Southeastern Finland Research Articles

Early asbestos ware in North-Western Russia

Early Asbestos Ware was spreading in the second half of the 5th – early 4th mil. BC in southeastern Finland. Complexes with similar pottery are also known in Russia: on the Karelian Isthmus, in Karelia, and on the Kola Peninsula. In this study, 23 sites were identified that contain the Early Asbestos Ware (at least 49 vessels). The considered materials generally correspond to the typological division of Kaunissaari and Ka I:2asb Ware, but they have originality in decoration. There are traits in ornamentation similar with the Sperrings 2 Ware, common in Finland, but not with the Karelian version of Sperrings as well as with Pit-Comb Ware. XRD analysis showed the presence of anthophyllite in six fragments of Early Asbestos Ware analyzed during the study, so it could be interpreted as the evidence of an impulse from the Lake Saimaa area.

Exploring forest changes in an Ips typographus L. outbreak area: insights from multi-temporal multispectral UAS remote sensing

AbstractUncrewed Aerial Systems (UAS) offer a versatile solution for monitoring forest ecosystems. This study aimed to develop and assess an individual tree-based methodology using multi-temporal, multispectral UAS images to track changes caused by the European spruce bark beetle (Ips typographus L.). The approach encompassed four key steps: (1) individual tree detection using structure-from-motion point clouds, (2) tree species classification, (3) health classification of spruce trees as healthy, declined, or dead, and (4) change detection, identifying fallen/removed trees and alterations in tree health status. The developed methodology was employed to quantify changes in a bark beetle outbreak area covering 215 hectares in southeastern Finland during 2019–2021. The dataset included two managed and two conserved forest areas. The uncertainty estimation demonstrated the overall accuracies ranging from 0.58 to 0.91 for individual tree detection, 0.84 for species classification, and 0.83–0.96 for health classification, and a F1-score of 0.91 for the fallen or removed tree detection. Maps and statistics were produced, containing information on the health of the spruce trees in the area and information on changes, including trees that died during monitoring and those that fell or were removed from the forest. The results demonstrated successful control of the outbreak in the managed stands, evidenced by moderate tree mortality. Conversely, in the conserved stands, the outbreak resulted in dramatic tree mortality. This method serves stakeholders by enabling large-scale outbreak impact monitoring, facilitating timely risk assessment, and validating bark beetle outbreak management strategies.

Politics of memory and place-making in local opera

This case study on the Kymi River Opera in south-eastern Finland, at the former border between Sweden and Russia, explores the potential of local operas to re-create a sense of place identity in a contemporary society in which people often seek to reconstruct identity through place memory. By engaging with Christopher Small’s (1998) idea of “musicking” and drawing from studies on place identity and place memory, the study focuses on how a local opera can strive towards new identity constructions through revitalising the forgotten local, historical past. Based on a purposive sample, the primary data set consists of semi-structured interviews and direct observation of the participants of the Kymi River Opera. Three thematic areas on the meanings of the opera, as conveyed by the participants, were identified in the abductive qualitative analysis: 1) Construction of a new place memory; 2) Equal possibility for participation; and 3) Integration of cultural politics and educational goals. The findings show the political nature of local opera in describing how the Kymi River Opera has become an arena for the politics of memory and place-making after a municipal merger in the 1990s resulted in a sense of loss of local identity.

Red pyterlite from Virolahti in southeastern Finland: a unique heritage stone with a classic rapakivi texture applied in historic and modern architecture

Red pyterlite from Virolahti in southeastern Finland: a unique heritage stone with a classic rapakivi texture applied in historic and modern architecture

Branch information extraction from Norway spruce using handheld laser scanning point clouds in Nordic forests

