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  2. 28-02-2011 eco nws - global warming - alternative energy - crop biofuel - forests - Turning Forests Into Fuel: Promise and Limits of Biomass Energy in Northeastern U.S. - ScienceDaily (Feb. 28, 2011) � Forest biomass could replace as much as one quarter of the liquid fossil fuel now being used for industrial and commercial heating in the Northeastern United States. That's according to a new report released February 17 by the Cary Institute of Ecosystem Studies. But the report also has sharp caveats: The potential for forest biomass varies widely within the region, and forest resources must be carefully managed to protect the other important services and goods they provide. Under the right circumstances, however, the report found that forest biomass can provide a domestic energy resource, create local jobs, and provide incentives to forest owners. "In targeted applications, the heat generated by locally-grown biomass can reduce dependence on fossil fuels and support local economies," said Dr. Charles D. Canham, a forest ecologist at the Cary Institute and co-author of the report. "But each forested landscape is different, and regional variation in forest conditions and energy infrastructure means there is no one-size-fits-all solution." The report analyzed U.S.D.A. Forest Service Forest data from Connecticut, Maine, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island, and Vermont. It found that using forest biomass for heat in the region was far more effective in replacing liquid fossil fuels than converting it to cellulosic ethanol for road transport. Biomass burned in combined heat and power plants reduced fossil fuel use more than five times more effectively than substituting gasoline with cellulosic ethanol. Under best-case scenarios, however, the energy generated sustainably from forest biomass in the Northeast could replace only 1.4% of the region's total fossil fuel energy. But for some states, biomass energy could be much more compelling when replacing fossil fuel use in certain sectors. "Maine and New Hampshire show the greatest potential for forest biomass energy," said Dr. Thomas Buchholz, a researcher at the University of Vermont's Carbon Dynamics Lab and co-author on the report. "Our study found that New Hampshire could replace as much as 84 percent of its liquid fossil fuel dependence in the industrial and commercial heating sector, and Maine could replace 49 percent of its liquid fossil fuel dependence in the home-heating sector." But the report cautioned that utmost care must be observed in all parts of the region. "There is a misconception that Northeastern forestland is a vast, untapped resource," Canham commented. "This is simply not true. Unrealistic growth in biomass energy facilities could lead to serious degradation of forest resources. While forest biomass is part of the renewable energy toolkit, it is by no means a panacea." "Forest biomass can be an important element of a low-carbon energy future," added contributing author Dr. Steven Hamburg of Environmental Defense Fund. "But we'll need ongoing scientific oversight to ensure it is done sustainably."

  3. 20-07-2011 eco nws - global warming - system - atmosphere - co2 - co2 storage - forests - World's Forests' Role in Carbon Storage Immense, Research Reveals - ScienceDaily (July 20, 2011) � Until recently, scientists were uncertain about how much and where in the world terrestrial carbon is being stored. In the July 14 issue of Science Express, scientists report that, between 1990 and 2007, the world's forests stored about 2.4 gigatons of carbon per year. Their results suggest that forests account for almost all of the world's land-based carbon uptake. Boreal forests are estimated to be responsible for 22 percent of the carbon stored in the forests. A warming climate has the potential to increase fires and insect damage in the boreal forest and reduce its capacity to sequester carbon. "Our results imply that clearly, forests play a critical role in Earth's terrestrial carbon balance, and exert considerable control over the evolution of atmospheric carbon dioxide," said A. David McGuire, co-author and professor of ecology at the University of Alaska Fairbanks Institute of Arctic Biology and co-leader of the USGS Alaska Cooperative Fish and Wildlife Research Unit. The report includes comprehensive estimates of carbon for the world's forests based on recent inventory data. The scientists included information on changes in carbon pools from dead wood, harvested wood products, living plants and plant litter, and soils to estimate changes in carbon across countries, regions and continents that represent boreal, temperate and tropical forests. The authors note that understanding the present and future role of forests in the sequestration and emission of carbon is essential for informed discussions on limiting greenhouse gases.

