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, glutathione, and tocopherol together with chlorophyll fluorescence were measured in needles of Pinus canariensis trees growing at four field stands at 4 different altitudes at the south-eastern 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 chlorophyll, higher carotenoid/chlorophyll-ratios, and lower α/β-carotene ratios. This pattern suits in a picture of elevated oxidative stress these trees are responding to. Decreases in Fv/Fm-ratios of chlorophyll fluorescence below 0.80 reflecting damages in the photosynthetic apparatus were only found at one site at 1500 m, where altitude stress was probably amplified by drought stress.