The green lungs of our planet are changing

A press release from Goethe University (Frankfurt, Germany): Are leaves and buds developing earlier in the spring? And do leaves stay on the trees longer in autumn? Do steppe ecosystems remaining green longer and are the savannas becoming drier and drier?  In fact, over recent decades, the growing seasons have changed everywhere around the world. This was determined by a doctoral candidate at the Goethe University as part of an international collaboration based on satellite data. The results are expected to have consequences for agriculture, interactions between species, the functioning of ecosystems, and the exchange of carbon dioxide and energy between the land surface and the atmosphere.

"There is almost no part of the Earth that is not affected by these changes", explains Robert Buitenwerf, doctoral candidate at the Institute for Ph
ysical Geography at the Goethe University. He has evaluated satellite data from 1981 to 2012 with regard to 21 parameters on vegetation activity, in order to determine the point in time, the duration, and the intensity of growth from the northernmost conifer forests to tropical rain forests. His conclusion: On 54 percent of the land surface, at least one parameter of vegetation activity has moved away from the mean value by more than two standard deviations.

As reported by researchers from Frankfurt, Freiburg and New Zealand in the current edition of the professional journal "Nature Climate Change", leaves are now sprouting earlier in most of the climate zones of the far north. Although they are also dropped somewhat earlier in autumn, the overall vegetation period has grown longer. On the other hand, in our latitudes, trees and shrubs are losing their leaves later than they have up to now.

To date, not much research has been conducted on the regions of the southern hemisphere.  In those areas, the researchers found that in several savannas of South America, southern Africa and Australia, the vegetation activity has decreased during dry seasons. "Although these savannas have similar vegetation and comparable climates, the changes in vegetation activity differ. That may be attributable to the differences in the functioning of the respective ecosystems", says Buitenwerf.

In this respect, the seasonal distribution of leaf growth constitutes a sensitive indicator: it indicates how various ecosystems react to changes in the environment. "Although vegetation changes in the northern hemisphere have conclusively been attributed to climate change by other studies, attributing all the changes found in our study would require a more complex analysis," Buitenwerf emphasizes. In the northern hemisphere it has already been shown that species whose life cycles depend on the vegetation period are endangered by these severe changes.  Consequences for species in the southern hemisphere are as yet unclear....

Redwoods in Muir Woods, shot by Meburian, Wikimedia Commons,  under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Munching bugs thwart eager trees, reducing the carbon sink

University of Wisconsin-Madison News: In a high carbon dioxide world, the trees would come out ahead. Except for the munching bugs. A new study published today [Monday, March 2, 2015] in Nature Plants shows that hungry, plant-eating insects may limit the ability of forests to take up elevated levels of carbon dioxide in the atmosphere, reducing their capacity to slow human-driven climate change.

The finding is significant because climate change models typically fail to consider changes in the activities of insects in the ecosystem, says Richard Lindroth, a professor of ecology at the University of Wisconsin-Madison and the leader of the study. The research suggests it’s time to add insects to the models.

Carbon dioxide typically makes plants grow faster and makes them more efficient in how they use nutrients. But the amount of damage caused by leaf-munching bugs in the study nearly doubled under high carbon dioxide conditions, leading to an estimated 70g of carbon-sequestering biomass lost per meter squared per year.

“This is the first time, at this scale, that insects have been shown to compromise the ability of forests to take up carbon dioxide,” Lindroth says.

In addition, as feeding increased, more nutrients moved from the canopy to the forest floor in the form of insect fecal material and chewed-on leaf scraps, mixing into the soil and likely altering the nutrient profile of the forest....

Photo of a tent caterpillar by Mary A. Jamieson/UW-Madison Department of Entomology

Museum specimens, modern cities show how an insect pest will respond to climate change

A press release from North Carolina State University: Researchers from North Carolina State University have found that century-old museum specimens hold clues to how global climate change will affect a common insect pest that can weaken and kill trees – and the news is not good. “Recent studies found that scale insect populations increase on oak and maple trees in warmer urban areas, which raises the possibility that these pests may also increase with global warming,” says Dr. Elsa Youngsteadt, a research associate at NC State and lead author of a paper on the work.

