Forests make heatwaves ‘initially warmer’


During heatwaves forests reduce their evaporation, causing the atmosphere to warm up even more, say researchers.

During extremely long periods of heat, however, this reduction enables the forests to continue their evaporation for longer, so the net effect is ultimately one of cooling in relation to the surroundings, explained a team of scientists led by Ryan Teuling from Wageningen University in the Netherlands.

Writing in the journal Nature Geoscience, Dr Teuling worked on the investigation in collaboration with climate researchers from a number of European countries.

The study was prompted by recent heatwaves in Europe, which had raised interest in questions about the influence of land use on temperatures and climate.

Up to now, scientists had assumed that a lack of precipitation during heatwaves automatically led to a reduction in evaporation.

That reduction was thought to be less for forests, because trees, with their deeper root systems, have more water available to them. Examination of the precise role of land use, however, has been largely neglected up to now.

The study found large differences in evaporation strategies during heat waves. Grasslands evaporate more at higher temperatures and stop only when no more water is available.

Forests, in contrast, respond to higher temperatures by evaporating less, which leaves more water at their disposal.

During brief heatwaves, therefore, the greatest warming is found above forests, but during prolonged heat waves the increased evaporation of grasslands ends up causing a shortage of water.

This can lead to exceptionally high temperatures, such as those measured in France in the summer of 2003.

This mechanism might also offer an explanation for the unusually high temperatures near Moscow this summer, the researchers suggest.

In these types of extreme situations, forests in fact have a cooling effect on the climate.

The research was done on the basis of observations made above forests and grasslands in Europe by an extensive network of flux towers. For areas without towers, satellite data were used.

Source: Wageningen University press release

Date: 06/09/2010

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

North Korea begins agroforestry scheme to halt degradation


A “pioneering agroforestry project” in North Korea is restoring heavily degraded landscapes and providing much-needed food for communities, says the World Agroforestry Centre.

Jianchu Xu, the Centre’s East-Asia co-ordinator,  said agroforestry – in this case the growing of trees on sloping land – was uniquely suited to DPR Korea for addressing food security and protecting the environment.

“What we have managed to achieve so far has had a dramatic impact on people’s lives and the local environment,” he explained.

“Previously malnourished communities are now producing their own trees and growing chestnut, walnut, peaches, pears and other fruits and berries as well as medicinal bushes.”

Following the collapse of the socialist bloc in 1989 and a lack of subsidies for agriculture in DPR Korea, famine and malnutrition became widespread in rural areas.

DPR Korea is a harsh mountainous country where only 16% of the land area is suitable for cultivation, data from the Centre suggests.

It addded that out of  desperation in the 1990s, people turned to the marginal sloping lands but this had a price: deforestation for cropping land and fuelwood left entire landscapes denuded and depleted of nutrients.

In an attempt to reverse the situation, an innovative project began in 2002 involving the Swiss Agency for Development and Cooperation (SDC) and Korea’s Ministry of Land and Environmental Protection. The World Agroforestry Centre was later brought in to provide technical advice.

A system of establishing user groups with one representative from each family enabled demonstration plots to be set up and a large number of households have benefited from knowledge about growing multi-purpose trees.

Using these types of trees have helped  improve and stabilise soils, as well as provide fertilizer, fodder or fruits.

To further support the development of appopriate skills in North Korea, the World Agroforestry Centre has announced plans to publish an agroforestry manual.

The Centre added that work was also underway to develop an agroforestry policy for sloping lands management, as well as establishing an agroforestry inventory.

Source: World Agroforestry Centre press release

Date: 27/08/2010

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

Deadly oak disease hits Welsh private woodland


An outbreak of the pathogen Phytophthora ramorum, otherwise known as sudden oak death, has been discovered for the first time in Wales on trees in a privately-owned woodland, reports the Forestry Commission Wales.

Staff from Forestry Commission Wales and the Food & Environment Research Agency (Fera) have visited the owner of the woodland in Denbighshire and a notice has been served to fell the infected Japanese larch trees. Only a small number of trees are infected, and the owner will use the timber on site.

Sudden oak death is a fungus pathogen that kills many of the trees that it infects. It was first found on Japanese larch trees in Wales in June this year in public woodlands  near Port Talbot, near Bridgend.

The outbreak in South Wales was the first time P. ramorum has been encountered on larch elsewhere in Great Britain since it was first discovered on larch in South-West England in 2009.