  4. 09-08-2011 eco nws - global warming - system - co2 - carbon sink - forests - Forests Absorb One Third of Fossil Fuel Emissions, Study Finds - ScienceDaily (Aug. 9, 2011) � The world's established forests remove 2.4 billion tonnes of carbon per year from the atmosphere -- equivalent to one third of current annual fossil fuel emissions -- according to new research published in the journal Science. This is the first time volumes of the greenhouse gas absorbed from the atmosphere by tropical, temperate and boreal forests have been so clearly identified. "This is really a timely breakthrough with which we can now clearly demonstrate how forests and changes in landscape such as wildfire or forest regrowth impact the removal or release of atmospheric carbon dioxide (CO2)," says CSIRO co-author of the paper, Dr Pep Canadell. "What this research tells us is that forests play a much larger role as carbon sinks as a result of tree growth and forest expansion." Dr Canadell, who is also the Executive Director of the Global Carbon Project, said the international research team combined data from forest inventories, models and satellites to construct a profile of forests as major regulators of atmospheric CO2. In addition to the large carbon sink, he said scientists now know that deforestation is responsible for emitting 2.9 billion tonnes of carbon per year -- an exchange that had not been known in the past because of a lack of data. For comparison, total emissions from fossil fuels are currently above eight billion tonnes of carbon per year. Dr Canadell said emissions from deforestation are much larger than previously thought, suggesting that the potential benefits of avoiding deforestation through the United Nations-backed Reduced Emissions from Deforestation and Degradation (REDD) scheme, are much larger than previously appreciated. The REDD scheme aims to formulate a financial value for the carbon stored in forests. Dr Canadell said a surprising finding was the large capacity of tropical forest re-growth to remove atmospheric CO2. Regrowth takes place following the end of logging and slash-and-burn land clearing projects. and, to a lesser extent, when new forest plantations are planted. "We estimate that tropical forest regrowth is removing an average of 1.6 billion tonnes of carbon per year. Unfortunately, some countries have not looked on forest regrowth as a component of REDD, and so are missing a very important opportunity to gain even further climate benefits from the conservation of forests. "Combining the uptake by established and forest re-growth plus emissions from deforestation, the world's forests have a net effect on atmospheric CO2 equivalent to the removal of 1.1 billion tonnes of carbon every year. "Carbon exchanges from tropical forests have the highest uncertainties in this analysis and this research has required a concerted effort to refine them to our best knowledge," Dr Canadell said.

  5. 11-08-2011 eco nws - global warming - system - atmosphere - co2 - carbon sink - forests - Carbon Sink: Up-And-Coming Forests Replacing Aging Forests of Upper Great Lakes - ScienceDaily (Aug. 11, 2011) � The aging forests of the Upper Great Lakes could be considered the baby boomers of the region's ecosystem. The decline of trees in this area is a cause for concern among policymakers and ecologists who wonder whether the end of the forests' most productive years means they will no longer offer the benefits they are known for: cleansed air, fertile soil, filtered water and, most important to climate change analysts, carbon storage that offsets greenhouse gas emissions. A team of ecologists led by Ohio State University researchers says, however, that coming up right underneath the old forests is a new generation of native trees that are younger, more diverse and highly competitive. They represent a vast unknown compared to what ecologists have long theorized about how forests work as carbon sinks, but these researchers expect the next generation to carry on the important work of carbon storage. "There's a conventional theory that aging forests, for a variety of reasons, store less carbon over time. We contend that that may be true in certain systems that are less species-rich. But in our forests in the Midwest, the tree species we will end up with are much different from what we started with," said Peter Curtis, professor and chair of evolution, ecology and organismal biology at Ohio State and a lead investigator on this research. "We argue that in this case, as forests age, they get rejuvenated with younger individuals of different species -- a more complex and diverse community will be replacing the old guard. They may even outdo the boomer generation and be more productive." Curtis and colleagues base their predictions on preliminary findings from a project in which they have accelerated the generational shift in part of a forest in northern Michigan. By cutting strips of bark from thousands of aspen trees to hasten their death, the scientists are able to observe the characteristics of the trees that will replace this 100-year-old cohort. So