Ozone effects on the growth of grafted mature and juvenile red spruce

Abstract

Grafted juvenile and mature scions of red spruce (Picearubens Sarg.) were grown in open-top chambers at a low-elevation site in central Maine to determine if developmental age of tissue affects response to oxidant pollution. After 18 weeks of ozone exposure, grafted red spruce showed little or no growth response to ozone. No significant ozone effect on biomass production was measured, although there were significant differences between juvenile and mature scions. At the final harvest, juvenile scion stem, stem needles, branches, branch needles, and roots had 60, 18, 74, 73, and 35% more dry weight, respectively, than mature scions. Despite the observed differences in growth and biomass production, the two graft types did not differ in their responses to ozone, suggesting that tissue age may not be a factor in ozone-tolerant woody species such as red spruce. It does not preclude the importance of assessing the influence of age on other woody species' response to air pollution. This type of information is critical for extrapolation of seedling data to field conditions with mature trees.