For the first time in at least 125 years, Giant Sequoias in the southern Sierra Nevada Mountains of California are showing significant amounts of “dieback” in their foliage due to several years of drought.
The U.S. Forest Service contributed emergency funding to a collaborative research project involving scientists from U.C. Berkeley, Sequoia and Kings Canyon National Parks, U.S. Geological Survey, andCarnegie Airborne Observatory to examine the effects of the current historic drought on Giant Sequoias.
If they get adequate water and nutrients, Giant Sequoias can live to be well over 3,000 years. They are the largest single-stem tree species in the world, with respect to wood volume and mass, and they grow best in a climate of snowy winters and dry summers. A big decline in snow pack in California over the last few years is a major reason for the observed dieback.
Ambrose and his colleagues intend to construct a “vulnerability map” for the Giant Sequoias using a combination of traditional ground-based monitoring and data collected aerially by the Carnegie Airborne Observatory. The map will reveal which stands of trees are the most susceptible to drought conditions, allowing managers to prioritize those stands most in need of prescribed fire, mechanical thinning, or other treatments.
“Obviously, given the water needs of Giant Sequoias, we cannot water an entire forest during periods of extended drought,” Ambrose said.
NOTE: For an interactive look at USDA’s work in conservation and forestry over the course of this Administration, visit http://medium.com/usda-results.