USGS Newsroom

Wolf Harassment Has Little Impact on Elk

OC_Web@usgs.gov (Office of Communications and Publishing) — Tue, 11 Jun 2013 14:00:00 EDT

LARAMIE, Wyo. — The mere presence of wolves, previously shown to affect the behavior of elk in the greater Yellowstone ecosystem, is not potent enough to reduce the body condition and reproductive rates of female elk, according to new research published today.

The research, led by recent University of Wyoming Ph.D. graduate Arthur Middleton, provides the most comprehensive evidence to date refuting the idea that wolves are capable of reducing elk calf recruitment indirectly through predation risk. The findings were published in the scientific journal Ecology Letters.

"Elk respond to wolves, but less strongly and less frequently than we thought," says Middleton, who for three years closely followed the Clarks Fork elk herd west of Cody, along with the wolf packs that prey on it. "We found that wolves influence elk behavior, but the responses were subtle and -- over the course of winter -- did not reduce body fat or pregnancy. Our work indicates that the effect of wolves on elk populations is limited to direct predation and doesn't include so-called harassment, stress and fear, which have been proposed as additional indirect effects on prey populations."

Working as part of the Wyoming Cooperative Fish and Wildlife Research Unit -- a U.S. Geological Survey program housed at UW in cooperation with the Wyoming Game and Fish Department -- Middleton and colleagues used state-of-the-art GPS collars and firsthand observation to track the interactions of the Clarks Fork herd with wolves from the Sunlight, Hoodoo, Beartooth and Absaroka wolf packs in 2008, 2009 and 2010. The detailed movement data on both wolves and elk allowed the researchers to identify each time one of the collared elk encountered a collared wolf. The elk herd, one of several migratory herds in the greater Yellowstone area, spends summers in Yellowstone National Park and moves into the Sunlight Basin during winter. The researchers also recaptured GPS-collared elk at the end of winter and the end of summer each year to assess their annual fat dynamics and pregnancy rates using ultrasonography.

The research found that when wolves approached within 1 kilometer (a little over a half mile), elk increased their rates of movement, displacement and vigilance. However, the behaviors only lasted about 24 hours and didn't significantly reduce elk foraging or force elk into poor habitats. And such encounters with wolves took place at a rate of only one in nine days on average for the migratory elk in the Clarks Fork herd -- the maximum was once every four days.

The key finding of the study is that even though elk varied widely in their encounters with wolves, those that encountered wolves frequently were not less fat -- or any less likely to be pregnant -- than those that rarely bumped into the predators. This finding differs from some previous studies that indicated wolves influence elk behavior strongly enough to contribute to regionwide declines in calf production.

"Our research was unique in that we tracked wolves while also monitoring the movements, foraging behavior, body fat and pregnancy of the elk they hunted," says Middleton, who worked under Matt Kauffman, head of the Wyoming Cooperative Fish and Wildlife Research Unit working under a dual appointment with the USGS and the UW's Department of Zoology and Physiology where he is an assistant professor. "This approach, essentially connecting the dots from wolf movements all the way to elk behavior and nutrition, revealed that elk respond to wolves too weakly and too infrequently for those behaviors to carry nutritional costs."

The study casts additional doubt on the idea that wolf reintroduction has caused what scientists call a "behaviorally mediated trophic cascade" in the greater Yellowstone ecosystem -- prompting elk to alter their foraging behavior or avoid risky areas, thereby allowing aspen and willows to recover from overbrowsing. These new findings are consistent with studies by Kauffman and others showing little or no evidence for cascading effects caused by purported broad-scale shifts in elk habitat use or foraging behavior in response to wolves.

Both Middleton and Kauffman have pointed out in their studies that the wide-ranging hunting strategy of wolves, which differs from the tactics of a stalking predator, might be the reason that elk responses are too weak and inconsistent to alter their foraging patterns or nutritional gain.

"A key factor in the ability of predators to cause these sorts of cascading effects is the ways in which they hunt and kill their prey," says Kauffman, who initiated the study in 2006 along with Game and Fish Department wildlife biologist Doug McWhirter and U.S. Fish and Wildlife Service wolf manager Mike Jimenez. "Wolves are coursing predators that chase down their prey, as opposed to stalking predators that lurk in concealed areas. We are learning that coursing predators are less likely to induce strong behavioral responses in their prey, and this new work suggests that the coursing hunting mode of wolves may constrain both their ability to influence prey condition and cause cascading ecological effects on plants."

Kauffman adds that the concept of non-consumptive effects of predators on prey has been well tested in small, well-controlled environments -- often involving insect predators and prey -- but that researchers are still sorting out how it all works in the large landscapes occupied by species such as wolves and elk.

Calf production has been declining among migratory elk herds in the greater Yellowstone area, but wolves may not be the primary culprit, Middleton says. For the Clarks Fork herd at least, other recent research findings point to high rates of bear predation and reduced habitat quality due to drought -- both on summer ranges largely inside Yellowstone -- as being the more likely cause of declines in elk calf numbers.

"The recovery of large carnivores, particularly grizzly bears, has brought major increases in predation on newborn elk during early summer," wrote Middleton, who added that the region has experienced severe drought and warmer temperatures in recent years. "These effects of drought and predation could largely explain both low pregnancy and declining calf production among elk of the Yellowstone region."

Kauffman, a USGS scientist, is one of the co-authors of the report published today -- along with a collaborative team of researchers from the Game and Fish Department, the Fish and Wildlife Service, the National Council for Air and Stream Improvement, Yellowstone National Park and UW.

The article summarizing the research in Ecology Letters is available online.

