© 2003 Heron Publishing—Victoria, Canada
Variation in morphological and biochemical O3 injury attributes of mature Jeffrey pine within canopies and between microsites
N. E. Grulke (1, 2), R. Johnson (1), S. Monschein (3), P. Nikolova (3, 4) and M. Tausz (3)
1. Pacific Southwest Research Station, USDA Forest Service, 4955 Canyon Crest Drive, Riverside, CA 92507, USA / 2. Author to whom correspondence should be addressed (ngrulke@fs.fed.us) / 3. Institut für Pflanzenphysiologie, Karl-Franzens-Universität, Schubertstraße 51, A-8010 Graz, Austria / 4. Department of Forest Botany, University of Munich, Hohenbachernstraße 22, D-85354 Freising, Germany / Received November 22, 2002; accepted February 15, 2003; published online August 1, 2003
Summary
Crown morphology and leaf tissue chemical and biochemical attributes associated with ozone (O3) injury were assessed in the lower, mid- and upper canopy of Jeffrey pine (Pinus jeffreyi Grev. & Balf.) growing in mesic and xeric microsites in Sequoia National Park, California. Microsites were designated mesic
or xeric based on topography and bole growth in response to years of above-average precipitation. In mesic microsites, canopy
response to O3 was characterized by thinner branches, earlier needle fall, less chlorotic leaf mottling, and lower foliar antioxidant capacity,
especially of the aqueous fraction. In xeric microsites, canopy response to O3 was characterized by higher chlorotic leaf mottling, shorter needles, lower needle chlorophyll concentration, and greater
foliar antioxidant capacity. Increased leaf chlorotic mottle in xeric microsites was related to drought stress and increased
concurrent internal production of highly reactive oxygen species, and not necessarily to stomatal O3 uptake. Within-canopy position also influenced the expression of O3 injury in Jeffrey pine.
Keywords:
antioxidants, drought stress.
