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

Africa push for ‘great tree wall’


African leaders are meeting in Chad to push the idea of planting a tree belt across Africa from Senegal in the west to Djibouti in the east, reports the BBC News website.

The Great Green Wall project is backed by the African Union and is aimed at halting the advancing Sahara Desert.

The belt would be 15km (nine miles) wide and 7,775km (4,831 miles) long.

The initiative, conceived five years ago, has not started because of a lack of funding and some experts worry it would not be maintained properly.

The BBC’s Tidiane Sy in Senegal says the initiative has the full backing of Senegalese President Abdoulaye Wade, who is in Chad with 10 other heads of state to discuss desertification.

His government has created the website dedicated to the Great Green Wall. But our reporter says many other leaders seem ready to forget the project.

At the Copenhagen Climate Change summit last year, for instance, the Senegalese delegation made a presentation on the project.

It is envisaged that the belt would go through 11 countries from east to west.

The trees should be “drought-adapted species”, preferably native to the areas planted, the Great Green Wall website says, listing 37 suitable species.

The initiative says it hopes the trees will slow soil erosion; slow wind speeds and help rain water filter into the ground, to stop the desert from growing.

It also says a richer soil content will help communities across the Sahel who depend on land for grazing and agriculture.

Senegal says it has spent about $2m (£1.35m) on it and communities are being encouraged to plant trees.

The BBC’s former Chad correspondent Celeste Hicks says older people in N’Djamena – where the conference is being held – talk anecdotally about how the capital city has become a dustbowl over the last 20 years as the Sahara Desert has encroached southwards.

The country has made efforts to plant a green belt of trees around the capital, and tens of thousands of young trees are being grown in nurseries on the outskirts of the city, she says.

But so far little has been done to transplant these trees to the northern desert areas to become part of the Great Green Wall.

Source: BBC News website

Date: 17/06/2010

Wildlife flee Kenyan forest fires


Hundreds of thousands of flamingos and other wildlife are at risk after five forest fires erupted in Kenya on Saturday, say wildlife officials.

The BBC News website reports that police say they suspect some of the still-raging blazes were started by communities to make space for farmland.

The fires have had an adverse effect on the Masai Mara and in Tanzania on the Serengeti national park, officials say.

Other wildlife reserves are under threat, including Lake Nakuru, which is home to almost a million flamingos.

According to the Kenya Wildlife Service (KWS), all the rivers that drain from south-western Kenya’s Mau forest into the lake have dried drastically.

Nearly 60 species of wildlife, including white rhino, depend on the lake.

By Sunday an estimated 200 hectares (500 acres) of woodland had been razed in Mau – East Africa’s largest indigenous forest.

KWS communications manager Paul Udoto told the BBC: “We now have to pump water from underground bore holes to shallow pans to water the animals in the park otherwise they will all die. This is costing us a lot of money.”

Members of communities opposed to government plans to move them out of the Mau forest are suspected, say police, and several people have been arrested, accused of arson.

Another blaze nearby has destroyed about a quarter of the 52 sq km (20 square miles) Mount Longonot National Park, an extinct volcano in Kenya’s Rift Valley, said officials.

Zebras, buffaloes, antelopes, gazelles and giraffes have fled the fires, crossing roads and residential areas to reach safety, said witnesses.

But some wildlife experts said snakes and smaller animals, like rabbits and mongooses, may not have managed to escape.

Kenya is suffering a drought this year that has contributed to hunger the government says is affecting 10 million people.

Source: BBC News website

Date: 23/03/2009

Trees: More than just carbon sinks


“In the absence of trees, our communities would simply collapse,” states Andrew Dokurugu, a project officer for Tree Aid tells BBC News.

Speaking from the charity’s West Africa offices in Burkina Faso, he explains how trees are vital for poor rural villages to survive in the long-term.

“We are looking at ways to promote sustainable agriculture and agroforestry,” he says.

“This will help ensure that the remaining trees are well looked after and that communities have access to the trees they require.”

Using the Family Trees and Land Use scheme in northern Ghana, one of Tree Aid-led projects that have helped 600,000 villagers, Mr Dokurgu outlines why so many communities in West Africa are facing tough times.

“Rural settlements located close to big cities have particularly difficult challenges,” he says.

“Urban developments damage the environment and remove trees for use in the cities.

“This quickly deprives rural areas of their sources of food, fuel and other tree products.”