Migration No Longer Best Strategy for Yellowstone Elk

OC_Web@usgs.gov (Office of Communications and Publishing) — Wed, 5 Jun 2013 13:00:00 EDT

LARAMIE, Wyo. — Migratory elk are coming back from Yellowstone National Park with fewer calves due to drought and increased numbers of big predators – two landscape-level changes that are reducing the benefits of migration with broader implications for conservation of migratory animals, according to a new study published in the journal Ecology.

The new study by the Wyoming Cooperative Fish and Wildlife Research Unit – a joint program involving U.S. Geological Survey, the University of Wyoming, and the Wyoming Game and Fish Department, describes a long-term decline in the number of calves produced annually by the Clarks Fork herd, a population of about 4000 elk whose migrants travel annually between winter ranges near Cody, Wyoming and summer ranges within Yellowstone National Park. Migratory elk experienced a 19 percent depression in rates of pregnancy over the four years of the study and a 70 percent decline in calf production over 21 years of monitoring by the WGFD, while the elk that did not migrate, known as resident elk, in the same herd experienced high pregnancy and calf production and are expanding their numbers and range into private lands outside of the park.

"This is one of North America's wildest and best-protected landscapes, where elk and other ungulates still retain their long-distance seasonal migrations – and yet it is the migratory elk that are struggling while their resident counterparts thrive in the foothills," said Arthur Middleton, who led this work as a University of Wyoming doctoral student and is now a postdoctoral fellow at the Yale School of Forestry and Environmental Studies.

A key finding of the study was that only 70 percent of migratory elk were pregnant, compared to 90 percent of residents – a rate more typical of Rocky Mountain elk. The study shows that the hotter and dryer summer conditions of the last two decades, coincident with the long-term drought widely affecting the West, has reduced the duration of the spring period when tender new grasses are available to elk. This makes it harder for female migratory elk to find the forage they need to both nurse a calf and breed. Though elk typically bear a calf every year, migratory elk that nursed a calf had only a 23 percent chance of becoming pregnant again in the following year.

Another likely cause of the declining calf numbers among migrants was predation. Migrants share their range with four times as many grizzly bears and wolves than resident elk, and both predators are well known to prey on young elk calves. Resident elk get a break from high levels of predation in part because when predators kill livestock on the resident range, they are often lethally removed by wildlife managers and ranchers.

"A lower pregnancy rate reduces the number of calves that are born in the first place, then predation seems to reduce the number of migratory calves that survive the first few months of life," said Matthew Kauffman a research wildlife biologist with the USGS and Assistant Professor at the University of Wyoming. Kauffman goes on to explain that resident elk numbers are growing in the foothills not because migrants are choosing to stay behind, but rather because irrigated fields and lower predator numbers are allowing residents to raise more calves to adulthood.

Globally, wildlife migration is a dwindling phenomenon. Research and management often focus on conspicuous barriers like fences, roads, and other kinds of development that can physically impede migration corridors. While those are important, this study suggests that even in a landscape as well-protected as the Greater Yellowstone Ecosystem, subtler changes in predator management and forage quality on the seasonal ranges of migratory animals will also play an important role. Migration is conventionally understood as a strategy to gain better forage quality while also reducing exposure to denning predators, but in this case, it seems those benefits are instead being realized by the residents.

The study's authors note that their work does not predict that migratory elk will disappear, but rather that there could be a long-term shift underway in the relative abundance of migratory versus resident elk in the system. The study also highlights the perils of characterizing Yellowstone wolf re-introduction as a "natural experiment." Other key factors have changed since wolves were re-introduced, including growth in grizzly bears numbers and recurrent long-term drought associated with reduced snowpack and hotter summers. The authors caution that such factors should be taken into account in the effort to understand ongoing ecological changes in Yellowstone.

Middleton also points out that this work highlights the complex challenges facing regional wildlife managers and other stakeholders as they continue to adapt to the reintroduction and recovery of large carnivores, and severe drought that some studies suggest is linked to longer-term climate change. "Most immediately, these trends have meant lost hunting opportunity in the backcountry areas frequented by migratory elk, and increasing crop damage and forage competition with domestic livestock in the frontcountry areas where resident elk are expanding," said Middleton.

This work was a collaboration among the USGS’s Wyoming Cooperative Fish and Wildlife Research Unit, the WGFD, and the U.S. Fish and Wildlife Service, with cooperation from YNP and other agencies. Primary funders include the WGFD, the Rocky Mountain Elk Foundation, the Wyoming Animal Damage Management Board, the Wyoming Governor’s Big Game License Coalition, and USGS, among others.

The study is featured in a Forum section of Ecology, with a series of commentaries from other ecologists who study wildlife migration and predator-prey interactions.

Funding from the USGS National Climate Change and Wildlife Science Center contributed to this study.

Measuring Landscape Disturbance of Gas Exploration in Fayette and Lycoming Counties

OC_Web@usgs.gov (Office of Communications and Publishing) — Mon, 3 Jun 2013 15:41:55 EDT

Landscape change in Pennsylvania's Fayette and Lycoming counties resulting from construction of well pads, new roads and pipelines for natural gas and coalbed methane exploration is being documented to help determine the potential consequences for ecosystems and wildlife, according to a U.S. Geological Survey report released today.

Using geospatial data and high resolution aerial imagery from 2004-2010, USGS researchers documented spatially explicit patterns of disturbance, or land use, related to natural gas resource development, such as hydraulic fracturing, particularly disturbance patterns related to well pads, roads and pipeline construction.

Spatially explicit data on the level of landscape disturbance -- which is geographic information systems data, mapped to a high degree of spatial accuracy -- is critically important to the long-term study of the potential impacts of natural gas development on human and ecological health.

Through programs such as the National Land Cover Database, and Land Cover Trends, USGS has a long record of studying the consequences of land-use and land-cover changes. The current level of natural gas development in much of the country, and its effects on the landscape, is an important contemporary land-use/land-cover issue.

