Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Category Archive: Ecology

  1. Controlled burns limited severity of Rim Fire – Yosemite 2013

    Leave a Comment
    • In fire-prone forests, self-reinforcing fire behavior may generate a mosaic of vegetation types and structures. In forests long subject to fire exclusion, such feedbacks may result in forest loss when surface and canopy fuel accumulations lead to unusually severe fires.
    • Self-reinforcing fire behavior results mainly from effects of vegetation structure and fuels on fire severity and that this behavior is mediated by topographic setting and the time since last fire.
    • The best predictor of fire severity was how severe the area last burned– Low severity burning seems to be very effective at limiting the severity of subsequent fires.
    • Severe fires leave behind a new legacy on the landscape. Less frequent, more severe fires caused by human intervention can change the composition of the forest and make future severe fires more likely to occur. For example, shrubs, which grow quickly after a fire, can take over forestland and then burn again before trees are able to re-establish.

    December 8, 2017 Penn State  read full ScienceDaily article here

    Controlled burning of forestland helped limit the severity of one of California’s largest wildfires, according to geographers.

    Fire burning in forest. Credit: Alan Taylor, Penn State

    ….The researchers studying the Rim Fire, which in 2013 burned nearly 400 square miles of forest in the Sierra Nevadas, found the blaze was less severe in areas recently treated with controlled burns.

    ….”It points to the potential use of prescribed fires to reduce severe fire effects across landscapes,” he said. “You can fight fire with fire. You can fight severe fires using these more controlled fires under conditions that are suitable.

    Scientists examined 21 previous fires within the Rim Fire’s perimeter, which burned in and around Yosemite National Park. They found areas that had burned within the preceding 15 years fared better in the 2013 blaze.

    The best predictor of fire severity was how severe the area last burned, according to the findings published in the journal Ecosphere.

    Low severity burning seems to be very effective at limiting the severity of subsequent fires,” said Lucas Harris, a graduate student in geography and lead author on the paper.

    …”Fire severity has been increasing for about the past three decades,” Taylor said. “There are real questions about whether we are beginning to see a shift in vegetation types driven by fire activity fueled by fire suppression and climate change.”

    The researchers said severe fires leave behind a new legacy on the landscape. Less frequent, more severe fires caused by human intervention can change the composition of the forest and make future severe fires more likely to occur. For example, shrubs, which grow quickly after a fire, can take over forestland and then burn again before trees are able to re-establish….

    “If you have a high severity initial fire, that’s a real lost opportunity,” Harris said. “You are probably getting a vegetation change due to that first fire that’s going to cause more high-severity fires in the future and potentially the emergence of non-forest that could last for a long time.

    Lucas Harris, Alan H. Taylor. Previous burns and topography limit and reinforce fire severity in a large wildfire. Ecosphere, 2017; 8 (11): e02019 DOI: 10.1002/ecs2.2019

  2. Marine organisms can shred a plastic bag into 1.75 million pieces, study shows

    Leave a Comment
    • The type of plastic (conventional, degradable and biodegradable) had no effect on the rate of ingestion, however the presence of a biofilm meant the shredding took place around four times as quickly.

    December 8, 2017 University of Plymouth read full ScienceDaily article here

    A single plastic grocery bag could be shredded by marine organisms into 1.75 million microscopic fragments, according to new research.

    Marine scientists at the University of Plymouth examined the rate at which bags were broken down by the amphipod Orchestia gammarellus, which inhabits coastal areas in northern and western Europe.

    They believe the results are an example of marine wildlife actually contributing to the spread of microplastics within the marine environment, rather than them simply being emitted from the water supply or forming through the physical and chemical break down of larger items.

    The type of plastic (conventional, degradable and biodegradable) had no effect on the rate of ingestion, however the presence of a biofilm meant the shredding took place around four times as quickly.

    This, the researchers say, is consistent with recent studies into the feeding behaviour of seabirds and suggests marine life might be increasingly attracted to marine debris as a source of food regardless of the potential harm caused…..

