Austria is experiencing a rapid warming of its climate, with a notable increase in drought intensity over the past decades. This heightened occurrence of droughts has placed additional stress on vegetation, leading to a surge in bark beetle infestations among spruce trees and diminished yields from both grass- and croplands. It is evident that we need to improve our understanding of how vegetation will respond to a warming climate, climate extremes, and abrupt changes. However, the dynamics of vegetation exhibit significant variations in both space and time, presenting a challenge in extending high-quality, on-site observations to different regions. Therefore, the monitoring of vegetation demands the availability of high-resolution, accurate, and reliable datasets that cover Austria comprehensively, providing easy access for users.
Presently, data suitable for analyzing vegetation productivity and phenology is solely accessible through Sentinel-2 optical imagery. Although this contains a wealth of information on leaf area and greenness, its sensitivity to is primarily confined to the topmost vegetation layers. In tracking vegetation response to drought, insights into plant hydraulics and structure need to be available, considering the diverse coping mechanisms of plants, such as stomata closure or leaf shedding. Microwave remote sensing provides information on both structure and water content of the vegetation, where lower frequencies provide information from deeper within the vegetation layer. Therefore, to monitor forests and biomass, the upcoming Copernicus missions ROSE-L and BIOMASS will monitor in P- and L-band.
The goal of this project is to bring together multi-frequency Earth observation (EO) datasets and laser scanning, with high quality in situ data sets from the Long-term Ecosystem Research (LTER) network to obtain a multi-scale dataset to improve vegetation monitoring capabilities in Austria. Vegetation indicators will be retrieved from SAOCOM L-band, preparing for ROSE-L and BIOMASS, and from Sentinel-1 C-band. All datasets, including in situ and laser scanning data, will be added to the AustrianDataCube to enable easy access for users. The EO products will be evaluated in the time domain using the LTER observations from sites in Austria, covering forest sites, cropland, alpine and managed grasslands and wetlands. Spatially, evaluation of variability will be done using laser scanning datasets of vegetation. Vegetation drought response across scales will be investigated, demonstrating the potential of the data.
The innovation is the combination of observation techniques at different scales to obtain a holistic understanding of vegetation response to drought. Multi-frequency SAR data has so far not been tested in detail for its benefits for monitoring vegetation and its response to drought. The project is novel in the consistent and rigorous evaluation with high quality in situ data from LTER. It will also prepare Austria and the partners for the upcoming Copernicus missions and will provide Austrian stakeholders with a high quality and reliable vegetation monitoring tools. The project will benefit the research and development capacities of the partners, TU Wien, Umweltbundesamt, Earth Observation Data Centre and University of Modena and Reggio Emilia, on the use of radar C- and L-band data in combination with laser scanning, ecosystem research on vegetation and drought response and further developing the AustrianDataCube.