“More scale insects would be a problem, since scales can weaken or kill the trees they live on,” Youngsteadt says. “But cities are unique, so we wanted to know whether warming causes scale insect population explosions in rural forests, the way it does in cities.”

To address that question, Youngsteadt examined more than 300 museum specimens of red maple branches collected between 1895 and 2011 in rural areas of North Carolina, South Carolina and Georgia. By evaluating the scale insect remains attached to each specimen, Youngsteadt estimated scale population density and compared it to the average August temperature for the year and place where the specimen was collected. Youngsteadt then compared the findings from the historical specimens with more recent data from urban Raleigh, North Carolina.

“Scale insect density in rural areas was not as high as it was in the city, but there was a common pattern,” Youngsteadt says. “Scale insects were most likely to be present on specimens collected during warm historical time periods, and scales were most abundant when temperatures were similar to modern, urban Raleigh.”

Given the shared urban and historical pattern, the researchers also predicted that scale insects would be more abundant in rural forests today than in the past, as a result of recent climate warming. To test this prediction, Youngsteadt went to 20 sites where historical specimens were collected from 1970 to 1997 and sampled their modern scale insect populations.

“Sure enough, scale abundance had increased at 16 of the 20 sites,” Youngsteadt says. “Overall, we found a total of about five times more scale insects in 2013 than on the historical specimens from the same locations. The urban and historical data are so well-aligned that we can view scale insect populations in cities as a preview of what to expect elsewhere,” Youngsteadt adds. “It also suggests that we should begin looking at cities for clues to how other insect species will respond to higher global temperatures.”...

A red maple museum sample of evaluated as part of the study. Image credit: North Carolina State University Herbarium. 

Pakistan's juniper forest sacrificed for fuel, fruit orchards

Aamir Saeed in Thomson Reuters Foundation: One of the world’s largest and most ancient juniper forests in southwestern Pakistan, already stressed by water shortages, faces a further threat as its trees are cut down for fuel and to clear land for orchards.

Some of the trees in the juniper forest in the picturesque Ziarat valley of Balochistan province are believed to be as much as 7,000 years old. The forest covers an area of around 280,000 hectares (700,000 acres), of which around a third belongs to the state.

Protecting forests is crucial to curbing extreme weather and other problems associated with climate change, as trees absorb carbon dioxide, the main greenhouse gas. But persuading local residents not to fell them is difficult due to the profits to be made from selling timber, and because many people lack other sources of energy to heat their homes and cook food.

“We know the forest is an asset and we really want to protect, it but unfortunately we don’t have any alternative to firewood,” said Muhammad Hashim, a resident of Baba Kharwari, a village 8 km (5 miles) from the town of Ziarat.

Hashim, 55, is the only breadwinner for the 15 members of his family. He owns a 5-acre tract of land in the juniper forest, and to make ends meethe sells the trees to a local “mafia” that trades timber illegally....

A snow-dusted road in the Ziarat valley. Maybe those are junipers on that bluff. Shot by Akashahmed007, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license 

Carbohydrates boost trees' drought survival chances

Mark Kinver in BBC News: Higher levels of compounds called non-structural carbohydrates (NSCs) boost tropical trees' chances of surviving droughts, a study has suggested. An international team of scientists found that species with elevated NSC levels survived up to 17 days longer.

The discovery could help restore forests devastated by logging and increase their resilience to future climate change, they added. The findings have been published in the journal Nature Climate Change.

"The diversity of tropical trees is staggering but explaining why this diversity arose and how it is maintained is a puzzle," explained co-author Andrew Hector from the University of Oxford's Department of Plant Sciences.

"We've shown that different species appear to have evolved different levels of drought-busting compounds, which probably play an important role in defining their different ecological niches and which means diverse mixtures of species may be an important insurance against the increasing droughts predicted by climate change models."

