Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Tag Archive: forests

  1. Tree die-offs in CA can harm trees on the opposite coast

    Leave a Comment
    • If a whole forest disappears, new research shows, this has ricocheting effects in the atmosphere that affect vegetation on the other side of the country.
    • The Pacific Southwest region, which covers most of California, has the smallest total area of tree cover. But removing those trees had the biggest influence on growing conditions nationally, by reducing vegetation in the Eastern U.S.
    • Forest loss is disrupting or changing the flow patterns in the atmosphere that is leading to a slightly different summertime climate in the eastern part of the country.

    May 16, 2018 University of Washington Read full ScienceDaily article here

    Large swaths of U.S. forests are vulnerable to drought, forest fires and disease. Many local impacts of forest loss are well known: drier soils, stronger winds, increased erosion, loss of shade and habitat. But if a whole forest disappears, new research shows, this has ricocheting effects in the atmosphere that can affect vegetation on the other side of the country.

    ….forest die-offs in specific regions of the United States can influence plant growth in other parts of the country. The largest impacts seen were from losing forest cover in California, a region that is currently experiencing dramatic tree mortality.

    “These smaller areas of forest can have continental-scale impacts, and we really need to be considering this when we’re thinking about ecological changes,” said first author Abigail Swann, a UW assistant professor of atmospheric sciences and of biology. Such far-off effects are accepted in the atmospheric sciences community, Swann said, but the idea is only beginning to be accepted by ecologists….

    “Forest loss is disrupting or changing the flow patterns in the atmosphere that is leading to a slightly different summertime climate in the eastern part of the country,” Swann said. “It’s very analogous to El Niño or ‘the blob,’ something that’s occurring that causes the atmosphere to move around, which causes these warmer or cooler conditions, or wetter and drier conditions, somewhere else.”…

    …The study suggests that current forest loss in Western regions is big enough to trigger changes in plant growth, though it might not be possible to detect these small changes over large areas of the country…

    Abigail L S Swann, Marysa M Laguë, Elizabeth S Garcia, Jason P Field, David D Breshears, David J P Moore, Scott R Saleska, Scott C Stark, Juan Camilo Villegas, Darin J Law, David M Minor. Continental-scale consequences of tree die-offs in North America: identifying where forest loss matters most. Environmental Research Letters, 2018; 13 (5): 055014 DOI: 10.1088/1748-9326/aaba0f

  2. Mixed forests: Ecologically and economically superior around the globe

    Leave a Comment
    • Meta-analysis provides facts on mixed-species forest stand productivity for science and practice
    May 9, 2018 Technical University of Munich (TUM)
    Mixed forests are more productive than monocultures. This is true on all five continents, and particularly in regions with high precipitation. These findings are highly relevant for forest science and forest management on a global scale….

    …This meta-analysis and overview study now shows that a prudent selection of the combination of tree species leads not only to more ecological and resilient forests, but also to greater productivity, explains Pretzsch. The study documents that mixed stands perform better in terms of productivity than monocultures, particularly in areas with favorable water supplies, such as in Central Europe….

    H. Jactel, E. S. Gritti, L. Drössler, D. I. Forrester, W. L. Mason, X. Morin, H. Pretzsch, B. Castagneyrol. Positive biodiversity–productivity relationships in forests: climate matters. Biology Letters, 2018; 14 (4): 20170747 DOI: 10.1098/rsbl.2017.0747
  3. Soil fungi may help determine the resilience of forests to environmental change

    Leave a Comment
    • Association of ectomycorrhizal trees with high carbon-to-nitrogen ratio soils across temperate forests is driven by smaller nitrogen not larger carbon stocks
    • the findings suggest that the mycorrhizal guild could be an emerging “functional trait” that define species in terms of their ecological roles — how they interact with the environment and with other species.
    • they are particularly valuable to scientists who are monitoring environmental responses to climate change as they can tell us how the ecosystem is responding
    • understanding how mycorrhizal relationships impact ecosystems will help us predict how forests will respond to global change.

    March 16, 2018 University of California – Santa Cruz Read full ScienceDaily article here

    A new study reveals that soil fungi could play a significant role in the ability of forests to adapt to environmental change. [The study used a] “big data” approach to investigating the role of symbiotic fungi in tree migration in forests across the eastern United States.

