Forestry Friday … Millions of Dead Trees

This story appeared in the May 2015, California Forest Pest Council newsletter. The effects of the drought are manifesting in Southern California forests through massive tree die-off.

Early Aerial Surveys Find Millions of Dead Trees 

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2015 Pine Mortality Near Tehachapi. By J. Moore, USFS.

The US Forest Service, Forest Health Protection conducted special early season aerial surveys of Southern California and the Southern Sierras in April to get a preliminary assessment of forest conditions in some of the most severely drought-impacted areas of the state. The Southern California survey covered more than 4.2 million acres and identified approximately 2 million dead trees over 164,000 acres. It included most of the Cleveland, San Bernardino, Angeles, and Los Padres National Forests as well as Pinnacles National Monument and nearby private lands. Noteworthy finds included a substantial increase in pine mortality on the Descanso Ranger District of the Cleveland National Forest as well as a large area of scattered live oak mortality south of the Palomar Ranger District. Increased pine mortality was also observed on the San Jacinto District, and large areas of live oak mortality were observed along the southern extent of the Angeles National Forest. In Los Padres National Forest, expanded severe Jeffrey and pinyon pine mortality was observed, and private lands north of Pinnacles National Monument had extensive areas of Coulter and gray pine mortality, as well as live oak mortality, for a third year in a row.

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Hardwood Mortality in the Sierra Foothills. By Z. Heath, USFS.

The Southern Sierra survey included more than 4.1 million acres and identified nearly 10½ million dead trees over 835,000 acres. It covered western portions of Stanislaus, Sierra, and Sequoia National Forests and Yosemite and Sequoia-Kings Canyon National Parks as well as the Tehachapi Range and nearby private lands. Mortality in the Southern Sierras was quite severe in many pine species, especially ponderosa and pinyon at lower elevations and to the south, and foothill mortality was often widespread and severe, especially in ponderosa and gray pine. Mortality on the Stanislaus roughly doubled since July 2014 in the areas resurveyed this spring, with severe pockets of ponderosa and other pine mortality seen in the low areas to the south. On the Sierra and Sequoia National Forests, western pine beetle-associated pine mortality was common and severe at lower elevations, with an estimated 5 million trees killed, compared to about 300,000 trees last year in the same area. Southeastern portions of the Sequoia National Forest and wilderness areas further east also had intense pinyon mortality, and on the Tehachapi Range and private lands along the Sierra foothills, extensive areas of pine mortality were common.