far, the scientists are finding that the canopy created by the newcomers' leaves use light more efficiently to manufacture carbohydrates and release oxygen through photosynthesis than did the aspen canopy that preceded it. The researchers also are able to use sophisticated instruments to quantify nitrogen cycling in the transitioning forest, and observe that nitrogen losses throughout the system are small even with the death of thousands of trees. As long as nitrogen remains available -- within tree wood and leaves as well as in the soil -- for the trees to renew themselves annually, the forest will continue to function as an effective carbon sink. Curtis presented portions of the research on August 10 at the Ecological Society of America annual meeting in Austin, Texas. The research team conducts its work at the University of Michigan Biological Station (UMBS). The composition of this forested research facility is representative of the forests stretching about 40,000 square miles -- the equivalent of the land mass of Ohio -- across the entire upper Midwest. Aspens compose the vast majority of old trees in the region, cropping up quickly after a period of deforestation between 1880 and 1920 that was followed by abandonment of the land and a rash of wildfires. Curtis describes aspens as trees that "live fast and die young." Their seeds spread easily and that allowed the species to revegetate the deforested areas rapidly, but they do not grow well in shade underneath their own canopies. Because of that weakness, the aspens are being replaced by tree species that were once native to the region but take longer to get established. Aspens live only about 100 years on average, compared to the oak, sugar maple, beech, hemlock and pine species that are replacing them, which can live for as long as 600 years. The researchers previously calculated that the Midwestern forests could offset the greenhouse gas emissions of almost two-thirds of nearby populations by storing an average of 1,300 pounds of carbon per acre -- a total of 350,000 tons -- per year. To test the forests' future carbon storage capacity, the researchers launched the Forest Accelerated Succession Experiment (FASET) in 2008, girdling almost 7,000 aspen trees across about 100 acres. Girdling involves cutting a strip of bark from the circumference of a tree trunk. To date, about 75 percent of the aspen trees are dead, and about 15 percent have fallen. Their demise is making way for a more diverse forest, Curtis said. Though some ecological theories suggest that a simple system -- say, all pine or all aspen -- can be more productive in the short term, a more complex system is needed to withstand the inevitable disturbance that will accompany climate change, he said. "The more diverse system can solve problems that are thrown at it by the environment," Curtis said. "Adaptation is a key word here. As animal and plant species are moving around or changing seasonally, a diverse and resilient ecosystem is going to be much better able to provide ecological niches and the goods and services that we can hope to get from it." So far, the accelerated succession is showing that with the loss of the aspens, the light-use efficiency of the forest canopy increased. "Even with fewer leaves, the leaf area was better distributed. It's happening quite rapidly. As soon as you take away these aspen, you get a lot more nitrogen and more light, and other species react to that very quickly," Curtis said. "There was more nitrogen available because aspens weren't there to take it up, and dead leaves and dead roots were releasing nitrogen." Considering the magnitude of the disturbance of killing thousands of trees, the researchers were surprised to see that the system lost almost no nitrogen. Plants use nitrogen, which becomes available through the decomposition of organic matter, to produce the next year's leaves and wood. Plants also need nitrogen to take up carbon. Clear-cutting trees would allow nitrogen to drain out of the bottom of the system because no roots would exist to intercept that loss, Curtis explained. Though the rapid loss of aspens did lead to about a 10 percent loss of nitrogen, almost that same amount was recaptured in atmospheric nitrogen that comes down to the land surface in rain. The wood mass and soil organic matter are vital to a forest's carbon-storage capacity; in the UMBS forest, stem wood, leaves and debris contain about 42 percent of the carbon there. Though forests also release carbon dioxide into the atmosphere, the instrumentation used by these researchers to analyze the ongoing carbon exchange between the forest and atmosphere has been able to confirm the forest's status as an important national carbon sink, Curtis said. The concept of using forests to store carbon has steadily gained attention among policymakers, especially since the Kyoto Protocol was adopted in 1997 as a global program to reduce greenhouse gas emissions. Curtis's group has received $1 million in additional funding from the U.S. Department of Energy to continue evaluating forests' role in storing carbon.

