Tree Crown Condition in 2016

S. 48-64

Artikel aus einer Zeitschrift

200203806

Analyses of the chemical composition of leaves and needles over time and space allow the identification of trends and spatial patterns of the nutritional state of single trees and forest stands. At the specific monitoring site, nutrient limitations and surpluses can be detected as well as the impact of air pollutants which affect the chemical and physical condition of forest plots and therefore their nutritional state. These effects are reflected in changes of the nutrient concentrations in tree foliage and the corresponding nutrient concentration ratios. Other factors such as the productivity of foliar mass (Goswami 2015), soil acidity and tree age additionally influence nutrient concentrations depending on the species.
In 2016, the average crown defoliation in the participating countries was 22.1% for broadleaved and 20.1% for conifer species. For most species, it remained largely in the range of observations from previous years. The defoliation of Scots pine, which generally does not deviate much from the trend, was higher in 2016 than the long-term mean, and the defoliation of Norway spruce remained on the level above the longterm trend for the third consecutive year. For Norway spruce especially, a large share of damage symptoms could not be assigned to specific damage agents, complicating the interpretation of defoliation assessments. After several years of improved crown condition, the defoliation of beech increased to the highest value ever recorded. The most common identified causes of damage on beech in 2016 were mining insects and defoliators.