    …In forests, tree growth largely depends on the nutrients available in the soil, while the transfer of carbon through roots to the soil regulates ecosystem processes. Mycorrhizal (“MY-koe-RY-zull”) fungi grow on the roots of most plants and drive the nutrient-carbon exchange between plants and soil: They take up carbon resources from their hosts and provide soil nutrients that plants need.

    The two most common fungi associated with forest trees are: ectomycorrhizal (ECM), which grow on conifers, including pines, as well as oaks and beeches; and arbuscular (AM), which grow on most nonconifers, such as maples.

    ...soil carbon-to-nitrogen ratios increase with greater ECM dominance — even after accounting for climate, soil texture, and foliar nitrogen. Moreover, ECM dominance is more associated with low soil nitrogen rather than high soil carbon.

    …”These findings suggest that AM and ECM trees have differential success along nitrogen fertility gradients, or perhaps that AM and ECM trees promote differences in cycling rates of carbon and nitrogen because of traits associated with nitrogen acquisition,” he said. “Both processes may occur simultaneously, leading to a self-reinforcing positive plant-soil feedback.”

    Zhu’s findings suggest that the mycorrhizal guild could be an emerging “functional trait.”

    Functional traits are those that define species in terms of their ecological roles — how they interact with the environment and with other species. As such, they are predictable and easily measured from the ground or by satellite, which makes them particularly valuable to scientists who are monitoring environmental responses to climate change. “They tell us how the ecosystem is responding,” said Zhu.

    Kai Zhu, M. Luke McCormack, Richard A. Lankau, J. Franklin Egan, Nina Wurzburger. Association of ectomycorrhizal trees with high carbon-to-nitrogen ratio soils across temperate forests is driven by smaller nitrogen not larger carbon stocks. Journal of Ecology, 2018; 106 (2): 524 DOI: 10.1111/1365-2745.12918

  4. Climate value of Earth’s intact forests

    Leave a Comment
    • Conservation efforts and the fight against climate change risk failure unless intact forests are preserved

    February 26, 2018 Wildlife Conservation Society read full ScienceDaily article here

    New research published today in Nature Ecology & Evolution demonstrates the extraordinary value of Earth’s remaining intact forests for addressing climate change and protecting wildlife, critical watersheds, indigenous cultures, and human health.

    Yet the global policy and science communities do not differentiate among the relative values of different types of forest landscapes — which range from highly intact ones to those which are heavily logged, fragmented, burnt, drained and/or over-hunted — due in part to the lack of a uniform way of measuring their quality….

    ….Retaining the integrity of intact forests must be a central component of global and national environmental strategies, alongside current efforts to stabilize deforestation frontiers and stimulate restoration. The researchers recommend several policy interventions to fill this gap, including:

    • Creating new standard metrics of intactness that can be used to raise awareness of the importance of forest quality and to help target action towards the most intact places.
    • Embedding the intact forests concept in the UN Framework Convention on Climate and the Intergovernmental Panel on Climate Change’s Special Reports, to help ensure the Paris Agreement’s climate commitments include intact forest protections.
    • Supporting global and local forest policies that limit road expansion; regulate hunting, extraction, and development; invest in restoration and protected areas; and help secure indigenous communities’ land tenure rights.
    • Supporting efforts that both restore and make degraded forests more productive while also conserving at-risk intact systems — rather than opening intact forests to activity.

    James E. M. Watson, Tom Evans, Oscar Venter, Brooke Williams, Ayesha Tulloch, Claire Stewart, Ian Thompson, Justina C. Ray, Kris Murray, Alvaro Salazar, Clive McAlpine, Peter Potapov, Joe Walston, John G. Robinson, Michael Painter, David Wilkie, Christopher Filardi, William F. Laurance, Richard A. Houghton, Sean Maxwell, Hedley Grantham, Cristián Samper, Stephanie Wang, Lars Laestadius, Rebecca K. Runting, Gustavo A. Silva-Chávez, Jamison Ervin, David Lindenmayer. The exceptional value of intact forest ecosystems. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-018-0490-x

  5. Researchers find post-fire logging harms spotted owls

    Leave a Comment
    • Post-fire logging damages important spotted owl foraging areas in “snag forest habitat” that is created by patches of intense fire. This habitat is rich in the small mammal prey species that the owls feed upon, but post-fire logging largely removes this habitat, thereby causing higher rates of territory abandonment
    January 17, 2018 by John Muir Project read full article at phys.org

    Wildlife ecologists studying the rare spotted owl in the forests of California have discovered that large, intense wildfires are not responsible for abandonment of breeding territories. Instead, the researchers found that post-fire logging operations, which are common on both private and National Forest lands, most likely caused declines in territory occupancy of this imperiled wildlife species.

