ELEMENT CONTENTS AND STRESS-PHYSIOLOGICAL CHARACTERIZATION OF PINUS-CANARIENSIS NEEDLES IN MEDITERRANEAN-TYPE FIELD STANDS IN TENERIFE

Contents of Ca, Mg, K, Na, S, Cl, P, N, pigments, ascorbic acid, gluta thione, and tocopherol together with chlorophyll fluorescence were mea sured in needles of Pinus canariensis trees growing at four field Stan ds at 4 different altitudes at the southeastern slope of the Teide in Tenerife. S contents reflected impacts of SO2 at lower altitudes. Via Na and Cl contents the influence from the sea was assessed up to 1000 m. Above 1000 m we found higher levels of ascorbic acid, less chloroph yll, higher carotenoid/chlorophyll-ratios, and lower alpha/beta-carote ne ratios. This pattern suits in a picture of elevated oxidative stres s these trees are responding to. Decreases in Fv/Fm-ratios of chloroph yll fluorescence below 0.80 reflecting damages in the photosynthetic a pparatus were only found at one site at 1500 m, where altitude stress was probably amplified by drought stress. (C) 1998 Elsevier Science Lt d.