Posts tagged temperature
CU led mountain forest study shows vulnerability to climate change
Sep 9th
Forests where people live and play to be hit hardest
Led by CU-Boulder researcher Ernesto Trujillo and Assistant Professor Noah Molotch, the study team used the data — including satellite images and ground measurements — to identify the threshold where mid-level forests sustained primarily by moisture change to higher-elevation forests sustained primarily by sunlight and temperature. Being able to identify this “tipping point” is important because it is in the mid-level forests — at altitudes from roughly 6,500 to 8,000 feet — where many people live and play in the West and which are associated with increasing wildfires, beetle outbreaks and increased tree mortality, said Molotch.
“Our results provide the first direct observations of the snowpack-forest connections across broad spatial scales,” said Molotch, also a research scientist at CU-Boulder’s Institute of Arctic and Alpine Research. “Finding the tipping point between water-limited forests and energy-limited forests defines for us the region of the greatest sensitivity to climate change — the mid-elevation forests — which is where we should focus future research.”
While the research by Molotch and his team took place in the Sierra Nevada mountain range in California, it is applicable to other mountain ranges across the West, he said. The implications are important, since climate studies indicate the snowpack in mid-elevation forests in the Western United States and other similar forests around the world has been decreasing in the past 50 years because of regional warming.
Forests are drying and becoming more vulnerable
“We found that mid-elevation forests show a dramatic sensitivity to snow that fell the previous winter in terms of accumulation and subsequent melt,” said Molotch, also a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “If snowpack declines, forests become more stressed, which can lead to ecological changes that include alterations in the distribution and abundance of plant and animal species as well as vulnerability to perturbations like fire and beetle kill.”
A paper on the subject was published online Sept. 9 in Nature Geosciences. Co-authors on the study include Ernesto Trujillo of INSTAAR and the Ecole Polytechnique Fédérale de Lausanne in Switzerland, Michael Golden and Anne Kelly of the University of California, Irvine, and Roger Bales of the University of California, Merced. The National Science Foundation and NASA funded the study.
Molotch said the study team attributed about 50 percent of the greenness in mid-elevation forests by satellites to maximum snow accumulation from the previous winter, with the other 50 percent caused by conditions like soil depth, soil nutrients, temperature and sunlight. “The strength of the relationship between forest greenness and snowpack from the previous year was quite surprising to us,” Molotch said.
The research team initially set out to identify the various components of drought that lead to vegetation stress, particularly in mountain snowpack, said Molotch. “We went after snowpack in the western U.S. because it provides about 60 to 80 percent of the water input in high elevation mountains.”
The team used 26 years of continuous data from the Advanced Very High Resolution Radiometer, a space-borne sensor flying on a National Oceanic and Atmospheric Administration satellite, to measure the forest greenness. The researchers compared it to long-term data from 107 snow stations maintained by the California Cooperative Snow Survey, a consortium of state and federal agencies.
In addition, the researchers used information gathered from several “flux towers” in the southern Sierra Nevada mountain range, which measure the exchanges of carbon dioxide, water vapor and energy between terrestrial ecosystems and the atmosphere. Instruments on the towers, which are roughly 100 feet high, allowed them to measure the sensitivity of both mid-level and high-level mountainous regions in both wet and dry years — data that matched up well with the satellite and ground data, he said.
“The implications of this study are profound when you think about the potential for ecological change in mountainous environments in the West in the not too distant future,” said Molotch, an assistant professor in the geography department. “If we take our study and project forward in time when climate models are calling for warming and drying conditions, the implication is that forests will be increasingly water-stressed in the future and thus more vulnerable to fires and insect outbreaks.
“When you put this into the context of recent losses in Colorado and elsewhere in the West to forest fire devastation, then it becomes something we really have to pay attention to,” he said. “This tipping-point elevation is very likely to migrate up the mountainsides as the climate warms.”
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Valmont Dog Park reopens Friday, Aug. 24
Aug 23rd
Valmont Dog Park, located at 5325 Valmont Road, will reopen to the public this Friday, Aug. 24, after being closed since early May for major renovations and improvements.
Valmont Dog Park improvements included widening the parking lot access, putting in a new entry plaza, fencing, surfacing, landscaping and water hydrants. A portion of the new park will also include an enclosed, irrigated turf area, low berms, a new 16-foot square shade shelter (to be installed later this fall), and two smaller shelters. The shelters are funded by the Capital Improvement Bond passed by voters in November 2011. A ribbon-cutting ceremony is anticipated for later this fall.
Additionally, the Parks and Recreation Department is now offering dog waste composting at the newly remodeled Valmont Dog Park as part of the department’s efforts to create a more environmentally sustainable community. The city will be providing compostable dog waste bags for use by dog guardians to pick up their dog’s waste and place it into a specially marked container at the main entrance of the dog park.
The dog waste compost container will be emptied periodically and its contents will be made into compost using a special high temperature composting technique. Placing dog waste in your yard compost bin is not recommended. Dog guardians are encouraged not to bring plastic bags to Valmont Dog Park anymore, but instead use the compostable bags provided by the city. Please continue to donate unwanted plastic bags at any public park, trails and the other three dog parks in town: East Boulder (5660 Sioux Drive), Foothills (west of Broadway between Locust Avenue and Lee Hill Road), and Howard Heuston (on 34th Street, south of Iris Avenue and east of 30th Street).
