Defoliation of older Norway spruce (Picea abies L Karst.) stands in the Polish Sudety and Carpathian mountains

Spruce forests of the southern, mountainous region of Poland are amongst the most endangered in Europe. The study presents the dynamics of defoliation in 80-200-year-old stands in the Sudety and the Carpathian mountains during the period 1989-1999. Defoliation was assessed in 5-year intervals, using the following scale, based on the percentage of lost foliage: 0-up to 10%, 1-from 11 to 25%, 2-from 26 to 60%, 3-from 61 to 99% and 4-100% (dead). Analysis of the relations between defoliation and: stand age, elevation, aspect, SO2 and NOx emission, temperature, precipitation and hydrothermic index, was performed. It was found that the defoliation of the investigated spruce stands is progressing dramatically, while the pollution of SO, and NOx has been declining since 1989, and while generally, the forests across Poland are showing a recovery since 1995. It seems that the accumulation of pollutants, the exhaustion of self-regulation capacity of older trees and the destabilization of sensitive spruce ecosystems are the reasons. (C) 2003 Elsevier Science B.V. All rights reserved.