disappeared in last 50 years.
The Associated Press
<!--start /published/index.comp -->Published: October 23, 2006
Last Modified: October 23, 2006 at 01:08 AM
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FAIRBANKS -- Global warming is causing permafrost to melt, allowing thousands of ponds to shrink across Alaska, according to a new study.
Researchers in the four-year study used aerial images from the past 50 years to measure the landscape-level shrinkage of more than 10,000 closed-basin ponds, or those with no streams or leading in or out, across Alaska. The study's results were published this month in the Journal of Geophysical Research.
Researchers compared black-and-white aerial photographs from the 1950s, color infrared aerial photographs from 1978 to 1982 and digital satellite images from 1999 to 2002.
Brian Riordan is lead author of the paper and data manager for the Bonanza Creek Long-Term Ecological Research program at University of Alaska Fairbanks.
Riordan and his fellow scientists compared outlines and discovered more than half of the ponds surveyed in the subarctic boreal regions of the state, the region bounded on the north by the Brooks Range and on the south by the Alaska Range, have disappeared in the last 50 years.
The others have all shrunk, with some losing as much as 31 percent of their surface water area, with most changes occurring in the last three decades.
The ponds are typically formed when depressions in the ground are filled with water that isn't able to drain, usually because of permafrost beneath the pond.
"Like a plugged bathtub," co-author David McGuire, a professor of landscape ecology at the Institute of Arctic Biology, told the Fairbanks Daily News-Miner. "If you pull the plug, which is what we're thinking is happening, you get catastrophic drainage."
In this case, he said the pulled plug is most likely melting permafrost caused by warmer and longer growing seasons.
McGuire said the data confirms what Native elders say they have noticed during their lifetimes.
"This is something people have been talking about for a while," he said. "There was anecdotal information from some of the Native villages that things were drying up. We had a lot of anecdotal information that it was occurring."
The data will "allow land managers to stop speculating about possible water body loss and begin to address the implications of this loss," Riordan said.
The shrinking ponds could have several environmental impacts, including lowering the water table for migratory birds, which could affect their reproduction.
The dryer landscape also could mean higher levels of carbon dioxide would be released into the atmosphere as the carbon stored in the usually wet Alaska soil decomposes as the soil dries, McGuire said.
Institute of Arctic Biology students and researchers will physically inspect these shrinking lakes to try to understand exactly what is going on, said institute spokeswoman Marie Gilbert.
.
http://www.adn.com/news/environment/story/8334961p-8231059c.html
4-YEAR STUDY: Fifty percent of ponds in subarctic boreal regions have disappeared in last 50 years.
The Associated Press
<!--start /published/index.comp -->Published: October 23, 2006
Last Modified: October 23, 2006 at 01:08 AM
<!-- end /published/index.comp -->
<!-- Component: ADN : component/redesign/modules/primcol/story/storyhead.comp --><!-- Component: ADN : component/redesign/modules/primcol/story/inset.comp -->
<!-- Component: ADN : component/redesign/modules/primcol/story/inset.comp -->
FAIRBANKS -- Global warming is causing permafrost to melt, allowing thousands of ponds to shrink across Alaska, according to a new study.
Researchers in the four-year study used aerial images from the past 50 years to measure the landscape-level shrinkage of more than 10,000 closed-basin ponds, or those with no streams or leading in or out, across Alaska. The study's results were published this month in the Journal of Geophysical Research.
Researchers compared black-and-white aerial photographs from the 1950s, color infrared aerial photographs from 1978 to 1982 and digital satellite images from 1999 to 2002.
Brian Riordan is lead author of the paper and data manager for the Bonanza Creek Long-Term Ecological Research program at University of Alaska Fairbanks.
Riordan and his fellow scientists compared outlines and discovered more than half of the ponds surveyed in the subarctic boreal regions of the state, the region bounded on the north by the Brooks Range and on the south by the Alaska Range, have disappeared in the last 50 years.
The others have all shrunk, with some losing as much as 31 percent of their surface water area, with most changes occurring in the last three decades.
The ponds are typically formed when depressions in the ground are filled with water that isn't able to drain, usually because of permafrost beneath the pond.
"Like a plugged bathtub," co-author David McGuire, a professor of landscape ecology at the Institute of Arctic Biology, told the Fairbanks Daily News-Miner. "If you pull the plug, which is what we're thinking is happening, you get catastrophic drainage."
In this case, he said the pulled plug is most likely melting permafrost caused by warmer and longer growing seasons.
McGuire said the data confirms what Native elders say they have noticed during their lifetimes.
"This is something people have been talking about for a while," he said. "There was anecdotal information from some of the Native villages that things were drying up. We had a lot of anecdotal information that it was occurring."
The data will "allow land managers to stop speculating about possible water body loss and begin to address the implications of this loss," Riordan said.
The shrinking ponds could have several environmental impacts, including lowering the water table for migratory birds, which could affect their reproduction.
The dryer landscape also could mean higher levels of carbon dioxide would be released into the atmosphere as the carbon stored in the usually wet Alaska soil decomposes as the soil dries, McGuire said.
Institute of Arctic Biology students and researchers will physically inspect these shrinking lakes to try to understand exactly what is going on, said institute spokeswoman Marie Gilbert.
.