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Conservation Science for a Healthy Planet

Tag Archive: grasslands

  1. Industrial farming disrupts burn-regrowth cycle in grasslands

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    June 29, 2017 University of California – Irvine  see full ScienceDaily article here

    The world’s open grasslands and the beneficial fires that sustain them have shrunk rapidly over the past two decades, thanks to a massive increase in agriculture, according to a new study led by University of California, Irvine and NASA researchers published today in Science.

    Analyzing 1998 to 2015 data from NASA’s Terra and Aqua satellites, the international team found that the total area of Earth’s surface torched by flames had fallen by nearly 25 percent, or 452,000 square miles (1.2 million square kilometers). Decreases were greatest in Central America and South America, across the Eurasian steppe and in northern Africa, home to fast-disappearing lions, rhinoceroses and other iconic species that live on these fire-forged savannas.

    A billion and a half more people have been added to the planet over the past 20 years, livestock has doubled in many places, and wide-open areas once kept open by fire are now being farmed,” said James Randerson, Chancellor’s Professor of Earth system science at UCI. “Our fire data are a sensitive indicator of the intense pressure humans are placing on these important ecosystems.”…

    Sharp increases in the number of livestock, the expansion of croplands, and new buildings and roads have fragmented the savannas and reduced highly flammable dried grasses. The expanses have become prized assets for private landowners who want to prevent brush fires. Unlike international efforts to combat tropical deforestation, there’s been less focus on protecting these vast semiarid stretches.

    “Humans are interrupting the ancient, natural cycle of burning and recovery in these areas,” Randerson said. Losing a fourth of the planet’s fires has benefits, increasing storage of dangerous carbon emissions and reducing lung-damaging smoke. But the drop-off in smoke in the atmosphere also allows more sunlight to reach the Earth’s surface, causing more global warming.

    The change is not uniform. Consistent with previous reports, more wildfires have occurred in the western U.S. and across North American boreal forests, where climate change is lengthening the fire season and drying out flammable vegetation faster.

    N. Andela, D. C. Morton, L. Giglio, Y. Chen, G. R. Van Der Werf, P. S. Kasibhatla, R. S. Defries, G. J. Collatz, S. Hantson, S. Kloster, D. Bachelet, M. Forrest, G. Lasslop, F. Li, S. Mangeon, J. R. Melton, C. Yue, J. T. Randerson. A human-driven decline in global burned area. Science, 2017 DOI: 10.1126/science.aal4108

  2. Animals, not drought, shaped grasslands environment in Africa

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    University of Utah  June 26 2017  full ScienceDaily article here
    The expansion of grasslands isn’t solely due to drought, but more complex climate factors are at work, both for modern Africans now and ancient Africans in the Pleistocene, suggests new research….

    Researchers from the University of Utah have found a better way. By analyzing isotopes of oxygen preserved in herbivore teeth and tusks, they can quantify the aridity of the region and compare it to indicators of plant type and herbivore diet. The results show that, unexpectedly, no long-term drying trend was associated with the expansion of grasses and grazing herbivores. Instead, variability in climate events, such as rainfall timing, and interactions between plants and animals may have had more influence on our ancestors’ environment. This shows that the expansion of grasslands isn’t solely due to drought, but more complex climate factors are at work, both for modern Africans now and ancient Africans in the Pleistocene.

    Scott A. Blumenthal, Naomi E. Levin, Francis H. Brown, Jean-Philip Brugal, Kendra L. Chritz, John M. Harris, Glynis E. Jehle, Thure E. Cerling. Aridity and hominin environments. Proceedings of the National Academy of Sciences, 2017; 201700597 DOI: 10.1073/pnas.1700597114

  3. Grasslands with diverse plant species have more carbon storage capacity

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    Grasslands’ carbon storage value now quantified

    Posted: 19 Apr 2017 06:15 AM PDT

    Grasslands that feature diverse plant species have more carbon storage capacity than less-diverse grasslands, largely because the former produce more biomass, the researchers say. They found that increasing the number of plant species from one to 10 had twice the value of increasing from one to two species, from the standpoint of carbon storage capacity.

    And the ability to measure the economic value of biodiversity for enhancing carbon storage could help in making decisions about land management, the paper published in the journal Science Advances concludes….

