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illustration frequent droughts
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In a new paper published in Nature, research assistant professor Christopher Schwalm of Northern Arizona University’s Center for Ecosystem Science and Society (Ecoss) shares the results of a study investigating the impact of more frequent droughts on ecosystem resiliency and how this phenomenon could endanger the land carbon sink. Read the full NAU article here. Illustration by Victor Leshyk
norma rivera core from aspen tree in alaska
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Nitrogen isotopes in tree rings record the history of the nitrogen cycle—the critical nutrient that limits growth in many US forests.  ECOSS faculty member Michelle Mack, along with colleagues from seven other institutions, recently published a paper that shows nitrogen availability in US forests declining over the past century, with cool, wet forests demonstrating the greatest declines. The paper is open access and can be accessed here: www.nature.com/articles/s41598-017-08170-z. NAU Biology major Norma Rivera takes a core from an aspen tree in Alaska. Photo credit: Samantha Miller.
leshyk illustration combat antibiotic resistance
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Antibiotic-resistant bacteria are widespread and are increasingly associated with human infections.  Inappropriate antibiotic use – both in people and in animals raised for food – drives the evolution of multi-drug-resistant pathogens and threatens a post-antibiotic era – one in which minor infections can kill. The majority of antibiotics are actually sold for use in food animals, rather than in people, and as a result, farms are major sources of many new types of antibiotic-resistant bacteria.“We clearly need to use antibiotics more responsibly,” says Ecoss researcher Ben Koch.  “However, limiting the spread of antibiotic resistance also requires knowing the extent to which antibiotic-resistant microbes move among farms, the environment, and people.” Koch, along with Ecoss colleagues Bruce Hungate and Lance Price, published a study in the journal Frontiers in Ecology and the Environment that examined the potential for merging ecology and genomics to better understand those microbial movements. They found that combining ecological principles with newly available genomic data on antibiotic-resistant bacteria...
leshyk illustration biochar
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Biochar illustration by Victor O. Leshyk Scientists believe that biochar, the partially burned remains of plants, has been used as fertilizer for at least 2,000 years in the Amazon Basin. Since initial studies published several years ago promoted biochar, farmers around the world have been using it as a soil additive to increase fertility and crop yields. But a new study casts doubt on biochar’s efficacy, finding that using it only improves crop growth in the tropics, with no yield benefit at all in the temperate zone. "We saw a huge boost for crops grown in the tropics, but zero results for crops in the temperate zone," said Dr. Bruce Hungate, Director of the Center for Ecosystem Science and Society at Northern Arizona University and co-author on the study. "Given all the talk about the benefits of biochar, we were...
leshyk illustration quantify economic value
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Illustration by Victor Leshyk Wildflowers splashed across a meadow in different sizes, shapes and colors offer more than just beauty. The natural mix of plant species in an ecosystem—its biodiversity—helps it grow faster and cycle nutrients more efficiently. These ecosystem functions also deliver life-sustaining services on which humans rely, such as purifying water and providing food, fuel and oxygen. Illustration by Victor Leshyk Biodiversity is declining around the world due to a variety of causes, including changes in land use, pollution and climate change, so it is more important than ever that land managers and other policymakers are better informed when making decisions that affect biodiversity in their regions. But how do you measure the value of biodiversity? Northern Arizona University ecologist and Regents’ Professor Bruce Hungate led a team of scientists who developed one of the first models to...
leshyk illustration rhizosphere
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A future is depicted in which rhizobacteria sourced from stressful areas around the world may be used as a metaphorical “prescription for drought.” (Illustration by Victor Leshyk 2016) ECOSS researchers recently published findings in the scientific journal Plant and Soil showing that rhizosphere bacteria could help reduce crop losses due to drought. See the full article Listen to an interview by Knau with Rachel Rubin Watch an interview with Rachel Rubin for Arizona PBS
Cover_American_Journal_Botany
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American Journal of Botany Ready to climb a California coast redwood (Sequoia sempervirens), to sample branches for fungi. In this issue, Harrison et al. delved into a largely unexplored reservoir of fungal diversity—the forest canopy—using a high-throughput sequence-based approach to characterize the composition of the fungal community at different heights within the crowns of redwood trees at sites spanning the geographical range of the world’s tallest species. They found pervasive shifts in community composition with height of the trees and distinct assemblages of fungi on individual trees, which warrant further research to understand the ecological role and consequences of such vertically stratified fungal communities in tree species. See pp. 2087–2095, Harrison et al.—Vertical stratification of the foliar fungal community in the world’s tallest trees.Image credit: George Koch, taken at Landel’s Hill-Big Creek Reserve, California. Read the full article here
cover for oecologia
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Oecologia Giant Sequoia trees can be thousands of years old, are the most massive organisms on Earth, and reach astounding heights. But they can't just keep on getting taller indefinitely, it seems. There are limits. Figuring out these limits and how they shape these giant forests is a main focus of Professor George Koch's research, featured on the cover of this month's issue of the prestigious journal, Oecologia. At the tops of the trees, the leaves have just as much nitrogen as leaves lower in the canopy, they have the capacity to photosynthesize at high rates, and they are equally efficient with water. So, what's missing? It turns out that lifting water against gravity is hard, and it gets harder and harder the higher you go. So at the tops of the giant redwood trees, the leaves are water stressed, and tree height approaches the physical limits...
Microscopic visual illustration of Ectomycorrhizal fungi on the roots of a tree.
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Ectomycorrhizal fungi (the mushrooms connected to the roots of the tree) increase the uptake of nitrogen by the plant, even when that nutrient is scarce in soils. Artwork by Victor O. Leshyk. Plants can grow faster as atmospheric CO2 concentrations increase, but only if they have enough nitrogen or partner with fungi that help them get it, according to new research published this week in Science. The study was lead by César Terrer Moreno, a PhD student at Imperial College London, and included researchers from Northern Arizona University, the University of Antwerp (Belgium), Indiana University, and New South Wales University (Australia). The team synthesized more than 80 past experiments, and they found that higher CO2 boosted plant growth, as long as the plants received enough nitrogen. Without added nitrogen, CO2 had no effect, confirming the long-standing idea that nitrogen limits...
Illustration of permafrost releasing carbon dioxide
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In thawing Arctic permafrost soils, carbon dioxide is produced by microbes in dry conditions, while both methane and carbon dioxide are produced by microbes in wet conditions. Artwork by Victor Leshyk. When it comes to climate change, not all carbon is created equal. Among greenhouse gases, methane is 34 times more potent than carbon dioxide. In this recent study published in Nature Climate Change, Northern Arizona University assistant research professor and lead author of the study, Christina Schädel, analyzed carbon release from 25 Arctic soil incubation studies to learn more about the conditions promoting either carbon dioxide or methane release. Read more about the findings of the study here