US wolf re-introduction still leaves aspens quaking


The re-introduction of wolves in a US National Park in the mid-1990s is not helping quaking aspens (Populus tremuloides) to become re-established, as many researchers hoped.

In a study published in the journal Ecology showed that the population of wolves in Yellowstone Park was not deterring elks from eating young trees and saplings.

It was assumed that the presence of wolves would create a “landscape of fear”, resulting in no-go areas for elks.

Researchers writing in the Ecological Society of America’s (ESA) journal said that the aspens were not regenerating well in the park as a result of the elk eating the young trees.

However, they added that the conventional wisdom suggested that as the wolves were predators of the elk, it was thought that the elk would eventually learn to avoid high-risk areas in which the wolves were found.

This would then allow plants in those areas – such as aspen – to grow big enough without being eaten and killed by the elk. And in the long-term, the thinking went, the habitat would be restored.

In this latest study, lead author Matthew Kauffman – a US Geological Survey scientist – suggested the findings showed that claims of an ecosystem-wide recovery of aspen were premature.

“This study not only confirms that elk are responsible for the decline of aspen in Yellowstone beginning in the 1890s, but also that none of the aspen groves studied after wolf restoration appear to be regenerating, even in areas risky to elk,” Dr Kauffman explained.

Because the “landscape of fear” idea did not appear to be benefiting aspen, the team concluded that if the Northern Range elk population did not continue to decline (their numbers are 40% of what they were before wolves), many of Yellowstone’s aspen stands were unlikely to recover.

“A landscape-level aspen recovery is likely only to occur if wolves, in combination with other predators and climate factors, further reduce the elk population,” observed Dr Kauffman.

The paper, Are wolves saving Yellowstone’s aspen? A landscape-level test of a behaviorally mediated trophic cascade, has been published online in Ecology. The authors of the paper are: Matthew Kauffman (USGS), Jedediah Brodie (University of Montana) and Erik Jules (Humboldt State University).

Source: ESA press release

Date: 01/09/2010

Model shows ‘waves of forest degradation’


An international team of researchers has developed a model that suggests degradation of tropical forests occurs in a series of “waves”, reports the BBC News website’s Mark Kinver.

High-value trees were felled in the first “wave”, followed by a wave that removed mid-value timber before the remaining wood was felled for charcoal.

The team hopes the model will help manage forests as vital carbon sinks and limit the loss of biodiversity.

The findings appear in the Proceedings of the National Academy of Sciences.

The researchers said an economic theory was used to provide a general model to predict patterns of tree loss.

This translates to a prediction that waves of forest degradation will emanate from major demand centres and expand into nearby forested areas, targeting resources in sequence, starting with those of highest value,” they wrote in their PNAS paper.

“Such a sequence of demand, linked to resource utilisation, has been demonstrated for unmanaged fisheries… but has not been shown for the exploitation of differently valued tropical forest products.”

The team used data collected in the area surrounding Tanzania’s largest city, Dar es Salaam, to see how far the degradation “waves” had travelled between 1991 and 2005.

“The first wave that emanates is high-value timber, and that is mostly used for export,” explained co-author Antje Ahrends, an ecologist at the Royal Botanical Garden, Edinburgh.

“There has been a massive demand for this in China, and this is where most of the timber ends up.”

Dr Ahrends said the first wave moved out from Dar es Salaam rapidly, averaging about nine kilometres each year, because the “timber companies had lorries and loads of people working for them”.

“For the firms, it is only worthwhile to stay in a forest when timber can be accessed relatively easily,” she told BBC News.

“So once it becomes not so easy to get hold of the rest, the companies generally move on.”

The first wave had already moved outside of the team’s study area, and Dr Ahrends estimated that it was already more than 200km from Dar es Salaam.

The second wave saw trees being felled for medium-valued timber, which was generally used in the city for construction and furniture.

“This is expanding very rapidly, in line with urban migration,” she explained. “The town has an average growth rate of about 7% each year, so there is – again – a rapidly growing demand for this material.”

The timber is harvested by local companies, again with lorries, allowing large volumes to be collected in a relatively short space of time. This resulted in this degradation wave to also cover about nine kilometres each year.