  6. 14-09-2011 eco nws - global warming - impact - forests - atmosphere - temperature - Water Evaporated from Trees Cools Global Climate, Researchers Find - ScienceDaily (Sep. 14, 2011) � Scientists have long debated about the impact on global climate of water evaporated from vegetation. New research from Carnegie's Global Ecology department concludes that evaporated water helps cool Earth as a whole, not just the local area of evaporation, demonstrating that evaporation of water from trees and lakes could have a cooling effect on the entire atmosphere. These findings, published Sept. 14 in Environmental Research Letters, have major implications for land-use decision making. Evaporative cooling is the process by which a local area is cooled by the energy used in the evaporation process, energy that would have otherwise heated the area's surface. It is well known that the paving over of urban areas and the clearing of forests can contribute to local warming by decreasing local evaporative cooling, but it was not understood whether this decreased evaporation would also contribute to global warming Earth has been getting warmer over at least the past several decades, primarily as a result of the emissions of carbon dioxide from the burning of coal, oil, and gas, as well as the clearing of forests. But because water vapor plays so many roles in the climate system, the global climate effects of changes in evaporation were not well understood. The researchers even thought it was possible that evaporation could have a warming effect on global climate, because water vapor acts as a greenhouse gas in the atmosphere. Also, the energy taken up in evaporating water is released back into the environment when the water vapor condenses and returns to earth, mostly as rain. Globally, this cycle of evaporation and condensation moves energy around, but cannot create or destroy energy. So, evaporation cannot directly affect the global balance of energy on our planet. The team led by George Ban-Weiss, formerly of Carnegie and currently at Lawrence Berkeley National Laboratory, included Carnegie's Long Cao, Julia Pongratz and Ken Caldeira, as well as Govindasamy Bala of the Indian Institute of Science in Bangalore. Using a climate model, they found that increased evaporation actually had an overall cooling effect on the global climate. Increased evaporation tends to cause clouds to form low in the atmosphere, which act to reflect the sun's warming rays back out into space. This has a cooling influence. "This shows us that the evaporation of water from trees and lakes in urban parks, like New York's Central Park, not only help keep our cities cool, but also helps keep the whole planet cool," Caldeira said. "Our research also shows that we need to improve our understanding of how our daily activities can drive changes in both local and global climate. That steam coming out of your tea-kettle may be helping to cool the Earth, but that cooling influence will be overwhelmed if that water was boiled by burning gas or coal."

  7. 13-10-2011 eco nws - global warming - impact - forests - atmosphere - co2 - ozone - Future Forests May Soak Up More Carbon Dioxide Than Previously Believed - ScienceDaily (Oct. 13, 2011) � North American forests appear to have a greater capacity to soak up heat-trapping carbon dioxide gas than researchers had previously anticipated. As a result, they could help slow the pace of human-caused climate warming more than most scientists had thought, a U-M ecologist and his colleagues have concluded. The results of a 12-year study at an experimental forest in northeastern Wisconsin challenge several long-held assumptions about how future forests will respond to the rising levels of atmospheric carbon dioxide blamed for human-caused climate change, said University of Michigan microbial ecologist Donald Zak, lead author of a paper published online this week in Ecology Letters. "Some of the initial assumptions about ecosystem response are not correct and will have to be revised," said Zak, a professor at the U-M School of Natural Resources and Environment and the Department of Ecology and Evolutionary Biology in the College of Literature, Science, and the Arts. To simulate atmospheric conditions expected in the latter half of this century, Zak and his colleagues continuously pumped extra carbon dioxide into the canopies of trembling aspen, paper birch and sugar maple trees at a 38-acre experimental forest in Rhinelander, Wis., from 1997 to 2008. Some of the trees were also bathed in elevated levels of ground-level ozone, the primary constituent in smog, to simulate the increasingly polluted air of the future. Both parts of the federally funded experiment -- the carbon dioxide and the ozone treatments -- produced unexpected results. In addition to trapping heat, carbon dioxide is known to have a fertilizing effect on trees and other plants, making them grow faster than they normally would. Climate researchers and ecosystem modelers assume that in coming decades, carbon dioxide's fertilizing effect will temporarily boost the growth rate of northern temperate forests. Previous studies have concluded that this growth spurt would be short-lived, grinding to a halt when the trees can no longer extract the essential nutrient nitrogen from the soil. But in the Rhinelander study, the