We showed that a mobile handheld laser scanner (HHLS) provides useful features concerning the wood quality-influencing external structures of trees. When linked with wood properties measured at a sawmill utilizing state-of-the-art X-ray scanners, these data enable the training of various wood quality models for use in targeting and planning future wood procurement. A total of 457 Norway spruce sample trees (Picea abies (L.) H. Karst.) from 13 spruce-dominated stands in southeastern Finland were used in the study. All test sites were recorded with a ZEB Horizon HHLS, and the sample trees were tracked to a sawmill and subjected to X-rays. Two branch extraction techniques were applied to the HHLS point clouds: 1) a method developed in this study that was based on the density-based spatial clustering of applications with noise (DBSCAN) and 2) segmentation-based quantitative structure model (treeQSM). On average, the treeQSM method detected 46% more branches per tree than the DBSCAN did. However, compared with the X-rayed references, some of the branches detected by the treeQSM may either be false positives or so small in size that the X-rays are unable to detect them as knots, as the method overestimated the whorl count by 19% when compared with the X-rays. On the other hand, the DBSCAN method only detected larger branches and showed a −11% bias in whorl count. Overall, the DBSCAN underestimated knot volumes within trees by 6%, while the treeQSM overestimated them by 25%. When we input the HHLS features into a Random Forest model, the knottiness variables measured at the sawmill were predicted with R2s of 0.47–0.64. The results were comparable with previous results derived with the static terrestrial laser scanners. The obtained stem branching data are relevant for predicting wood quality attributes but do not provide data that are directly comparable with the X-ray features. Future work should combine terrestrial point clouds with dense above-canopy point clouds to overcome the limitations related to vertical coverage.

Off-grid solar PV–wind power–battery–water electrolyzer plant: Simultaneous optimization of component capacities and system control

Green hydrogen production systems will play an important role in the energy transition from fossil-based fuels to zero-carbon technologies. This paper investigates a concept of an off-grid alkaline water electrolyzer plant integrated with solar photovoltaic (PV), wind power, and a battery energy storage system (BESS). The operation of the plant is simulated over 30years with 5min time resolution based on measured power generation data collected from a solar photovoltaic installation and a wind farm located in southeastern Finland. Levelized cost of hydrogen (LCOH) is calculated based on the capital expenditures (CAPEX), the operating expenses (OPEX), and the respective learning curves for each of the components. Component degradation and replacements during the operational lifetime are included in the model, and the capacity of the components and the system control are simultaneously optimized to obtain the minimum LCOH. A sensitivity analysis performed over different installation years and discount rates reveals that for the off-grid alkaline system, the implementation of a wind farm as the sole power supply is the most economical solution until the installation years 2035–2040. Solar PV and a BESS are found to increase the full-load hours of the electrolyzer and reduce the electricity curtailed in the off-grid plant to less than 8%. However, with the current component prices and the climate in the studied region, they are not economically beneficial. It is found that the cost of hydrogen can be reduced to 2 €/kg by the year 2030.

Impacts of climate‐driven changes in habitat phenology on dynamics of niche overlaps and spatial associations in a boreal waterbird community

A fundamental, yet little‐explored, question is if climate change has affected niche relationships and spatial associations of native non‐invasive species in established local communities, potentially affecting interspecific interactions and community organization. Here, long‐term (1991‒2020) changes in habitat niche overlaps (HNOs; measured in terms of three habitat categories describing the amount and development of shore vegetation and shore depth) and spatial associations (SAs; measured as co‐occurrence on lakes) were studied in relation to climate‐driven changes in habitat phenology in a community of eight migratory waterbird species breeding on 37 lakes in southeastern Finland. Overall timing of ice‐out date (IOD) and within‐season variation in the timing of ice‐out (standard deviation of IOD, SDIOD) in lakes determine habitat (lake) availability for waterbirds during the settling phase. Previous work has documented that IOD has advanced and SDIOD increased during 1991‒2020, with species responding differently to these changes in their habitat use. HNO and SA varied considerably in the 28 species pairs of eight species during the study period. The effect of IOD and SDIOD on that variation was generally small, effect sizes differing from zero only in eight out of 112 cases. However, the direction and magnitude of the effects of IOD and SDIOD on HNO and SA varied considerably among the species pairs. Although not statistically significant, overall differences in the direction and magnitude of the effect sizes suggested that the impacts of IOD and SDIOD on HNO and SA were stronger in species pairs in which the species were more similar in terms of settling phenology, and stronger for early settling species than for late settling species. Observed changes in niche relationships probably reflect changes in interspecific interactions and affect the possibilities for heterospecific information use in habitat selection.