    D.J. Hodgson, A.L. Bréchon, R.C. Thompson. Ingestion and fragmentation of plastic carrier bags by the amphipod Orchestia gammarellus Effects of plastic type and fouling load. Marine Pollution Bulletin, 2018; 127: 154 DOI: 10.1016/j.marpolbul.2017.11.057

  3. Winter rains make SF Bay less salty, knocking back some invaders

    Leave a Comment
    • Dry and wet periods drive rapid shifts in community assembly in an estuarine ecosystem.
    • Chang’s team also found that a couple native species did better in wet years too. This suggests with the right strategy, managers could use the situation to help native species instead.

    December 7, 2017  Smithsonian Read full ScienceDaily article here

    For many Californians, last year’s wet winter triggered a case of whiplash. After five years of drought, rain from October 2016 to February 2017 broke more than a century of records. In San Francisco Bay, biologists discovered a hidden side effect: All that freshwater rain can turn the tables on some of the bay’s invasive species….

    …During dry years, when bay waters remained salty, one invader dominated above all others: the invasive tunicate Ciona robusta. A translucent, vase-shaped filter feeder from Asia, Ciona has invaded five continents, including North America’s West Coast. It has a reputation for crowding out other species, thanks to its rapid growth, and similar Ciona species have thrown a wrench into shellfish aquaculture.

    But when the wetter winters of 2006 and 2011 hit, Ciona and other solitary tunicates like it were unable to cope with the massive influxes of freshwater. In their place, mat-like colonial tunicates and encrusting bryozoans took over….

    Andrew L. Chang, Christopher W. Brown, Jeffrey A. Crooks, Gregory M. Ruiz. Dry and wet periods drive rapid shifts in community assembly in an estuarine ecosystem. Global Change Biology, 2017; DOI: 10.1111/gcb.13972

  4. Can US beef production be ‘sustainable’? A model for ‘sustainable’ US beef production

    Leave a Comment

    Nov 29 2017 Background blog perspective on this publication here

    • We are not saying grass based beef is sustainable, or unsustainable, we are just asking “suppose it is sustainable, how much can the U.S. have?”
    • Can US beef be sustainable? Depends on your metric of “sustainability”. We offer one preliminary, tentative metric of “sustainability”, and show that with beef conforming to this metric, we can meet just shy of half of today’s demand.
    • Because we believe land use must rationally balance food production, wildlife conservation and ample supply of clean fresh water, among other societal objectives, we devise our main calculation so as to provide not a single answer to the above question, but instead a continuous beef availability function that spans the full range of pastureland utilization from no grazing to full occupation of the pastureland area U.S beef currently use, ≈275 million ha.
    • In the latter most extreme case, we can have just under half of current beef supply. Amazingly (and somewhat less certainly), cutting used pastureland to half the current area will diminish this amount only trivially.
    • Is this beef sustainable? Since agricultural sustainability is yet to be generally and cogently defined, the question is ill-defined and currently unanswerable. But we doubt that by the definition we will eventfully rally behind, using 2.7 million square km—about the size of Argentina or Kazakhstan—to produce 16 g protein person-1 d-1 (or 13% of the overall per capita daily protein intake of 120 g) while jeopardizing already imperiled wildlife or degrading western hydrology and fluvial geomorphology will prove sustainable. This doubt is what the quotes enclosing the title’s “sustainable” mean.

