Evidence of Growth Reduction in Ozone-Injured Jeffrey Pine (Pinus Jeffreyi Grev. and Balf.) in Sequoia and Kings Canyon National Parks

Evidence is presented for a reduction in radial growth of Jeffrey pine in the mixed conifer forest of Sequoia and Kings Canyon National Parks, California. Mean annual radial increment of trees with symptoms of ozone injury was 11 percent less than trees at sites without ozone injury. Larger diameter trees (>40 cm) and older trees (>100 yr) had greater decreases in growth than smaller and younger trees. Differences in radial growth patterns of injured and uninjured trees were prominent after 1965. Winter precipitation accounted for a large proportion of the variance in growth of all trees, although ozone-stressed trees were more sensitive to interannual variation in precipitation and temperature during recent years. These results corroborate surveys of visible ozone injury to foliage and are the first evidence of forest growth reduction associated with ozone injury in North America outside the Los Angeles basin.