Multi-decadal changes in open-water areas on northern peatlands

Peatlands are important components of the boreal and high-latitude landscape,
where they are often characterised by extensive surface water. In this thesis, I use
remote sensing and Earth Observation sources to measure changes in high-latitude
peatlands, to improve our understanding of these variations and the potential
mechanisms driving them. My findings highlight the importance of the continued
monitoring of high-latitude peatlands. Through employing historical aerial imagery,
combined with a contemporary Uncrewed Aerial Vehicle survey, I show 61 years of
changes in open-water pools at a patterned raised bog in central Sweden. The
open-water pool area declined by 26.8 % during the study period. These data show a rapid loss of
open-water pool area primarily due to overgrowth of open-water pools by
Sphagnum, with ongoing climate warming postulated to accelerate Sphagnum
colonisation. Earth observation methods have started to be utilised to monitor
peatland landscapes on small scales, however thus far no large-scale monitoring
system exists. To address this, I developed and implemented processing and
classification algorithms to identify boreal land covers across latitudinal extents based
on Sentinel-1 Synthetic Aperture Radar data. My work shows these data to be highly
effective in detecting surface water cover in peatland environments, however these
data are currently under-utilised for spatiotemporal monitoring at large spatial scales.
To resolve this, I designed and executed a cloud-based classification algorithm to
identify open-water cover across the WSL, an area constrained between 55° N, 66.5°
N, 65° E and 90°N, and comprising a mosaic of Sentinel-1 scenes. My analysis
quantified total water-cover and its spatial distribution for the years 2017 through
2022. My research has highlighted the importance of monitoring high-latitude
peatland environments. Together, the findings presented could lead to consistent
spatiotemporal observations of high-latitude peatlands to help further our
understanding of these landscapes’ dynamism.