BIOLOGICAL AND CHEMICAL WOOD PROPERTIES OF LONG-TERM POLLUTED SPRUCE (PICEA-ABIES [L] KARST) AT HIGH-ALTITUDE STANDS OF THE ERZGEBIRGE

In the present study, biological and chemical wood properties of long- term polluted spruce trees in extremely wind-stressed high-altitude fo rest stands of the Erzgebirge, Germany, were investigated. As to the b iological experiments the dynamics of wood formation was identified by pin-marker dating of cambial cell division, cell enlargement, and cel l wall production. The reduction of annual growth of heavily polluted trees compared to undamaged/slightly damaged trees was due to a reduce d period of cambial cell divisions and a reduced rate of periclinal ce ll divisions per time unit. In all trees, an increase of ray cells in the outer xylem occurred, and traumatic resin canals could be found. A dditionally the osmotic potential in the cambial zone indicated a rela tionship between the turgor pressure as a driving force for cell enlar gement and the decrease of radial cell diameters in narrow tree rings. Consequently, compared to undamaged/slightly damaged trees, a decreas e of the maximum cell wall area could be observed in heavily damaged t rees. But long-term pollution did not have any impact on wood density. In total, the xylem production of heavily damaged trees was less than 20%, compared to undamaged/slightly damaged trees. The chemical wood properties were studied in terms of the composition of carbohydrate, l ignin, and accessory compounds. In addition, the distribution of ligni n and accessory compounds within the xylem was monitored on a subcellu lar level by UV-spectroscopy It can be derived that high fumigation le vels did not have any qualitative impact on cell wall synthesis. Furth ermore, the element content of the phloem, the cambial zone, and the x ylem was determined by bulk-analysis (ICP-OES) and also on a subcellul ar level by energy dispersive x-ray analysis (EDX). On the one hand, t he element analyses indicated a reduced K- and P-supply of the cambial zone of heavily damaged trees versus undamaged ones. On the other han d the subcellular analysis did not show any alterations of the C:O rat io in the cell wall of long-term polluted trees. In conclusion it can be stated that even high and long-term pollution had only little influ ence on the structure of xylem cells, and that it revealed no impact o n the chemical composition of the cell walls.