Last month, we talked about the US Forest Service’s program “Forests to Faucets”, which is designed to raise awareness about the relationship between watersheds and environmental hazards. As I explained in my previous blog, the Forests to Faucets project uses GIS modeling and mapping to create an interactive map that illustrates the locations of watersheds throughout the country in an attempt to highlight “the role forests play in protecting these areas, and the extent to which these forests are threatened by development, insects, disease, and wildland fire.”
Explaining the importance of the Forests to Faucets program, US Forest Service Chief Tom Tidwell says, “Spending money on forest management upstream in a watershed saves money on water treatment downstream. The Forests to Faucets project provides powerful information that can help identify forest areas that play a key role in providing clean drinking water.”
But unfortunately, forests are in danger—facing a variety of risks including deforestation due to urbanization and agricultural expansion, and climate change. For example, according to a study released by Duke University last month, the nation’s forests have failed to adapt to recent changes in climate and weather patterns. And just this week, a new study published in Global Change Biology has concludes that although forests are an integral part of the hydrological cycle, they are not being adequately protected.
The study, conducted by Martyn Futter and Kevin Bishop at the Swedish University of Agricultural Sciences (SLU), highlights the relationship between forest size and regional rainfall. The moisture generated by forests is responsible for much of Europe’s rainfall, and the study found a direct correlation between forest area reductions and corresponding reductions in regional and continental rainfall.
In a statement about the study, team member David Ellison from the Hungarian Academy of Sciences, says, “Are forests good for water? An apparently simple question divides scientists in two camps—those who see trees as demanding water and those who see trees as supplying water. This paper demonstrates that the difference between these two camps has to do with the spatial scale being considered. Forests, whose contribution to the water cycle is crucial for human survival and future well being, should be regarded as a global public good, to be preserved and used for the benefit of all.”
The idea of seeing forests as water providers rather than water users can seem counter intuitive. While on an individual basis, trees are water consumers, but on a larger scale—as part of a forest for example—trees can also be water suppliers because they generate the atmospheric moisture that eventually becomes rain. Nevertheless, the view that trees use—rather than generate—water informs many public policy decisions, including the EU Water Framework Directive (WFD) and many water footprint calculations (www.waterfootprint.net).
The study concludes that continued deforestation and land conversion as a result of increased agricultural and urban use of forest lands will negatively impact regional rainfall totals. And while on a case-by-case basis this rainfall reduction may seem insignificant, when viewed on a global scale it’s hard to ignore the ramifications this deforestation will have on both rainfall and climate change.
As Ellison explains, “Forests, whose contribution to the water cycle is crucial for human survival and future well being, should be regarded as a global public good, to be preserved and used for the benefit of all.”