Drawing on four decades of research with gorillas, starting as an assisstant to Dian Fossey, Ian Redmond OBE passionately argues why we must protect these and other species such as elephants because of their important impacts on ecosystem processes that we, even in the industrialised countries of the north, depend on.
Forests
Amazon Inhales More Carbon than It Emits, NASA Finds
Old-growth Amazon tree canopy in Tapajós National Forest, Brazil. A new NASA study shows that the living trees in the undisturbed Amazon forest draw more carbon dioxide from the air than the forest’s dead trees emit. Image credit: NASA/JPL-Caltech
A new NASA-led study seven years in the making has confirmed that natural forests in the Amazon remove more carbon dioxide from the atmosphere than they emit, therefore reducing global warming. This finding resolves a long-standing debate about a key component of the overall carbon balance of the Amazon basin.
The Amazon’s carbon balance is a matter of life and death: living trees take carbon dioxide out of the air as they grow, and dead trees put the greenhouse gas back into the air as they decompose. The new study, published in Nature Communications on March 18, is the first to measure tree deaths caused by natural processes throughout the Amazon forest, even in remote areas where no data have been collected at ground level.
Fernando Espírito-Santo of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., lead author of the study, created new techniques to analyze satellite and other data. He found that each year, dead Amazonian trees emit an estimated 1.9 billion tons (1.7 billion metric tons) of carbon to the atmosphere. To compare this with Amazon carbon absorption, the researchers used censuses of forest growth and different modeling scenarios that accounted for uncertainties. In every scenario, carbon absorption by living trees outweighed emissions from the dead ones, indicating that the prevailing effect in natural forests of the Amazon is absorption.
Until now, scientists had only been able to estimate the Amazon’s carbon balance from limited observations in small forest areas called plots. On these plots, the forest removes more carbon than it emits, but the scientific community has been vigorously debating how well the plots represent all the natural processes in the huge Amazon region. That debate began with the discovery in the 1990s that large areas of the forest can be killed off by intense storms in events called blowdowns.
Espírito-Santo said that the idea for the study arose from a 2006 workshop where scientists from several nations came together to identify NASA satellite instruments that might help them better understand the carbon cycle of the Amazon. In the years since then, he worked with 21 coauthors in five nations to measure the carbon impacts of tree deaths in the Amazon from all natural causes — from large-area blowdowns to single trees that died of old age. He used airborne lidar data, satellite images, and a 10-year set of plot measurements collected by the University of Leeds, England, under the leadership of Emanuel Gloor and Oliver Phillips. He estimates that he himself spent a year-and-a-half doing fieldwork in the Amazon.
“It was a difficult and audacious study, and only Espírito-Santo’s dedication made it possible,” said Michael Keller, a research scientist at the U.S. Forest Service and co-author of the study.
Correlating satellite and airborne-instrument data with ground observations, Espírito-Santo and his colleagues devised methods to identify dead trees in different types of remotely sensed images. For example, fallen trees create a gap in the forest canopy that can be measured by lidar on research aircraft, and dead wood changes the colors in a satellite optical image. The researchers then scaled up their techniques so they could be applied to satellite and airborne data for parts of the Amazon with no corresponding ground data.
“We found that large natural disturbances — the sort not captured by plots — have only a tiny effect on carbon cycling throughout the Amazon,” said Sassan Saatchi of JPL, also a co-author. Each year, about two percent of the entire Amazon forest dies of natural causes. The researchers found that only about 0.1 percent of those deaths are caused by blowdowns.
This study looked only at natural processes in Amazonia, not at the results of human activities such as logging and deforestation, which vary widely and rapidly with changing political and social conditions.
The other institutions participating in the study are the University of New Hampshire, Durham; the Universities of Leeds and Nottingham, U.K.; Oxford University, U.K.; James Cook University, Cairns, Australia; U.S. Forest Service International Institute of Tropical Forestry, Puerto Rico; EMBRAPA Satellite Monitoring Center, Campinas, Brazil; National Institute for Research in Amazonia, Manaus, Brazil; EMBRAPA Eastern Amazonia, Santarém, Brazil; National Institute for Space Research (INPE), São José dos Campos, Brazil; the Missouri Botanical Garden, Oxapampa, Peru; and the Carnegie Institute for Science, Stanford, Calif.
NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.
Source: http://www.jpl.nasa.gov/news/news.php?release=2014-084
For more information about NASA’s Earth science activities in 2014, visit: http://www.nasa.gov/earthrightnow
Tree growth never slows
Idea debunked that young trees have the edge on their older siblings in carbon accumulation. by Jeff Tollefson
Native forest in Ancares Mountains, NW of Iberian Peninsula. Rubén Portas Copyright.
Many foresters have long assumed that trees gradually lose their vigour as they mature, but a new analysis suggests that the larger a tree gets, the more kilos of carbon it puts on each year.
“The trees that are adding the most mass are the biggest ones, and that holds pretty much everywhere on Earth that we looked,” says Nathan Stephenson, an ecologist at the US Geological Survey in Three Rivers, California, and the first author of the study, which appears today inNature1. “Trees have the equivalent of an adolescent growth spurt, but it just keeps going.”
The scientific literature is chock-full of studies that focus on forests’ initial growth and their gradual move towards a plateau in the amount of carbon they store as they reach maturity2. Researchers have also documented a reduction in growth at the level of individual leaves in older trees3.
In their study, Stephenson and his colleagues analysed reams of data on 673,046 trees from 403 species in monitored forest plots, in both tropical and temperate areas around the world. They found that the largest trees gained the most mass each year in 97% of the species, capitalizing on their additional leaves and adding ever more girth high in the sky.
Although they relied mostly on existing data, the team calculated growth rates at the level of the individual trees, whereas earlier studies had typically looked at the overall carbon stored in a plot.
Estimating absolute growth for any tree remains problematic, in part because researchers typically take measurements at a person’s height and have to extrapolate the growth rate higher up. But the researchers’ calculations consistently showed that larger trees added the most mass. In one old-growth forest plot in the western United States, for instance, trees larger than 100 centimetres in diameter comprised just 6% of trees, but accounted for 33% of the growth.
The findings build on a detailed case study published in 2010, which showed similar growth trends for two of the world’s tallest trees — the coast redwood (Sequoia sempervirens) and the eucalyptus (Eucalyptus regnans)4, both of which can grow well past 100 metres in height. In that study, researchers climbed, and took detailed measurements of, branches and limbs throughout the canopy to calculate overall tree growth. Stephen Sillett, a botanist at Humboldt State University in Arcata, California, who led the 2010 study, says that the latest analysis confirms that his group’s basic findings apply to almost all trees.
The results are consistent with the known reduction in growth at the leaf level as trees age. Although individual leaves may be less efficient, older trees have more of them. And in older forests, fewer large trees dominate growth trends until they are eventually brought down by a combination of fungi, fires, wind and gravity; the rate of carbon accumulation depends on how fast old forests turn over.
“It’s the geometric reality of tree growth: bigger trees have more leaves, and they have more surface across which wood is deposited,” Sillett says. “The idea that older forests are decadent — it’s really just a myth.”
The findings help to resolve some of these contradictions, says Maurizio Mencuccini, a forest ecologist at the University of Edinburgh, UK. The younger trees may grow faster on a relative scale, he says, meaning that they take less time to, say, double in size. ”But on an absolute scale, the old trees keep growing far more.”
The study has broad implications for forest management, whether in maximizing the yield of timber harvests or providing old-growth habitat and increasing carbon stocks. More broadly, the research could help scientists to develop better models of how forests function and their role in regulating the climate.
- Nature: doi:10.1038/nature.2014.14536
- Source: http://www.nature.com/news/tree-growth-never-slows-1.14536?
References
- Stephenson, N. L. et al. Nature http://dx.doi.org/10.1038/nature12914 (2014). Show context
- Ryan, M. G., Binkley, D. & Fownes, J. H. Adv. Ecol. Res. 27, 213–262 (1997). Article Show context
- Mencuccini, M. et al. Ecol. Lett. 8, 1183–1190 (2005). Article PubMed ISI ChemPort Show context
- Sillett, S. C. et al. Forest Ecol. Manag. 259, 976–994 (2010). Article Show context
Big trees, like the old-growth forests they inhabit, are declining globally
Rhett Butler, mongabay.com
Already on the decline, demise of giant trees may be hastened by global warming.