"Large-scale landscape disturbance can have a significant impact on ecological resources and the services they provide. This study provides a quantitative look at the levels of disturbance, forest loss and other changes to land use and land cover," said Terry Slonecker, lead author of the research.

Data from this report will be used to assess the effects of disturbance and land-cover change on wildlife, water quality, invasive species and socioeconomic impacts, among other investigations.

The study found that in Fayette County, 1297 natural gas extraction sites resulted in more than 1765.1 hectares of disturbance, including 466.9 kilometers (290 miles) of new roads and 3.7 kilometers (2 miles) of new pipelines. Disturbance in Fayette County occurs on the western side of the county.

In Lycoming County, 83 natural gas extraction sites resulted in more than 421 hectares of disturbance, including 37 kilometers (22 miles) of new roads and 73.7 kilometers (45 miles) of new pipelines. Disturbance in Lycoming County is scattered with most of it occurring in clusters in the eastern and western edges of the county.

The study, "Landscape consequences of natural gas extraction in Fayette and Lycoming Counties, Pennsylvania, 2004-2010," by E.T. Slonecker, L.E. Milheim, C.M. Roig-Silva, A.R. Malizia, and B.H. Gillenwater Open File Report 2013-1119, is the fourth of a series planned relating to natural gas landscape disturbance and is available online.

Spring 2012 Earliest on Record

OC_Web@usgs.gov (Office of Communications and Publishing) — Wed, 15 May 2013 13:25:26 EDT

March 2012 set records for warm temperatures that promoted early leafing and flowering across large areas of the United States. A team of scientists at the USA National Phenology Network, which is sponsored by the U.S. Geological Survey, have published a study which shows that 2012 was the earliest spring over the 48 U.S. states since 1900 when systematic weather data began to be available for the entire area.

Phenology is the study of recurring plant and animal life cycle stages, especially their timing and relationships with weather and climate. Assessing the severity and impacts of such extreme climatic events, either in the past or as they happen, requires consistent indicators of variability and change that can be mapped both nationally and historically.

The USA National Phenology Network provides a suite of "spring indices" based on the accumulated warmth needed to end dormancy and initiate growth in many native and cultivated plants. These complex, evidence-based algorithms can be calculated for any weather station that records daily maximum and minimum temperatures. Spring indices are independently validated using historical observations of leafing and flowering in lilac and honeysuckle nationwide.

The historical trend of spring indices suggests that the 2012 growing season advanced as much as 20-30 days in the East and Midwest from the 1900-2012 long-term mean.

"The results of this study clearly demonstrate the great importance of long-term monitoring of natural processes. A long record allows us to identify patterns of change that we might otherwise miss," said Suzette Kimball, acting USGS Director.

Today the response of vegetation to temperature and precipitation can be readily observed across wide areas by Earth-observing satellites at intervals of only a few days. USGS scientist Julio Betancourt, a co-author of the study, noted, "Indicators such as spring indices and satellite-based evaluations of vegetation growth will become essential tools for assessing climate variability and change and their impacts."

Satellite data show that the cumulative effects of the unusually early 2012 spring were most pronounced across the Corn Belt, the western Great Lakes region, and the northeastern U.S.

The beneficial effects of spring's quick start in 2012 were subsequently offset by a late spring frost and summer drought. In fact, the unusually early spring combined with late frosts in April to produce a so-called "false spring" that damaged fruit trees across the Upper Midwest and Great Lakes regions.

The study appears in EOS, Transactions of the American Geophysical Union.

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Warmer Springs Causing Loss of Snow Cover throughout the Rocky Mountains

OC_Web@usgs.gov (Office of Communications and Publishing) — Mon, 13 May 2013 14:00:00 EDT

BOZEMAN, Mont. – Warmer spring temperatures since 1980 are causing an estimated 20 percent loss of snow cover across the Rocky Mountains of western North America, according to new research from the U.S. Geological Survey.

The new study builds upon a previous USGS snowpack investigation which showed that, until the 1980s, the northern Rocky Mountains experienced large snowpacks when the central and southern Rockies experienced meager ones, and vice versa. Yet, since the 1980s, there have been simultaneous snowpack declines along the entire length of the Rocky Mountains, and unusually severe declines in the north.

The new study has teased apart and quantified the different influences of winter temperature, spring temperature, and precipitation on historic snowpack variations and trends in the region. To distinguish those varying influences, the researchers implemented a regional snow model that uses inputs of monthly temperature and precipitation data from 1895 to 2011.

"Each year we looked at temperature and precipitation variations and the amount of water contained within the snowpack as of April," said USGS scientist Greg Pederson, the lead author of the study. "Snow deficits were consistent throughout the Rockies due to the lack of precipitation during the cool seasons during the 1930s – coinciding with the Dust Bowl era. From 1980 on, warmer spring temperatures melted snowpack throughout the Rockies early, regardless of winter precipitation. The model in turn shows temperature as the major driving factor in snowpack declines over the past thirty years."

Runoff from Rocky Mountain winter snowpack accounts for 60 to 80 percent of the annual water supply for more than 70 million people living in the western U.S., and is influenced by factors such as the snowpack’s water content, known as snow water equivalent, and the timing of snowmelt.

The timing of snowmelt affects not only when water is available for crop irrigation and energy production from hydroelectric dams, but also the risk of regional floods and wildfires. Earlier and faster snowmelt could have repercussions for water supply, risk management, and ecosystem health in western watersheds.

