Mapping Vegetation Dynamics Under Drought Stress : Integrating Satellite, Meteorological, and Terrestrial Geospatial Data

In an era of climate change, as the intensity and frequency of droughts are expected to increase, effectiveclimate adaptation strategies become increasingly important for both natural ecosystems and society.Understanding vegetation's responses to drought and monitoring the impacts of drought on terrestrialecosystems are essential for developing reliable decision-support systems. This thesis aimed to develop,test, and apply methodologies for detecting and quantifying the spatially explicit effects of drought onSwedish agricultural and forest ecosystems and their productivity. The thesis includes four researchpapers. Paper I focused on developing a change-detection framework that quantifies immediate anddelayed drought-related vegetation changes in forest ecosystems and their recovery times. Resultsshowed that using Sentinel-2 satellite data, successive stages of vegetation drought stress could bedetected, and recovery times could be estimated. Paper II focused on identifying the drivers and mappingforest areas at high risk of disturbances from the European spruce bark beetle (Ips Typographus L.) dueto drought-related effects. The forest stands predisposed to bark beetle attacks were accuratelyidentified, and the methodology provided quantifiable information on the importance and dynamics ofenvironmental features contributing to the predisposition risk. Paper III developed a causal inferenceframework to quantify the impacts of drought on crop yields while accounting for confounding variables.The methodology considered the effects of crop rotation and variations in local soil attributes, predictingregional and field level yields and identifying factors driving local variations in yield losses. Paper IVestimated the foliar and radial growth responses of Norway spruce (Picea abies (L.)) and Scots pine(Pinus sylvestris (L.)) trees to drought at a multidecadal level. Results indicate that the drivers of variancein annual radial growth were identified, with pine stands exhibiting higher drought resilience and fasterrecovery rates than spruce. Overall, this thesis demonstrates that effectively using multi-sourcegeospatial data can identify and map the risks and effects of drought on forests and agriculturalecosystems over time and space, thereby enhancing our understanding of vegetation drought responsesand resilience patterns. The methodologies presented in this thesis provide essential information forpolicy planning and decision-making supported by scientific knowledge, contributing to a shift towardsmore sustainable management practices in a changing climate.