Prof Hector told BBC News that previous studies on plant physiology had indicated that NSCs played a role in a tree's drought resilience abilities. The researchers say the findings could help identify species that are vulnerable in drought conditions "Why this isthe case in not very well known. We set out to test that, but it was a tricky thing to do," he said....

A 1920 painting of a tropical forest

Tree species choices critical to effective coastal bioshields

Sandhya Sekar in SciDev.net: Injudicious site and species selection while planting 'bioshields' — plantations that protect coastlines against natural disasters — could be ecologically damaging in the long term, a study warns.

Catastrophic cyclones and a devastating tsunami over the last decade have prompted the planting of bioshields, but whether they actually work to protect the coastline remains unanswered, the study published online in February in Acta Oecologica says.

Bioshields range from pristine ecosystems of mangroves to plantations of such species as Casuarina equisetifolia or ‘whistling pine’. After the Indian Ocean tsunami in December 2004, governments across South Asia launched large-scale planting of bioshields as part of coastal restoration efforts.

Nibedita Mukherjee and colleagues from Université libre de Bruxelles, Brussels, and the Centre for Ecological Sciences, Indian Institute of Science, Bangalore, surveyed coastal districts in the southern Indian states of Andhra Pradesh, Tamil Nadu and Kerala and interviewed key persons involved in formulating the bioshield policy and implementing it.

The survey found a general lack of awareness about conservation laws relating to coastal forests. While India's state forest departments have traditionally planted trees along the coast since the 1950s, post-tsunami planting initiatives were taken up largely by non-governmental organisations with external funding....  

Coastal erosion at Benacre Broad, UK, shot by John Goldsmith, Wikimedia Commons via Geograph UK,  under the Creative Commons Attribution-Share Alike 2.0 Generic license

Tropical trees absorb 2 billion tons of carbon yearly

Futurity via the University of Leeds (posted by Sarah Reed): Reducing deforestation in the tropics would significantly cut the amount of carbon dioxide emitted into the atmosphere by as much as one-fifth, research shows. In the first study of its kind, scientists have calculated the amount of carbon absorbed by the world’s tropical forests and the amounts of greenhouse gas emissions created by loss of trees, as a result of human activity.

Scientists analyzed data from previous studies, including satellite studies, to determine the amount of carbon absorbed and emitted by the world’s tropical forests in South and Central America, equatorial Africa, and Asia.

“Forest census data from an Amazon-wide network of forest plots, maintained by the Universities of Leeds and Oxford, played a critical part in the analysis,” says Professor Emanuel Gloor, a coauthor of the study from the School of Geography at the University of Leeds. The research appears in Global Change Biology.

The researchers found that tropical forests absorb almost two billion tons of carbon each year, equivalent to one-fifth of the world’s carbon emissions, by storing it in their bark, leaves, and soil.

However, an equivalent amount is lost through logging, clearing of land for grazing, and growing biofuel crops such as palm oil, soy beans, and sugar. Peat fires in forests add significantly to the greenhouse gas emissions. Researchers say emissions from tropical forests will increase as the climate warms, as rising temperatures accelerate the decay of dead plants and trees, giving off more carbon dioxide.

...“If we limit human activity in the tropical forests of the world, this could play a valuable role in helping to curb the rise in carbon dioxide in the atmosphere. Preventing further losses of carbon from our tropical forests must remain a high priority,” says Professor John Grace of the University of Edinburgh’s School of GeoSciences, who led the study....

Deforestation in Kalimantan, Indonesia, shot by Josh Estey of AusAID, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license

Philippines coconut industry struggles to recover after Typhoon Haiyan

Voice of America: Last December, Typhoon Haiyan's destructive winds devastated the Philippines. Parts of the archipelago nation are still recovering. Among those hardest hit were farmers, nearly half of whom harvest coconuts. In Leyte province, efforts to revitalize the coconut farming industry are underway.

Before the storm, farmers at a farm in rural Leyte harvested the dried meat, or copra, of coconuts to make oil, but Typhoon Haiyan’s destruction has made the future of this and many other small plantations unclear.

