The use of remote sensing for studying environmental changes in a palsa mire zone of Northern Finland in the period 1985–2024

Abstract. The palsa mires – hummocks with a permafrost core – of northern Finland are among the southernmost periglacial features in the Northern Hemisphere and mark the southern boundary of permafrost range. The rapid warming of circumpolar regions demands a better understand of the complex of environmental changes in the marginal permafrost zone. The study aims to investigate changes in selected environmental features (vegetation, water conditions and land moisture) in northern Finland in the years 1985–2024 using Landsat satellite data, with particular emphasis on the differences taking place in palsa mires. The calculated spectral indices NDVI, NDWI, MNDWI, NDMI and LST were analysed in relation to each other and to environmental data. The analysis of changes in spectral indices over time showed a small but systematic increase in the vegetation index value, an increase in soil moisture, and varied responses in indices related to surface water. Principal component analysis (PCA), linear mixed-effects models (LMM) and redundancy analysis (RDA) indicated the multidimensional structure of remote sensing indices and revealed the main environmental factors determining changes in vegetation and moisture in the study area. One of the main predictors differentiating the spectral response was determined to be palsa mires, which differed from mineral soils, but also from other organic soils. The results confirmed the effectiveness of RS and multispectral indices based on Landsat data for studying environmental changes, while indicating the need for multidimensional analyses that include various indicators and local environmental predictors.