Within the temperate broad-leaved forests, European beech (Fagus sylvatica L.) is one of the most important native tree species in Europe where it forms widespread forests. The annual precipitation is expected to remain constant, but their seasonality patterns are predicted to change. Moreover, heat and drought events are expected to increase their frequency and intensity due to climate change. European beech is a species sensitive to water deficit and its capacity to adapt may be critical in determining its survival under climate change. Our aim is to monitor European beech saplings and other broad-leaved saplings during and after the extreme drought event from 2018 in order to assess their vitality and survival rate.
Material and Methods
Based on random sampling, we made 235 plots, 10 x 10 m (in 2018) in the three types of forest in central-eastern Germany. Diameter at breast height (DBH) and vitality were measured for 10 random saplings from each plot. The basal area and the tree cover were measured for each plot. To assess sapling vitality after the drought event we did a second round of monitoring of existing plots in 2019. The field measurements were analyzed and correlated with temperature and precipitation datasets, as well as with the NDVI data.
The results show that half of the European beech seedlings affected by drought in 2018 recovered in 2019. The same patterns were observed for Betula pendula, Carpinus betulus, Quercus sp. and Sorbus aucuparia. The most affected species by the drought event were Carpinus betulus and Sorbus aucuparia, however, they also recorded the best vitality recovery in 2019. In addition, the number of mature trees and the canopy cover correlated negatively with the number of saplings and their canopy cover.
A better understanding of sapling and adult trees response to heat and drought events are essential for implementing adaptive forest management strategies to mitigate the impact of climate change on plant growth.