Multispectral and thermal UAV monitoring of peatland response to climate warming

Montane peatlands are one of the most sensible ecosystems influencing water storage, runoff volume, dynamics of runoff response, and water chemistry. Peat bogs in headwater catchments are also highly vulnerable to climate change's effects, particularly climate warming. This study examines the changes in mid-latitude montane peatland in response to the effects of climate warming. We tested a methodological approach for monitoring peatland changes in transient climate using multispectral and thermal Unpiloted Aerial Vehicles (UAV) imaging, enabling the understanding of spatial and temporal dynamics of changes in the peat bog at a high level of spatial detail. Our research aims to test the hypothesis, assuming that the decrease in precipitation and rise in air temperatures translates to drying, degradation, and reduction of the retention potential of montane peatlands. The study was conducted on the Rokytka mountain peat bog in Šumava, Czech Republic, which represents the largest complex of mountain peat bogs in Central Europe. The monitoring took place in the 2018-19 growing season, which represented the culmination of a prolonged period of heat and drought in the region, and was compared with 2021-22, representing, on the contrary, a wet season. Images were taken from an altitude of 100 meters using a UAV platform and Micasense RedEdge/Altum and FLIR sensors. The UAV monitoring was combined with continuous hydrological and hydropedological monitoring and in-situ calibration measurements. The high-resolution data showed different trajectories of changes in spectral vegetation indices and thermal response in the montane peatland. Multispectral imaging showed a progression of changes in the extent of wetland areas in response to warming and drought. High-resolution thermal mapping using UAVs then showed differential land surface temperatures in different vegetation categories and peatland zones. The study showed that the response of montane peatlands to climate change is highly diversified, even at a high level of spatial detail, among different zones of the given peat bog. For montane peatlands in remote areas and with often limited access, UAV monitoring using multispectral and thermal sensors proved to be a reliable tool for determining and modeling changing environmental conditions.