The third and final wave involved local people collecting wood to make charcoal for cooking.

“It’s the most destructive of all of the waves because charcoal burners would collect everything,” observed Dr Ahrends, who was based at the York Institute for Tropical Ecosystem Dynamics when she carried out this research.

“It is only worthwhile moving on once there are no sizeable trees left in the forest.”

As a result, the charcoal wave had moved relatively slowly – from 20km outside Dar es Salaam in 1991 to 50km away in 2005.

“It is the most difficult of the waves to tackle because it is very poor people who burn charcoal and their livelihoods depend upon it.”

“Targeting that wave would mean trying to provide alternative resources for cooking, and alternative incomes for people who burn charcoal.

Species loss

The team also developed their model to gauge what impact forest degradation had on “public good” services, such as carbon storage and biodiversity.

They did this by recording what species of trees were in a particular area of the study, and what size the individual trees were.

“This later enabled us to calculate species richness and also the amount of carbon those trees were storing,” Dr Ahrends said.

“We found that there was a very strong linear impacts; for example, tree species richness dropped to only 14 species-per-sample-unit close to Dar es Salaam, whereas it is more than 40 species in areas 200km away.”

Dr Ahrends suggested that the model could be used to understand the impact of forest degradation in other sub-Sarahan nations in Africa.

“This is because conditions are very similar: high levels of corruption, weak law enforcement and very rapid rates of urbanisation.”

She added that the team’s model could help policymakers who were looking at ways to limit deforestation rates.

“What is really important is to understand the pattern of degradation and the way it spreads,” she suggested.

“While we have a good understanding of deforestation – which is the complete clearance of a forest – it is much more difficult to measure degradation.

“So if you have this simple model, then you have a basic understanding of how degradation might spread… which may help you develop some prediction of where it might spread from and how far it might spread.”

Source: BBC News website

Date: 03/08/2010

Indonesia ‘failing on pledge to reduce forest fires’


The Indonesian government failed to live up to its promises to reduce fires across the tropical nation last year, reports Mongabay.com.Take Cover library picture

It quotes The Jakarta Post as saying that the nation’s 2009 State Environment Report revealed a 59% increase in the number of fire hotspots from 19,192 in 2008 to 32,416 last year.

Officials are reported as saying that land clearing was the primary cause because, unlike temperature forests, intact rainforests rarely burn naturally.

“Illegal land clearing with fires by local people in Kalimantan and Sumatra is still rampant,” Heddy Mukna, deputy assistant for forest and land management at the Environment Ministry told the Post.

The state of Kalimantan on the island of Borneo saw fires triple in some areas from 2008 to 2009.

Haze blanketed much of the island last year during the “burning season”.

In 2007, the Indonesian government announced plan to cut forest fires in half to mitigate climate change from 35,279 fires in 2006.

The government has since revised that reduction from 50% to just 20%.

Indonesia is the third largest emitter of greenhouse gases in the world behind China and the US.

An estimated 80% of the nation’s 2.3 billion tonnes of greenhouse gas emissions is from rainforest and peatland destruction.

Source: Mongabay.com

Date: 13/06/2010

Cancer drug derived from rainforest shrub set for human trials


A potential cancer drug developed from an Australian rainforest plant is set to progress to human trials, reports the Strait Times.

Quoting the AFP wires, the newspaper explains that the drug is being put forward to the next stage after fighting off inoperable tumours in pets.

Queensland firm QBiotics Limited said its EBC-46, derived from the seeds of a tropical rainforest shrub, was ready to be tested on humans after successfully treating solid tumours in more than 100 dogs, cats and horses.

“We’ve treated over 150 animals… with a variety of tumours, and we’re prepared to move into human studies,” explained chief executive Victoria Gordon.

Dr Gordon said the results so far indicated the drug could work to counter a range of malignant growths, such as skin cancers, head and neck cancer, breast cancer and prostate cancer.

She said the drug works like a detonator inside tumours, prompting inactive beneficial white cells to begin to fight and destroy the cancer.

