Nation's Authoritative Land Cover Map New and Improved plus 1 more |
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Nation's Authoritative Land Cover Map New and Improved Posted: 07 Apr 2014 05:48 AM PDT
Summary: Just released, the latest edition of the nation’s most comprehensive look at land-surface conditions from coast to coast shows the extent of land cover types from forests to urban areas
Detailed Reference Based on Landsat ImagesContact Information: Jon Campbell ( Phone: 571-230-6831 ); Collin Homer ( Phone: 605-594-2714 ); Tom Holm ( Phone: 605-594-6127 );
Just released, the latest edition of the nation’s most comprehensive look at land-surface conditions from coast to coast shows the extent of land cover types from forests to urban areas. The National Land Cover Database (NLCD 2011) is made available to the public by the U.S. Geological Survey and partners. Dividing the lower 48 states into 9 billion geographic cells, the massive database provides consistent information about land conditions at regional to nationwide scales. Collected in repeated five-year cycles, NLCD data is used by resource managers and decision-makers to conduct ecosystem studies, determine spatial patterns of biodiversity, trace indications of climate change, and develop best practices in land management. “America’s land and waters face unprecedented challenges from natural disasters, climate change, development pressures, and population growth,” said Anne Castle, Assistant Secretary of the Interior for Water and Science. “Prudently using our public lands and developing our energy potential, while protecting our natural resources at the same time, requires a keen appreciation of how the landscape is changing over time and the causes of those changes. The digital view that the National Land Cover Dataset affords us is sweeping, yet amazingly precise. It is one of the most important tools, for the Department of the Interior or any other land or water manager, in fostering an impartial perspective of landscape dynamics.” Based on Landsat satellite imagery taken in 2011, NLCD 2011 describes the land cover of each 30-meter cell of land in the conterminous United States and identifies which ones have changed since the year 2006. Nearly six such cells — each 98 feet long and wide — would fit on a football field. Land cover is broadly defined as the biophysical pattern of natural vegetation, agriculture, and urban areas. It is shaped by both natural processes and human influences. NLCD 2011 updates the previous database version, NLCD 2006. The NLCD program is designed to provide five-year cyclical updating of our nation's land cover, similar to the cyclical population updating done by the U.S. Census. NLCD is constructed by the 10-member federal interagency Multi‑Resolution Land Characteristics Consortium (MRLC). “The ongoing 20-year collaboration of the consortium is a model of cooperation among government entities,” said Matt Larsen, USGS associate director for climate and land use change. “Combining resources from MRLC member agencies to provide digital land cover for the Nation is the best kind of teamwork. It not only advances land change science, but it saves taxpayer money.” The range and the spatial accuracy of NLCD have made it essential to thousands of expert users. The carefully calibrated data enables managers of public and private lands, urban planners, agricultural experts, and scientists with many different interests (for instance, climate, invasive species or hydrogeography) to identify critical characteristics of the land and patterns of land cover change, informing a variety of investigations from monitoring forests to modeling water runoff in urban areas. NLCD 2011 products depict 16 classes of land cover in the lower 48 states, define the degree of surface imperviousness in urban areas (impervious surface extent — concrete, asphalt, etc. — serves as a marker for urban environmental quality), and quantify the amount of tree canopy cover (essential for applications dealing with wildfire, carbon sequestration, wildlife habitat, and biodiversity). Additionally, NLCD editions from 2001 to 2011 have been integrated to provide a 10-year land cover change comparison for our nation at five year intervals. Having a decade of change information readily available for any location enables users to better understand the trajectory of land cover change patterns and provides specialists with critical information to advance the understanding of land cover change processes. NLCD 2011 products will be also released for Alaska later this year. For more information on NLCD and to download NLCD data free of charge, visit the MLRC website. |
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New DNA Tool Helps Scientists Identify Invasive Species of Aquatic Plants Posted: 07 Apr 2014 04:00 AM PDT
Summary: A new DNA protocol developed by the U.S. Geological Survey helps biologists distinguish between native and invasive species of aquatic vegetation that have almost identical appearances
Contact Information: Jon Campbell ( Phone: 571-230-6831 ); Nancy Rybicki ( Phone: 703-648-5728 ); A new DNA protocol developed by the U.S. Geological Survey helps biologists distinguish between native and invasive species of aquatic vegetation that have almost identical appearances. Until now, measuring the dispersal of these various invasive plants has been hampered by confusion about where and when the plants arrived. Invasive aquatic plants from Korea, Brazil, and the Indian subcontinent have been spreading through U.S. waterways for decades. The new DNA protocol will help biologists identify species, track their progress, and provide facts to local managers who can develop appropriate control measures. “When invasive plants appear in a body of water, local people naturally are alarmed” said Nancy Rybicki, the USGS biologist who teamed up with molecular biologists to develop the new DNA testing technique. “Enormous amounts of money are spent on control. Some species may look very nearly identical, but they have unique reproductive and growth characteristics. Identification, the first step for control or eradication, needs to be precise.” Co-author and previous USGS employee, Mary Voytek has had extensive experience with the use of molecular tools for microbial identification. In the case of microbes, there are established standards for identification using portions of an organism’s DNA. Not so with plants. It was difficult to know where to start. The authors were able to develop a simple protocol that was verified on voucher specimens and tested on numerous plant samples. The environmental implications of the results were clear as new information on the range and recent history of these invasive species was revealed. Using this new protocol, Rybicki determined that hydrilla arrived in both the Potomac River and Chesapeake Bay earlier than previously thought, a finding that revises earlier ideas of how it was first introduced into the area. The authors found that hydrilla was in the Potomac River in 1976. Thus, the original introduction of hydrilla to the Potomac was not from National Park Service experiments conducted in 1980 at Dyke Marsh on the tidal Potomac River as previously thought. It is probable that hydrilla was already present, but was misidentified. It may still be undiscovered in many locations today. The two biotypes of hydrilla, one first introduced into Florida and the other first introduced into Washington, DC, are both spreading toward Canada, well beyond their predicted range. “We anticipate that hydrilla will continue to move into colder regions, including, the Great Lakes, where a native plant called elodea is common,” Rybicki explained. “Without DNA verification, misidentification of the two plants is likely.” DNA analysis to identify underwater grasses, a service provided at the USGS lab in Reston, VA, enables quick identification of these species. Future use of DNA analysis will likely reveal that many more misidentifications have occurred and are waiting to be discovered. Positive identification is the key first step in any discussion of management options to deal with invasive species. Learn more Rybicki, N. B., Kirshtein, J. D., and Voytek, M. A., 2013, Molecular techniques to distinguish morphologically similar Hydrilla verticillata, Egeria densa, Elodea nuttallii, and Elodea canadensis, Journal of Aquatic Plant Management, v. 51, p. 94 -102. Corresponding author, nrybicki@xxxxxxxx Ecological Research on Wetlands and Submersed Aquatic Vegetation
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