    In the absence of post-fire logging, they found no significant effect of large forest fires on spotted owl territory occupancy. Post-fire logging damages important spotted owl foraging areas in “snag forest habitat” that is created by patches of intense fire. This habitat is rich in the small mammal prey species that the owls feed upon, but post-fire logging largely removes this habitat, thereby causing higher rates of territory abandonment.

    “This is good news for declining California because this is something that we can control—we can make policy decisions to stop post-fire logging operations in spotted owl habitat….

    …The scientists’ findings also expand upon previous research that found very high spotted owl occupancy after the 257,000-acre Rim fire of 2013 in the Sierra Nevada prior to post-fire logging. The current study found a decline in owl territory occupancy in the same area after post-fire logging occurred. A co-author on both studies, Dr. Derek Lee, also of Wild Nature Institute, said, “It is time to stop thinking logging will help the forest; we need to take a much more hands-off approach to forest management so natural processes can re-establish.”

  6. Managing forests for cooler microclimates

    Leave a Comment
    • Forest density has a large impact on the microclimatic landscape near the ground.
    • Forest management has the potential to slow down biodiversity loss by reducing forest fragmentation and creating buffer zones around cold places so they remain cold, when close-by forest is cut down.

    January 11, 2018 Stockholm University Read full ScienceDaily article here

    When studying the effect of climate change on biodiversity, it is important to consider the climate near the ground (microclimate) which a plant or an animal actually experiences. Deep shady depressions, dense old forests or places close to water for example are always considerably cooler than their surroundings.

    “Knowing where cold climate refugia are in the landscape means we can protect these cold spots and help cold-adapted species to survive a warmer climate. Knowing how colder microclimates are generated means we could even create colder spots by wisely managing our forests,” says Caroline Greiser, PhD student at Department of Ecology, Environment and Plant Sciences.

    The scientists found out that summer maximum temperatures at the forest floor can differ more than 10°C over only 100 meters.

    “We also found out that the forest plays a dominant role in controlling warm near-ground temperatures in the summer, more than local topography. In other words, the temperature differences between open and dense forest stands are larger than the differences between the sunny and the shady side of a hill” says Caroline Greiser….

    …Microclimate is the climate near the ground which can be colder or warmer than in the free atmosphere, depending on local topography (e.g. north vs. south side of a hill, higher vs. lower elevation) and vegetation (e.g. young sparse vs. old dense forest).

    Caroline Greiser, Eric Meineri, Miska Luoto, Johan Ehrlén, Kristoffer Hylander. Monthly microclimate models in a managed boreal forest landscape. Agricultural and Forest Meteorology, 2018; 250-251: 147 DOI: 10.1016/j.agrformet.2017.12.252

  7. In California’s wildfires, a looming threat to climate goals

    Leave a Comment
    • CA’s environmental regulations apply only to human-caused emissions. Carbon and other pollution generated by wildfires is outside state law.
    • Forests are part of the state’s strategy for cutting greenhouse-gas emissions significantly by 2020 and beyond…. The air board will direct state agencies to determine more precisely how much carbon can be absorbed by California’s variety of landscapes….
    • The U.S. Forest Service this week updated its estimate of dead trees across California to 129 million. That loss alone could be a blow to the state’s vision of a low-carbon future.

    by Julie Cart December 14 2017 Read full CalMatters article here

    Beyond the devastation and personal tragedy of the fires that have ravaged California in recent months,  another disaster looms: an alarming uptick in unhealthy air and the sudden release of the carbon dioxide that drives climate change.

    …..The state’s environmental regulations are known to be stringent, but they have limits: They apply only to human-caused emissions. Carbon and other pollution generated by wildfires is outside the grasp of state law.

    ….In less than one week, for example, October’s wine-country fires discharged harmful emissions equal to that of every car, truck and big rig on the state’s roads in a year. The calculations from the subsequent fires in Southern California are not yet available, but given the duration and scope of the multiple blazes, the more recent complex of fires could well exceed that level.