Regional snowpack accumulation is highly sensitive to variations in both temperature and precipitation over time. Patterns and sources of these variations are difficult to discern due to complex mountain topography, the different influence of Pacific Ocean climate, like La Niña and El Niño, on winter precipitation in the northern versus southern and central Rockies, and the brevity and patchiness of detailed snow records.

In the study, the regional snow model used by Pederson and his USGS colleagues Julio Betancourt and Greg McCabe allows estimation of snow water and cover variability at different latitudes and elevations during the last century regardless of the absence of direct and long-term observations everywhere. Recent snowpack variations also were evaluated in the context of snowpack evidence from tree-rings, allowing the scientists to compare recent observations to measurements from the past 800 years.

McCabe, co-author of the study, explains that "recent springtime warming also reduced the extent of snow cover at low to middle elevations where temperature has had the greatest impact."

"Both natural variability in temperature and anthropogenic warming have contributed to the recent snowpack decline, though disentangling their influences exactly remains elusive." Betancourt said,

"Regardless of the ultimate causes, continuation of present snowpack trends in the Rocky Mountains will pose difficult challenges for watershed management and conventional water planning in the American West."

The study, "Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains," is available from Geophysical Research Letters, a journal of the American Geophysical Union.

Landsat Images Provide the Gold Standard for New Earth Applications

OC_Web@usgs.gov (Office of Communications and Publishing) — Thu, 9 May 2013 12:29:39 EDT

WASHINGTON — Images from Landsat satellites provided free to the public by the Department of the Interior's U.S. Geological Survey were the starting points for "a new breakthrough" reported today by Time and announced on the Official Google Blog. Using its Earth Engine technology, Google has compiled decades of Landsat images into a new, interactive time-lapse experience.

"This news is the latest example of how the Department of the Interior's policy of unrestricted access and free distribution of Landsat satellite imagery to the public fosters innovation and mutual awareness of environmental conditions around the globe," said Anne Castle, Assistant Secretary of the Interior for Water and Science. "The 40-year archive of Landsat images of every spot on earth is a treasure trove of scientific information that can form the basis for a myriad of useful applications by commercial enterprises, government scientists and managers, the academic community, and the public at large."

Other commercial products, such as ESRI's Change Matters, also utilize Landsat imagery, providing data for a deeper geographic understanding of the changing world.

Landsat data can assist a broad range of specialists in managing the world's food, water, forests, and other natural resources for a growing world population. The Landsat images contain many layers of data collected at different points along the visible and invisible light spectrum. Consequently, they can show where vegetation is thriving and where it is stressed, where droughts are occurring, where wildland fire is a danger, and where erosion has altered coastlines or river courses.

Landsat satellites provide a view as broad as 12,000 square miles per scene while describing land cover in pixels the size of a baseball diamond. From a distance of more than 400 miles above the earth surface, a single Landsat scene can record the condition of hundreds of thousands of acres of grassland, agricultural crops, or forests.

"With its long-term historical record of the entire globe and widely recognized high quality of data, Landsat is valued all over the world as the gold standard of land observation," said Castle.

Ready access to authoritative Landsat images provides a reliable common record of Earth conditions that advances the mutual understanding of environmental challenges by citizens, researchers, and decision makers around the globe.

USGS and NASA have distinct roles in the Landsat program. NASA develops remote-sensing instruments and spacecraft, launches satellites, and validates their performance. The USGS then assumes ownership and operation. For example, USGS will operate the newest satellite in the Landsat series – Landsat 8 – starting on May 30, 2013, following a successful launch from the Vandenberg AFB on February 11, 2013.

For More Information

See the USGS website for more information on Landsat and to view the entire image gallery
See today's Google Blog to learn about Google's announcement, the Google Earth Engine and how to explore the new global, zoomable time-lapse map as part of TIME Magazine's new TIMElapse project
Read the Time Magazine article TIME and Space
For another example of the application of Landsat imagery, go to ESRI's Change Matters
Learn more about NASA and the Landsat Program

Disclaimer: Any use of trade, firm or product names does not imply endorsement by the U.S. Government. No warranty, expressed or implied, is made by the Department of the Interior or the U.S. Government as to the accuracy and functioning of the commercial software programs cited in this news release, and the U.S. Government shall not be held liable for improper or incorrect use of the Landsat satellite imagery and data employing these software programs.

Interior Appoints New Climate Change Advisory Committee

OC_Web@usgs.gov (Office of Communications and Publishing) — Wed, 8 May 2013 12:31:13 EDT

Members to Provide Guidance on Adaptation Science Initiatives

WASHINGTON, D.C. — Secretary of the Interior Sally Jewell today announced the members of a newly created federal advisory committee who will provide guidance about the Interior Department's climate change adaptation science initiatives.

Rising Seas Could Threaten Many Acadia NP Marshes

OC_Web@usgs.gov (Office of Communications and Publishing) — Mon, 29 Apr 2013 14:06:12 EDT

The report and maps are available online.

AUGUSTA, Maine – More than 800 acres of uplands in and near Acadia National Park will likely be flooded by the ocean if sea level rises 2 feet during this century, leaving 75 percent of the saltwater marshes along this part of central Maine's rugged coast with very little upland area to migrate into, according to a new U.S. Geological Survey study and maps.

If plant material and sediments can accumulate in Maine's salt marshes fast enough to keep pace with sea-level rise, the uplands could provide areas for new salt marsh habitat. But that would require faster accumulation rates than those observed in the last century.

"The precise amount of sea-level rise that we should expect this century is not known," said USGS scientist Martha Nielsen, who led the study. "This report and maps are intended to inform decision makers with science to assist in planning for an uncertain future. By identifying the uplands that could support new salt marshes ahead of time, we hope to aid land management and preservation efforts to sustain marsh ecosystems in the area."