The farm’s caretaker, Arnulflo Barcero, 52, said the typhoon knocked out the large majority of the farm's trees. “Before the typhoon we had 700 trees and now there are only 90 trees still standing. It’s a problem for the community because we rely on the copras to earn a living,” said Barcero.

Around 40 percent of farmers in Leyte province work in the coconut industry.  The downed trees mean they have nothing to sell and the help they employ have no work. But for others, the devastation is creating income.

Francisco Alverca, a chainsaw operator who has been called in to help cut up the fallen and damaged trees, is one of those benefiting. “I think it will take several months to complete all the work here, it is a big property,” said Alverca....

A few palm trees left standing in Tacloban after Haiyan, shot by DFID - UK Department for International Development, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

Tree roots in the mountains 'acted like a thermostat' for millions of years

EurekAlert via the University of Oxford: For the first time, scientists have discovered how tree roots in the mountains may play an important role in controlling long-term global temperatures. Researchers from Oxford and Sheffield Universities have found that temperatures affect the thickness of the leaf litter and organic soil layers, as well as the rate at which the tree roots grow. In a warmer world, this means that tree roots are more likely to grow into the mineral layer of the soil, breaking down rock into component parts which will eventually combine with carbon dioxide. This process, called weathering, draws carbon dioxide out of the atmosphere and cools the planet. The researchers say this theory suggests that mountainous ecosystems have acted like the Earth's thermostat, addressing the risk of 'catastrophic' overheating or cooling over millions of years.

In their research paper published online in Geophysical Research Letters, the researchers carried out studies in tropical rain forests in Peru, measuring tree roots across different sites of varying altitude – from the warm Amazonian Lowlands to the cooler mountain ranges of the Andes. They measured the growth of the tree roots to 30 cm beneath the surface, every three months over several years. At each of the sites, they also measured the thickness of the organic layer above the soil. This information was then combined with existing data of monthly temperature, humidity, rainfall, and soil moisture in order to calculate the likely breakdown process of the basalt and granite rocks found in the mountain ranges of Peru.

Using this model, based on field data in Peru, the scientists were able to scale up in order to calculate the likely contribution of mountain forests worldwide to global weathering rates. The researchers then calculated the likely amount of carbon to be pulled out of the atmosphere through weathering when the Earth became very hot. They looked at the volcanic eruptions in India 65 million years ago (known as the Deccan traps). The model also allowed them to calculate the weathering process and carbon feedback after the Earth's cooling 45 million years ago, when great mountain ranges like the Andes and the Himalayas were first formed.

The paper suggests that mountainous regions may play a particularly important role in drawing carbon out of the atmosphere because they have abundant volcanic rock which is highly reactive to weathering when it disintegrates...

A 1924 photograph by Eugene Atget of tree roots in St. Cloud

In Haiti, planting trees is no simple matter

IPS News in Doucet, Haiti: Reforestation and soil conservation programmes costing many thousands of dollars in this rural community have resulted in hundreds of small ledges built of straw or sacks of earth. In certain areas, the earthworks seem to be lasting, but in others, they are disintegrating.

The construction and destruction of the anti-erosion ledges – all made with foreign development and humanitarian money – offer an example of how at least some of Haiti’s reforestation projects turn out. No matter what promises were made, a farmer will always be concerned with the immediate need of feeding and clothing his or her family first.

In the years since the 2010 earthquake, the 11th and 12th communal sections of Petit-Goâve, located 60 kilometres southwest of the capital, have hosted several soil conservation and agricultural programmes with budgets in the tens and even hundreds of thousands. The U.N.’s Food and Agricultural Organisation (FAO), Helvetas and Action Agro Allemande (AAA), sometimes working with a local development organisation – Mouvman Kole Zepòl (MKOZE) – oversaw projects aimed at rehabilitating the watershed of the Ladigue River.

The steep slopes around the river “are very vulnerable to water erosion and mudslides,” MKOZE explained in a report on one project that had a budget of 91,534 dollars. “During rainy season, the waters from the Ladigue River dump a lot of sediment and rocks at the river’s mouth, destroying fields and causing homes to flood. Sometimes harvests, homes, animals and even human lives are lost.”