    Bruce A. Hungate, Edward B. Barbier, Amy W. Ando, Samuel P. Marks, Peter B. Reich, Natasja van Gestel, David Tilman, Johannes M. H. Knops, David U. Hooper, Bradley J. Butterfield, Bradley J. Cardinale. The economic value of grassland species for carbon storage. Science Advances, 2017; 3 (4): e1601880 DOI: 10.1126/sciadv.1601880

  4. Grasslands may be more sensitive to rising temperatures than precipitation

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    March 8, 2017 0 Comments Fangzhou Liu  Managing Editor of News  Stanford University full article here

    A team of Stanford and Columbia University researchers have found that U.S. grasslands may be more sensitive to atmospheric dryness than rainfall; their study suggests that scientists may have to look more to rising temperatures than precipitation in predicting plants’ response to global warming. Published on March 6 in Nature Geoscience, the researchers’ study examined 33 years of satellite data to understand grassland productivity in dry conditions. The timescale and quantity of data the team examined allows the study to inform predictive models of how environments will respond to droughts — which are likely to become more prevalent with rising temperatures around the globe.  …”U.S. grasslands are way more sensitive to vapor pressure deficit (VPD), which is important. Because VPD is so tightly linked to temperature, we can predict that it’s going to keep going up in the future.”…

    Sensitivity of grassland productivity to aridity controlled by stomatal and xylem regulation

    1. Konings, A. P. Williams & P. Gentine Nature Geoscience (2017) doi:10.1038/ngeo2903

    …We conclude that increases in vapour pressure deficit rather than changes in precipitation—both of which are expected impacts of climate change—will be a dominant influence on future grassland productivity.

  5. Grasslands hold potential for increased food production

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    Posted: 11 Jan 2017 06:34 AM PST  see full article here

    Managing grazing on grasslands in a more efficient way could significantly increase global milk and meat production or free up land for other uses.…”but to achieve this target in a sustainable manner, our study suggests that we should focus on making more efficient use of currently available land resources, instead of converting land from other uses.”…

    ….[the study] identified areas where additional biomass could potentially be extracted from the landscape, by comparing the current level of grazing intensity to the maximum levels supported in periods of minimum biomass supply, such as winter or dry periods…”reveals a certain potential to increase grazing intensity in some places, yet shows that the actual grassland area available for other purposes remains limited”…

    Tamara Fetzel, Petr Havlik, Mario Herrero, Karl-Heinz Erb. Seasonality constraints to livestock grazing intensity. Global Change Biology, 2017; DOI: 10.1111/gcb.13591

  6. Intensification of land use leads to the same species everywhere

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    Homogenization of species communities in our landscape documented; reducing ecosystem services
    November 30, 2016 Technical University of Munich (TUM)  ScienceDaily

    https://www.sciencedaily.com/releases/2016/11/161130133911.htm

    In places where humans use grasslands more intensively, it is not only the species diversity which decreases — the landscape also becomes more monotonous, and ultimately only the same species remain everywhere. This results in nature no longer being able to provide its ‘services’, which range from soil formation for food production to pest control.….

    …What was unique in this case was that data from organisms in the ground such as from bacteria, fungi, and millipedes were also included….The findings showed that it did not matter whether grassland areas were used moderately or intensively by humans….

    It is only when as many species as possible are able to find the unique habitats they require across large areas that ‘ecosystem services’, which improve human well-being, can remain intact. Because ‘nature’s services’ help increase food production by improving soil formation, for example, but they also help keep pests in check.

    Gossner et al. Land-use intensification causes multitrophic homogenization of grassland communities. Nature, 2016; DOI: 10.1038/nature20575

  7. New WWF Report on Grasslands Loss in US Great Plains

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    The Plowprint Report: https://www.worldwildlife.org/projects/plowprint-report

    And summary news article:

    Goodbye Grasslands. Goodbye Birds. Goodbye Carbon Sink.

    America’s Great Plains are being plowed under at an alarming rate  Nov 30 2016

    Much attention has been given to the deforestation in the Amazon and the environmental impacts that go with it. But in 2014, the American Great Plains—an area stretching from Texas into Canada—actually lost more acreage of grasslands than Brazil lost to deforestation, the World Wildlife Fund (WWF) says. In fact, said Martha Kauffman, WWF’s managing director of the Northern Great Plains program, “America’s Great Plains are being plowed under at an alarming rate.”….