Exploring the Role of Weather and Forest Management on Nutrient Export in Boreal Forested Catchments Using Spatially Distributed Model

Weather-driven hydrological variability and forest management influence the nutrient export from terrestrial to aquatic systems. We quantified the effect and range of variation in total nitrogen and phosphorus export in Vehka-Kuonanjärvi catchment located in southeastern Finland. A distributed model NutSpaFHy was used with varying weather scenarios (compiled from observed extreme years of dry, wet and wet & mild) and forest management scenarios (including no additional management and intensive clear-cutting of all mature stands in the existing forest structure). Nutrient exports by scenario combinations were compared to modeled baseline export in observed weather. The results showed that the increase in nutrient export by wet & mild weather (over 55%) exceeded the increase caused by the clear-cutting scenario (23 %). Dry weather decreased the exports to tenth of the baseline, which was per hectare 2.22 kg for N, 0.08 kg for P). The results suggest that in future maintaining a good ecological status in aquatic systems can be challenging if extreme wet years with mild winters occur more frequently. Certain catchment characteristics, e.g., deciduous tree percentage, open area percentage and site fertility, influence the export increase induced by the extreme weather. Hotspot analysis enabled identifying areas with currently high nutrient export and areas with high increase induced by the extreme weather. This helps targeting water protection efficiently.

Effect of nine-year soil contact on physical performance of crude tall oil impregnated, copper salt impregnated, and non-treated Scots pine posts

ABSTRACT Crude tall oil (CTO), a side product of sulphate pulping, has promising results in moisture and decay resistance. This article reports the Pilodyn indentation hardness, basic density, and mechanical performance of 600-mm long Scots pine posts after a nine-year soil contact test. The material consisted of round and square-shaped CTO-impregnated posts, supplemented by copper salt-impregnated and untreated reference posts. In total, 240 posts were installed in fertile soil in south-eastern Finland in spring 2010. Posts were harvested in May 2019. At the end of the test, 192 posts were in a condition that allowed the preparation of specimens for density and compression tests. Discs were sawn from the ground level, as well as above and below the ground level to measure the density and deformation under static 45,000 N parallel-to-the-grain compression load. Altogether 80% of the untreated control posts were rejected from further tests due to severe decay. Square-shaped control posts had a slightly higher survival rate than the round ones. After a nine-year soil contact, the performance of CTO impregnated. Scots pine posts were clearly better than that of untreated control posts and comparable to that of copper salt-impregnated posts. The study suggests that CTO has a high potential as a non-biocide wood preservative even in structures in soil contact.

Study supporting restoration of rapakivi granite in St. Petersburg

The focus of this ongoing study has been on two rapakivi granites, wiborgite and pyterlite, that have been utilized in St Petersburg since the 1760s but originate from south-eastern Finland. The aims of this study have been to describe the two types of rapakivi granites in their geological settings, to assess the needs for restoration of stones utilized in constructions and to establish databases of stones utilized in historical buildings and of the original and alternative quarries. The focus of this study has been on defining the original quarries for the old building stones or finding other similar substitute granite deposits. Chemical analysis with a handheld XRF instrument was found to be the most promising approach when combined with multivariate mathematical tools. In addition, the applicability of chemical treatment of the surface of rapakivi granite for changing the appearance of stones was investigated. The visual appearance and texture of natural stones used in restoration are the key factors, in addition to the stone type and quality. The chemical treatment of stone surfaces using acidic or metal salt treatments altered the colour tone and visual pattern. Thermal treatment was also found to be effective, but it might be harmful to the surface structure. With further optimisation, chemical treatment could be a feasible method to change the visual appearance of fresh stone in the case of substitution of weathered stone. In addition, this project has initiated cross-border activities that aim to create opportunities for establishing first contacts between the authorities, construction companies, stone producers and the manufacturer who produces the needed high-quality stone pieces.

Corporate conduct, commodity and place: Ongoing mining and mineral exploration disputes in Finland and their implications for the social license to operate

The Finnish mining and mineral exploration disputes (MMEDs) of the 2000s started with the uranium dispute (2006–2008), when the global mining industry rushed into Finland. The Finnish mining skeptical movement originated by focusing on projects associated with uranium. One of these projects, the Talvivaara polymetallic mine, became the key event of the following mining dispute because of its gypsum pond leakage in 2012. Many disputes have persisted for years, while others have ended, and new ones have appeared.Twenty ongoing disputes were identified in Finland. Fourteen of the cases are related to mineral exploration, four to mine projects, and two to mines. The long-term disputes are mostly focused on mines and mine projects in northern Finland, whereas the most recent disputes are mostly related to mineral exploration in southeastern Finland. The main reasons for disputes are the conflicting use of land (indigenous Sámi homeland, lake regions with holiday homes, nature conservation, reindeer herding, and tourism), an association with uranium, poor corporate conduct (lack of communication and stakeholder engagement) and/or reputation.The identification, mapping and monitoring of MMEDs in Finland will support future studies regarding the analysis of their causes, dynamics, evolution, actors, and possible solutions. Their investigation can help to understand and avoid disputes, conciliate diverse interests, and solve disagreements.