The study, done in cooperation with the National Park Service, identified more than 40 potential barriers that, in addition to rugged topography, would further restrict inland migration of some marshes. The barriers are mostly roads that limit water and sediment movement. This study is intended to help managers proactively plan for mitigation of those barriers.

Salt marshes provide significant ecological value and aesthetic beauty to Maine's coasts. Their ecological functions include nursery and breeding habitat for many fish, shellfish, and wildlife species; storm, flood, and erosion protection; organic-matter production that feeds many commercially and recreationally valuable species; and filtration for sediments and contaminants.

The study area included all coastal areas in Maine from the eastern half of Penobscot Bay to the eastern edge of the Schoodic Peninsula. The 114 saltwater marshes included in the study range in size from larger than half an acre, up to 128 acres.

The analysis was based on high-resolution elevation data collected for coastal New England in 2010 with American Recovery and Reinvestment Act stimulus funding. The data were independently assessed for accuracy, and the maps show the expected inundation around each marsh to a 95 percent confidence interval. The manmade barriers to migration identified in the study are also shown.

New Map Sharpens View of African Ecosystems

OC_Web@usgs.gov (Office of Communications and Publishing) — Thu, 11 Apr 2013 12:49:00 EDT

A team of African and North American scientists led by the U.S. Geological Survey and NatureServe, a conservation non-profit organization, has created a series of continent-wide ecosystem maps that offer the most detailed portrayals of Africa's natural setting yet produced. The new maps and related data on landforms, geology, bioclimates, and vegetation can be used across Africa for conservation planning and resource management, as well as for impact assessments of climate change and changes in land use, such as agriculture, deforestation, and urbanization.

"This was a multi-organizational, international collaboration to create new earth science datasets for the entire continent at finer resolutions than ever before," said Matt Larsen, USGS Associate Director for Climate and Land Use Change. "An added benefit is that this information about ecosystem conditions can be put to many different uses. It will have tremendous utility beyond ecosystem assessments."

USGS and NatureServe researchers collaborated with the Regional Centre for Mapping of Resources for Development (RCMRD), based in Nairobi, Kenya. RCMRD hosted two workshops where invited experts from many African nations developed a new classification of African ecosystems and provided location data for the newly classified ecosystems.

Overall, a total of 37 experts from 18 countries worked together to formulate the ecosystem classifications (126 distinct ecosystems were mapped) and produce the maps at a base resolution of 90 meters.

"This much improved baseline of Africa's ecosystem conditions has the potential for more accurate carbon assessment studies in Africa," observed USGS scientist Roger Sayre, lead author of the publication.

Determination of biological carbon stocks in ecosystems is an emerging science. Currently, carbon stocks are assessed in general biome categories like forests, grasses, shrublands, wetlands, deserts, and agricultural lands. The increased classification resolution supplied by the new African ecosystems maps will facilitate a more robust assignment of carbon inventories to a greater, more precise number of biological sources.

The Association of American Geographers (AAG) provided key support for the final publication. The publication is available in digital form from the USGS.

Citation

A new map of standardized terrestrial ecosystems of Africa

2013, Sayre, Roger; Comer, Patrick; Hak, Jon; Josse, Carmen; Bow, Jacquie; et al.

African Geographical Review

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New Sea-Level-Rise Modeling Forecasts Major Climate Impact to Low-Lying Pacific Islands

OC_Web@usgs.gov (Office of Communications and Publishing) — Thu, 11 Apr 2013 12:00:00 EDT

SANTA CRUZ, Calif. — Dynamic modeling of sea-level rise, which takes storm wind and wave action into account, paints a much graver picture for some low-lying Pacific islands under climate-change scenarios than the passive computer modeling used in earlier research, according to a new U.S. Geological Survey report.

A team led by research oceanographer Curt Storlazzi of the USGS Pacific Coastal and Marine Science Center compared passive "bathtub" inundation models with dynamic models for two of the Northwestern Hawaiian Islands in the Papahānaumokuākea Marine National Monument. The team studied Midway, a classic atoll with islands on the shallow (2–8 meters or 6–26 feet deep) atoll rim and a deep, central lagoon, and Laysan, which is higher, with a 20–30 meter (65–98 feet) deep rim and an island in the center of the atoll. Together, the two locations exhibit landforms and coastal features common to many Pacific islands. Managed by the U.S. Fish and Wildlife Service, they are also among the world’s most important nesting and breeding sites for migratory birds and other wildlife.

"Passive 'bathtub' inundation models typically used to forecast sea-level rise impacts suggest that most of the low-lying atolls in the Pacific Islands will still be above sea level for the next 50-150 years. By taking wave-driven processes into account, we forecast that many of the atolls will be inundated, contaminating freshwater supplies and thus making the islands uninhabitable, much sooner," Storlazzi said.

The team found that at least twice as much land is forecast to be inundated on Midway and Laysan by sea-level rise than was projected by passive models. For example, 91 percent of Midway's Eastern Island is projected to be inundated under a model that takes into account storm and wave activity accompanied by a sea-level rise of 2 meters (6.5 feet), as compared with only 19 percent under passive sea-level-rise models. Storm waves on Midway are also projected to be three to four times higher than they are today, because more deep-water wave energy could propagate over the atoll rim and larger wind-driven waves could develop on the atoll.

"This report demonstrates the future threat to refuges with the Monument, and the potential impact on nesting seabirds, endangered monk seals and green sea turtles will be considered as we plan for the future," said Doug Staller, the Service's Superintendent of the Papahānaumokuākea Marine National Monument.

