Biochemische und strukturelle Streß-Symptome von Fichten

Biochemical amd Structural Stress-Symptoms of Spruce Trees

1998

Unselbständiges Werk

12985

200065917

Biochemical and structural stress-symptoms of spruce trees (Picea abies (L.) Karst.) were investigated in a forest decline area in Austria (Glein) where severe needle chlorosis is the main symptom. Ascorbic acid and thiol contents, which are components of the cellular antioxidative system known to respond to oxidative stress impacts, were measured together with chloroplast pigments, which reflect the status of the photosynthetic apparatus. Oxidative stress may be induced by altitudinal stress, consisting of a combination of harsh climate, low temperatures and high ozone impacts. In the present study, the altitudinal dependence of antioxidants were insignificant (over a range from 1 000 to 1 500 m above sea level), indicating that oxidative stress is not the main reason for the decline symptoms in this area. The ultrastructure of chloroplasts in some cases exhibited severe alterations, but could not be assigned to an environmental gradient. The ultrastructure of epicuticular waxes demonstrated a good constitution of the wax tubes proving that severe impacts of acid or alkaline pollutants have been absent in recent years. On the other hand, significant correlation's were detected between pigment concentrations (as an indicator for needle chlorosis) and potassium contents pointing to an important contribution of the nutrional conditions to the present situation of the forest system.