The company is reported as spending six years developing the drug since the previously unknown molecule in the native Australian plant blushwood was discovered.

It hopes to raise enough funds to begin human trials in 2011.

Dr Gordon said the compound proves the value of retaining Australia’s unique tropical rainforests.

Source: The Strait Times (Singapore)/AFP

Date: 14/06/2010

Wales to update its ancient woodlands map


Forestry Commission Wales has announced plans to update the nation’s Ancient Woodland Inventory.

Take Cover library image In a press release, the commission said that these habitats, which date back to at least the 17th Century, “support many species of plants and wildlife that depend on the evolving but continuous environments created by dead and dying wood and broken sunlight”.

It added that the inventory was first produced about 30 years ago, and since then, technology for gathering data had improved dramatically and better sources of information had come to light.

The update, which will be carried out over the next 12 months, will identify former ancient woodlands that have subsequently been planted with conifer trees to satisfy the demand for timber over many decades.

These woodlands are known as Plantations on Ancient Woodland Sites (PAWS).

This information will guide decisions on restoring some of the PAWS to their natural state by removing non-native trees and planting native broadleaf species such as oak, birch, rowan and ash.

“Such work helps to increase the variety of different plant and wildlife species in the woodland by improving habitats and providing food and shelter,” the commission explained.

Wood pastures – ancient and veteran trees found on grazed sites – will also be systematically recorded as part of the update to the inventory.

Despite the ecological value of wood pasture, it has no legal protection, so identification on the inventory may help protect these sites from damage or destruction.

The concept of  “ancient woodland” was developed in the 1970s and 1980s, when studies showed that woodlands that have had a continuous woodland cover for centuries were typically of higher nature conservation value than those that had developed recently.

The baseline date of 1600 AD was adopted because reasonable maps were available from this time (in England, at least).

But the commission admitted that it was an arbitrary date, and there was no clear ecological cut-off.

Michelle van Velzen, forestry and environment policy and programme manager at Forestry Commission Wales, said: “Ancient woodlands are a precious and finite resource that cannot be recreated.

“This update to the Ancient Woodland Inventory will ensure we have the most comprehensive and accurate information on the extent and nature of ancient woodlands in Wales.”

The update to the inventory will be completed in March 2011 and the new information will be supplied to local authorities for their use when developing planning policy that affects woodland.

Source: Forestry Commission Wales press release

Date: 11/06/2010

Study finds 25 news beetle species on Turkey’s oaks


Twenty-five hitherto unknown species of beetle have been found on the Turkey’s oak trees, according to a study by Swedish researchers.

Take Cover library picture“Most of them would disappear if the trees were to be cut down, and the risk is great”, says project leader Nicklas Jansson, beetle ecologist at Linkoping University (LiU) in Sweden.

In Turkey, there are 18 species of the oak family, and Dr Jansson and his research team spent five years collecting beetles from oak trees in four large pastures in the south of the country.

They said the study areas – 1,200-1,500 metres above sea level – were important for sheep and goat farming, but were now threatened by felling to make way for productive forest management.

They warned that as with all felling there is a major risk that some species become extinct since the oak dwelling beetles stay so faithful to their biotope.

“Some of the species seem to have a very low motivation to leave and find a new oak,” Dr Jansson observed.

Most of the newly discovered beetles belong to the Elateridae and Tenobrionidae families and have been identified by some 20 specialists across Europe.

The results were presented at a conference on oak ecology in Isparta, Turkey.

The researchers identified a number of factors that could be responsible for the greater diversity of beetles:

  • a climate that allowed species to hibernate during the Ice Ages
  • the topography which creates many barriers in the form of mountain ranges and other obstacles to the mixing of species
  • the geographic location as a bridge between Asia and Europe.

In a follow-up project, the research team planned to compare the oak fauna of seven countries, including Israel, Turkey, Italy, France, the UK  and Sweden.

The oaks in the Turkish pastures are pollarded. Shepherd people prune the trees in July and during the dry season use the leaves as feed for sheep and goats while the branches become fuel.

As a result of pollarding, many of the oaks were hollow and contain wood mould, a very rich compost of decomposed wood, fungi, excrement and remains of dead animals.

