The influence of acid mist upon transpiration, shoot water potential and pressure—volume curves of red spruce seedlings

Abstract

Widespread forest decline has been documented in Europe and NE-U.S.A. (Johnson,1987; Woodman, 1987). This decline increases with increasing altitude (Mc-Laughlin, 1985). One hypothesis to explain the decline and its altitude dependence is that excessive proton input has a deleterious effect upon tree growth. Acid input to the foliage and soil via wet and dry deposition may be a major factor in causing decline directly or indirectly by predisposing the tree to additional biotic and/or abiotic stress factors. The maintenance of a favorable water status is a priority for continued growth and survival, and many of the symptoms associated with forest decline (crown thinning, root necroses) may be expected to influence plant water status. This paper presents some of the results of a detailed study of the influence of acid mist on the water relations of red spruce seedlings.