trees bathed in elevated carbon dioxide continued to grow at an accelerated rate throughout the 12-year experiment. In the final three years of the study, the CO2-soaked trees grew 26 percent more than those exposed to normal levels of carbon dioxide. It appears that the extra carbon dioxide allowed trees to grow more small roots and "forage" more successfully for nitrogen in the soil, Zak said. At the same time, the rate at which microorganisms released nitrogen back to the soil, as fallen leaves and branches decayed, increased. "The greater growth has been sustained by an acceleration, rather than a slowing down, of soil nitrogen cycling," Zak said. "Under elevated carbon dioxide, the trees did a better job of getting nitrogen out of the soil, and there was more of it for plants to use." Zak stressed that growth-enhancing effects of CO2 in forests will eventually "hit the wall" and come to a halt. The trees' roots will eventually "fully exploit" the soil's nitrogen resources. No one knows how long it will take to reach that limit, he said. The ozone portion of the 12-year experiment also held surprises. Ground-level ozone is known to damage plant tissues and interfere with photosynthesis. Conventional wisdom has held that in the future, increasing levels of ozone would constrain the degree to which rising levels of carbon dioxide would promote tree growth, canceling out some of a forest's ability to buffer projected climate warming. In the first few years of the Rhinelander experiment, that's exactly what was observed. Trees exposed to elevated levels of ozone did not grow as fast as other trees. But by the end of study, ozone had no effect at all on forest productivity. "What happened is that ozone-tolerant species and genotypes in our experiment more or less took up the slack left behind by those who were negatively affected, and that's called compensatory growth," Zak said. The same thing happened with growth under elevated carbon dioxide, under which some genotypes and species fared better than others. "The interesting take home point with this is that aspects of biological diversity -- like genetic diversity and plant species compositions -- are important components of an ecosystem's response to climate change," he said. "Biodiversity matters, in this regard."

  8. 23-10-2011 eco nws - global warming - alternative energy - crop biofuel - wood - forest - forests - Production of Biofuel from Forests Will Increase Greenhouse Gas Emissions, Study Finds - ScienceDaily (Oct. 23, 2011) � The largest and most comprehensive study yet done on the effect of biofuel production from West Coast forests has concluded that an emphasis on bioenergy would increase carbon dioxide emissions from these forests at least 14 percent, if the efficiency of such operations is optimal. The findings are contrary to assumptions and some previous studies that suggest biofuels from this source would be carbon-neutral or even reduce greenhouse gas emissions. In this research, that wasn't true in any scenario. The study was published in Nature Climate Change, by scientists from the College of Forestry at Oregon State University and other institutions in Germany and France. It was supported by the U.S. Department of Energy. During the past four years, the study examined 80 forest types in 19 eco-regions in Oregon, Washington and California, ranging from temperate rainforests to semi-arid woodlands. It included both public and private lands and different forest management approaches. "On the West Coast, we found that projected forest biomass removal and use for bioenergy in any form will release more carbon dioxide to the atmosphere than current forest management practices," said Tara Hudiburg, a doctoral candidate at OSU and lead author on the study. "Most people assume that wood bioenergy will be carbon-neutral, because the forest re-grows and there's also the chance of protecting forests from carbon emissions due to wildfire," Hudiburg said. "However, our research showed that the emissions from these activities proved to be more than the savings." The only exception to this, the researchers said, was if forests in high fire-risk zones become weakened due to insect outbreaks or drought, which impairs their growth and carbon sequestration, as well as setting the stage for major fires. It's possible some thinning for bioenergy production might result in lower emissions in such cases if several specific criteria are met, they said. "Until now there have been a lot of misconceptions about impacts of forest thinning, fire prevention and biofuels production as it relates to carbon emissions from forests," said Beverly Law, a professor in the OSU Department of Forest Ecosystems and Society and co-author of this study. "If our ultimate goal is to reduce greenhouse gas emissions, producing bioenergy from forests will be counterproductive," Law said. "Some of these forest management practices may also have negative impacts on soils, biodiversity and habitat. These issues have not been thought out very fully." The study examined thousands of forest plots with detailed data and observations, considering 27 parameters, including the role of forest fire, emissions savings from bioenergy use, wood product substitution, insect infestations, forest thinning, energy and processes needed to produce biofuels, and many