Evaluation of the loss of assimilation apparatus and its causes in Scots pine stands (Pinus sylvestris L.) of the Kampinos National Park

The Kampinos National Park (KNP), in terms of ecology, is an exceptionally valuable place in the Polish lowland region. Until the 20th century, as a result of limited human influence on the natural resources of the Kampinos Forest, it can be presumed that the 100-year-old tree stands were shaped by natural ecological processes. This study contains a detailed assessment of crown conditions, dendrometric measurements and visible disease symptoms in the oldest fragments of the KNP, as well as statistical evaluation of the relationships between these factors. Results were correlated with ecological factors such as precipitation and temperature. For the purpose of the study, five tree stands, each over 130 years old, were selected. In each stand, the level of defoliation was assessed, based on the forest monitoring methodology performed in Poland for the State Environmental Monitoring. Tree height, circumference, and diameter at breast height measurements were performed for all the trees, and any visible disease symptoms were described. Defoliation data were used to classify 93.6% of the trees as the second level of stand damage (the so-called ‘warning’ level) according to the monitoring methodology. Observed disease factors confirm the physiological weakening of the trees. The populations studied exhibited a range of mean height and stem volume, and these were not significantly related to the level of defoliation or visible disease symptoms. Ecological factors, especially the drought in 2015, probably did not have a negative impact on the examined stands. The analysed pine populations demonstrate physiological weakness, but this appears to be related to their age and natural ecological processes.