“I hope that in finding new and unique species we will get the Turkish forestry authorities to open their eyes to their oak treasures and to begin conservation work in the most valuable areas,” Dr Jansson explained.

Source: AlphaGalileo press release

Date: 01/06/2010

Key role of forests ‘may be lost’


Forests’ role as massive carbon sinks is “at risk of being lost entirely”, the BBC’s Mark Kinver has reported top forestry scientists as warning.

The International Union of Forest Research Organizations (IUFRO) says forests are under increasing degrees of stress as a result of climate change.

Forests could release vast amounts of carbon if temperatures rise 2.5C (4.5F) above pre-industrial levels, it adds.

The findings will be presented at the UN Forum on Forests, which begins on Monday in New York.

Compiled by 35 leading forestry scientists, the report provides what is described as the first global assessment of the ability of forests to adapt to climate change.

“We normally think of forests as putting the brakes on global warming,” observed Professor Risto Seppala from the Finnish Forest Research Institute, who chaired the report’s expert panel.

“But over the next few decades, damage induced by climate change could cause forests to release huge quantities of carbon and create a situation in which they do more to accelerate warming than to slow it down.”

The scientists hope that the report, called Adaption of Forests and People to Climate Change – A Global Assessment, will help inform climate negotiators.

The international climate debate has focused primarily on emissions from deforestation, but the researchers say their analysis shows that attention must also be paid to the impacts of climate change on forests.

While deforestation is responsible for about 20% of greenhouse gas emissions from human activities, forests currently absorb more carbon than they emit.

But the problem is that the balance could shift as the planet warms, the report concludes, and the sequestration service provided by the forest biomes “could be lost entirely if the Earth heats up by 2.5C or more”.

The assessment says higher temperatures – along with prolonged droughts, more pest invasions, and other environmental stresses – would trigger considerable forest destruction and degradation.

This could create a dangerous feedback loop, it adds, in which damage to forests from climate change would increase global carbon emissions that then exacerbate global warming.

The report’s key findings include:

  • Droughts are projected to become more intense and frequent in subtropical and southern temperate forests
  • Commercial timber plantations are set to become unviable in some areas, but more productive in others
  • Climate change could result in “deepening poverty, deteriorating public health, and social conflict” among African forest-dependent communities

The IUFRO assessment will be considered by delegates at the eighth session of the UN Forum on Forests, which has the objective of promoting the “management, conservation and sustainable development of all types of forest”.

Co-author Professor Andreas Fischlin from the Swiss Federal Institute of Technology commented: “Even if adaption measures are fully implemented, unmitigated climate change would – during the course of the current century – exceed the adaptive capacity of many forests.

“The fact remains that the only way to ensure that forests do not suffer unprecedented harm is to achieve large reductions in greenhouse gas emissions.”

Source: BBC News website

Date: 18/04/2009

Top five invasive threats to US southern forests


Apologies that this post refers to information issued in a press release by the US Forest Service back in January, but it contains interesting data and links that could be of use to people – Take Cover team.

US Forest Service Southern Research Station (SRS) ecologist Jim Miller, considered to be one of the foremost authorities on non-native plants in the  southern US, has identified the five invasive plant species he believes pose the biggest threats to southern forest ecosystems in 2009.

“Cogongrass, tallowtree, and Japanese climbing fern are among the fastest moving and most destructive non-native plant species facing many southern landowners this year,” Dr Miller warned.

“Rounding out the top five invasive species that I’m very concerned about would be tree-of-heaven and non-native privets.

“While our forests are besieged by numerous invasive plants, these and other non-native species present serious financial and ecological threats to the South and its forests.”

Non-native species often out-compete native forest plants and may degrade forest productivity, wildlife habitat, recreational values, and water quality.

Invasive species also greatly increase expenses as public and private land managers work to combat their spread and deal with their effects (such as increased wildfire risk and severity).

Non-native plants can be introduced and spread by wildlife or through other natural means.

Humans also spread invasive species by planting them in their gardens and yards and as a result of seeds hitchhiking on clothes.