Already on the decline worldwide, big trees face a dire future due to habitat fragmentation, selective harvesting by loggers, exotic invaders, and the effects of climate change, warns an article published this week in New Scientist magazine.
Reviewing research from forests around the world, William F. Laurance, an ecologist at James Cook University in Cairns, Australia, provides evidence of decline among the world’s “biggest and most magnificent” trees and details the range of threats they face. He says their demise will have substantial impacts on biodiversity and forest ecology, while worsening climate change.
“To persist, big trees need a safe place to live and long periods of stability,” he told mongabay.com via email. “But time and stability are becoming very rare commodities in our modern world.”
Giant trees offer critical habitat and forage for wildlife, while transpiring massive amounts of water through their leaves, contributing to local rainfall. Old trees also lock up massive amounts of carbon — in some forests they can account for up to a quarter of living biomass.
 Dipterocarps are commonly targeted by loggers in Southeast Asia. This Dipterocarp was photographed in Borneo by Rhett A. Butler. |
But their ability to sequester carbon and render other ecosystem services is threatened by human activities. Some of the world’s largest trees are particularly targeted by loggers. The oldest trees are among the most valuable and therefore the first to be cut in “virgin” forest areas.
Big trees are also sensitive to fragmentation, which exposes them to stronger winds and drier conditions. Laurance’s own work in the Amazon has shown substantial die-off of canopy giants in small forest fragments. Their susceptibility seems counter-intuitive given big trees’ life histories, which invariably include periods of drought and other stress.
“All around the tropics, big canopy and emergent trees are succumbing to strong droughts,” Laurance said. “That’s been a surprise to me and many other ecologists, because big, ancient trees would have had to survive many droughts in the past.”
Forest giants may suffer disproportionately from climate change, writes Laurance in New Scientist, highlighting research in La Selva, Costa Rica by David and Deborah Clark.
- “Trees are probably getting a double-whammy when the thermometer rises,’ says David Clark. “During the day, their photosynthesis shuts down when it gets too warm, and at night they consume more energy because their metabolic rate increases, much as a reptile’s would do when it gets warmer.” With less energy being produced in warmer years and more being consumed just to survive, there is less energy available for growth.
- The Clarks’ hypothesis, if correct, means tropical forests could shrink over time. The largest, oldest trees would progressively die off and tend not to be replaced. Alarmingly, this might trigger a positive feedback that could destabilize the climate: as older trees die, forests would release some of their stored carbon into the atmosphere, prompting a vicious circle of further warming, forest shrinkage and carbon emissions.
 Giant Kapok tree in the Brazilian Amazon. Photo by Rhett A. Butler. |
Laurance notes climate change is having less direct impacts on forests, including creating conditions for exotic pathogens to thrive. For example, pathogens such as Dutch Elm Disease, introduced by trade or circumstance, can devastate native forests.
All told, the outlook for big trees is not good, according to Laurance.
“The decline of big trees foretells a different world where ancient behemoths are replaced by short-lived pioneers and generalists that can grow anywhere, where forests store less carbon and sustain fewer dependent animals, where giant cathedral-like crowns become a thing of the past.”
UMD Leads 1st Local-to-Global Mapping of Forest
COLLEGE PARK, Md. – A University of Maryland-led, multi-organizational team has created the first high-resolution global map of forest extent, loss and gain. This free resource greatly improves the ability to understand human and naturally-induced forest changes and the local to global implications of these changes on environmental, economic and other natural and societal systems, members of the team say.
In a new study, the team of 15 university, Google and government researchers reports a global loss of 2.3 million square kilometers (888,000 square miles) of forest between 2000 and 2012 and a gain of 800,000 square kilometers (309,000 square miles) of new forest.
Their study, published online on November 14 in the journal Science, documents the new database, including a number of key findings on global forest change. For example, the tropics were the only climate domain to exhibit a trend, with forest loss increasing by 2,101 square kilometers (811 square miles) per year. Brazil’s well-documented reduction in deforestation during the last decade was more than offset by increasing forest loss in Indonesia, Malaysia, Paraguay, Bolivia, Zambia, Angola and elsewhere.
