Rasterelektronenmikroskopische und chemische Untersuchungen grüner und chlorotischer Nadeln eines immissionsgeschädigten Kiefernbestandes

Abstract

Summary The Dueben Heath lies in an industrial agglomeration area and serves as an example of a forest region heavily polluted by flue ash and SO2. In recent years phenomena occur on pines (Pinus sylvestris L.) that differ from the classical damage caused by SO2. They manifest themselves for instance in chloroses that are observed mainly in autumn and winter on the upper side of the branches. The intensity of the chloroses depends upon the weather conditions in the corresponding year and varies considerably within stands. In the investigated pine stand the chlorotic trees are characterized by reduced potassium and water contents in the one- and two-year-old needles as well as lower weight of the one-year-old needles as compared with those being free from such symptoms. A reduction of the Mg, Ca and Zn contents does not take place. The needle surface is contaminated by pollutants containing Si, Al, and Fe and shows gypsum crystals formed on it. The lantently damaged and one-two-year-old green needles have more of these crystals than the chlorotic ones. The naturally with advancing years increasing aggregation of the epicuticular wax fibrils on the needle surface and in the epistomatal chambers is considerably accelerated especially in the case of the chlorotic needles.