Biological nitrogen fixation in logging residue piles of different tree species after final felling

Logging residues influence the nitrogen cycling processes that play a key role in risks for nitrogen losses from the ecosystem after the clear cut. Therefore, our aim was to identify the potential ability of logging residues to gain external nitrogen via biological nitrogen fixation. We measured biological nitrogen fixation as nitrogenase activity in logging residues of three different tree species (Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and silver birch (Betula pendula Roth.). The study site was located in south-eastern Finland and was clear cut in 2014 and piles of logging residues were established. Sampling was performed in June 2016, September 2018, and August 2019 and nitrogenase activity in branches and needles or leaves was measured using the acetylene (C2H2) reduction assay. Nitrogenase activity (ethylene production) was shown in all residue types. Nitrogenase activity tended to be higher in branches than in needles or leaves and in coniferous residues than in birch. C-to-N ratios were higher in branches than in needles/leaves and in coniferous residues than in birch. Our results indicate that logging residues can acquire external nitrogen from the atmosphere via biological nitrogen fixation and can thus bring nitrogen to the forest ecosystem and substitute some part of the N losses occurring when residues are retained at the site after clear cutting.

Local variation in the timing and advancement of lake ice breakup and impacts on settling dynamics in a migratory waterbird

Timing of ice-out is important to fundamental hydrological and ecological processes in freshwater ecosystems at high northern latitudes. While earlier ice-out in lakes during the last century is a well-documented phenomenon across the Northern Hemisphere, local variation in the rate of advancement of ice-out has received little attention. Here, records of ice-out date in 1991–2020 from 37 small lakes in a boreal catchment area in southeastern Finland were used to study variation in the timing of ice-out and its advancement. In addition, data of settling phenology of migratory common goldeneyes (Bucephala clangula) at the study lakes were used to examine how between-year and within-season variation in the timing of ice-out affects lake settlement of the species. Overall, ice-out date (IOD, the timing of ice break-up in the spring) advanced 9.8 days during the 30-year study period, April temperature being more important than winter temperature (severity) in determining the IOD. Rate of the advancement of IOD in individual lakes varied from 1.5 to 16.1 days, having advanced more in relatively larger lakes. Lakes at higher elevations had later mean IOD than lakes at lower elevations. Within-season differences among the lakes in IOD increased from 1991 to 2020, this variation being mainly driven by temperature during the ice melting period. Lakes with late mean IOD were settled later in a season by breeding common goldeneyes than lakes with early IOD. The faster the ice melting progressed within a season, the faster common goldeneyes settled the breeding lakes. The results demonstrate how global warming differently affects IOD in boreal lakes even within the same catchment area. More research in the landscape context is needed to enhance our understanding of changes in IOD in boreal lakes and how differently advancing IOD affects local dynamics of species dependent on open water.

Machine learning techniques for acid sulfate soil mapping in southeastern Finland

Acid sulfate soils are one of the most environmentally harmful soils existing in nature. This is because they produce sulfuric acid and release metals, which may cause several ecological damages. In Finland, the occurrence of this type of soil in the coastal areas constitutes one of the major environmental problems of the country. To address this problem, it is essential to precisely locate acid sulfate soils. Thus, the creation of occurrence maps for these soils is required. Nowadays, different machine learning methods can be used following the digital soil mapping approach. The main goal of this study is the evaluation of different supervised machine learning techniques for acid sulfate soil mapping. The methods analyzed are Random Forest, Gradient Boosting and Support Vector Machine. We show that Gradient Boosting and Random Forest are suitable methods for the classification of acid sulfate soils, the resulting probability maps have high precision. However, the accuracy of the probability map created with Support Vector Machine is lower because this method overestimates the non-AS soils occurrences. We also compare these modeled probability maps with the conventionally produced occurrence map. In general, the modeled maps are more objective and accurate than the conventional maps. Moreover, the mapping process using machine learning techniques is faster and less expensive.

