Multi-scale and multi-compartment monitoring of tree vitality – integrating soil, stem, crown, and remote sensing observations

Abstract. Forest ecosystems in Central Europe are increasingly affected by climate change, with rising temperatures and more frequent drought events posing substantial challenges to dominant tree species such as beech and oak. Understanding how site-specific factors interact with climatic stressors is therefore essential for assessing forest resilience and future viability. In particular, soil properties such as texture (sand, silt, clay) influence water retention capacity and root penetration, thereby directly affecting tree growth and vitality. To quantify tree water balance and physiological condition, trunk circumference and sap flow are continuously monitored at multiple sites. These in situ measurements are complemented by remote sensing data derived from drone-based and satellite imagery, as well as by meteorological observations. This integrative monitoring framework enables a comprehensive assessment of drought stress susceptibility in relation to site conditions. This article introduces the research design and first findings of the DryTrees project, funded by the Baden-Württemberg Foundation, including the applied in-situ and remote sensing methodologies and initial results from the first two project years. The generated dataset has the potential to reveal unprecedented insights into biophysical and climatological interactions in typical German forest ecosystems and to support the development of site-specific, climate-resilient, and cost-efficient forest management strategies.