    The greenhouse gases released when forests burn not only do immediate harm, discharging carbon dioxide and other planet-warming gases, but also continue to inflict damage long after the fires are put out. In a state where emissions from nearly every industry are tightly regulated, if wildfires were treated like other carbon emitters, Mother Nature would be castigated, fined and shut down.

    The air board estimates that between 2001 and 2010, wildfires generated approximately 120 million tons of carbon. But Clegern said a direct comparison with regulated emissions is difficult, in part because of limited monitoring data….

    ….Scientists estimate that in severely burned areas, only a fraction of a scorched tree’s emissions are released during the fire, perhaps as little as 15 percent. The bulk of greenhouse gases are released over months and years as the plant dies and decomposes.  And if a burned-out forest is replaced by chaparral or brush, that landscape loses more than 90 percent of its capacity to take in and retain carbon, according to the [Sierra Nevada] Conservancy….

    ….The role of wildfire as a major source of pollution was identified a decade ago, when a study conducted by the National Center for Atmospheric Research concluded that “a severe fire season lasting only one or two months can release as much carbon as the annual emissions from the entire transportation or energy sector of an individual state.”

    ….The entire equation has been made worse by the state’s epidemic of tree death, caused by drought, disease and insect infestation. The U.S. Forest Service this week updated its estimate of dead trees across California to 129 million. That loss alone could be a blow to the state’s vision of a low-carbon future.

    ….Forests as carbon-chewers are part of the state’s strategy for cutting greenhouse-gas emissions significantly by 2020 and beyond—a goal that could be undermined by nature’s caprice. The air board will direct state agencies to determine more precisely how much carbon can be absorbed by California’s variety of landscapes….

    ….Sean Raffuse, an analyst at the Air Quality Research Center at the University of California, Davis, came up with the “back of the envelope” calculations for October’s Sonoma County fires.

    Raffuse said he used federal emissions inventories from fires and calculated that five days of ashy spew from the northern California blazes equated to the annual air pollution from every vehicle in California….

     

  8. Forest resilience declines in face of wildfires in a warmer climate

    Leave a Comment
    • They found significant decreases in tree regeneration following wildfires in the early 21st century, a period markedly hotter and drier than the late 20th century. The research team said that with a warming climate, forests are less resilient after wildfires.
    • While trees similar to the ones that burned have typically been planted on a fire-ravaged site, that may no longer be the smartest approach. Managers may want to plant species that are adapted to the current and future climate, not the climate of the past.

    December 12, 2017 Colorado State University read full ScienceDaily article here

    The forests you see today are not what you will see in the future. That’s the overarching finding from a new study on the resilience of Rocky Mountain forests.

    ….They wanted to understand if and how changing climate over the last several decades affected post-fire tree regeneration, a key indicator of forest resilience.

    They found sobering results, including significant decreases in tree regeneration following wildfires in the early 21st century, a period markedly hotter and drier than the late 20th century. The research team said that with a warming climate, forests are less resilient after wildfires.

    ….Stevens-Rumann said that while trees similar to the ones that burned have typically been planted on a fire-ravaged site, that may no longer be the smartest approach….

    Managers may want to plant species that are adapted to the current and future climate, not the climate of the past,” she said. “There also are areas that could support certain tree species but there isn’t any regeneration currently; these are the ideal places to plant after a fire.”

    The problem could also be addressed when a fire happens.

    Another strategy is to foster fires burning under less extreme conditions, so that more trees survive to provide seed for future forests,” said Penny Morgan, professor at the University of Idaho and co-author of the study. “When fires are patchy, more areas are within reach of a surviving tree.”…

    Camille S. Stevens-Rumann, Kerry B. Kemp, Philip E. Higuera, Brian J. Harvey, Monica T. Rother, Daniel C. Donato, Penelope Morgan, Thomas T. Veblen. Evidence for declining forest resilience to wildfires under climate change. Ecology Letters, 2017; DOI: 10.1111/ele.12889

  9. Mapping biodiversity of forests with remote sensing; the more diverse, the more resilient

    Leave a Comment

    Posted: 13 Nov 2017 06:55 AM PST  read full ScienceDaily article here

    Productivity and stability of forest ecosystems strongly depend on the functional diversity of plant communities. Researchers have developed a new method to measure and map functional diversity of forests at different scales — from individual trees to whole communities — using remote sensing by aircraft [paving] the way for future airborne and satellite missions to monitor global plant functional diversity.

