BOGOR, Indonesia (22 March, 2012)_The fact that trees play a critical role in supplying clean water is a point yet to be fully grasped by many cities in the world. Not New York City, which is actively protecting a forest 100 miles away for the role its trees play in providing the Big Apple with a clean water supply.

The surprising role of forests in supplying clean water for one of the most densely populated cities on the planet reminds us that forests also deserve applause for their vital role in sustainable water and food resources as we celebrate World Water Day and the 2012 theme, ‘water and food security’.

Water is one of seven critical issues to be discussed at Rio+20, and the link between water and food security is immediately made on the campaign website: “Water scarcity, poor water quality and inadequate sanitation negatively impact food security, livelihood choices and educational opportunities for poor families across the world.”

What is not mentioned by the Rio+20 website is the vital role that forests play in water availability, water quality, climate regulation and food security, highlighted in recent research by CIFOR and others. A recent report by the International Water Management Institute and UN Environment Programme discusses how a new focus on ecosystems, such as forests, can deliver improved food and water security.

Forests help sustain the soil and water base that underpins agriculture. According to the UN Food and Agriculture Organization (FAO), eight percent of the world’s forests play a primary role in soil and water conservation. Forested catchments supply a vital source of clean water for human use: an estimated 75% of usable water worldwide.

“Forests provide a range of watershed services, such as the protection of water quality, the reduction of flows during storms, the recharge of groundwater aquifers and the conservation of water flow during dry seasons,” said CIFOR and CIRAD scientist Bruno Locatelli.

“These services are essential to many of us: for example, the conservation of dry season stream flows is essential for drinking water supply, agriculture, navigation, hydropower, freshwater wildlife, or recreation. The reduction of storm flow benefits housing, infrastructure, or agriculture in flood-prone areas.”

Forests may even help attract rain. While there are many uncertainties surrounding the links between deforestation and declining rainfall, recent research (also discussed by CIFOR scientists Daniel Murdiyarso and Douglas Sheil in their 2009 paper) suggests that forest cover plays a much greater role in determining rainfall than previously recognised by climatologists.

According to Locatelli, these hydrological services are particularly crucial for rural communities in the tropics, where livelihoods depend directly on seasonal rainfall and river flows, for example for agriculture, fishing or transportation.

And the hydrological services of forests are equally important for urban populations. According to a report published by the World Wildlife Fund in 2003, around a third (33 of 105) of the world’s largest cities get a significant proportion of their drinking water directly from forest protected areas. Eight more cities get their water from forests that are managed in a way that prioritises their functions in providing water.

One of the major functions forests provide in this respect is improving water quality. Water pollution is a main cause of reduced water availability and can have serious impacts on the environment and on human health, particularly in developing countries where 70 percent of industrial wastes are pumped, untreated, into the water system — not to mention the two million tonnes of sewage and other effluents draining into the world’s waters every day.

Scientists refer to wetlands as ‘the world’s kidneys’ because they purify and slow the flow of water to the sea, helping to control floods and water pollution. But our world is experiencing kidney failure — according to UN Water, half of the world’s wetlands have been lost since 1900. When forests around lakes and streams are intact, they act as a filtering system, reducing the amount of sediment, agricultural chemicals and pesticides in the water table.

Apart from being the world’s kidneys, forests are also often called ‘the world’s lungs’ because they take carbon from the atmosphere and produce oxygen, and it is this function has attracted growing attention in recent years as the world faces the challenge of climate change.

Forests are instrumental to efforts to help communities and agriculture handle the more frequent droughts and floods that come with an increasingly variable climate.

While the role of forests in mitigating large-scale floods is still under debate, a study by CIFOR and FAO has shown that forests mitigate small and local floods, and appear to slow down the floodwaters from bigger floods as they run downstream.

Forests can also act as ‘emergency supplies’ in disaster situations. For example, when rural communities in Indonesia were recently devastated by a catastrophic flash flood, a CIFOR study found that nearby forests helped provide vulnerable communities with basic subsistence for many months following the disaster. And they provide a similar function during drought.

But it is not only in times of crisis that people depend on forests — more than a billion of the world’s poorest people live in and around forested areas and depend on the resources forests supply. Forest fruits and greens supply many of the micronutrients that keep rural communities nourished and healthy. Meat hunted in forests is a crucial source of protein for forest-dependent people (for example, many rural communities in the Congo Basin depend on bushmeat for up to 80 percent of the fats and proteins in their diets). Communities even use forests as their medicine cabinets.

In short, having only scratched the surface of all the ways in which forests benefit water and food security, future food and water supplies cannot be secured without forests.

But even as demand for food and water is increasing, remaining forest lands are disappearing — due to land use change, climate change, insect or disease epidemics and more frequent fires — affecting the vitality of ecosystems and compromising their hydrological buffering function.

To preserve the essential services and safety net functions forest ecosystems provide to the livelihoods of local communities, and to preserve those forest services of which the world may not yet be aware, forests need to be kept on the global agenda at events like Rio+20.

“It is right to avoid considering forests as a panacea for all water-related problems, but we also cannot avoid the fact that forest management and conservation are key to water management,” said Locatelli.

To ensure that  Rio+20 delivers a global message that forests matter to sustainable development, CIFOR will coordinate one of the most important conferences on forests on 19 June, 2012. Forests: The 8th Roundtable at Rio+20 will discuss new research findings, remaining knowledge gaps and policy implications for integrating forests into the solutions to four key challenges to progress toward a green economy: energy, food and income, water, and climate. Seats are limited so register here to avoid disappointment!