Frequent droughts and floods in eastern Africa can partly be blamed on widespread deforestation in the region, experts have said.
"Trees actually do two processes. They drill water into the ground. They funnel water into underground aquifers where it is stored to supply rivers during drought," Nick Nuttal, spokesman for the United Nations Environment Programme (UNEP), said.
"They also hold soil. Where there are no trees, the soil is washed away into rivers causing siltation into the oceans choking coral reefs," he told IRIN on the sidelines of the 6-17 November conference of the UN Framework Convention on Climate Change in Nairobi. "The link between deforestation and
drought is very significant".
The loss of ground cover due to deforestation resulted in flash floods during heavy rainfall, leading to soil erosion. "That is the start of desertification," said Beneah Odhiambo, a professor of geography at Moi University in western Kenya.
Contrary to conventional wisdom, an estimated 62 percent of precipitation occurs over land as a result of evapotranspiration from lakes and wetlands and dense vegetation, particularly forests, which pump ground water into the sky. The moisture then condenses and falls as rain, according to Nuttal.
Only about 38 percent of the precipitation is generated over oceans and seas.
Africa was characterised by divergent climate conditions ranging from dry to moist. With climate change, this was becoming more pronounced with the frequent occurrence of floods and droughts.
"Forests are needed to build in resilience in the natural ecosystem. They are a buffer against extreme floods and droughts," said Nuttal.
The more frequent return of drought and loss of life from floods was an indication that climate change has set in, he added.
Trees not only moderate climate, but act as water reservoirs, sources of medicine, and habitats for wildlife which earned countries like Kenya millions of dollars in foreign exchange through tourism.
Kenya, one of the countries in East Africa that has been affected by severe droughts in recent decades, has had a high rate of deforestation.
Environmentalist and Nobel Peace laureate, Wangari Maathai, has estimated that the country needs to conserve at least 10 percent of its indigenous forest cover.
The findings of a study carried out by UNEP following the 1999-2000 drought estmated that between 2000 and 2003 the country's main water catchment areas - Mt Kenya Forest, Mau Forest, Mt Elgon Forest, Cherangani Forest - were deforested by between 0.2 and 2 percent over a two-year period.
The deforestation of the Mau Forest has continued unabated, Nuttal said, noting that charcoal burnig and farming activities were the main causes of the destruction. An estimated 11,000 sq km of the forest have been affected by the destruction.
"It is crucial that Kenya invests in vegetation as one way of storing and returning moisture to the air so as to increase the chances of regular rainfall throughout the year," Nuttal said.
Globally, only 20 percent of forests remain intact. Six million hectares of primary forest are lost every year due to deforestation and modification through selective logging and other human interventions.
Primary forests are those where there is no clearly visible indication of human activity and where ecological processes are not significantly disturbed, according to UNEP.
According to the international environmental conservation organisation, the World Wildlife Fund (WWF), ongoing encroachment on forest mountain ranges threatens the existence of rare plant and animal species.
The Rwenzori massif, for example, which is a UNESCO heritage site, is home to the rare Rwenzori Duiker antelope and over 75 rare plant species which are threatened by the changing habitat due to climate change.
Glaciers on the mountain have receded from 650 hactares in 1905 to 108 in 2005, according to WWF, which estimated that the massif will be without any glaciers by 2025 if the current rate of climate change continues.
The Rwenzori, which is shared by Uganda and the Democratic Republic of the Congo, is a water source for an estimated one million people in both countries.
Global warming blamed on carbon emissions has also caused the shrinking of the ice cap on Mt Kenya, another important water reservoir in East Africa.
Achim Steiner, UNEP's Executive Director, said curbing deforestation is one of the most cost-effective ways of reducing emissions of harmful gases.
Steiner and Maathai this week launched a global campaign to plant a billion trees in 2007. "When we plant trees, we plant the seeds of peace and seeds of hope for future generations," Maathai said on Wednesday.
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This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions