January 2, 2016

Seeing the Water Basins for the Trees

Rachel Friedman

It’s pretty easy to continue with accepted theories, among like-minded colleagues.

This article originally appeared on the Landscapes for People, Food and Nature blog.

Yet, a collegial discussion on managing forests for water and climate, hosted by WeForest at the Global Landscapes Forum, pushed boundaries a bit. In this talk, world leaders moved beyond mere mechanics of the water cycle to more fully embrace the complexity of integrated landscape management. Despite a deep-rooted appreciation for trees, it was clearly not enough.

  1. We don’t always know what “we know.” One of the characteristics often attributed to scientists is their love of caveats – what errors could the methodology have caused, what assumptions were made, what conflating factors could completely nullify the conclusions. So it’s not surprising that “new research reveals” was the explanation of choice for why certain forest processes are now more important than originally anticipated. WeForest reviewed five processes that connect arboreal and forest systems to hydrologic and atmospheric functions, emphasizing that the usual mantras about trees are not always applicable. There was also a recognition that forest ecologists and ecologists have to link more with the policy and management implications at the nexus of forest, water, and climate (and energy and food, as well).
  2. Scale matters. The group left no factor of the ecosystem unconsidered. By drawing connections between individual raindrops, watersheds, and global atmospheric processes, the scientists resisted the traditional siloed approach to research. Typically, water management decisions occur at very local levels, such as the classic discussion of how upstream land use, such as deforestation and forest degradation, affects downstream water quality and quantity. Without considering how decisions in one watershed impact processes that extend beyond this localized system, policy that is designed at the national and international scales misses the ability to capture important links between land use, hydrology, and climate. David Ellison, from the Swedish University of Agricultural Sciences, addressed this gap by emphasizing the role of trees in generating rainfall, which, in turn, influences water infiltration in to the soil, and drives local and regional weather. He also discussed the Nile River Basin and the importance of transboundary governance for addressing water issues.
  3. Context is the final word. We talk a lot about scale when landscapes are on the menu, but it’s not everything. Meine van Noordwijk of the World Agroforestry Centre warned against assuming that “all forests are good for water everywhere in the world.” Trees play a vital role in cycling water from soil through vegetation into the atmosphere, but the types of trees and the density of forests depend on the characteristics of the accompanying soils and aridity of the local climate. For instance, in arid regions of sub-Saharan Africa, balancing the role of trees in recharging groundwater and reducing erosion with their use and storage of water is important.

At the end of the day, trees fulfill an important function in regulating flows of water in various types of systems, but as in most integrated solutions, applications of these principles require a careful consideration of the various factors at work in a landscape.

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Rachel Friedman recently completed an MPhil in biodiversity, conservation, and management at Oxford University, focused on climate change vulnerability of women cocoa farmers in Ghana. Previously, she has worked in both research and communications on agriculture and sustainable development with EcoAgriculture Partners and the UN FAO liaison office in Washington. Currently working with a local food organization in Oxford city, she will be starting a PhD at University of Queensland in the spring, looking at ecosystem services in agricultural landscapes.

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