The influence of acid precipitation and ozone on nitrogen nutrition of young loblolly pine

Field grown loblolly pine (Pinus taeda L.) seedlings from two half-sibling families were exposed to three levels of acid precipitation and four levels of O₃ in open top chambers at Auburn, AL. At the end of one growing season, dry weight and total N accumulation of seedlings was directly related. to rainfall acidity, possibly indicating a fertilizer response in the N deficient soil. Increasing O₃ levels elicited an increase in N content of permanent tissues that was not related to a dry weight response. The origin of this N was believed to be increased internal translocation associated with enhanced premature needle senescence observed at higher O₃ levels.