Academic journal article The Science Teacher

Headline Science

Academic journal article The Science Teacher

Headline Science

Article excerpt

Wood Frogs In a Warming Climate

As conditions warm, fish and wildlife living at the southern edge of their species' ranges are most at risk, according to researchers who studied the effects of climate change on wood frogs.

Local and regional precipitation trends are nearly as important as temperature in determining the fate of many animals, said researcher David Miller, and that's especially true with moisture-sensitive creatures such as amphibians.

Miller's lab spearheaded the study that included 14 universities, the U.S. Geological Survey, and several other state and federal agencies, looking at long-term monitoring data from 746 wood frog populations in 27 study areas from Tennessee to Canada. The research focused on how climatic variation affected population growth rates.

In many of the wood frog populations studied, researchers found evidence of warmer summers having less of a negative effect in areas that received more precipitation. Some of these findings were counter-intuitive, Miller noted, such as positive effects of higher than normal rainfall in wetter parts of the range and positive responses to winter warming, especially in milder areas. In general, researchers found wood frogs were more sensitive to changes in temperature or temperature interacting with precipitation than to changes in precipitation alone.

Northward shifts in wildlife ranges may be expected in coming years or decades, noted lead researcher Staci Amburgey. The study's results suggest that sensitivity to changes in climate cannot be predicted simply by knowing locations within the species' climate envelope, she pointed out. Many climate processes did not affect population growth rates as expected, based on range position. Processes such as species interactions, local adaptation and interactions with the physical landscape likely affect the responses researchers observed.

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"Wood frogs are really broadly distributed, so I don't think the species is going to be declining anytime soon," Amburgey said. "But it appears that populations in the southern portion of the wood frog's range are vulnerable if we have more hot, dry summers. Certainly frogs in the southern part of their range are more sensitive to hot years than frogs farther north, where the conditions will not push their physiological tolerances."

This study was novel because researchers did not simply document where wood frogs exist and where they do not, Amburgey explained. Instead, they analyzed reproduction rates by counting egg masses in spring pools to determine where the amphibian's populations were growing or declining--trying to determine how each population was responding to year-to-year differences in climate. Wood frogs are an ideal species to study to develop predictions about how animals will respond to warming conditions, Miller said. They have evolved with some amazing adaptations, such as the ability to survive being frozen solid in winters.

"In a warming world, wood frogs at the southern end of their range may be in trouble," he said. "But by freezing solid, they thrive as far north as Alaska. They are an important part of our forested ecosystems in the Northeast and a truly unique species." (Penn State) http://bit.ly/wood-frogs-climate

"Weather Whiplash" to Degrade Water Quality

One consequence of global climate change is the likelihood of more extreme seesawing between drought and flood, a phenomenon dubbed "weather whiplash."

Now, researchers have shown that weather whiplash in the Midwest's agricultural regions will degrade

"As rainfall patterns change with climate change, there will be more times of drought and more times of excessive rainfall--really big storms," said Terry Loecke, lead author of the investigation.

Loecke said the extreme flux between drought and rainfall changes how the agricultural landscape stores nutrients, particularly nitrogen used in fertilizing farms. …

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