In the Petit-Goâve region, deforestation started about a half-century ago, according to many residents. It began with the devastating 1963 Hurricane Flora, which caused great damage and over 5,000 deaths in Haiti’s western and southern regions.

...Haiti has less than three percent tree cover, down from about 60 percent a century ago, and perhaps 80 percent when Christopher Columbus first disembarked. In Haiti, trees are cut down primarily for fuel....

A view above Milot in Haiti, shot by Carol4929, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license 

Large old trees grow fastest, storing more carbon

A press release from the US Geological Survey: Trees do not slow in their growth rate as they get older and larger — instead, their growth keeps accelerating, according to a study published today in the journal Nature. "This finding contradicts the usual assumption that tree growth eventually declines as trees get older and bigger," says Nate Stephenson, the study's lead author and a forest ecologist with the U.S. Geological Survey. "It also means that big, old trees are better at absorbing carbon from the atmosphere than has been commonly assumed."

An international team of researchers compiled growth measurements of 673,046 trees belonging to 403 tree species from tropical, subtropical and temperate regions across six continents, calculating the mass growth rates for each species and then analyzing for trends across the 403 species. The results showed that for most tree species, mass growth rate increases continuously with tree size — in some cases, large trees appear to be adding the carbon mass equivalent of an entire smaller tree each year.

"In human terms, it is as if our growth just keeps accelerating after adolescence, instead of slowing down," explains Stephenson. "By that measure, humans could weigh half a ton by middle age, and well over a ton at retirement."

This continuously increasing growth rate means that on an individual basis, large, old trees are better at absorbing carbon from the atmosphere. Carbon that is absorbed or "sequestered" through natural processes reduces the amount of carbon dioxide in the atmosphere, and can help counter-balance the amount of CO2 people generate.

However, the researchers are careful to note that the rapid absorption rate of individual trees does not necessarily translate into a net increase in carbon storage for an entire forest. "Old trees, after all, can die and lose carbon back into the atmosphere as they decompose," says Adrian Das, a USGS coauthor. "But our findings do suggest that while they are alive, large old trees play a disproportionately important role within a forest’s carbon dynamics. It is as if the star players on your favorite sports team were a bunch of 90-year-olds."...

Albert Bierstadt's painting of a sequoia, circa 1860-1870

Massive spruce beetle outbreak in Colorado tied to drought

University of Colorado at Boulder: A new University of Colorado Boulder study indicates drought high in the northern Colorado mountains is the primary trigger of a massive spruce beetle outbreak that is tied to long-term changes in sea-surface temperatures from the Northern Atlantic Ocean, a trend that is expected to continue for decades.

The new study is important because it shows that drought is a better predictor of spruce beetle outbreaks in northern Colorado than temperature alone, said lead study author Sarah Hart, a CU-Boulder doctoral student in geography. Drought conditions appear to decrease host tree defenses against spruce beetles, which attack the inner layers of bark, feeding and breeding in the phloem, a soft inner bark tissue, which impedes tree growth and eventually kills vast swaths of forest.

Spruce beetles, like their close relatives, mountain pine beetles, are attacking large areas of coniferous forests across the West. While the mountain pine beetle outbreak in the Southern Rocky Mountains is the best known and appears to be the worst in the historical record, the lesser known spruce beetle infestation has the potential to be equally or even more devastating in Colorado, said Hart, lead author on the new study.

 “It was interesting that drought was a better predictor for spruce beetle outbreaks than temperature,” said Hart of the geography department.  “The study suggests that spruce beetle outbreaks occur when warm and dry conditions cause stress in the host trees.”

...The new study also puts to rest false claims that fire suppression in the West is the trigger for spruce beetle outbreaks, said Veblen.

...The strongest climate correlation to spruce beetle outbreaks was above average annual values for the Atlantic Multi-decadal Oscillation, or AMO, a long-term phenomenon that changes sea-surface temperatures in the North Atlantic. Believed to shift from cool to warm phases roughly every 60 years, positive AMO conditions are linked to warmer and drier conditions over much of North America, including the West....

