Productivity increase in Northern Austria Norway spruce forests due to changes in nitrogen cycling and climate

Weinheim

2007

S. 157-165

4 Abb., 4 Tab., 44 Lit. Ang.

200144893

We investigated the long-term temporal trend in growth rate, soil chemical status, and nutrient content of needles of two Norway spruce (Picea abies) stands in the Bohemian Massif, Austria. The aim was to quantify changes in the site productivity over the last four decades as a consequence of the enriching effect of N deposition, rising CO2 levels in the atmosphere, and changes in forest-management practices. We used the data records of control plots from forest-amelioration experiments that have been monitored for more than four decades. Both stands showed increased growth rates and a large deviation from the growth pattern of earlier applicable yield tables. The nutrient levels in the foliage remained unchanged and neither suggested luxury consumption nor nutrient imbalances. Results from soil chemistry analysis were inconclusive in respect of changes in soil conditions: an enrichment of the mineral soil with N and a decrease in the C : N ratio. Changes were confined to the uppermost part of the soil profile. Our data support the hypothesis that the sites are in a steady process of aggradation and that site productivity is rising.