    Eshol, G et al. A model for ‘sustainable’ US beef production. Nature Ecology & Evolution (2017) doi:10.1038/s41559-017-0390-5

    ABSTRACT: Food production dominates land, water and fertilizer use and is a greenhouse gas source. In the United States, beef production is the main agricultural resource user overall, as well as per kcal or g of protein. Here, we offer a possible, non-unique, definition of ‘sustainable’ beef as that subsisting exclusively on grass and by-products, and quantify its expected US production as a function of pastureland use. Assuming today’s pastureland characteristics, all of the pastureland that US beef currently use can sustainably deliver ≈45% of current production. Rewilding this pastureland’s less productive half (≈135 million ha) can still deliver ≈43% of current beef production. In all considered scenarios, the ≈32 million ha of high-quality cropland that beef currently use are reallocated for plant-based food production. These plant items deliver 2- to 20-fold more calories and protein than the replaced beef and increase the delivery of protective nutrients, but deliver no B12. Increased deployment of rapid rotational grazing or grassland multi-purposing may increase beef production capacity.

  5. Riparian restoration’s leaf litter can reduce nitrate pollution from fertilizers

    Leave a Comment
    • Riparian restoration in agricultural landscapes can result in leaf litter that enhances microbial activity and reduction of polluting nitrates from fertilizers- and downstream impacts of the nitrates through eutrophication (major increases in algal growth that create dead zones without oxygen).
    • Leaf inputs associated with increased riparian cover had the potential to double the catchment level rate of denitrification, offering a promising way to mitigate nitrate pollution in agricultural streams
    • For the riparian plants to be effective in adding sufficient organic matter, the number of plants and species (e.g., leaf traits, quality) and ability of stream to retain organic matter would need to be addressed in riparian management plans.
    • Riparian restoration has the greatest potential to remove nitrogen in comparison with hyporheic restoration or floodplain reconnection (Lammers and Bledsoe 2017).
    • Riparian restoration is not a silver bullet and will only address some of the nitrogen problems, and a targeted approach to increasing denitrification needs to be combined with other land-based nutrient management practices, including reductions in fertilizer application (Newcomer Johnson et al. 2016).

    O’Brien J et al. Leaf litter additions enhance stream metabolism, denitrification, and restoration prospects for agricultural catchments. Ecosphere Full publication history DOI: 10.1002/ecs2.201

    Abstract: Globally intensive agriculture has both increased nitrogen pollution in adjacent waterways and decreased availability of terrestrially derived carbon frequently used by stream heterotrophs in nitrogen cycling. We tested the potential for carbon additions via leaf litter from riparian restoration plantings to act as a tool for enhancing denitrification in agricultural streams with relatively high concentrations of nitrate (1.3–8.1 mg/L) in Canterbury, New Zealand. Experimental additions of leaf packs (N = 200, mass = 350 g each) were carried out in 200-m reaches of three randomly selected treatment streams and compared to three control streams receiving no additional leaf carbon. Litter additions increased ecosystem respiration in treatment streams compared to control streams but did not affect gross primary production, indicating the carbon addition boosted heterotrophic activity, a useful gauge of the activities of microbes involved in denitrification. Bench-top assays with denitrifying enzymes using acetylene inhibition techniques also suggested that the coarse particulate organic matter added from leaf packs would have provided substrates suitable for high rates of denitrification. Quantifying denitrification directly in experimental reaches by open-channel methods based on membrane inlet mass spectrophotometry indicated that denitrification was around three times higher in treatment streams where litter was added compared to control streams. We further assessed the potential for riparian plantings to reduce large-scale downstream nitrogen losses through increasing in-stream denitrification by modeling the effects of increasing riparian vegetation cover on nitrogen fluxes. Here, we combined estimates of in-stream ecosystem processes derived from our experiment with a network model of catchment-scale nitrogen retention and removal based on empirical measurements of nitrogen flux in this typical agricultural catchment. Our model indicated leaf inputs associated with increased riparian cover had the potential to double the catchment level rate of denitrification, offering a promising way to mitigate nitrate pollution in agricultural streams. Altogether, our study indicates that overcoming carbon limitation and boosting heterotrophic processes will be important for reducing nitrogen pollution in agricultural streams and that combining empirical approaches for predictions suggests there are large potential benefits from riparian re-vegetation efforts at catchment scales.

