The goal of planting one billion trees around the world has been achieved in one year thanks to the United Nations and Nobel Peace Prize winner and Kenyan Green Belt Movement founder, Wangari Maathai. "I am elated beyond words at the global interest and action that was motivated by the Billion Tree Campaign. I knew we had it within us as a human family to rise up! We called you to action almost exactly a year ago and you responded beyond our dreams!"

A UN report said Wednesday that the billionth tree was probably planted in Ethiopia where close to 700 million trees have been planted alone. Half of all those who participated were private citizens or households planting one to three trees, according to UN Environment Program (UNEP), while another 13 percent were planted by the private sector.

A big boost came in Mexico where the government and local authorities-with support from the army and inspired by President Felipe Calderón-pledged and planted over 200 million trees. Several million more trees are expected to be planted by Guatemala, China and Spain.

The news comes as thousands of delegates across the world are ready to arrive on the Indonesian island of Bali for the next and most crucial round of global warming negotiations under the UN Framework Convention on Climate Change.

The Billion Tree Campaign was launched at UNEP headquarters in Nairobi last November in the garden of a staff member.

While not all numbers are in, UNEP said the top-ranking countries appear to be Ethiopia, over 700 million trees planted; Mexico, 217 million trees; Turkey, 150 million; Kenya, 100 million; Cuba, 96.5 million; Rwanda, 50 million; Republic of Korea, 43 million; Tunisia, 21 million; Morocco, 20 million; Myanmar, 20 million and Brazil, 16 million. The Green Belt Movement planted 4.7 million trees, double the number of trees it had initially pledged.

"There had been a few cynical smiles and shaking of heads when the Billion Tree Campaign was launched," said Achim Steiner, UN Under-Secretary-General and UNEP Executive Director. "Some said it would never happen, but citizen after citizen, community after community and country after country, have proved the doubters wrong and demonstrated an abiding truth in 2007."