Rising urban populations and expanding cities makes life tougher both inside and outside the city boundaries.

Tree Aid was set up in 1987 by a small group of foresters who were keen to use their expertise to help people in Africa, explained programme director Tony Hill.

“They saw that trees, potentially, were a way for poor rural families to help themselves in the long-term,” he told BBC News.

And in 1997, the charity established a permanent office in Ouagadougou, the capital of Burkina Faso.

Mr Hill described this development as a “step change” for Tree Aid, which has now planted more than 6.5 million trees.

“We were then able to work directly with local partners,” he said.

“Projects always have a beginning and an end, but the needs of the villagers do not end when the scheme finishes – particularly when you are dealing with trees.

“You need to have the continuity of attention, care and protection if you are going to deliver the benefits long-term.”

The need to plant and manage the region’s tree stocks is becoming increasingly important, Mr Hill says.

“If you go back several decades, the wild tree resources were rich enough for villagers to get more or less all of the products they needed without having to plant trees.

“Now, growing populations and an erratic climate means that villages have to invest in trees, rather than letting nature do its own thing.”

However, it is not simply the case of telling people to plant saplings and sitting back and waiting for them to grow.

Some cultures, Mr Hill reveals, have traditionally considered planting fruit trees as taboo: “People believed that if you planted a tree, you were bound to die before it bore fruit.”

But he says one of the biggest challenges is the issue of land tenure.

“For farmers, it is like a declaration of ownership. Planting trees says ‘this is my land and it is going to be mine for a long time.

“For many people, it is difficult to negotiate adequate secure tenure and get permission from all of the relevant authorities.”

This is one area where Tree Aid has been focusing its efforts, especially for women, who generally are not allowed to own land.

“In the drylands of Africa, where Tree Aid operates, the real value of trees is the products that they can take: fruits, leaves, bark and roots, firewood, building materials,” Mr Hill says.

He adds that healthy trees also help maintain the area’s ecosystems.

“People rely on trees to recycle nutrients, prevent erosion and maintain moderate water flows.

“Without trees in the landscape, you cannot have a sustainable farming system.

“Without farming, you do not have any life in these communities.”

Source: BBC News website

Date: 19/03/2009

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

Africa’s urban trees are casualties of overcrowded cities


It is not only the rural regions in developing nations that are losing tree cover.

In an article published by the Ugandan website, New Vision, environmental journalist Ebenezer Bifubyeka highlights the issue of urban trees being felled.

The reason? Apparently, it is because of the rising population in cities, which is increasing the demand for urban open spaces to be converted into housing.

In his article, reproduced below, he highlights why authorities’ decisions to sacrifice the green urban spaces are is not without consequence:

On January 2, The New Vision published an article quoting the director of Natural Resources in the National Forestry Authority, Hudson Andura, as saying:

“Fifteen urban forest reserves are to be degazzated to cater for the growing population and development in 15 towns countrywide.”

Do we ever ask ourselves why trees stand side by side with skyscrapers in cities within developed countries? The reason is to mitigate city noise and absorb pollutant gases. Trees reduce on noise and absorb toxic gases.

The move by the National Forest Authority to degazzate forest reserves in 15 towns is not only a miscalculation but also a disastrous move. It is in urban centres that greenhouse gases are most emitted from factories and trees are the immediate reducers of such pollutant gases.

Is anybody bothered about the loss of national tree cover from 28% in 1988 to 13% by 2008? The loss of water catchment areas has led to poor and filthy water quality, thus the subsequent deaths of fish.

Besides, ornamental and ambient roles, trees in urban compounds, streets, recreational centres and hospitals keep the cycle of air flow fresh. In public hospitals like Mbarara Hospital, there used to be enough shed trees purposely to reduce noise of vehicles for the sick. It is unfortunate that these trees are being felled.

Trees reflect noise upwards in the atmosphere, according to Jeconious Musingwire, the western regional environment awareness officer.

As Uganda moves towards development circles, we have started going more brown (non-green environment). Despite pressure from investors and politicians to develop urban areas, development should be in harmony with conservation. Otherwise, we shall head for desertification and famine.

The escalating global warming – evidenced by climate change – warns us to stop further degradation of other green belts such as swamps, parks, green grass and forests.

In this regard I implore the Government to take environment concerns seriously and discourage cementing pavements and compounds. The green grasses are vital, for they ease the percolation of water into the soil.

Source: New Vision website

Date: 14/01/2009

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