    Ecological studies have demonstrated positive relationships between plant diversity and ecosystem functioning. Forests with higher functional diversity are generally more productive and stable over long timescales than less diverse forests. Diverse plant communities ….can better cope with changing environmental conditions — an insurance effect of biodiversity. They are also less vulnerable to diseases, insect attacks, fire and storms.

    Researchers from the UZH and the California Institute of Technology / NASA Jet Propulsion Laboratory have now developed a new remote-sensing method to map functional diversity of forests from small to large scales, independent of any predefined vegetation units or species information and without the need for ground-based calibration….

    With airborne laser scanning, the scientists measured morphological characteristics of the forest canopy such as canopy height, foliage and branch densities. These measurements indicate how the sunlight is taken up by the canopy to assimilate carbon dioxide from the air and use the carbon to grow. In a canopy with a more diverse structure, light can better spread between different vertical canopy layers and among individual tree crowns, allowing for a more efficient capture of light. The researchers also characterized the forest with regards to its biochemical properties using airborne imaging spectroscopy. By measuring how leaves reflect the light in many spectral bands, they were able to derive physiological traits such as the content of leaf pigments (chlorophylls, carotenoids) and leaf water content

    We can see, for example, if a tree is suffering water stress, and what resource allocation strategy a tree is following or how it adapts to the environment,”

    Fabian D. Schneider et al. Mapping functional diversity from remotely sensed morphological and physiological forest traits. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-01530-3


  10. Carbon feedback from forest soils accelerates global warming

    Leave a Comment
    • Soil warming stimulates periods of abundant carbon release from the soil to the atmosphere alternating with periods of no detectable loss in soil carbon stores
    • Humans release about 10 billion metric tons (Gt) of carbon into the atmosphere each year and Earth’s soils contain about 3500 billion metric tons (Gt) of carbon which if added to atmosphere could accelerate global warming
    • Over the course of the 26-year experiment (which still continues), the warmed plots lost 17 percent of the carbon that had been stored in organic matter in the top 60 centimeters of soil
    • Study demonstrates value of long term data sets

    October 5, 2017  Marine Biological Laboratory  read full ScienceDaily article here

    After 26 years, the world’s longest-running experiment to discover how warming temperatures affect forest soils has revealed a surprising, cyclical response: Soil warming stimulates periods of abundant carbon release from the soil to the atmosphere alternating with periods of no detectable loss in soil carbon stores. The study indicates that in a warming world, a self-reinforcing and perhaps uncontrollable carbon feedback will occur between forest soils and the climate system, accelerating global warming.

    ….each year, mostly from fossil fuel burning, we are releasing about 10 billion metric tons of carbon into the atmosphere. That’s what’s causing the increase in atmospheric carbon dioxide concentration and global warming. The world’s soils contain about 3,500 billion metric tons of carbon. If a significant amount of that soil carbon is added to the atmosphere, due to microbial activity in warmer soils, that will accelerate the global warming process. And once this self-reinforcing feedback begins, there is no easy way to turn it off. There is no switch to flip.”…

    ….”if the microbes in all landscapes respond to warming in the same way as we’ve observed in mid-latitude forest soils, this self-reinforcing feedback phenomenon will go on for a while and we are not going to be able to turn those microbes off. Of special concern is the big pool of easily decomposed carbon that is frozen in Arctic soils. As those [Arctic] soils thaw out, this feedback phenomenon would be an important component of the climate system, with climate change feeding itself in a warming world….”

    Heated and control plots in a long-term soil warming study at Harvard Forest, Petersham, Mass. Jerry Melillo of the Marine Biological Laboratory, Woods Hole, Mass., and colleagues began the study in 1991.
    Credit: Audrey Barker-Plotkin
    …Melillo and colleagues began this pioneering experiment in 1991 in a deciduous forest stand at the Harvard Forest in Massachusetts. They buried electrical cables in a set of plots and heated the soil 5° C above the ambient temperature of control plots. Over the course of the 26-year experiment (which still continues), the warmed plots lost 17 percent of the carbon that had been stored in organic matter in the top 60 centimeters of soil….
    J. M. Melillo, S. D. Frey, K. M. DeAngelis, W. J. Werner, M. J. Bernard, F. P. Bowles, G. Pold, M. A. Knorr, A. S. Grandy. Long-term pattern and magnitude of soil carbon feedback to the climate system in a warming world. Science, 2017; 358 (6359): 101 DOI: 10.1126/science.aan2874