Study may help cities manage watersheds
Which is better for managing a watershed: young trees or old growth forests?
There is some evidence that young trees use less moisture because of their size. At the same time, other research indicates that old-growth forests retain more water in the landscape. Old-growth forests on ridges and hilltops are tall enough to be brushed by low-elevation clouds, and the foliage can be so saturated that water drips down though no rain has fallen.
To help resolve the debate, UW forest resources professors and students have built probably the largest research tower for studying tree canopies in the United States—a 135-foot tower in the Cedar River watershed of the central Cascade Mountains.
Made out of a ton and a half of metal that had to be carried—by hand—a mile to the research site, the tower enables researchers to take readings from the ground to the treetops. The results may help cities that rely on surface water better conserve the resource. During the year, 40 percent or more of the rain and snow that falls in a typical watershed doesn’t end up in the waterways, says Forest Resources Professor Tom Hinckley.