Additionally, tractors and mowers used in multiple locations without being cleaned often spread the plants.

In an effort to inform forest managers, landowners, and others about where the most threatening invasive plants are in the South, Dr Miller collaborated with SRS Forest Inventory and Analysis (FIA) scientists to develop maps showing the spread, county-by-county, across the south-east of more than 30 of the most serious non-native plant species.

The invasive plant data were collected on FIA plots throughout the southern US in co-operation with state forestry agencies.

In partnership with the University of Georgia’s Center for Invasive Species Science and Ecosystem Health, SRS researchers recently posted the maps and occupation levels online.

Dr Miller hopes government agencies, forest managers, natural resource professionals, landowners, students, and others will use the information to help combat the spread of non-native plant species in southern forest and grassland ecosystems.

Source: US Forest Service press release

Date: 12/01/2009

Climate shift ‘killing US trees’


Old growth trees in western parts of the US are probably being killed as a result of regional changes to the climate, a study has suggested.

BBC News environment reporter Mark Kinver reports researchers as saying that analysis of undisturbed forests showed the trees’ mortality rate had doubled since 1955, researchers said.

They warned that the loss of old growth trees could have implications for the areas’ ecology and for the amount of carbon that the forests could store.

The findings have been published in the journal Science.

“Data from unmanaged old forests in the western US showed that background mortality rates have increased rapidly in recent decades,” the team of US and Canadian scientists wrote.

“Because mortality increased in small trees, the overall increase in mortality rates cannot be attributed to ageing of large trees,” they added.

“Regional warming and consequent increases in water deficits are likely contributors to the increase in tree mortality rates.”

After ruling out a variety of other possible factors, including insect attacks and air pollution, the researchers concluded that regional warming was the dominant contributor.

“From the 1970s to 2006, the mean annual temperature of the western US increased at a rate of 0.3C to 0.4C per decade, even approached 0.5C,” they observed.

“This regional warming has contributed to widespread hydrological changes, such as declining fraction of precipitation falling as snow, declining snowpack water content, earlier spring snowmelt and a consequent lengthening of summer drought.”

The team, led by the US Geological Society (USGS), examined data from 76 temperate forest stands older than 200 years, which contained almost 59,000 trees.

Over the study period, which stretched back to 1955, more than 11,000 trees died.

The researchers reported that the increased mortality rate affected a range of species, different sized trees, and all elevations.

“The same way that in any group of people, a small number will die each year; in any forest, a small number of trees will die,” explained co-author Phil van Mantgem, a USGS ecologist.

“But our long-term monitoring shows that tree mortality has been climbing, while the establishment of replacement trees has not.”

The change in the forests’ dynamics, the team noted, was going to have an impact on the forests’ ecology and carbon storage capabilities.

“We may only be talking about an annual tree mortality rate changing from 1% a year to 2%, but over time a lot of small numbers add up,” said co-author Professor Mark Harmon from Oregon State University.

He feared that the die-back was the first sign of a “feedback loop” developing.

As regional warming caused an increased number of trees to die, there would be less living trees to absorb carbon dioxide from the atmosphere.

Yet there would be an increased proportion of decaying trees, releasing the carbon that had been locked away inside the trees’ wood.

Warmer temperatures might also increase the number and prevalence of insects and diseases that attack trees, the team added.

They used the example of recent outbreaks of tree-killing bark beetles in the US, which have been linked to a rise in temperatures.

Another member of the team, Dr Nate Stephenson, said increasing tree deaths could indicate a forest that was vulnerable to sudden, widespread die-back.

“That may be our biggest concern,” he warned.

“Is the trend we’re seeing a prelude to bigger, more abrupt changes to our forests.”

Source: BBC News website

Date: 23/01/2009


Nowhere to run for tropical species


Climbing temperatures may doom many tropical species to extinction if they are unable to migrate to higher elevations or cooler latitudes, reports Mongabay.com.

Analysing data for 1,902 species of plants, insects, and fungi in the tropics, Robert Colwell and colleagues, writing in the journal Science, warn that lowland areas are particularly at risk of biodiversity loss due to warming since “there is no source of species adapted to higher temperatures to replace those driven upslope by warming”.