The woodland owner, Wendy Charles-Warner, contacted Take Cover, to say: “We feel rather aggrieved at the tone of the [Forestry Commission] press releases stating that we have been served with enforcement notices as if we were responsible for this outbreak and somehow in the wrong.

“We could take no steps to prevent this disease which is mainly airborne, have done nothing wrong and have at every point done everything we can to assist the forestry commission.”

A motor rally set to attract thousands of spectators to South Wales in July was postponed as a result of an ou6tbreak of the tree disease.

The route of the Swansea Bay Rally ran through forests that had been hit by the infection.

Richard Siddons from the Forestry Commission Wales said the organisation was “determined to minimise the impacts of this serious tree disease on woodlands, and the support of woodland owners in looking out for early signs of P. ramorum infection will play a key part in achieving that”.

It seems as if the warm but wet summer has been a key driver in the development of tree pathogens, with a number of cases making the headlines.

In April, a group of woodland experts expressed their fears for the future of British native oaks in light of the emergence of a disease called Acute Oak Decline, a bacterial infection that, they warned, could be as devastating for the English Landscape as Dutch elm disease in the 1970s.

They called for much more financial support from the UK government to help tackle the problem through research and land management measures.

In July, the Forestry Commission announced a £600,000 support package for woodland owners in South-West England and Wales to help tackle the outbreak of P. ramorum infection on larch trees. The package is part of Defra’s £25 million, five-year Phytophthora management programme.

Forestry Commission Wales is developing a complementary programme of support for private woodland owners who have P. ramorum confirmed on their land. Details of this support will be announced in September.

Ms Charles-Warner, in her comment to the story on this blog (see below for her full response), added: “

The ‘package of assistance’ that the Commission have announced is £300 per hectare, which we are not receiving or going to receive.

“If you have knowledge of tree felling you will appreciate that in a situation where stringent biosecurity measures have to be used and the trees have to be felled and brashed by hand that is a paltry sum, even in the highly unlikely event that you receive it.

She went on to say that she was “deeply concerned” about the situation: “If the Commission wishes landowners to report Phytopthora Ramorum and control it, in order to protect commercial forestry, then realistic support needs to be in place.

“Many landowners faced with a the prospect of funding felling and site clearance work themselves with the attendant stress and unpleasantness, are likely to ignore the disease and not report it.”

More information about sudden oak death can be found on the Forestry Commission’s website at www.forestry.gov.uk/pramorum.

To find out more about the support fund or to report suspected P. ramorum infection in their trees, woodland owners should contact Forestry Commission Wales’s Grants & Regulations Office on tel: 0300 068 0300 or email: bww.ts@forestry.gsi.gov.uk.

Source: Forestry Commission Wales press release

Date: 25/08/2010

British public ‘ignorant about trees’


According to a survey reported in Horticulture Week, a trade magazine, more than three-quarters of the people questioned believed that the main role of trees was to provide shade.

The questions, posed on behalf of Velvet Tissues – a UK-based toilet paper firm – also had a few more positive messages when it came to people’s attitudes towards trees, such as 75% agreed that trees featured in a favourite memory and 9% remember kissing a childhood sweetheart under a tree.

More than two-thirds of the people questioned considered the oak to be the UK’s most iconic tree, yet – depressingly – a third were not able to identify it.

The survey is hardly scientific,  and it is surely closely tied to a PR campaign in which the company describes itself as a tree lover (its website says it plants three trees for every one it cuts down to make its products), we felt it was worth featuring on this blog.

Sadly, it was not possible to get more details on the survey’s background because there is nothing on the company’s website and Horticulture Week only ran a very short story on the findings.

Source: Horticulture Week

Date: 25/08/2010

International forestry researchers look to future


The Center for International Forestry Research (CIFOR) has released a plan of work for 2011-2013, as a part of its 2008-2018 Strategy.

The organisation – established in 1999 – sets out its mission statement as advancing “human well-being, environmental conservation, and equity by conducting research to inform policies and practices that affect forests in developing countries”.

The updated plan provides more details on CIFOR’s six projects, and what outcomes they hope to achieve:

  • Enhancing the role of forests in climate mitigation
  • Enhancing the role of forests in adaptation to climate change
  • Improving livelihoods through smallholder and community forestry
  • Managing trade-offs between conservation and development at landscape scales
  • Managing impacts of globalized trade and investment on forests and forest communities
  • Sustainable management of tropical production forests

The 145-page work plan, Medium term plan for 2011-13, is available as a free-to-download pdf (size: 1.5MB)

Source: Climate-L.org

Date: 25/08/2010

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