July 13, 2015--When a tree falls in the forest, what’s the impact on water resources? (phys.org)

Forest management practices such as cutting or thinning trees reduce the risk of wildfires, and enhance the overall health of the woodlands. However, they also can speed up the pace of snow melt, which in turn may increase erosion and destabilize streams. Too much melt within a short time interval sends excessive sediment and nutrients into streams, harming ecosystems and degrading water quality, which is expensive to treat. Mukesh Kumar, assistant professor of hydrology and water resources at Duke University, thinks there needs to be an equilibrium between maintaining the well-being of the forest through sound forest management practices, and preserving seasonal snow in forested uplands that serve as a critical water source for most of the western United States. It is an issue that assumes added importance now, during a time of severe and prolonged drought in the West. "Generally in most of the western United States and many snow dominated settings in the world, most of the water supply is recharged from snow melt, and much of this happens in forested areas," he says. "At the same time, many forest management practices are done every few years, trying to maintain a certain density of trees that allows every tree to get sufficient nutrients and sunlight…[and] reduce fire risk." As a result, more sun hits the snow on the ground, and it melts faster, causing an increase in so-called "spring stream flow peak," which means "the largest flow in the stream or river during the melt season," he explains, adding: "This can be a problem. What we are trying to do is strike a balance between maximizing forest productivity and minimizing its impact on water resources." To view the full article visit phys.org.