The authors estimate that more than half the species they studied in Costa Rica could potentially face such risks.

At the same time species adapted to high elevations will be faced with “mountaintop extinctions” when they reach the summit of mountains.

A second study, by Craig Moritz and colleagues, found that warming in California’s Yosemite National Park has already caused elevational shifts in the range of mammals species.

“These kinds of changes in community composition have been going on forever,” said James Patton, a UC Berkeley professor emeritus of integrative biology who led the field work for the second study in Yosemite.

“The only thing that makes this different is that it has probably happened in our lifetime. It is the speed with which these changes are taking place that gives one pause.”

Source: Mongabay.com

Date: 10/10/2008

Urban trees linked to cutting childhood asthma


US researchers suggest that urban trees have a wider role to play than just an aesthetic one. They are undertaking a study into claims that tree-lined avenues can cut the number of children who develop asthma.

City officials are going to embark on a 10-year project to see if increasing the number of trees per square kilometre leads to a decline in the number of children suffering from the lung condition.

It appears as if the initial hypothesis is based on observations that a wealthly New York neighbourhood, with a high ratio of trees , had a  low  level of asthma among  young residents; whereas a poor district (with considerably less trees) had a much higher percentage of cases of childhood asthma.

Columbia University researchers found that asthma rates among children aged four and five fell by 25% for every extra 343 trees per square kilometre.

They believe more trees may aid air quality or simply encourage children to play outside, although they say the true reason for the finding is unclear.

The study appears in the Journal of Epidemiology and Community Health.

Here is the report from Reuters:

NEW YORK – City blocks boasting plenty of trees aren’t only more pleasing to the eye; they may be healthier for children’s lungs, according to research conducted in New York City.
Four- and five-year-olds living along the city’s greenest streets were less likely to have asthma than young children living in sparsely planted neighborhoods, Dr. Gina S. Lovasi and colleagues from Columbia University found. “We think that trees might have a beneficial effect on air quality — affecting air quality right at the street level,” Lovasi told Reuters Health. While the effects were independent of poverty and pollution, the researcher added, its possible street trees may simply be a stand-in for a healthful environment. “We’re not confident that it’s the trees themselves that are what’s driving this.”

Asthma rates have risen sharply in the US since 1980, and inner cities have been hit particularly hard, Lovasi and her colleagues note in their report. Trees could cut asthma risk by cleaning the air and encouraging kids to play outdoors, they add; but the pollen they release could also contribute to asthma attacks. To investigate, the researchers compared a census of New York City’s half-million street trees from 1995 to statistics on asthma prevalence and hospitalisation rates for 1999.

The wealthy Upper East Side of Manhattan was the greenest neighbourhood in the city, with 1,675 trees per square kilometre, or nearly seven trees an acre, while the impoverished Hunt’s Point-Mott Haven neighbourhood in the Bronx was the city’s barest, with only 109 trees per square kilometre or less than half a tree per acre.

As the density of trees in a neighbourhood rose, asthma prevalence fell, even after the researchers accounted for the percentage of residents living below the poverty line, a neighbourhood’s proximity to pollution sources such as busy truck routes, and other relevant factors.

An increase of 343 trees per square kilometre, or roughly 1.5 trees per acre, translated to 29% lower asthma prevalence. For example, asthma prevalence among 4- and 5-year-olds would be 9% in a neighbourhood with 2.5 trees per acre, but just 6% in a neighbourhood with four trees per acre.

Rates of asthma hospitalisation tended to be lower in neighbourhoods with more street trees, but the relationship wasn’t statistically significant; nevertheless, this suggests that trees aren’t a major contributor to asthma attacks, Lovasi said.

A “natural experiment” set to take place over the next decade will help to answer the question of whether street trees really do make for healthier kids; New York City Mayor Mike Bloomberg has launched an effort to plant a million new trees by 2017, and Lovasi and her colleagues are now working with the city government to study neighbourhood health as the project progresses.


Story by Anne Harding

REUTERS NEWS SERVICE
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