Seasonal changes in the pigments, carbohydrates and growth of red spruce as affected by exposure to ozone for two growing seasons

Abstract

SUMMARYThree-year-old red spruce seedlings were exposed to various concentrations of ozone, from 0-4 to 3 times ambient, for two consecutive growing seasons in open-top chambers in Ithaca, NY, USA, Exposures, which varied with changes in daylength, were from 30 May to 14 December 1987 and 1 June to 1 December 1988, Seedling biomass, foliar pigments and carbohydrate content of roots and shoots were assessed once or twice per month. Tree biomass increased through the summer and declined slightly in late autumn, regardless of" ozone treatment. Biomass and contents of sugar and starch of 1988 fixed growth declined linearly with exposure to increasing levels of ozone. Rates of decline in total shoot biomass and old shoot biomass increased linearly with exposure to increasing concentrations of ozone, but tree height was not affected. Seasonal means of starch content of roots decreased linearly with increasing doses of ozone, but in contrast seasonal mean sugar content and rate of sugar accumulation of roots increased linearly, Chlorophy!! a and chlorophyll b contents were not affected by ozone.These data are consistent with the concept that ozone stress is cumulative, since effects on biomass and carbohydrate content of roots and shoots were not detected after the first year of exposure, but were detected after the second year of treatments. Furthermore, biomass was reduced by ozone only in tissues that were initiated during the first year of exposures and developed during the second year of exposures (1988 fixed grow-th). Key words; Picea rubem, forest decline, ozone, biomass, carbohydrates. Roberts & Blank, 1987;Barnes & Davison, 1988; INTRODUCTION L^^^^ ^, ^^ jgggj Ozone is the most widespread air The dieback of red spruce (Picea rubens Sarg.) at pollutant in the United States and is responsible for high elevation sites in the eastern United States, and major economic losses of crops (Heck et al., 1982, of other species across Central Europe, is thought to 1983). Since ozone concentrations at high elevations, be associated with the interaction of multiple stresses where red spruce trees are dying, are twice those at (Johnson & Siccama, 1983 Blank, 1985; low elevations where crop losses are found (Johnson Rehfuess, 1987;Johnson, Cook & Siccama, 1988, there is a clear need for research on the Air pollution, and in particular, ozone, may pre-effects of ozone on red spruce physiology. In recent dispose trees to injury from naturally occurring studies, exposure to elevated levels of ozone for one stresses such as summer drought, freezing injury and growing season had no effect on photosynthetic rates winter desiccation (Friedland e/a/., 1984; Guderian, or growth of red spruce seedlings (Taylor et al., Kuppers & Six, 1985; McLaughlin, 1985; Brow^n, 1986; Laurence. Kohut & Amundson, 1989;Alscher et al., 1989). Only recently, information has become • Author to whon-i correspondence should be addressed, available on seasonal changes in other parameters 128 R. G. Amundsort and othersthat are necessary to start to assess ...

Field studies on Norway spruce trees at high altitudes

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Effects of long‐term ozone exposure and drought on the photosynthetic capacity of ponderosa pine (Pinus ponderosa Laws.)

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Respective and Interactive Effects of O3 and CO2 and Drought Stress on Photosynthesis, Stomatal Conductance, Antioxidative Ability and Yield of Wheat Plants

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