Two‐year‐old red spruce seedlings were exposed to various levels ot ozone, from 0.4 to 3 times ambient levels, in open‐top chambers in Ithaca, NY, USA. Exposures, which varied with changes in day length, commenced on May 30, 1987 and continued until December 14, 1987. Seedling biomass, carbohydrate contents, pigment contents, and rate of electron transport were assessed twice monthly during the fumigation period. Orthogonal quadratic or cubic polynomials were used to model the response through time each variable measured. A one‐way analysis of variance model was fitted to every regression coefficient in each polynomial model to test for ozone effects on seasonal physiological patterns. Ozone did not influence growth, foliar pigment content, foliar starch content, root carbohydrate content, or rate of electron transport. The seasonal change of needle raffinose content differed between exposed to low (0.4 ×, 1×) and high (2×, 3×) ozone levels. There was also a trend towards reduced total soluble sugar content foliage during late autumn in higher ozone treatments.

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 ...

Abstract. Acid-soluble nucleotides of unifoliate leaves of Pinto bean plants (Phaseolus vulgaris L.) were determined at young, mature, and senescent stages of development. At least 25 components could be distinguished on the basis of inorganic phosphorus determinations and 37 or more fractions on the basis of 82p labeling, with adenosine di-and triphosphates accounting for 60 % of the total moles of nucleotide. The total nucleotide P and inorganic P, on a fresh weight basis, decreased about 44 % between each stage of leaf development, but decrements in the levels of individual nucleotides varied from this over-all pattern.Minor changes in the relative abundance of the individual nucleotides accompanied aging although the percentage of purine-containing nucleotides decreased with age. Total 82p activity per leaf in the nucleotide pool increased about 3-fold between the young and mature leaves and decreased slightly as leaves became senescent. In general, the specific activities of the nucleotides increased with increased age and adenosine-, guanosine-, uridine-, and cytidine triphosphates and adenosine diphosphate accounted for approximately 90 % of the total activity. The changes in the relative sizes and energy status of the nucleotide pools were not so obvious as the changes in other metabolites that have been reported to accompany aging in leaf tissue.

Rain and snow were collected in plastic beakers either manually or with a Wong sampler during 58 precipitation events in 1974 at Yonkers, New York approximately 24 km north of the center of New York City. Determinations were made of total dissolved ionic species, free H ions, total H ions, sulfate, nitrate, chloride, and fluoride. Conductivity measurements ranged from 6.8 to 162 gmhos, pH from 3.4 to 4.9, total acidity from 36 to 557 p.eq 1-1 sulfate from less than 1 to 20 mg 1 -I, nitrate from less than 1 to 14 mg 1-1, and chloride from less than 1 to 7 mg 1-1. All fluoride concentrations were less than 0.1 mg 1-1.The results indicate that precipitation at this suburban location adjacent to New York City is consistently acidic and contains concentrations of sulfate, nitrate, and chloride which are similar to values found for other locations in the northeastern United States. Positive correlations were found between nitrate and sulfate concentrations and acidity suggesting that the atmospheric contaminants, SO2, and NO 2 are causally-related to the occurrence of acidic precipitation. Further research will be necessary to clarify the relative influence of natural and man-made sources of N and S compounds and the contributions of gaseous and particulate contaminants in the atmosphere to the acidity of precipitation at this location.

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