These findings have importance not only for island wildlife on the largely uninhabited Northwestern Hawaiian Islands, Storlazzi said, but for the tens of thousands of people who live on other low-lying Pacific Island groups such as those found in the Republic of the Marshall Islands and the Federated States of Micronesia. Because the models attempt to characterize how much land will be washed over by storm waves even if it is not permanently inundated, they offer tools for forecasting where agricultural land may be damaged by repeated saltwater overwash, as well as where groundwater may be contaminated by saltwater. The findings suggest that inundation and impacts to infrastructure and terrestrial habitats will occur at lower values of predicted sea-level rise, and thus sooner in the 21st century, than suggested by passive map-based "bathtub" inundation models.

The report, "Forecasting the Impact of Storm Waves and Sea-Level Rise on Midway Atoll and Laysan Island within the Papahānaumokuākea Marine National Monument—A Comparison of Passive Versus Dynamic Inundation Models," is available online.

New Tools to Help Manage Saltwater Intrusion

OC_Web@usgs.gov (Office of Communications and Publishing) — Wed, 3 Apr 2013 15:21:18 EDT

Climate Change, Sea-Level Rise to Impact When Water is Available

COLUMBIA, S.C. – South Carolina and Georgia water resource managers have powerful new tools at their fingertips to help make critical decisions on the timing and quantity of freshwater availability in coastal rivers.

Developed by the U.S. Geological Survey and Advanced Data Mining International, the two new decision support systems will help decision makers determine how much drinking water they will be able to pull from rivers in the face of climate change, sea-level rise and saltwater intrusion.

The user-friendly products were developed as part a new report titled Simulation of salinity intrusion along the Georgia and South Carolina coasts using climate change scenarios.

Research shows that the availability of freshwater in coastal streams will likely be affected in the future due to the combination of climate change and sea-level rise. The balance between freshwater and saltwater in coastal streams is primarily governed by the interaction between streamflow and sea level, and coastal rivers are constantly responding to changing streamflow and tidal conditions.

The decision support systems -- which include salinity simulation models, model controls, historical databases, and model output in a spreadsheet application – were created for the cities and towns on the Georgia and South Carolina coast that withdraw drinking water from the Atlantic Intracoastal Water and the Waccamaw River in South Carolina, and the Savannah River in Georgia, to predict saltwater intrusion near municipal intakes.

"Predicting the changes in the frequency of salinity intrusion event is critical for water-resource planning in the coastal region of the Southeastern United States due to the large number of municipal water-supply intakes in coastal rivers," said Paul Conrads, a USGS hydrologist and lead author of the study.

At a location just downstream from an intake that provides drinking water for Myrtle Beach area, the decision support system estimated that a 1-foot rise in sea level would increase the frequency of salinity at the intake and double the amount of time that freshwater would not be available at the intake.

"The decision support systems for the two rivers are essentially easy-to-use spreadsheets that integrate all the science, data, and models needed to perform high quality risk assessments," said Edwin Roehl, lead software developer for the project.

The study also evaluated the effect of climate-change projections from a global circulation model on change in salinity intrusion. The global circulation models predict changes in precipitation and temperature. These changes can affect streamflows to the coasts and change salinity intrusion. The results from the global circulation model projections indicates that, for one intake, the annual number of salinity intrusion events will increase and there would be a seasonal shift, with most salinity intrusion events occurring in the fall rather than the summer.

Although increases in sea-level and reductions in streamflow show substantial effects that would have operational consequence for municipal water-treatment plants, the climate change scenarios shown in the report would allow water-resource managers to plan adaptation efforts to minimize the effect of increased salinity of source water. Adaptation efforts may include timing of withdrawals during outgoing tides, increased storage of raw water, timing larger releases of regulated flows appropriately to move the saltwater-freshwater interface downstream, and the blending of higher conductance surface water with lower conductance water from an alternative source such as groundwater.

Recovering Soil Fertility after Forest Fires

OC_Web@usgs.gov (Office of Communications and Publishing) — Wed, 3 Apr 2013 14:00:00 EDT

CORVALLIS, Ore.— New scientific findings published in Ecology reveal that interactions of climate, soils, shrubs, and a natural nitrogen fertilization process affect regrowth of forests following wildfire in southern Oregon and northern California. Managers can use this information to consider post-fire management practices, including fertilization and shrub-removal.

Scientists studying forests that burned in 1987 discovered an interesting pattern in a natural fertilization process. The highest levels of natural nitrogen fertilization occurred at cool, dry sites where tree growth is slow and where nitrogen for growth is needed the least. In contrast, the lowest nitrogen additions occurred at warm, moist sites where tree growth and associated nitrogen needs are greatest.

This counterintuitive result occurred because natural nitrogen fertilization by nitrogen-fixing shrubs was suppressed by competition with oaks, maples, and other vegetation where tree growth was greatest, in warm, moist sites.

Nitrogen, an essential nutrient for tree growth, often is lost during a forest fire. An important way to recover forest fertility is an ecological process called biological nitrogen fixation. Some common shrubs, like Ceanothus, form unique relationships with bacteria and convert inert nitrogen gas from the air into forms of nitrogen in the soil that the trees can use for growth. Free-living soil bacteria also fix nitrogen. This natural process is the main source of nitrogen fertility in forests.

The scientists found that the rate at which Ceanothus shrubs added nitrogen to the system could be suppressed as tree biomass increased. Even though warm, wet sites stimulated the growth of nitrogen-fixing shrubs, these conditions stimulated the growth of other plants even more. Eventually, these changes limited the recovery of nitrogen fertility in the most productive sites.

According to Stephanie Yelenik, the lead author of the study, nitrogen additions by Ceanothus shrubs and by free-living soil bacteria provided an average of 7.5 pounds of nitrogen per acre per year. Over the 22 years following the major fire when the forest’s vegetation and nitrogen burned, this added up to about 165 pounds of nitrogen per acre. Although probably insufficient to fully replace wildfire nitrogen losses on the study sites, these contributions were substantial. Yelenik was affiliated with Oregon State University at the time of the study.

