Swiss President Moritz Leuenberger has met Nobel Prize winner and Kenyan environmentalist Wangaari Maathai during the post-Kyoto climate change talks in Nairobi.
Leuenberger signed an agreement on Wednesday with the Green Belt Movement, founded by Maathai, to finance a reforestation project and planted a tree as part of its recent "Plant for the Planet: Billion Tree" campaign.
"To plant a tree is to give a sign of hope," said Leuenberger. "It is a sign of political action by which you can save the world."
Switzerland has agreed to fund a small reforestation project – around 3,000 trees - at Karura Forest, just outside Nairobi, which has suffered badly from logging.
"We really appreciate this gesture from Switzerland which is particularly relevant during the climate change conference," said Maathai.
"We believe that governments in developing countries, including Kenya, need to be supported in reforestation initiatives which can involve our own people."
Deforestation is on the increase in African countries. In Kenya forest cover is less than two per cent, while the United Nations recommends at least ten per cent.
The Kenyan environmental group, together with the UN Environment Programme, is aiming to plant one billion trees worldwide by 2007 as part of its efforts to empower communities to protect the environment, promote good governance and cultures of peace. They have already received pledges for about 19 million trees.
Leuenberger was full of praise for the work of the Nobel Prize winner and her organisation.
"Some journalists asked me earlier what was concrete about this conference and I had to confess that it is sometimes difficult to provide concrete results," he said.
"But politics is not just about prescriptions – bilateral or multilateral agreements – it's also about doing something. If Rio was a vision, Kyoto was an obligation and here in Nairobi what you are doing is concrete action."
The tree-planting ceremony at Karura Forest, attended by the Swiss delegation, followed the signing of a similar agreement between the environmental movement and the World Bank to reforest regions of Kenya.
"If we stop cutting our indigenous forests and plant trees we can counteract a significant part of our carbon emissions that are causing climate change; this is something all of us can do," said Maathai.
Addressing around 70 environment ministers at the UN climate conference earlier in the day, Leuenberger called for the introduction of an international tax on carbon dioxide (CO2) emissions to fight global warming.
He explained that each individual and business would pay the tax based on their CO2 emissions, with revenue going towards measures mitigating the effects of global warming.
Leuenberger also called on those countries that had refused to ratify Kyoto - including the United States and Australia – to reconsider their decisions.
During his address, UN Secretary-General Kofi Annan criticized a "frightening lack of leadership" in fighting global warming and urged top emitters led by the US and China to do more to curb greenhouse gases.
He told a news conference that his remarks were "not directed at any individual or president" when asked if he was especially targeting the US, the world's biggest source of emissions and which pulled out of Kyoto in 2001.
Still, he added: "I think it would be preferable if they signed the Kyoto agreement."
swissinfo, Simon Bradley in Nairobi
Swiss President Moritz Leuenberger is visiting Kenya and Ethiopia from November 13 to 17.
The 12th UN Climate Conference in Nairobi runs until November 17.
Around 6,000 delegates and observers from 190 countries are attending the two-week summit.
Switzerland was the 110th country to ratify the Kyoto Protocol in 2003.
Swiss development aid to Africa in 2005 totalled SFr392.4 million ($314.3 million)