  6. Deforestation in wintering grounds drives decline of wood thrushes, not habitat fragmentation of breeding grounds

    Leave a Comment
    • Wood thrushes are sensitive to breeding forest fragmentation but the loss and/or degradation of habitat in the winter range in Central America is the cause of their population decline.

    November 29, 2017 Tulane University

    A decline in the number of wood thrushes is probably due to deforestation in Central America, a new study has concluded.

    ….Wood thrushes breed in the forests of the eastern United States and migrate in the winter to the forests of Central America. Although they remain a relatively common bird, the species has been declining rapidly since the early 1970’s and several researchers have suggested that fragmentation of forests in breeding grounds are playing a major role….

    Caz M. Taylor. The shape of density dependence in fragmented landscapes explains an inverse buffer effect in a migratory songbird. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-15180-4

  7. Translational ecology- connecting scientists, policymakers and natural resource managers (special issue of Frontiers in Ecology & the Environment)

    Leave a Comment

    Southwest Climate Science Center research team leads emerging transdisciplinary field

    By: Dominika Heusinkveld December 1, 2017 Southwest Climate Science Cente

    A new issue of Frontiers in Ecology and the Environment published on December 1, 2017 focuses on the emerging field of translational ecology. Modeled after translational medicine, the field aims to connect researchers in ecology with the people who apply that research on a day-to-day basis—policy makers, local governments, and natural resource managers. The goal is to help these groups utilize ecological research for issues such as fire management strategies, forest and land management, and fish and wildlife habitat restoration, among others.

    The Southwest Climate Science Research Center is a collaborative partnership between the U.S. Geological Survey (USGS) and six academic institutions across the Southwest U.S., including the University of Arizona which serves as the host institution.

    One of the core principles of translational ecology is that resource management decisions informed by scientific research will be better decisions, says Gregg Garfin, author of several papers in the new issue. Scientists and natural resource managers have discovered, however, that this is not always easy.

    “It takes around 20 years for scientific findings to make their way to use, when following a traditional pathway,” says Garfin. “It turns out that resource managers don’t have time to follow the scientific literature and that, in order to get management-relevant scientific results on the radars of resource managers, ecologists need to be more proactive—and less insular and academic—by working in partnership with stakeholders.”

    Garfin, of the University of Arizona School of Natural Resources and the Environment (SNRE), and Institute of the Environment, is University Director of the Southwest Climate Science Center. Other authors in the issue include Connie Woodhouse of the School of Geography and Development, Carolyn Enquist (SNRE affiliated faculty and Deputy Director of the SW CSC), and Steve Jackson (Geosciences and SNRE affiliated faculty and Federal Director of the SW CSC).

    Translational ecology was originally proposed in 2010 by William Schlesinger, former president of the Ecological Society of America. He advocated “constant two-way communication between stakeholders and scientists” as part of a continuing process of learning between researchers and end-users of the research.

    “These kinds of collaborations allow decision makers and scientists to better understand each other’s professional cultures, operational languages, and norms,” says Garfin. The end result should be better-informed decisions on issues which affect us all.

    Everyone is a stakeholder when it comes to ecology,” says Garfin.

    He acknowledges that not all science is suited for translation. “Basic, applied, and actionable science all eventually benefit society. Not every ecologist is interested in translational science approaches…Our aim is to create the space for translational ecology to flourish.”

    Work featured in the special issue was funded by the USGS through the Southwest Climate Science Center (www.swcsc.arizona.edu) and National Climate Change and Wildlife Science Center.

  8. Entangled North Atlantic right whales’ scat reveal ‘sky-high’ stress levels due to entanglements

    Leave a Comment
    • Endangered Species Research journal publishes pioneering whale feces research; also being used to investigate unprecedented number of right whale deaths this summer.
    • “These levels show stress from extreme physical trauma. It’s an animal welfare issue.”

    November 30, 2017 New England Aquarium Read full ScienceDaily article here

    North Atlantic right whale scientists found that whales who undergo prolonged entanglements in fishing gear endure ‘sky-high hormone levels,’ indicating severe stress, which researchers discovered using a pioneering technique of examining scat from live, entangled, and dead whales over 15 years….

    ….For the highly endangered North Atlantic right whale population, it was a devastating summer with 16 deaths — 12 in Canada and four in the US — due to vessel strikes and entanglements for a population that now only numbers around 450….

    RM Rolland, WA McLellan, MJ Moore, CA Harms, EA Burgess, KE Hunt. Fecal glucocorticoids and anthropogenic injury and mortality in North Atlantic right whales Eubalaena glacialis. Endangered Species Research, 2017; 34: 417 DOI: 10.3354/esr00866

  9. A Population of Billions May Have Contributed to Passenger Pigeon Extinction

    Leave a Comment
    • Passenger pigeons were so plentiful and so mobile that beneficial genetic mutations spread and detrimental ones disappeared very quickly throughout their population. This caused a loss in overall genetic diversity, which meant less raw material for adapting to human-induced change

    by Steph Yin November 16, 2017   read full NYTimes article here

    North America was once a utopia for passenger pigeons. When European colonizers first arrived, as many as 5 billion of the gray-backed, copper-breasted and iridescent beauties roamed the continent, possibly the most abundant bird to have ever graced the planet. When they migrated, they swept across the entire sky, obscuring daylight for hours or even days at a time, the seeming embodiment of infinity. Then, in just a few decades, the inconceivable happened: Commercialized and excessively hunted, the birds vanished.

    A paper published in Science on Thursday sheds new light on why the creatures went extinct so swiftly and thoroughly. Analyzing the DNA of preserved birds, the researchers found evidence that natural selection was extremely efficient in passenger pigeons.

    This might have made the pigeons particularly well-suited for living in dense flocks, but unable to cope with living in sparse groups once their numbers started to plummet, the authors suggest.

    Biologists generally assume that a large population corresponds to high genetic diversity, which acts as a buffer to extinction, said Susanne Fritz, an evolution expert at the Senckenberg Biodiversity and Climate Research Center in Frankfurt, Germany, who was not involved in the research.

    But passenger pigeons were so plentiful and so mobile that beneficial genetic mutations spread and detrimental ones disappeared very quickly throughout their population. This caused a loss in overall genetic diversity, which meant less raw material for adapting to human-induced change.

    It’s “totally the opposite of what you would expect,” Dr. Fritz said….

     

  10. Consumption of chinook salmon increases with recovery of West Coast marine mammals

    Leave a Comment

    November 20, 2017 Oregon State University

    The researchers estimate that from 1975 to 2015, the yearly biomass of chinook salmon consumed by pinnipeds (sea lions and harbor seals) and killer whales increased from 6,100 to 15,200 metric tons, and from five to 31.5 million individual salmon.

    ….While the recovery of marine mammals represents a conservation success, it creates complex tradeoffs for managers also charged with protecting the salmon they prey on, the study concludes. The U.S. Marine Mammal Protection Act of 1972 protects all marine mammals, including whales and pinnipeds (seals and sea lions) within the waters of the United States. and the Endangered Species Act protects nine West Coast populations of chinook salmon….

    While the recovery of marine mammals represents a conservation success, it creates complex tradeoffs for managers also charged with protecting the salmon they prey on. Credit: © Lori Pagel / Fotolia

    Brandon E. Chasco, Isaac C. Kaplan, Austen C. Thomas, Alejandro Acevedo-Gutiérrez, Dawn P. Noren, Michael J. Ford, M. Bradley Hanson, Jonathan J. Scordino, Steven J. Jeffries, Kristin N. Marshall, Andrew O. Shelton, Craig Matkin, Brian J. Burke, Eric J. Ward. Competing tradeoffs between increasing marine mammal predation and fisheries harvest of Chinook salmon. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-14984-8