"There are important related results. Biological nitrogen fixation involving Ceanothus shrubs was up to 90 times greater than contributions from free-living soil microorganisms," said USGS scientist Steve Perakis, who participated in the study. "The contribution from Ceanothus would be even greater if other plants didn't compete so strongly. So ultimately competition among different plant species governed nitrogen input in the forests studied."

"The loss of nitrogen to wildfire has always been of concern to managers; however, the enormity of this loss only recently has been quantified," said Tom Sensenig, a U.S. Forest Service ecologist. "This study not only informs managers about the importance of shrubs for restoring nitrogen, but identifies the dynamics among species and the specific processes influencing nitrogen fixation and recovery across differing sites. Principally, this new information will help in developing post-fire management options and plans for specific forest types in this region. For example, on drier lower-quality sites, Ceanothus, the most prevalent nitrogen-fixing shrub identified, could be retained to the greatest extent possible by only treating the minimal vegetation necessary to assure seedling survival. On wetter, higher-productivity sites, treating more competitive species at a higher intensity may be more effective for maximizing nitrogen recovery, while benefiting seedling survival as well."

According to Yelenik, without additional fire or other forms of disturbance, Ceanothus largely disappears from productive sites in about 30 years as the tree canopy shades out the understory vegetation. Because Ceanothus is the major player in biological nitrogen fixation, from then on, nitrogen levels may remain consistently low in sites that have the necessary temperature and moisture conditions to promote rapid tree growth. On these sites, there may be opportunities to conduct vegetation management or to allow low-severity fires to burn as a way of encouraging the presence of nitrogen-fixing shrubs in the forest understory.

The study sites were located in forested mountains of the Klamath Region. This region is prone to wildfires, and the frequency and severity of the fires shape vegetation patterns. The study occurred 20 to 22 years after fire in sites that were salvage logged in the first 2 to 3 years after fire and then planted with conifer trees. Perakis believes the results are best applied to this region, but the interactions between climate, soils, shrubs, and natural nitrogen fertilization merit study elsewhere to see if similar constraints to nitrogen fixation occur in other forests recovering from fire.

The publication is Yelenik, S.G., S.S. Perakis, and D.E.Hibbs. 2013. Regional constraints to biological nitrogen fixation in post-fire forest communities. Ecology.

First Images Released From Newest Earth Observation Satellite

OC_Web@usgs.gov (Office of Communications and Publishing) — Thu, 21 Mar 2013 12:01:00 EDT

WASHINGTON -- NASA and the Department of the Interior's U.S. Geological Survey (USGS) have released the first images from the Landsat Data Continuity Mission (LDCM) satellite, which was launched Feb. 11.

The natural-color images show the intersection of the United States Great Plains and the Front Range of the Rocky Mountains in Wyoming and Colorado. In the images, green coniferous forests in the mountains stretch down to the brown plains with Denver and other cities strung south to north.

LDCM acquired the images at about 1:40 p.m. EDT March 18. The satellite's Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) instruments observed the scene simultaneously. The USGS Earth Resources Observation and Science Center in Sioux Falls, S.D., processed the data.

"We are very excited about this first collection of simultaneous imagery," said Jim Irons, LDCM project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "These images confirm we have two healthy, functioning sensors that survived the rigors of launch and insertion into Earth orbit."

Since launch, LDCM has been going through on-orbit testing. The mission operations team has completed its review of all major spacecraft and instrument subsystems, and performed multiple spacecraft attitude maneuvers to verify the ability to accurately point the instruments.

The two LDCM sensors collect data simultaneously over the same ground path. OLI collects light reflected off the surface of Earth in nine different regions of the electromagnetic spectrum, including bands of visible light and near-infrared and short-wave-infrared bands, which are beyond human vision. TIRS collects data at two longer wavelength thermal infrared bands that measure heat emitted from the surface.

By looking at different band combinations, scientists can distinguish features on the land surface. These features include forests and how they respond to natural and human-caused disturbances, and the health of agricultural crops and how much water they use. Data from LDCM will extend a continuous, 40-year-long data record of Earth's surface from previous Landsat satellites, an unmatched, impartial perspective that allows scientists to study how landscapes all across the world change through time.

"These first scenes from the new Landsat satellite continue the remarkable output from the Landsat program with better, more useful imagery and information," said Matthew C. Larsen, associate director for climate and land use change at the U.S. Geological Survey in Reston, Va. "We are gratified that this productive partnership between USGS and NASA has maintained the continuity and utility of this essential satellite tool, providing the foundation for land and water management around the globe."

As planned, LDCM currently is flying in an orbit slightly lower than its operational orbit of 438 miles (705 kilometers) above Earth's surface. As the spacecraft's thrusters raise its orbit, the NASA-USGS team will take the opportunity to collect imagery while LDCM is flying under Landsat 7, also operating in orbit. Measurements collected simultaneously from both satellites will allow the team to cross-calibrate the LDCM sensors with Landsat 7's Enhanced Thematic Mapper-Plus instrument.

"So far, our checkout activities have gone extremely well," said Ken Schwer, LDCM project manager at Goddard. "The mission operations team has done a tremendous job getting us to the point of imaging Earth." During the next few weeks, this team will calibrate the instruments and verify they meet performance specifications.

After its checkout and commissioning phase is complete, LDCM will begin its normal operations in May. At that time, NASA will hand over control of the satellite to the USGS, which will operate it throughout its planned five-year mission life. The satellite will be renamed Landsat 8. USGS will process data from OLI and TIRS and add it to the Landsat Data Archive at the USGS Earth Resources Observation and Science Center, where it will be distributed for free via the Internet.