Wolf Creek Pass ski area in Colorado, shot by Doc Searls, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license

Carbon farming schemes should consider multiple cobenefits

Seed Daily via SPX: Carbon markets and related international schemes that allow payments to landholders for planting trees, sometimes called carbon farming, are intended to support sequestration of carbon from the atmosphere.

But they will have harmful effects, such as degrading ecosystems and causing food supply problems, if other benefits and disbenefits from revegetating agricultural landscapes are not also taken into account in land-use decisions, according to an article published in the October issue of BioScience.

Brenda B. Lin of the Australian Commonwealth Scientific and Industrial Research Organization and her colleagues assessed a variety of ways that people have attempted carbon farming. Simple maximization of profit can lead landholders accessing carbon markets to create monoculture plantations, which do not support biodiversity and provide few environmental benefits to local inhabitants.

But alternatives such as planting strips of trees on farms, agroforestry-integrating trees into cropping systems-and revegetation of marginal or crop land can sequester carbon while also yielding a broad spectrum of environmental benefits. These benefits may include, for example, reduced pollution outflow and erosion, and better wind protection, pest control, and pollination....

A christmas tree farm, public domain

Could planting trees in the desert mitigate climate change?

A press release from the European Geosciences Union: As the world starts feeling the effects of increasing atmospheric carbon dioxide and consequent global temperature rise, researchers are looking for a Plan B to mitigate climate change. A group of German scientists has now come up with an environmentally friendly method that they say could do just that. The technique, dubbed carbon farming, consists in planting trees in arid regions on a large scale to capture CO2. They publish their study today in Earth System Dynamics, a journal of the European Geosciences Union (EGU).

“Carbon farming addresses the root source of climate change: the emission of carbon dioxide by human activities,” says first-author Klaus Becker of the University of Hohenheim in Stuttgart. “Nature does it better,” adds Becker’s colleague Volker Wulfmeyer, “if we understand and can make use of it in a sustainable manner.”

When it comes to sequestering carbon from the atmosphere, the team shows that Jatropha curcas does it better. This small tree is very resistant to aridity so it can be planted in hot and dry land in soil unsuitable for food production. The plant does need water to grow though, so coastal areas where desalinated seawater can be made available are ideal.

“To our knowledge, this is the first time experts in irrigation, desalination, carbon sequestration, economics and atmospheric sciences have come together to analyse the feasibility of a large-scale plantation to capture carbon dioxide in a comprehensive manner. We did this by applying a series of computer models and using data from Jatropha curcas plantations in Egypt, India and Madagascar,” says Wulfmeyer.

...“From our point of view, afforestation as a geoengineering option for carbon sequestration is the most efficient and environmentally safe approach for climate change mitigation. Vegetation has played a key role in the global carbon cycle for millions of years, in contrast to many technical and very expensive geoengineering techniques,” explains Becker...

Processes involved in carbon farming (Credit: Becker et al. 2013)

Tree-ring data show history, pattern to droughts

University of Arkansas Newswire: Dendrochronologists have shown that tree-ring data produce a remarkably accurate history of droughts and other climate changes. Combined with reliable drought indices and historical descriptions of climate conditions, dendrochronology – the technique of dating events and environmental change by relying on characteristic patterns of tree-ring growth – can provide a climate perspective on important events such as large-scale human migration and even the rise and fall of entire civilizations.

A research team, including University of Arkansas Distinguished Professor and dendrochronologist David Stahle and Ewing Research Professor Edward Cook of Columbia University, used more than 1,400 climate-sensitive tree-ring chronologies from multiple tree species across North America to reconstruct the Palmer drought severity index (PDSI), a widely used soil moisture index. Stahle presented his research Friday, Feb. 15, in a symposium on “U.S. Climate and Weather Extremes:  Past, Present, and Future,” during the American Association for the Advancement of Science annual meeting in Boston. He also participated in a panel discussion with other climate experts.