Information: Boulder Parks & Recreation Department, 303-413-7200.
CU scientists find life forms in a lifeless land
Jun 14th
A new DNA analysis of rocky soils in the Martian-like landscape on some volcanoes in South America has revealed a handful of bacteria, fungi and other rudimentary organisms called archaea, which seem to have a different way of converting energy than their cousins elsewhere in the world.
“We haven’t formally identified or characterized the species,” said Ryan Lynch, a CU-Boulder doctoral student involved in the study. “But these are very different than anything else that has been cultured. Genetically, they’re at least 5 percent different than anything else in the DNA database of 2.5 million sequences.”
Life gets little encouragement on the incredibly dry slopes of the tallest volcanoes in the Atacama region, where CU-Boulder Professor Steve Schmidt and his team collected soil samples. Much of the sparse snow that falls on the terrain sublimates back to the atmosphere soon after it hits the ground, and the soil is so depleted of nutrients that nitrogen levels in the scientists’ samples were below detection limits.
One of the most hostile environments on the planet
Ultraviolet radiation in the high-altitude environment can be twice as intense as in a low-elevation desert, said Schmidt of CU-Boulder’s ecology and evolutionary biology department. While the researchers were on site, temperatures dropped to 14 degrees Fahrenheit one night and spiked to 133 F the next day.
How the newfound organisms survive under such circumstances remains a mystery. Although Ryan, Schmidt and their colleagues looked for genes known to be involved in photosynthesis and peered into the cells using fluorescent techniques to look for chlorophyll, they couldn’t find evidence that the microbes were photosynthetic.
Instead, they think the microbes might slowly generate energy by means of chemical reactions that extract energy and carbon from wisps of gases such as carbon monoxide and dimethylsulfide that blow into the desolate mountain area. The process wouldn’t give the bugs a high-energy yield, Lynch said, but it could be enough as it adds up over time. A paper on the findings has been accepted by the Journal of Geophysical Research-Biogeosciences, published by the American Geophysical Union.
While normal soil has thousands of microbial species in just a gram of soil, and garden soils even more, remarkably few species have made their home in the barren Atacama mountain soil, the new research suggests. “To find a community dominated by less than 20 species is pretty amazing for a soil microbiologist,” Schmidt said.
Nearly 20,000 feet in altitude, snowless for 48,000 years
He has studied sites in the Peruvian Andes where, four years after a glacier retreats, there are thriving, diverse microbe communities. But on these volcanoes on the Chile-Argentina border, which rise to altitudes of more than 19,685 feet and which have been ice-free for 48,000 years, the bacterial and fungal ecosystems have not undergone succession to more diverse communities. “It’s mostly due to the lack of water, we think,” he said. “Without water, you’re not going to develop a complex community.”
“Overall, there was a good bit lower diversity in the Atacama samples than you would find in most soils, including other mountainous mineral soils,” Lynch said. That makes the Atacama microbes very unusual, he added. They probably had to adapt to the extremely harsh environment, or may have evolved in different directions than similar organisms elsewhere due to long-term geographic isolation.
Growth on the mountain might be intermittent, Schmidt suggested, especially if soils only have water for a short time after snowfall. In those situations, there could be microbes that grow when it snows, then fall dormant, perhaps for years, before they grow again. High-elevation sites are great places to study simple microbial communities, ecosystems that haven’t evolved past the very basics of a few bacteria and fungi, Schmidt said.
“There are a lot of areas in the world that haven’t been studied from a microbial perspective, and this is one of the main ones,” he said. “We’re interested in discovering new forms of life, and describing what those organisms are doing, how they make a living.”
Schmidt’s lab, along with others, is studying how microorganisms travel from one site to another. One common method of microbe transport is through the air — they’re caught up in winds, sucked up into clouds, form rain droplets and then fall back to the ground somewhere else as precipitation.
But on mountains like Volcán Llullaillaco and Volcán Socompa, the high UV radiation and extreme temperatures make the landscape inhospitable to outside microbes. “This environment is so restrictive, most of those things that are raining down are killed immediately,” Schmidt said. “There’s a huge environmental filter here that’s keeping most of these things from growing.”
The next steps for the researchers are laboratory experiments using an incubator that can mimic the extreme temperature fluctuations to better understand how any organism can live in such an unfriendly environment. Studying the microbes and finding out how they can live at such an extreme can help set boundaries for life on Earth, Schmidt said, and tells scientists what life can stand. There’s a possibility that some of the extremophiles might utilize completely new forms of metabolism, converting energy in a novel way.
Schmidt also is working with astrobiologists to model what past conditions were like on Mars. With their rocky terrain, thin atmosphere and high radiation, the Atacama volcanoes are some of the most similar places on Earth to the Red Planet.
“If we know, on Earth, what the outer limits for life were, and they know what the paleoclimates on Mars were like, we may have a better idea of what could have lived there,” he said.
Other paper authors included Andrew King of Ecosystem Sciences, CSIRO Black Mountain in Acton, Australia; Mariá Farías of Laboratorio de Investigaciones Microbiologicas de Lagunas Andinas, Planto Piloto de Procesos Industriales Microbiologicas, CCT, CONICET in Tucuman, Argentina; Preston Sowell of Geomega, an environmental consulting firm in Boulder; and Christian Vitry of Museo de Arqueologia de Alta Montana in Salta, Argentina.