Visit LDCM First Images to view the images.

For further information about LDCM, visit LDCM Mission.

For status and technical information about all Landsat satellites, visit Landsat Missions.

New Water Science Tools Help Communities Prepare for Floods

OC_Web@usgs.gov (Office of Communications and Publishing) — Mon, 18 Mar 2013 16:48:05 EDT

Commemorating the Great Flood of 1913

Editors: A USGS video about the 1913 flood is available online.

The WaterNow allows you to send an email or text message containing a USGS current-conditions streamgaging site number and quickly receive a reply with its most recent observation(s).
(High resolution image)

New flood inundation maps (bottom) are now available for Findlay, Killbuck, and Ottawa, Ohio. These maps show where flooding would occur at various high river levels. They are just one example of U.S. Geological Survey products and services developed in the 100 years since Ohio’s devastating Great Flood of 1913.

The 100-year anniversary of the Great Flood of 1913 falls during the 2013 Flood Safety Awareness Week.

The USGS prepared the new maps to help emergency managers and the public make more informed decisions when flooding is forecast. Flood inundation maps are connected to real-time river levels at USGS streamgages to help communities identify immediate risks during a flood. Since the historic flood of March 23-27, 1913, which caused more than 400 deaths and $300 million in damages throughout the Ohio River Valley, the USGS has developed streamgage networks and tools to better support flood preparedness and provide flood warnings.

“The 1913 statewide flood is Ohio’s ‘Greatest Natural Disaster’. Since then, the number of USGS streamgages increased from one to about 230 currently operating in Ohio,” said Scott Jackson, USGS Ohio Water Science Center Deputy Director. “Today, the USGS and its partners maintain about 8,000 streamgages nationwide.”

This collection of stream data is necessary to flood science because it provides real-time information and a database of field-measurement data, streamflow statistics, and annual peak streamflows that are available online through the USGS National Water Information System.

“The USGS and its partners are currently developing flood warning systems that serve as a foundation for making science-based decisions to better manage flood risks and mitigate flood impacts,” Jackson said.

New USGS flood inundation maps are underway for Marietta, Beverly, McConnellsville, and multiple sites in Licking County, Ohio.

The USGS WaterAlert service allows subscribers to receive daily or hourly updates about current conditions in rivers, lakes, and groundwater.
(High resolution image)

Other USGS flood-related tools include:

WaterWatch, a website that displays maps, graphs, and tables describing real-time, recent, and past streamflow conditions in the U.S.;
WaterNow which relays on-demand current conditions and water data to a user’s mobile phone or e-mail;
WaterAlert which sends an e-mail or text message when streamflow or streamgage measurements exceed user-defined thresholds.

Historical information on the 1913 flood and current-day tips on flood preparedness, mitigation, and more can be found on the Silver Jackets “Flood of 1913” website. The Silver Jackets program assembles teams of local, State, and Federal agencies, including the USGS, to work together to prepare and respond to natural disasters such as floods.

More information about USGS streamgaging in Ohio is available online.

The USGS network of about 8,000 streamgages are used to track rising water in order to minimize or mitigate flood damages. ((High resolution image)

Pika Populations Affected by Climate in the Great Basin

OC_Web@usgs.gov (Office of Communications and Publishing) — Wed, 13 Mar 2013 12:38:40 EDT

BOZEMAN, Mont. – Climate factors such as snowpack and precipitation are playing an increasingly important role in the abundance of American pikas in the Great Basin, according to a continuing ecological study by the U.S. Geological Survey, University of Montana and Montana State University.

Pikas are diminutive herbivores that resemble hamsters and live exclusively in rocky slopes across many mountain ranges in the American West. This study contributes to a legacy of more than 100 years of pika studies in the Great Basin – the internally draining area between the Sierra Nevada and Rocky Mountains. In the Basin, researchers are recording pikas' shrinking distribution, and finding their population sizes increasingly responsive to climate change but difficult to predict.

The size of pika populations did not correlate with the extent of habitat present in either the 1990s or 2000s, according to the researchers, who were revisiting sites where pikas were first recorded in historical surveys going back more than a century. Given how strongly pikas are tied to their rocky habitat, this current finding challenges the assumption that just because physically suitable habitat is present – even in remote, apparently relatively undisturbed locations – that pikas will continue to occupy those habitats.

Researchers also investigated the potential impact of climate stress on pika density. The results suggested that climate change may be adding another filter for suitability of habitats. "Precipitation during June-September and amount of snowpack appeared to be the most powerful predictors of pika density in the 2000s," said USGS research ecologist Erik Beever, lead author of the study. "Precipitation appears to be important because it can influence the amount of food available for pikas in the summer, and an insulating snowpack can minimize exposure of pikas to extreme cold-stress," Beever said. Across the western United States, snow-water equivalents have been declining and temperatures have been rising since the 1930s.

Perhaps the most surprising result was the direct relationship between population size and probability of future extinctions of local pika populations. "When we consider extinction risk, we intuitively think that smaller populations are at the highest risk," Beever said. "We looked at the record of extinctions up to 1999, and calculated the risk of future site-level extinction. We were surprised to find that sites with higher extinction risk in 1999 had larger populations in 2003-2008," he said. The authors suggest that this non-intuitive result may reflect changes in the rules governing abundance between the 1990s and 2000s surveys (perhaps ushered in by recent climate change), lags in response of abundance to extinction risk, or other mechanisms.

Researchers revisited sites of historical (1898-1956) pika records and performed surveys of pika abundance from 1994 to 1999 and from 2003 to 2008 to understand the factors predicting pika population sizes.

The study, "Understanding relationships among abundance, extinction and climate at ecoregional scales," to be published in the journal Ecology, is available online.