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

China timber sector looks at tougher EU/US import rules


The China Timber and Wood Products Circulation Association (CTWPCA) is seeking to establish a body to help importers navigate new environmental regulations in the US and EU that restrict trade in illegally logged timber, reports the International Tropical Timber Organization (ITTO).

In a recent market report, ITTO said that Chinese importers fear failing to meet the new regulations that govern the sourcing of timber products.

The US’s Lacey Act and the EU’s FLEGT ruling put the burden of responsibility on importing companies, holding them to the environmental laws of producing countries.

Companies found to be sourcing illegally logged timber could be subject to fines or worse.

A company accused of using illicit rosewood from Madagascar, was the first company to be charged and investigated under the Lacey Act.

The legislation was amended in 2008 to include “anyone who imported, exported, transported, sold, received, acquired or purchased the wood products made from that illegal timber, who knew or should have known that the wood was illegal.” The firm’s case is pending.

According to ITTO, CTWPCA believes traders need “guidance and support” on the new international requirements.

The body would also set up a “responsible procurement system” for timber imports, seek to address corruption in the timber import and trade sector, and aim to help Chinese timber traders meet international standards.

China already has guidelines governing Chinese companies operating forest concessions overseas.

These compel companies to abide by local environmental laws and take measures to reduce pollution. However, some observers suggest that there is no indication that these mandatory rules are being enforced.

Source: Mongabay.com

Date: 02/09/2010

Africa’s tropical forests ‘absorbing more carbon’


Trees across the tropics are getting bigger and offering unexpected help in the fight against climate change, scientists have discovered.

A report in the Guardian newspaper described how a study of the girth of 70,000 trees across Africa has shown that tropical forests are soaking up more carbon dioxide pollution that anybody realised.

Almost one-fifth of our fossil fuel emissions are absorbed by forests across Africa, Amazonia and Asia, the research suggests in the journal Nature.

Simon Lewis, a climate expert at the University of Leeds, who led the study, said: “We are receiving a free subsidy from nature. Tropical forest trees are absorbing about 18% of the carbon dioxide added to the atmosphere each year from burning fossil fuels, substantially buffering the rate of change.”

The study measured trees in 79 areas of intact forest across 10 African countries from Liberia to Tanzania, and compared records going back 40 years. “On average the trees are getting bigger,” Lewis said.

Compared to the 1960s, each hectare of intact African forest has trapped an extra 0.6 tonnes of carbon a year. Over the world’s tropical forests, this extra “carbon sink” effect adds up to 4.8bn tonnes of CO2 removed each year – close to the total carbon dioxide emissions from the US.

Although individual trees are known to soak up carbon as they photosynthesise and grow, large patches of mature forest were once thought to be carbon neutral, with the carbon absorbed by new trees balanced by that released as old trees die.

A similar project in South America challenged that assumption when it recorded surprise levels of tree growth a decade ago, Lewis said.

His study, he added, was to check whether the effect was global.

The discovery suggests that increased CO2 in the atmosphere could fertilise extra growth in the mature forests.

Lewis said: “It’s good news for now but the effect won’t last forever. The trees can’t keep on getting bigger and bigger.”

Helene Muller-Landau of the Smithsonian Tropical Research Institute in Ancon, Panama, used a commentary piece in Nature to suggest that the forests could be growing as they recover from past trauma.

“Tropical forests that we think of as intact [could have] suffered major disturbances in the not-too-distant past and are still in the process of growing back,” she said.

Droughts, fire and past human activity could be to blame, she added: “This recovery process is known as succession and takes hundreds or even thousands of years.”

The research comes as efforts intensify to find a way to include protection for tropical forests in carbon credit schemes, as part of a new global climate deal to replace the Kyoto protocol.

Lee White, Gabon’s chief climate change scientist, who worked on the new study, said: “To get an idea of the value of the sink, the removal of nearly 5bn tonnes of carbon dioxide from the atmosphere by intact tropical forests should be valued at about £13bn per year.”

David Ritter, senior forest campaigner at Greenpeace UK, said: “This research reveals how these rainforests are providing a huge service to mankind by absorbing carbon dioxide from our factories, power stations and cars.

“The case for forest protection has never been stronger, but we must not allow our politicians to use this as an excuse to avoid sweeping emissions cuts here in the UK.”

Source: Guardian newspaper

Date: 18/02/2009

UK charity gets funds to plant urban woodland


A multimillion-pound grant scheme to improve access to nature has targeted a project to plant urban woods to help people reconnect with nature, and avoid anti-social behaviour, Horticulture Week reports.

Access to Nature, managed by Natural England, aims to hand out £25 million of Big Lottery money to urban communities to start or improve nature projects.

One of the winners, conservation charity the Woodland Trust, aims to transform 10 of its urban woods in the North West.

Its grant of £213,000 will help launch a Woodland Communities project, said Woodland Trust woodland officer Tim Kirwin.

“The aim is to re-connect local people with their environment and reverse elements of antisocial behaviour,” he said of the target area around Warrington and Runcorn.

The zone straddled two boroughs containing some of the most deprived wards in England and within one mile of an estimated 155,000 people, Kirwin said.

“We want to increase local appreciation of woodland and tackle attitudes behind current antisocial activities and the dumping of rubbish.”

Events will include woodland-discovery sessions for schools, conservation work and efforts to help “make the sites an asset to the area rather than a blight”.

Mr Kirwin observed: “It will involve transforming areas that are often deserted and sometimes litter-strewn into bustling outdoor community facilities and give people the confidence to use woodland more fully.

“Many people in the area are just not connected with their natural environment, so we need to find ways to help make that happen, with schools playing a big part.”

Another project to receive the lottery funding was Wild About Plants, a project lead by charity Plantlife, which has received £327,000.

Dr Helen Phillips, chief executive of Natural England, said: “Modern life can mean losing regular contact with nature, and we must find a way of putting people back in touch.”

Source: Horticulture Week

Date: 13/01/2009

Researchers discover secret of plants’ ‘double fertilisation’ mystery


An enigma, unique to flowering plant, has been solved by a team of researchers from the UK and South Korea, reports Science Daily.

It was already known that flowering plants, unlike animals require not one, but two sperm cells for successful fertilisation.

However, how the “double fertilisation” was achieved from a single pollen grain, which then led to “twin” sperm cells, remained a mystery.

The process results in one sperm cell joining with the egg cell to produce the embryo, while the other to joins with a second cell in the ovary to produce the endosperm, a nutrient-rich tissue, inside the seed.

Double fertilisation is essential for fertility and seed production in flowering plants so increased understanding of the process is important.

Now Professor David Twell, of the Department of Biology at the University of Leicester and Professor Hong Gil Nam of POSTECH, South Korea, writing in the Journal Nature, report the discovery of a gene that has a critical role in allowing precursor reproductive cells to divide to form twin sperm cells.

Professor Twell said: “This collaborative project has produced results that unlock a key element in a botanical puzzle.

“The key discovery is that this gene, known as FBL17, is required to trigger the destruction of another protein that inhibits cell division,” he added.

“The FBL17 gene therefore acts as a switch within the young pollen grain to trigger precursor cells to divide into twin sperm cells.

“Plants with a mutated version of this gene produce pollen grains with a single sperm cell instead of the pair of sperm that are required for successful double fertilisation.

“Interestingly, the process employed by plants to control sperm cell reproduction was found to make use of an ancient mechanism found in yeast and in animals involving the selective destruction of inhibitor proteins that otherwise block the path to cell division.

“Removal of these blocks promotes the production of a twin sperm cell cargo in each pollen grain and thus ensures successful reproduction in flowering plants.

“This discovery is a significant step forward in uncovering the mysteries of flowering plant reproduction.

“This new knowledge will be useful in understanding the evolutionary origins of flowering plant reproduction and may be used by plant breeders to control crossing behaviour in crop plants.

“In the future such information may become increasingly important as we strive to breed superior crops that maintain yield in a changing climate.

“Given that flowering plants dominate the vegetation of our planet and that we are bound to them for our survival, it is heartening that we are one step closer to understanding their reproductive secrets.”

Researchers at the University of Leicester are continuing their investigation into plant reproduction.

Further research underway in Professor Twell’s laboratory is already beginning to reveal the answers to secrets about how the pair of sperm cells produced within each pollen grain aquires the ability to fertilise.

Prof Twell’s work, in the Department of Biology at the University of Leicester is financially supported by the UK Biotechnology and Biological Research Council (BBSRC).

Source: Science Daily

Date: 23/10/2008

Row over when plants first emerged on Earth


Researchers taking a second look at ancient sediments have concluded that they do not represent the earliest traces of the rise of sun-fuelled photosynthesis/oxygen-producing organisms on Earth as previously thought, reports ScienceNOW website.

It says the findings come as a relief to some scientists, whose data had been in conflict with an earlier study with the same sediments that suggested oxygen first emerged in the planet’s atmosphere some 300 million years later.

According to the geological record, oxygen first rose in Earth’s atmosphere about 2.4bn years ago. The problem with using fossils to track down the organisms that gave rise to the oxygen is that fossils can take you back only about 2bn years out of the planet’s 4.5bn.

To figure out what was stirring before that, scientists must rely on traces of chemicals produced by biological processes and, by inference, in certain environmental conditions.

That’s what happened in 1999, when researchers examined samples of 2.7bn-year-old shale from Western Australia.

They found certain types of hydrocarbons that indicated oxygen-producing bacteria had existed at the time. But the discovery also created a conundrum, because it placed the rise of photosynthesis some 300m years before chemical studies of ancient rocks indicated oxygen began to spread in Earth’s atmosphere.

This discrepancy continues to bedevil researchers, who have struggled to mesh their data with evolutionary models.

An Australian team, writing in Nature, analysed microscopic solidified oil droplets contained in the shale, the researchers inferred the composition of the organic materials present as the shale formed.

The analysis clearly shows the hydrocarbons identified in the 1999 study could not have been derived from bacteria contained in the sediments, says geochemist and lead author Birger Rasmussen of the Curtin University of Technology, Perth, Australia.

Instead, they probably represent contaminants introduced from younger sedimentary rocks that somehow got mixed in with the shale layer or by the drills the researchers used to extract the samples, he says.

The conclusions are “pretty strong and a lot of eyes will be focused on how this shakes out,” says geobiologist Woodward Fischer of the California Institute of Technology, Pasadena, US.

He says the previous findings had been regarded as a standard time measurement for both the rise of oxygen and for photosynthetic organisms, and, therefore, any conflicting data produced by other researchers had been regarded as suspect.

But overall he’s convinced that the new results ultimately “will free up people’s minds again” to find the other sources of early oxygen.

Source: ScienceNOW

Date: 22/10/2008

Leaves ‘keep their cool’


This is a bit of an old one, but this story featured on the Nature website by Heidi Ledford about how leaves regulate their temperature in order to maximise their metabolism is worth a mention on these pages:

Whether growing in the heat of Puerto Rico or in the icy chill of northern Canada, tree leaves are able to buffer against the outside temperature, new research has found.

A survey of 39 North American tree species over an area spanning 50° of latitude has shown that plants protect one of their most important functions – photosynthesis – by maintaining average leaf temperatures at around 21 °C, regardless of the weather.

Source: Nature.com

Date: 11/06/2008

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