Ongoing Fen–Bog Transition in a Boreal Aapa Mire Inferred from Repeated Field Sampling, Aerial Images, and Landsat Data

Abstract Northern aapa mire complexes are characterized by patterned fens with flarks (wet fen surfaces) and bog zone margins Sphagnum moss cover. Evidence exists of a recent increase in over that can alter ecosystem functions. Contrast between cover may enable remote sensing these changes satellite proxies. We explored hydro-morphological patterns vegetation south-boreal Finland tested the performance Landsat bands indices detecting mires. combined aerial image analysis survey, repeated after 60 years, to support analysis. Aerial revealed decrease flark area 46% 1947 2019. Repeated survey showed mosses ( S. pulchrum, papillosum ) deep-rooted vascular plants Menyanthes trifoliata, Carex rostrata ). A supervised classification high-resolution UAV recognized legacy infilled patterning carpets. Among variables, all separate spectral bands, Green Difference Vegetation Index (GDVI), Automated Water Extraction (AWEI) correlated area. Between 1985 2020, near-infrared (NIR) GDVI increased central area, AWEI decreased throughout In complexes, zones have contrasting NIR reflectance, band is suggested for monitoring flarks. The observed supports interpretation ongoing fen–bog transitions European mires, indicating significant ecosystem-scale changes.