Growth and water use of red spruce (Picea rubens Sarg.) exposed to ozone and simulated acidic precipitation for four growing seasons

Abstract

Red spruce (Picea rubens Sarg.) saplings from a pristine site in Maine were transplanted in native soil to 360 liter pots and relocated to Ithaca, New York. After a 1 yr establishment period, 90 saplings were chosen for use, assigned to treatments, placed in large open-top chambers, and exposed to ozone (0.5 to 2.0 x ambient concentration) and simulated acidic precipitation (at pH 3.1, 4.1, or 5.1) for 3 or 4 consecutive growing seasons (total ozone exposures of about 165 ppm·hr to almost 570 ppm·hr). Forty-five trees were grown on weighing lysimeters and were used to develop whole-tree water-use budgets. After 3 yr of exposure, the 45 trees not grown on lysimeters were harvested, and the plant tissues were weighed. After the fourth growing season, the remaining 45 trees were harvested, and the weight of the plant tissues was determined. Significant effects of ozone or simulated acidic precipitation were not detected, with the exception of a trend for increased needle dry weight with increasing ozone and, in 1990 needles only, with decreasing pH. No effects were detected in total dry weight, aboveground dry weight, coarse or fine root weight, stem dry weight, or relative growth rate. No significant interactions of ozone and pH treatment were detected. Neither ozone nor pH treatment affected the rate of water use by red spruce saplings, even when they were subjected to a dry-down period resulting in drought stress.