The effect of pollutant fog deposition on the wood anatomy of subalpine Norway spruce

In recent decades, significant changes have been observed in the atmospheric pollutant emissions and deposition in the mountain regions of Central Europe. Pollution caused significant deforestation, but the level of tree damage differs, even between neighboring locations. Thus, it is particularly important to examine the relationships between pollutant deposition rate and detrimental changes in the subalpine spruce ecosystems, and to correlate these with the intensity and structure of pollutant deposition. Radial wood cores were extracted at breast height from trees located in different montane areas: the Sudetes and both Western and Eastern Carpathians. Specific features of the secondary xylem, i.e., annual ring width as well as the width and lumen of early- and latewood tracheids, were analyzed for three decades: before the intense of environmental pollution (1950–1960), during essential stage of the ecological disaster (1980–1990) and after cessation of pollution (2000–2010). The narrowest annual rings and earlywood tracheids were formed in the 1980s in areas where fog was the main source of the pollutant deposition. In conclusion, it has been shown that fog could be an important factor increasing the destructive role of pollutants on wood formation. It was manifested in decreasing of cambial activity resulting in formation of narrower annual rings as well as in reduction in radial dimensions of earlywood tracheids.