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For more than two centuries, Russian larch (Larix sibirica; Larix sukaczewii; Larix archangelica) was considered an alien species within Fennoscandia forestry. Findings of ancient alpine macrofossils led the Swedish Forest Agency to a policy shift where the Russian larch became recognized as part of the native flora. Despite the ongoing use of larch within Fennoscandian forestry, we lack a thorough discussion about its historic extirpation from this region and the possibility that it may happen again. In this perspective, we highlight that paleoecological studies indicate that Russian larch existed not only in alpine regions of Fennoscandia as previously suggested, but also in boreal areas of Sweden, Finland and Latvia. We identified a longitudinal trend where larch populations disappeared from western alpine habitats in Early Holocene but lingered until the last millennia in easter part of Finland. Our empirical analyses of forest experiments suggest that Russian larch has a growth advantage against Scots pine (Pinus sylverstris) and Norway spruce (Picea abies) across contemporary cold Fennoscandian climates, making it unlikely that Russian larch was extirpated simply due to negative growth effects from a colder climate occurring after the Early/Mid Holocene thermal optimum. We highlight that the driver(s) behind the enigmatic extirpation of Russian larch remain unresolved but should warrant attention given the current interest for Russian larch within Fennoscandian forestry.

This study examines how human activities influenced soil development at two contrasting Arctic sites: Maiva, a 19th-century farmstead, and Snuvrejohka, a seasonal Sámi reindeer herding settlement in the Lake Torneträsk region, northern Sweden. Using geochemical and geophysical soil analyses, we explore the spatial distribution and vertical development of anthropogenic signals in the soil. At Maiva, prolonged agricultural use and earthworm bioturbation have led to extensive soil mixing and altered soil horizons, resulting in elevated phosphate, lead, and organic matter concentrations in Ap and Ah horizons. In contrast, Snuvrejohka displays more stratified profiles with localized chemical enrichment around hearths, primarily within E horizons. These results highlight how different land-use practices leave distinct geochemical fingerprints in Arctic soils and emphasize the need for sampling strategies adapted to site-specific soil formation processes. Our findings demonstrate that even short-term or seasonal human activities can leave distinct and detectable signatures in Arctic soils. Through an integrated approach combining soil science, geoarchaeological methods, and historical data, this study provides new insights into the reconstruction of past land-use practices and highlights the vulnerability of archaeological soil records in Arctic environments facing rapid climate-driven change.

In this thesis, soils and sediments have been used as sources of information on past human activity in Arctic environments. The study has combined geoarchaeological methods and techniques with information from historical documents, ethnographic accounts, and archaeological remains to create integrated narratives of human-landscape interactions in the past. The thesis consists of two parts: an introductory text and four research papers.

In the first paper, social and cultural aspects of the spatial organisation of Sámi hearth-row sites are presented and discussed through an analysis of the soil from two sites in northern Norway (Steintjørna and Brodtkorbneset) and one from northern Sweden (Hobergsträsk). Based on spatial patterns in the excavated and analysed materials, a socio-spatial ethnographic model of the Sámi goahti (tent/hut) was challenged and new insights into spatial organisation were generated.

The second paper revisits Steintjørna in Norway and presented a geoarchaeological methodology for identifying spaces used for corralling or controlling reindeer.The third paper deals with the human impact on soils from two contemporary sites representing short term, low intensity use, but under different socio-economic conditions. Snuvrejohka was a Sámi viste (camp site) in a high-altitude location connected to 19th and 20th century reindeer herding, whilst Maiva, was initially a farmstead that was turned into a tourist station, that later became a holiday cottage and lastly a research outpost. The interaction of humans with soils and sediments was explored using stratigraphic and spatial soil sampling strategies and analysis to provide interpretable data on land use.

The fourth paper approaches human impact from a different perspective, namely the introduction of invasive soil fauna in Arctic environments. An integrated cultural and natural historical approach, including soil sampling and analysis, was used to study archaeological and historical information at Maiva. The results suggest that earthworm driven bioturbation is a remnant of 19th and 20th century agricultural settlements, showing that ecological imperialism is present in Arctic Fennoscandia.

These studies have collectively and conclusively shown that human impact on soils is detectable, measurable, and essential for interpreting and understanding past events in human-environment relationships.