others. It looked at four basic scenarios: "business as usual"; forest management primarily for fire prevention purposes; additional levels of harvest to prevent fire but also make such operations more economically feasible; and significant bioenergy production while contributing to fire reduction. Compared to "business as usual" or current forest management approaches, all of the other approaches increased carbon emissions, the study found. Under the most optimal levels of efficiency, management just for fire prevention increased it 2 percent; for better economic return, 6 percent; and for higher bioenergy production, 14 percent. "However, we don't believe that an optimal efficiency of production is actually possible in real-world conditions," Hudiburg said. "With levels of efficiency that are more realistic, we project that the use of these forests for high bioenergy production would increase carbon emissions 17 percent from their current level." About 98 percent of the forests in this region are now estimated to be a carbon sink, meaning that even with existing management approaches they sequester more carbon than they release to the atmosphere. Plans for greenhouse gas reduction call for up to 10 percent lower emissions by 2020, and forest-derived fuels are now seen as a carbon-neutral solution to reducing energy emissions, the researchers note. However, this study suggests that increases in harvest volume on the West Coast, for any reason, will instead result in average increases in emissions above current levels. Forests capture a large portion of the carbon emitted worldwide, and some of this carbon is stored in pools such as wood and soil that can last hundreds to thousands of years, the scientists said. "Energy policy implemented without full carbon accounting and an understanding of the underlying processes risks increasing rather than decreasing emissions," the researchers wrote in their report.

  9. 05-02-2012 eco nws - global warming - glaciers - landcover - forests - plant life - Land-Cover Changes Do Not Impact Glacier Loss - ScienceDaily (Feb. 5, 2012) A new study shows that land-cover changes, in particular deforestation, in the vicinity of glaciers do not have an impact on glacier loss. However, the study, in which Innsbruck climate researcher were directly involved, also shows that deforestation decreases precipitation in mid elevation zones, which affects the quality of life of the population living in the surrounding areas. The composition of land surface -- such as vegetation type and land use -- regulates the interaction of radiation, sensible heat and humidity between the land surface and the atmosphere and, thus, influences ground level climate directly. For the first time, the Innsbruck climate scientists quantitatively examined whether land-cover changes (LCC) may potentially affect glacier loss. "We used Kilimanjaro in East Africa as a test case, where a significant decrease of forests at elevations between 1,800 and 3,000 meters, caused by illegal deforestation and an increased number of forest fires, has been documented since the 1970s," explains climate researcher Thomas Mlg, who has worked in Berlin since 1 October 2011 but finished the study with his team at the University of Innsbruck. The glaciers in the Kilimanjaro area have been shrinking for many decades, and climate researchers from Innsbruck and America have conducted thorough glaciological and meteorological measurements for ten years -ideal prerequisites for carrying out a comprehensive study about a potential connection between forest loss and glacier shrinking. - Novel methodology - The prerequisite for conducting this study was a novel methodology that links a glacier and atmospheric model in such a way that no statistical corrections are necessary (published by Kaser/Mlg, 2011 in Journal of Geophysical Research). Direct measurements of various climate elements on Kilimanjaro such as temperature, humidity, radiation, precipitation and glacier mass changes showed that reality can be simulated well by this new methodology. "Based on this evaluation we then modified vegetation cover in the atmospheric model -- first showing 1976 and subsequently the current state -- and calculated its effect on glacier mass," says Thomas Mlg. The results show that LCC mainly alter precipitation over glaciers but with different effects on the Northern and Southern ice fields of the mountain (increase or decrease respectively), which results in local increase or decrease of glacier mass. "Depending on the season, LCC contributes not more than seven to 17 % to glacier mass loss in the southern sector. We, therefore, cannot confirm the hypothesis that deforestation at Kilimanjaro contributes significantly to glacier loss," explains Thomas Mlg. Less precipitation in mid-mountain elevation zones The results of the study suggest that relatively small-scale land-cover changes, such as on Kilimanjaro, may not have enough impact on the mountain climate to surpass the effects of global climate change on glaciers. "However, another important aspect of the results is that deforestation decreases precipitation significantly more in mid-mountain elevation zones about two kilometers below the glacier than in summit zones." This affects local water reservoirs and reduces water supply for the local population.

