The ecophysiology of ozone-stressed Jeffrey pine

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:5519817

Patterson, M T

The effect of ozone on the physiological ecology of Jeffrey pine growing in the southern Sierra Nevada of California was studied over a three-year period. The extent and development of ozone-induced visible injury symptoms (foliar chlorosis and premature needle abscission) and the physiological consequence of visible injury was addressed in natural populations of Jeffrey pine. Seasonal and diurnal measurements of gas exchange, water relations and nutrient status distinguished ozone-injury related perturbations. Stable carbon isotope discrimination in conjunction with gas exchange was used to investigate the relationship between physiological capacity and ozone sensitivity in field situations. Approximately 10% of the trees studied exhibited severe ozone injury (sensitive) whereas 10% exhibited little or no visible sign of injury (resistant). Nearly 90% of the trees studied exhibited some form of visible injury symptom. Although there was a strong negative correlation between photosynthetic rate and needle chlorosis, whole plant carbon gain in sensitive trees was impacted more by the loss of photosynthetic needle area due to premature abscission than by ozone-induced reductions in photosynthetic rate. Resistant trees appeared to be experiencing less drought stress than sensitive trees. Patterns of nutrient accumulation and retranslocation suggested that sensitive trees had a smaller root system and smaller foliar pools of available nutrients to supply growing tissues. Stable carbon isotope discrimination in young needles was greater in sensitive trees and stomatal limitation varied such that intercellular CO[sub 2] concentration was always 15-20 ppm greater than in resistant trees. This suggests that sensitive trees operated at higher stomatal conductances which may have predisposed them to ozone injury. Long-term ozone stress on natural populations of Jeffrey pine resulted in both direct and indirect alterations in many physiological process.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 5519817
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL ADAPTATION
BIOLOGICAL EFFECTS
BIOLOGICAL STRESS
CHEMICAL REACTIONS
CHLOROSIS
CONIFERS
GROWTH
LEAVES
OZONE
PATHOLOGICAL CHANGES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PINES
PINOPHYTA
PLANT GROWTH
PLANTS
SYNTHESIS
TREES