The Palmer drought severity index is based on instrumental temperature and precipitation data dating back to 1895. Stahle and his colleagues inserted the index between fixed points on a grid covering most of North America. Their tree-ring reconstructions cover the same geographic area but extend back to 800 A.D. Stahle wanted to examine the reconstructed indices to test the accuracy of the records and to see if there were any patterns related to drought and other climate changes. The findings were dramatic.

“Comparisons of reconstructed PDSI with instrumentally measured PDSI during the 20th century document the remarkable accuracy with which the tree-ring data reproduce the spatial pattern and intensity of observed drought at annual and decadal time scales, including the Dust Bowl drought of the 1930s,” Stahle said.

The data also confirmed historical descriptions of climate conditions prior to the modern era of instrumentation for weather and climate measurements...

Tree rings shot by Lokilech, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Pine beetle outbreak buffers watersheds from nitrate pollution

University of Colorado-Boulder News: A research team involving several scientists from the University of Colorado Boulder has found an unexpected silver lining in the devastating pine beetle outbreaks ravaging the West: Such events do not harm water quality in adjacent streams as scientists had previously believed.

According to CU-Boulder team member Professor William Lewis, the new study shows that smaller trees and other vegetation that survive pine beetle invasions along waterways increase their uptake of nitrate, a common disturbance-related pollutant. While logging or damaging storms can drive stream nitrate concentrations up by 400 percent for multiple years, the team found no significant increase in the nitrate concentrations following extensive pine beetle tree mortality in a number of Colorado study areas.

“We found that the beetles do not disturb watersheds in the same way as logging and severe storms,” said Lewis, interim director of CU’s Cooperative Institute for Research in Environmental Sciences. “They leave behind smaller trees and other understory vegetation, which compensate for the loss of larger pine trees by taking up additional nitrate from the system. Beetle-kill conditions are a good benchmark for the protection of sub-canopy vegetation to preserve water quality during forest management activities.”

....“The U.S. Forest Service and other agencies have established harvesting practices that greatly mitigate damage to forests caused by logging, and they deserve credit for that,” said Lewis. “But this study shows just how important the survival of smaller trees and understory vegetation can be to stream water quality.”

In waterways adjacent to healthy pine forests, concentrations of nitrate is generally far lower than in rivers on the plains in the West like the South Platte, said Lewis. Nitrate pollution is caused by agricultural runoff from populated areas and by permitted discharges of treated effluent from water treatment facilities....

Fog at the treeline in Rocky Mountain State Park, shot by Michael Gäbler, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Pythons, lionfish and now willow invade Florida's waterways

University of Central Florida: Foreign invaders such as pythons and lionfish are not the only threats to Florida’s natural habitat. The native Carolina Willow is also starting to strangle portions of the St. Johns River.

Biologists at the University of Central Florida recently completed a study that shows this slender tree once used by Native Americans for medicinal purposes, may  be thriving because of water-management projects initiated in the 1950s. Canals were built to control  runoff and provide water for agriculture. The unintended consequence — stable water levels — allowed Carolina Willow to spread and thrive.

They now cover thousands of acres. Willows form impenetrable thickets that prevent boating and eliminate duck habitat. Willow thickets also use tremendous amounts of water, leaving less available for wildlife and people. The findings were published today in Restoration Ecology,  the peer-reviewed journal of the Society for Ecological Restoration. The St. Johns Water Management District funded the study.

While the trees previously were kept in check by natural annual flooding, they can now be found thriving in wetlands, swamps and marshes. Some trees grow as tall as 35 feet. The leaves of the tree contain salicin, which is the compound behind the pain-relieving effect of salicylic acid found in aspirin.

UCF professors Pedro F. Quintana-Ascencio and John Fauth worked with Kimberli Ponzio and Dianne Hall, scientists from the St. Johns River Water Management District, to run experiments that found ways to control the willow, which is taking over marshes in the upper St. Johns River basin....

St. John's River near Orange City, Florida, shot by Mwanner, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Tropical trees are largest emitter of methane in their ecosystem

The Open University News: Researchers at The Open University have found that trees in Bornean rainforests emit more methane than any other element of the ecosystem, which provides a new understanding about sources of this powerful greenhouse gas from tropical ecosystems.

