Growth variation and environmental stresses: Long-term observations on permanent research plots in Southwestern Germany

Abstract

The annual volume increment of Norway spruce and silver fir stands in the Black Forest varies greatly and is correlated with precipitation during the growing season and to some extent with temperature. Mortality is also correlated with climatic variation. Thus, low precipitation during the growing season is considered to be a main stress factor even at higher elevations in the Black Forest mountains where the average precipitation level is high. By silvicultural treatment, climatic stresses may be reduced to some extent. Increment on fertilized Norway spruce plots reacted moe sensitively to drought when fertilizer effect on increment was high. The high productivity in recent decades may have been caused partly by atmospheric deposition. A higher susceptibility to environmental stresses may be a consequence.