Study says disastrous tipping points could be reached by 2050
Forests of the future may not be able to remove heat-trapping CO2 from the atmosphere as effectively as previously thought, scientists said in a new study that’s based on an extensive analysis of tree ring data from the past.
“We utilized a network of more than two million tree-ring observations spanning North America. Tree-rings provide a record into how trees that grow in different climates respond to changes in temperature and rainfall,” said Brian Enquist, a professor in the UA’s Department of Ecology and Evolutionary Biology and a fellow of the Aspen Center for Environmental Studies in Aspen, Colorado.
The research challenges assumptions about how forests will respond to warmer average temperatures, increased greenhouse gas emissions, and shifting rainfall patterns. It also suggests that the warming climate already is rapidly pushing many forests towards an ecological tipping point, which may be reached as early as 2050, Exposure to unprecedented temperatures hampers tree growth and makes them susceptible to other stress factors. Continue reading “Forests may not benefit from rising CO2 levels”→
Migration changes could affect competition for nesting sites
As global warming speeds up the springtime northward migration of swallows, it could spell trouble for mountain bluebirds.
Both species are cavity nesters; at times they compete for the same habitat. Historically, mountain bluebirds have arrived in the breeding territories earlier than the swallows, giving them a chance to defend their nests. But if the swallows arrive first, the bluebirds may have a harder time finding a safe spot to lay eggs, according to new research published in The Auk: Ornithological Advances.
The scientists from the University of Saskatchewan acknowledged that the outcomes of interspecies battles for nest sites depend on a number of factors, but wanted to study what happens when tree swallows and mountain bluebirds compete for nest sites. So they set up side-by-side pairs of nest boxes in grassland habitat in central British Columbia.
When bluebird and swallow pairs moved in next door to each other, they would either block the entrance to one box and let the two pairs of birds compete for the one that remained, or remove both boxes and replace them with a fresh one.
“I became interested in this topic after watching many competitive interactions over natural tree holes during a long-term study of Northern Flickers in central British Columbia,” said researchers Karen Wiebe. “In early spring when the birds are trying to claim a nest site, these disputes can be intense and really grab your attention. Because bluebirds and swallows readily use nest boxes, I was motivated to try some experiments in a system where I could have more control over the spacing of nests and settlement patterns of the birds.”
Wiebe found that when Tree Swallows were defending their previously owned box or when the two species were competing over a new box, Tree Swallows won 65-70 percent of the time. Bluebirds got a boost when they defended a box they already occupied, however, fending off swallows 77 percent of the time.
Climate change may bring the two species into direct competition more often and reduce bluebirds’ ability to claim and defend nest sites.
“This is a nice set of clever and simple experiments that show that species are not the same when it comes to the importance of being the first one to occupy a nest site,” according to ecologist Hanna Kokko of the University of Zurich, an expert on interspecies competition in birds. “The one that currently tends to arrive first, the bluebird, relies more on this, which could easily cause problems if the arrival order changes on a changing planet.”
In findings from new study released this week, researchers from the University of California, Riverside and the University of Miami Rosenstiel School of Marine and Atmospheric Science reported that old, weathered oil from the spill is even more toxic than fresh crude oil. Ultraviolet light changes changes the chemistry of the oil, the scientists said, further threatening numerous commercially and ecologically important fishes.
British researchers say regional patterns of melting of glaciers on the Antarctic Peninsula are linked with warming oceans in the region. The Antarctic Peninsula is one of the biggest contributors to sea level rise, so the new finding will help pinpoint how fast and how high seas will rise in the decades ahead.
Many bird species could lose between 78 and 85 percent of their existing habitat
Birds and reptiles in the Southwest that live in fragmented habitat will be hit hardest by global warming in the decades ahead, according to a new study by scientists with the U.S. Geological Survey and the Northern Arizona University.
The researchers took a close look at about 30 different animals, including well-known species such as the Gila monster, horned lizard, chuckwalla, Sonoran desert tortoise, pinyon jay, pygmy nuthatch, sage thrasher and black-throated sparrow.
Air pollution is changing plant odors, which confuses bees and makes them less efficient at foraging and pollinating plants, Penn State researchers said in a new study that shows how ozone breaks down plant-emitted scent molecules.
The chemical interactions decrease both the scent molecules’ life spans and the distances they travel, the scientists reported in the new study. They found that plant-emitted hydrocarbons break down through chemical interactions with certain air pollutants such as ozone. This breakdown process results in the creation of more air pollutants, including hydroxyl and nitrate radicals, which further increase the breakdown rate of plant odors. Continue reading “Air pollution seen as another factor in honeybee decline”→
British Antarctic Survey scientists to monitor impacts of ash deposits
A volcanic eruption in the remote South Sandwich archipelago, near the tip of the Antarctic Peninsula, may threaten the largest known colony of chinstrap penguins, according to scientists with the British Antarctic Survey who have been monitoring the eruption.
The Mt. Curry volcano on Zavodovski Island has been erupting since March, sending ash toward the penguin enclave. The uninhabited island is part of the British Overseas Territory of South Georgia and the South Sandwich Islands. After reports of a 7.2 magnitude earthquake last month, researchers confirmed from satellite imagery that not one, but two volcanoes are erupting in the South Sandwich Islands — Mt. Curry on Zavodovski Island to the north of the archipelago and Mt. Sourabaya on Bristol Island to the south. Continue reading “Eruption poses threat to huge penguin colony”→