  10. 17-02-2012 eco nws - global warming - plant life - forests - NASA Map Sees Earth's Trees in a New Light - ScienceDaily (Feb. 17, 2012) A NASA-led science team has created an accurate, high-resolution map of the height of Earth's forests. The map will help scientists better understand the role forests play in climate change and how their heights influence wildlife habitats within them, while also helping them quantify the carbon stored in Earth's vegetation. Scientists from NASA's Jet Propulsion Laboratory, Pasadena, Calif.; the University of Maryland, College Park; and Woods Hole Research Center, Falmouth, Mass., created the map using 2.5 million carefully screened, globally distributed laser pulse measurements from space. The light detection and ranging (lidar) data were collected in 2005 by the Geoscience Laser Altimeter System instrument on NASA's Ice, Cloud and land Elevation Satellite (ICESat). "Knowing the height of Earth's forests is critical to estimating their biomass, or the amount of carbon they contain," said lead researcher Marc Simard of JPL. "Our map can be used to improve global efforts to monitor carbon. In addition, forest height is an integral characteristic of Earth's habitats, yet is poorly measured globally, so our results will also benefit studies of the varieties of life that are found in particular parts of the forest or habitats." The map, available at http://lidarradar.jpl.nasa.gov, depicts the highest points in the forest canopy. Its spatial resolution is 0.6 miles (1 kilometer). The map was validated against data from a network of nearly 70 ground sites around the world. The researchers found that, in general, forest heights decrease at higher elevations and are highest at low latitudes, decreasing in height the farther they are from the tropics. A major exception was found at around 40 degrees south latitude in southern tropical forests in Australia and New Zealand, where stands of eucalyptus, one of the world's tallest flowering plants, tower much higher than 130 feet (40 meters). The researchers augmented the ICESat data with other types of data to compensate for the sparse lidar data, the effects of topography and cloud cover. These included estimates of the percentage of global tree cover from NASA's Moderate Resolution Imaging Spectroradiometer on NASA's Terra satellite, elevation data from NASA's Shuttle Radar Topography Mission, and temperature and precipitation maps from NASA's Tropical Rainfall Measuring Mission and the WorldClim database. WorldClim is a set of freely available, high-resolution global climate data that can be used for mapping and spatial modeling. In general, estimates in the new map show forest heights were taller than in a previous ICESat-based map, particularly in the tropics and in boreal forests, and were shorter in mountainous regions. The accuracy of the new map varies across major ecological community types in the forests, and also depends on how much the forests have been disturbed by human activities and by variability in the forests' natural height. "Our map contains one of the best descriptions of the height of Earth's forests currently available at regional and global scales," Simard said. "This study demonstrates the tremendous potential that spaceborne lidar holds for revealing new information about Earth's forests. However, to monitor the long-term health of Earth's forests and other ecosystems, new Earth observing satellites will be needed."