“This is the first map of forest change that is globally consistent and locally relevant,” says University of Maryland Professor of Geographical Sciences Matthew Hansen, team leader and corresponding author on the Science paper.
“Losses or gains in forest cover shape many important aspects of an ecosystem, including climate regulation, carbon storage, biodiversity and water supplies, but until now there has not been a way to get detailed, accurate, satellite-based and readily available data on forest cover change from local to global scales,” Hansen says.
To build this first of its kind forest mapping resource, Hansen, UMD Research Associate Professor Peter Potapov and five other UMD geographical science researchers drew on the decades-long UMD experience in the use of satellite data to measure changes in forest and other types of land cover. Landsat 7 data from 1999 through 2012 were obtained from a freely available archive at the United States Geological Survey’s center for Earth Resources Observation and Science (EROS). More than 650,000 Landsat images were processed to derive the final characterization of forest extent and change.
The analysis was made possible through collaboration with colleagues from Google Earth Engine, who implemented the models developed at UMD for characterizing the Landsat data sets. Google Earth Engine is a massively parallel technology for high-performance processing of geospatial data and houses a copy of the entire Landsat image catalog. What would have taken a single computer 15 years to perform was completed in a matter of days using Google Earth Engine computing.
Hansen and his coauthors say their mapping tool greatly improves upon existing knowledge of global forest cover by providing fine resolution (30 meter) maps that accurately and consistently quantify annual loss or gain of forest over more than a decade. This mapping database, which will be updated annually, quantifies all forest stand-replacement disturbances, whether due to logging, fire, disease or storms. And they say it is based on repeatable definitions and measurements while previous efforts at national and global assessments of forest cover have been largely dependent on countries’ self-reported estimates based on widely varying definitions and measures of forest loss and gain.
Dynamics from local to regional to global scale are quantified. For example, subtropical forests were found to have the highest rates of change, largely due to intensive forestry land uses. The disturbance rate of North American subtropical forests, located in the Southeast United States, was found to be four times that of South American rainforests during the study period; more than 31 percent of U.S. southeastern forest cover was either lost or regrown. At national scales, Paraguay, Malaysia and Cambodia were found to have the highest rates of forest loss. Paraguay was found to have the highest ratio of forest loss to gain, indicating an intensive deforestation dynamic.
The study confirms that well-documented efforts by Brazil – which has long been responsible for a majority of the world’s tropical deforestation – to reduce its rainforest clearing have had a significant effect. Brazil showed the largest decline in annual forest loss of any country, cutting annual forest loss in half, from a high of approximately 40,000 square kilometers (15,444 square miles) in 2003-2004 to 20,000 square kilometers (7,722 square miles) in 2010-2011. Indonesia had the largest increase in forest loss, more than doubling its annual loss during the study period to nearly 20,000 square kilometers (7,722 square miles) in 2011-2012.
Hansen and colleagues say the global data sets of forest change they have created contain information that can provide a “transparent, sound and consistent basis to quantify critical environmental issues,” including the causes of the mapped changes in the amount of forest; the status of world’s remaining intact natural forests; biodiversity threats from changes in forest cover; the carbon stored or emitted as a result of gains or losses in tree cover in both managed and unmanaged forests; and the effects of efforts to halt or reduce forest loss.
For example, Hansen says, that while their study shows the efforts of Brazil’s government to slow loss of rainforest have been effective, it also shows that a 2011 Indonesian government moratorium on new logging licenses was actually followed by significant increases in deforestation in 2011 and 2012.
“Brazil used Landsat data to document its deforestation trends, then used this information in its policy formulation and implementation. They also shared these data, allowing others to assess and confirm their success,” Hansen says. “Such data have not been generically available for other parts of the world. Now, with our global mapping of forest changes every nation has access to this kind of information, for their own country and the rest of the world.”
