They are the lungs of the planet, but they're also its kidneys, which is why paying greater attention to the world's forests is key to solving its water problems.
According to dozens of leading forest and water experts, ensuring the continued flow of “green water”- the water moving through trees, plants and soils - is the only way to maintain a healthy global system.
“A global water crisis is looming,” say the authors of world report, The Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities.
“In many places around the world, it is at the doorstep rather than the horizon, exacerbated by a growing global population and accelerated climate change.”
These include the UK, which is in the midst of a heatwave, and warned of looming water shortages in Asian countries as well as Brazil, South Africa, Turkey, Iraq and Mexico, among others.
“Over 7 billion humans share the planet with about 3 trillion trees,” write the authors. “Both need water. Increasing scarcity challenges mean the role of forests in the water cycle is as important as their role in the carbon cycle in the face of climate change.”
Addressing “forests-water-people-climate links wisely, comprehensively and expeditiously is crucial to our long-term well-being, if not survival”.
But water is rarely considered a priority in forest management.
“Forestation projects, for example, have failed to consider adequately the water demands of newly introduced foliage, or to use species well-adapted to local conditions. In some cases, fast-growing species have been used without thinking about the relative impacts on locally available water supply.”
The report examines the intricate links among forests, water, people and the climate, a complex relationship “that is largely unrecognised”.
Forests, note the authors, can disperse waters to relatively distant areas. “Adding forest and vegetation cover, for example, to upwind coasts where moisture released in the air is likely to deliver water to drier inland areas represents one possible win-win strategy.
“Availability of waters in the Nile River basin, for instance, is potentially influenced by changes in the land use practice in the tropic forest belt across the West African rainforest and Congo Basin.”
More than 50 forest and water experts from around the world contributed to the report, prepared by the Global Forest Expert Panel, including a team of researchers from the CSIR.
The report singles out South Africa’s Working for Water as a successful programme developed by the government to augment stream flow, has a mandate to clear alien invasive species with the intention of improving ecosystem services, including water provision, while also focusing on job creation and the broader objectives of land management.
“The programme provides us with a useful example of a management approach that has tried (with acknowledged limitations) to focus not on one objective, but to take a positive synergies approach and yield benefits in a range of areas.
“Established in 1995, and managed by the Department of Environmental Affairs, it has worked on clearing alien invasive species with the intention of improving ecosystem services, including water provision, while also focusing on job creation and the broader objectives of land management.”