Effects of forest structure and canopy openness on tree vitality and ecosystem stability under climate change
Forests provide crucial ecosystem services such as carbon storage, biodiversity conservation, climate regulation, and timber production. In Central Europe, global change-type droughts and heatwaves have caused widespread tree mortality, even among traditionally drought-tolerant species, creating an urgent need for adaptive forest management. One key management practice, thinning, may either improve drought resilience by reducing competition for resources or increase stress by exposing trees to greater heat and evaporative demand through canopy opening, with effects should vary among species and site conditions. To better understand these responses, this project combines long-term tree-ring analyses with high-resolution dendrometer measurements. Thus, linking historical growth patterns with real-time indicators of tree water status, the study investigates how stand age and management influence forest resilience and drought stress.
We aim to identify what stand-structural attributes are species-specifically best suited to maintain ecosystem stability in times of climate change for a continuous provision of multiple ecosystem services, foremost carbon sequestration and hosting biodiversity. We consider short- and long-term tree growth patterns as indicators for tree vitality, as its temporal variability is linked to species resilience to environmental changes.
H1: Reduced stem density and increased canopy openness associated with higher stand age differentially affect drought tolerance indices due to species-specific physiological sensitivities.
H2: Resistance is predominantly driven by climatic extremes, whereas resilience and recovery are primarily influenced by edaphic and structural attributes, which is also mirrored in the seasonal tree water deficit estimates.
H3: An optimal intermediate forest management intensity defined by canopy openness, stemdensity as a result of the thinning regime can be identified based on integrated short- and long-term tree growth metrics, enhancing ecosystem stability across species.
For the forest Experimental Plots (EPs) representing a gradient from unmanaged over selection to age-class forests, we will perform long-term dendrochronological analyses for deriving drought response indices from past stem growth patterns before, during, and after extreme drought events. In addition, using high-resolution automated dendrometer readings to derive trees’ water deficit, we will be able to estimate robust short-term measures of tree water status. Finally, we will relate the short- and long-term indices of tree vitality to individual tree-level structural and environmental indices via LIDAR-derived surface and terrain models.
Scientific assistants