In a paper titled Trees are major conduits for methane egress from tropical forested wetlands by Dr Vincent Gauci and Sunitha Pangala, published in New Phytologist on 18 December, the researchers announced new findings which show that trees in tropical peat forests of Southeast Asia release more methane through their stems than is emitted from the soil surface.

Sunitha Pangala, final year PhD student at The Open University’s Centre for Earth, Planetary Space and Astronomical Research, and lead author on the paper said: "This is the first study to measure methane release from tree stems in tropical peat swamps and evaluate its importance at an ecosystem level. Our research establishes that trees in tropical peat swamps are the largest emission pathway of methane in that ecosystem."

Previously it was thought that methane was only emitted via diffusion and bubbles at the wetland surface. The team measured methane emissions from healthy tree stems in a tropical forested peatland in the upper Sebangau River catchment in Borneo. They found significant quantities of methane being released from the stems of seven of the eight tree species studied. They estimated up to 87% of the methane are released from tree stems, highlighting that the previous methane emission inventories of this ecosystem may have been severely underestimated.

"This work challenges our previous understanding of how these ecosystems exchange methane with the atmosphere and adds another piece to the tropical methane emission puzzle,” said Dr Vincent Gauci, Senior Lecturer, Earth Systems, and the project’s leader. "It further shows that for wet tropical forested ecosystems, the like of which span south America, Africa and southeast Asia, researchers may have been missing most of the methane emitted from these ecosystems if they neglected to measure tree stem emissions.”...

A 1859 rendering of Borneo

Canopy structure more important to climate than leaf nitrogen levels

Terra Daily via SPX: Claims that forest leaves rich in nitrogen may aid in reflecting infrared radiation - helping cool the atmosphere - have been challenged by new research that shows that the structure of tree canopies is a more important factor in infrared reflection. Recent studies have noticed a strong positive correlation between the concentration of nitrogen in forests and infrared reflectance measured from aircraft and satellites.

Some scientists have suggested this demonstrates a previously overlooked role for nitrogen in regulating the earth's climate system.

However, a new paper in Proceedings of the National Academy of Sciences, shows that the apparent relationship between leaves' nitrogen levels and infrared reflection is spurious and it is in fact the structure of forest canopies (the spatial arrangement of the leaves) that determines their ability to reflect infrared light.

The authors, including Professor Philip Lewis and Dr Mathias Disney (UCL Geography), show that the richer in nitrogen individual leaves are the worse at reflecting infrared radiation they become.

However, the complex arrangements of trees with radically different arrangements of leaves within a forest can act to mask this effect, making it appear as if higher levels of leaf nitrogen are leading to increased infrared reflection....

A tree canopy in Sri Lanka's Sinharaja Forest Reserve, shot by Chamal N, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Drought-stressed trees face race to adapt

CNN: Scientists have known for some time that climate change and the impacts of longer droughts and higher temperatures could pose a problem for forests. But many thought it would only affect a minority of trees, perhaps just those in extremely arid regions.

However, new research is showing that a large majority of tree species around the world are operating on the brink of collapse. If the predicted pace of climate change continues, many may not be able to adapt in time and large numbers could die-off.

The authors of the study, whose findings were published in the scientific journal Nature, looked at 226 different tree species from 81 sites around the world, covering the full range of climatic conditions, from Mediterranean-type arid to the tropical Amazon rainforest.

They found that 70% of the trees studied adapt closely to the local environment, whether arid or tropical, absorbing just enough water in order to survive, but leaving them highly vulnerable to minor shifts in rainfall and drought stress.

"We thought that in the dry areas, plants would have adapted to survive more than ones growing in the wet, but we found they were all equally vulnerable. It was a big surprise," says Steven Jansen, from Germany's Ulm University and co-author of the study.

In periods of drought, the vascular network (xylem) distributing water and nutrients around the tree develops air bubbles which hinder the passage of water. As drought stress increases, these blockages, or "embolisms," accumulate eventually causing the tree to dry out and die....

Tree rings shot by Arpingstone, public domain