Changes in the air pollution load in the Jizera Mts.: effects on the health status and mineral nutrition of the young Norway spruce stands

Abstract

The article evaluates changes in the forest health status and nutrition, caused by the historical development of the air pollution load, in the Norway spruce (Picea abies L. Karst) stands in the Jizera Mts. The Jizera Mts. are located in northern Bohemia, on the border between the Czech Republic and Poland close to western Saxony (Zittau). The 19 research plots selected on the plateau within the forest sites of the young Norway spruce stands were installed in 1991. Since 1993 the defoliation of the tree crown has been assessed every year; sampling of needles for nutrient analyses has also been undertaken annually. Soil samples were taken in 1995, 1999, 2003 and 2009. Long-term investigation confirmed that the health condition of the trees, evidenced by crown defoliation, is influenced by a combination of various stress factors. To define the relationship between the crown defoliation, nutrients and stress element contents, a linear regression model was proposed. The model for the current year needles demonstrates that the defoliation of the spruce crowns in the Jizera Mts. is a function of the nitrogen, phosphorus, potassium, magnesium sulphur and fluorine concentration. The crown defoliation of the spruce stands is increasing with the decrease in the nitrogen and magnesium concentrations and the increase in the sulphur and fluorine concentrations in the needles. The unbalanced nutrition in the Jizera Mts. is affected by the ongoing nitrogen deposition to the forest ecosystem. This is manifested as a disturbed N:P and N:Mg ratios in the needles. Acidification of the soil environment and the phosphorus and magnesium deficiency may be limiting factors to the forest’s nutrition in the future. The optimal range of N:Mg ratio (8–30) is relatively wide for the Jizera Mts. The upper optimal limit for the young spruce stands in the Jizera Mts. should be decreased to 25. The comparison of the element concentration in the needles and mineral soil confirmed the nutritional threat and the deterioration in the condition of the spruce stands in the Jizera Mts.