Shifts in fine‐scale distribution and breeding success of boreal waterbirds along gradients in ice‐out timing and habitat structure

Abstract Climate change and other anthropogenic stressors affect freshwater ecosystems worldwide. A prominent manifestation of climate change impacts on aquatic systems at high latitudes is the advance of ice‐out date (IOD). Earlier IOD should be advantageous for species such as migratory waterbirds that are dependent on open water to initiate breeding; earlier breeding usually means higher reproductive success. However, advance of IOD may induce phenological mismatches that have negative impacts on the species involved. This may alter habitat dynamics, challenging habitat selection by breeding individuals. An additional challenge is imposed by changes in habitat quality, particularly if preferred habitats deteriorate. Here, we investigated how the fine‐scale distribution of breeding individuals and breeding success have changed along gradients in IOD and habitat structure (richness of emergent vegetation) in a boreal waterbird assemblage in southeastern Finland from 1991 to 2018. IOD varied considerably between nearby lakes. The distribution of breeding individuals of the common teal (Anas crecca) and horned grebe (Podiceps auritus) shifted toward lakes with relatively late IOD while Eurasian wigeon (Mareca penelope) and tufted duck (Aythya fuligula) shifted toward lakes with sparse emergent vegetation. Also, breeding success in common teal showed a decreasing trend at lakes with relatively early IOD, while it increased on lakes with relatively late IOD. Success in tufted duck breeding decreased on lakes with rich emergent vegetation, while the opposite was true on lakes with sparse emergent vegetation. The mallard (Anas platyrhynchos) was the only species that did not show a shift in breeding distribution or breeding success along either of the environmental gradients. The findings suggest that a potentially positive climate‐driven impact on breeding phenology (earlier IOD) was over‐ridden by negative changes in habitat quality. The results underline the need to understand the complexity of the effects of multiple stressors in boreal freshwater ecosystems for their successful management.

Wind and gravity in shaping Picea trunks

Key messageSpruce trunk tapering corresponds closely to tapering required to resist bending forces caused by wind and gravity.Understanding why trunks (tree stems) are the size that they are is important. However, this understanding is fragmented into isolated schools of thought and has been far from complete. Realistic calculations on minimum trunk diameters needed to resist bending moments caused by wind and gravity would be a significant step forward. However, advancements using this biomechanical approach have been delayed by difficulties in modelling bending of trunks and wind gusts. We felled and measured five Norway spruces (Picea abies) in an unthinned monoculture in southeastern Finland planted 67 years earlier. We then focused on forces working on storm-bent (maximally bent) trees caused by gravity and the strongest gust in a 1-h simulation with a large-eddy simulation model. The weakest points along the trunks of the three largest trees resisted mean above-canopy wind speeds ranging from 10.2 to 12.7 m s−1 (3.3-fold in the strongest gust), but the two smallest were well protected by a dense layer of leaves from the bending tops of larger trees, and could have resisted stronger winds. Gravity caused approximately one quarter of the critical bending moments. The wind that breaks the trunks in their weakest points is close to breaking them in other points, supporting the importance of bending moments caused by wind and gravity in the evolution of trunk taper.

Suomen merimuseon museolaivakuulumisia

Katsaus käsittelee Suomen merimuseon suurimpien museoalusten ylläpitoa. Höyryjäänmurtaja Tarmo telakoitiin viimeksi vuosina 2016–2017, ja majakkalaiva Kemin tekointi alkoi talvella 2020–2021. Molemmat alukset ovat kansallisesti merkittäviä museolaivoja, jotka on päätetty museoida heti käyttövuosiensa jälkeen. Katsaus avaa suurten museolaivojen telakointiin liittyvää tutkimusta, työtehtäviä ja yllätyksiä.

Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64\xa0Ga Ahvenisto complex, Southeastern Finland

Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex, SE Finland, monzodioritic rocks occur as minor dike-like lenses closely associated with anorthositic rocks. We report new field, petrographic, and geochemical (XRF, ICP-MS, EMPA) data complemented with crystallization modeling (rhyolite-MELTS, MAGFRAC) for the monzodioritic rocks, apatite–oxide–gabbronorite, and olivine-bearing anorthositic rocks of the Ahvenisto complex. The presented evidence suggest that the monzodioritic rocks closely represent melt compositions while the apatite–oxide–gabbronorite and olivine-bearing anorthositic rocks are cumulates. The monzodioritic rocks seem to form a liquid line of descent (LLD) from primitive olivine monzodiorites to more evolved monzodiorites. Petrological modeling suggests that the interpreted LLD closely corresponds to a residual melt trend left after fractional crystallization (FC) and formation of the cumulate anorthositic rocks and minor apatite–oxide–gabbronorite in shallow magma chambers. Consequent equilibrium crystallization (EC) of separate monzodioritic residual magma batches can produce the observed mineral assemblages and the low Mg numbers measured from olivine (Fo25–45) and pyroxenes (En48–63, Mg#cpx 60–69). The monzodioritic rocks and apatite–oxide–gabbronorites show similar petrological and geochemical characteristics to corresponding rock types in other AMCG suites, and the model described in this study could be applicable to them as well.

From a F-rich granite to a NYF pegmatite: Magmatic-hydrothermal fluid evolution of the Kymi topaz granite stock, SE Finland

The hydrothermal evolution of the chemically highly evolved topaz granite Kymi stock in southeastern Finland was reconstructed from fluid inclusion petrography, microthermometry, and LA-ICP-MS analysis. The Kymi stock shows a clear zonation and intrusion sequence consisting of an early porphyritic granite, a subsequent equigranular granite, and a late marginal stockscheider pegmatite. Miarolitic cavities from different hydrothermal stages occur within all rock types of the stock, but they are more abundant near the contact between the porphyritic and equigranular granites. Three successive generations of miarolitic cavities and quartz from the stockscheider pegmatite provide the paragenetic and chronological framework for establishing the fluid evolution history. Based on petrographically established time relations, the microthermometric, and LA-ICP-MS data, fluids with different compositional trends were identified and linked to distinct fluid saturation events. The magmatic fluids from the Kymi stock contain high concentrations of elements that are characteristic of highly evolved granites and related pegmatites such as K, Li, B, Be, Rb, Tl, and Cs. Barium and Sr concentrations in fluid inclusions systematically decrease from the intermediately evolved miarolitic cavity to the stockscheider pegmatite and more evolved miarolitic cavities. Additionally, high As, Nb, and Ta concentrations were detected in fluid inclusions from the miarolitic cavities and stockscheider pegmatite. The fluids from the Kymi stock are significantly depleted in zinc, having low Zn/Pb ratios when compared to other magmatic fluids worldwide. This is interpreted to be caused by lower Zn availability in the melt resulting from the crystallization of Zn-enriched biotites in the early porphyritic granite. The most important fluid exsolution event between the crystallization of the porphyritic and the equigranular granite was key to generating the residual, highly evolved and strongly fluorine-enriched melt from which the later rocks including the stockscheider pegmatite crystallized.

Does free public transit increase physical activity and independent mobility in children? Study protocol for comparing children\u2019s activity between two Finnish towns with and without free public transit

BackgroundChildren’s habitual physical activity, including active travel and catching public transit (walking and cycling to and from destinations), and independent mobility (mobility without an adult) have decreased. Public transit trips are physically active and can provide access to hobbies independent of parents, but there is no device-measured data about children’s total physical activity time following the introduction of free public transit. Our aim is to compare physical activity and independent mobility between children living in two Finnish towns, one with a recently introduced free public transit system, and the other without free public transit.MethodsThe city of Mikkeli has provided free public transit for all comprehensive school children since 2017. Various districts from Mikkeli, and the reference town of Kouvola (towns from South-Eastern Finland with a comparative population size and geographical structure), are selected based on their accessibility and the availability of public transit services. Samples of 10–12-year-old children will be recruited through primary schools. We will compare moderate-to-vigorous physical activity time, sitting time (a thigh-worn Fibion® device) and independent mobility (a participatory mapping method, PPGIS) of children: 1) who live in towns with and without free public transit, 2) who live and go to school in districts with high vs. low perceived and objective access to free public transit, and 3) who report using vs. not using free public transit. In addition, ethnography will be used to get insights on the social and cultural effects of the free public transit on children’s and parent’s everyday life.DiscussionThere is a need for scalable solutions that can increase children’s physical activity independent of their socioeconomic background or place of residence. This project will give information on how a political action to provide free public transit for children is associated with their total physical activity time and independent mobility patterns, therefore providing highly relevant information for political decision-making and for promoting independent physical activity in children.