Kondycja jesionu wyniosłego (Fraxinus excelsior L.) w zależności od warunków wilgotnościowych wybranych siedlisk leśnych

The study aimed to determine the influence of site moisture conditions on the health status of European ash. The research plots were located in the Babki, Konstantynowo and Łopuchówko forest districts, as well as in the Poznań Municipal Forests (western Poland). The research was carried out on 30 research plots established in the part of the stands with at least 80% share of ash in the stand species composition. Ash aged from 48 to 144 years. The scope of the research included: (1) selection of the research plots and determination of the forest site type, (2) assessment of site moisture conditions – the type and degree of moisture and the depth of the groundwater level, (3) selection of 15 trees belonging to the 1st and 2nd Kraft’s class and assessment of their health status using the synthetic damage indicator, which is based on the crown defoliation and vitality of upper part of the crown. Results revealed that the best health status of ash stands was noted in mesic broadleaved forest. In contrast, within the stands in moist broadleaved forest, alder−ash forest and riparian forest we observed the highest share of damaged and dying trees. The more detailed analysis of moisture conditions showed that the lowest damage of ash was noted within the stands with the groundwater level at depth below 1.8 m and up to 0.5 m. Moreover, a high share of healthy and weakened trees occurred also within the stands with water flowing down the slope and in the compact soils, where water does not undergo significant level fluctuations. The most damaged stands occurred mostly in dehydrated soils, as well as in the soils where the depth of the groundwater was between 0.5 and 1.8 m.