Global map of forest change: http://earthenginepartners.appspot.com/science-2013-global-forest
Support for Landsat data analysis and characterization was provided by the Gordon and Betty Moore Foundation, the United States Geological Survey and Google, Inc. GLAS data analysis was supported by the David and Lucile Packard Foundation. Development of all methods was supported by NASA through its Land Cover and Land Use Change, Terrestrial Ecology, Applied Sciences and Measures programs (grants NNH05ZDA001N, NNH07ZDA001N, NNX12AB43G, NNX12AC78G, NNX08AP33A and NNG06GD95G) and by the United States Agency for International Development through its CARPE program.
High-resolution global maps 21st-century forest cover change, Science, Nov. 15, 2013, Vol 342 #6160, authors M. C. Hansen, P. V. Potapov, S. A. Turubanova, A. Tyukavina, L. Chini, C. O. Justice and J. R. G. Townshend of the University of Maryland; R. Moore, M. Hancher and D. Thau of Google, Inc.; S. V. Stehman of the State University of New York; S. J. Goetz of Woods Hole Research Center; T. R. Loveland of the United States Geological Survey; and A. Kommareddy, and A. Egorov of South Dakota State University.
Contacts:
Lee Tune, 301-405-4679
Laura Ours, 301-405-5722
Photos: Source: Hansen, Potapov, Moore, Hancher et al., 2013
Source: http://umdrightnow.umd.edu/news/umd-leads-1st-local-global-mapping-forest
On Boreal forests, fires and natural processes
Charcoal records reveal that far northern wildfires have doubled in frequency recently
By Stephanie Paige Ogburn and ClimateWire
Image: Flickr/Drew Brayshaw
Alaska is burning more than it has in the past 10,000 years.
That’s the finding of research released yesterday in the journal Proceedings of the National Academy of Sciences.
The study analyzed charcoal found in sediment cores from 14 lakes in the Yukon Flats region of the state to determine the frequency of past fires.
Over the last 3,000 years, the average fire frequency in the area was about 10 fires per thousand years.
In the last 50 years, the fire frequency has nearly doubled, up to 20 every thousand years, or one fire every 50 years.
Climate scientists care about what might happen in boreal forests because they cover 10 percent of land surface and store a lot of carbon in their soil, said Ryan Kelly, an ecologist and doctoral candidate at the University of Illinois who was lead author of the study.
“It is a significant player in the global carbon cycle,” Kelly said. “When the forests burn, the carbon goes into the atmosphere. If they burn more frequently, they are releasing more carbon, and storing less.”
The researchers were particularly interested in comparing fire frequency from the recent past with that of a period called the Medieval Climate Anomaly, when conditions were warm and dry, similar to recent decades.
Forest may self-regulate
When they did this, they found a surprising—and possibly hopeful—result. They noted that fire frequency was also high about 1,000 years ago, during the anomaly.
But pollen records the researchers analyzed show that during that time of increased fire, the forest responded by changing the vegetation that regrew after the fires. The trees shifted from evergreen to deciduous. The deciduous trees, like aspen and birch, did not burn as easily, and this slowed down the fire frequency.
“So that’s really interesting to us as ecologists, because it is a mechanism by which ecosystems are kind of regulating themselves,” he said.
Jennifer Marlon, a scientist at the Yale School of Forestry and Environmental Studies who studies wildfires and climate change, said the study was unique because it used a lot of records from one location. “Their conclusions were very robust because of the scope and scale of the study,” Marlon said.
The findings were also unique because the researchers were able to so closely link historical records with what is happening in the present and what might happen in the future, she said. “Using the paleo records, long historical records like this, it is fairly rare to be able to connect it so closely to what is happening today.”
The fact that the number of forest fires in a past warm period was reduced by the regrowth of different trees might offer some hope for reduced fire frequency in the future, even though the frequency in recent decades has been high, Kelly said.
This idea could be validated by modeling studies. It also might play out in the next few decades, as scientists watch, Kelly said.
Whether the regulating mechanism of deciduous trees kicks in could depend on how much that region warms, said Philip Higuera, an ecologist from the University of Idaho and a co-author on the study.
“To me, the key thing that that hangs on is how much we turn that temperature knob up,” said Higuera.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
Between Thorn Bushes and Claws 