With 1.8 billion people threatened by absolute water scarcity by 2025, and two-thirds of the world's population facing potential shortages, countries must better protect and manage forests to ensure the provision of clean water to vulnerable communities, a United Nations-backed forum warned last week.

"Forests are part of the natural infrastructure of any country and are essential to the water cycle," said UN Food and Agriculture Organization (FAO) Forestry Department Assistant Director General Eduardo Rojas-Briales.

The FAO is part of the 14-member Collaborative Partnership on Forests (CPF), a grouping comprising 14 international organizations, including several other UN agencies and bodies.

"They reduce the effects of floods, prevent soil erosion, regulate the water table and assure a high-quality water supply for people, industry and agriculture," Mr. Rojas-Briales said, speaking ahead of UN World Water Day, which will be celebrated this year on 22 March.

Today, at least one third of the world's biggest cities, such as New York, Singapore, Jakarta, Rio de Janeiro, Bogotá, Madrid and Cape Town, draw a significant portion of their drinking-water from forested areas. If properly utilized, forest catchment areas can provide at least a partial solution for municipalities needing more or cleaner water, according to CPF.

"The management of water and forests are closely linked and require innovative policy solutions which take into account the cross-cutting nature of these vital resources," said Jan McAlpine, Director of the UN Forum on Forests Secretariat.

The UN General Assembly has proclaimed 2011 the International Year of Forests and this "provides a unique platform to raise awareness of issues such as the water-soil-forests nexus, which directly affect the quality of people's lives, their livelihoods and their food security," she added.

Moreover, forests and trees contribute to the reduction of water-related risks such as landslides, local floods and droughts, and help prevent desertification and salinization. They are in most cases an optimal land cover for catchments supplying drinking water, and forest watersheds supply a high proportion of water for domestic, agricultural, industrial and ecological needs.