Growth, Physiological and Biochemical Response of Ponderosa Pine 'Pinusponderosa' to Ozone

摘要

In 1989 and 1990, the effects of multi-year ozone exposures on growth, foliarinjury and physiological responses in ponderosa pine were examined. Two-year old seedlings were exposed to four ozone treatments in open-top chambers: clean air (subambient levels of oxidants and particles); ambient ozone; twice-ambient ozone; or ambient air. The study was performed at Shirley Meadow in the southern Sierra Nevada. In both years, ambient ozone levels were representative of other forests in the region. While ozone is the most phytotoxic air pollutant, seedlings also experienced elevated concentrations of nitric acid and ammonia. In 1990, ambient ozone significantly increased injury to previous year needles. Premature senescence and alterations in physiological responses were also noted. Exposure to twice-ambient ozone reduced seedling biomass, increased injury and caused decreases in a variety of physiological responses.