Assessing thermal and hydrological responses to montane peatland rewetting using UAV monitoring

Abstract

Highlights. UAV monitoring revealed complex responses to peatland rewetting.. Surface water extent more than doubled after installation of rewetting dams.. Land surface temperature increased by 2-3 °C in rewetted zones.. Thermal rise linked to corridor clearance in bog pine canopy and shallow dam design.. Comparison with decade-old dams shows persistence of changes.Abstract: This study investigates the thermal and hydrological effects of montane peatland restoration using multispectral and thermal UAV monitoring in combination with in-situ instrumental measurements. We analyzed the response of the Rokytka montane peat bog, located in the core of Central Europe's largest montane peatland complex, to large-scale rewetting interventions. Changes in surface water extent and land surface temperature (LST) distribution were assessed across vegetation seasons from 2019 to 2024, covering the installation of new systems of wooden dams that blocked former drainage channels. This enabled evaluation of both pre- and post-restoration conditions, as well as comparison with older dams built over a decade ago. Multispectral and thermal UAV data facilitated detailed analysis of changes in canopy structure, surface wetness, and thermal dynamics within the peatland core zone. The results showed that artificially waterlogged surfaces more than doubled following rewetting. However, LST in rewetted zones increased by 2-3 °C after dam installation, particularly along newly constructed dam corridors where values approached even those of open peatlands. This unexpected warming is attributed to the removal of mature bog pine canopy during corridor construction, which eliminated microclimatic stabilization, and to the shallow design of the dams (20-60 cm actual depth versus 60-130 cm planned), which limited their capacity for thermal buffering. These findings demonstrate that while drain-blocking dams can effectively restore hydrological functioning, associated vegetation clearance and suboptimal dam design can introduce thermal instability, increasing vulnerability to warming and drying cycles. Restoration planning should therefore integrate microclimatic considerations, minimize vegetation removal, and ensure adequate dam depth to enhance thermal regulation.