Southern Finland Research Articles

VKORC1-based resistance to anticoagulant rodenticides widespread in Finnish house mice but not in brown rats

Anticoagulant rodenticide (AR) resistance is widespread across Europe, but its prevalence has not been previously studied in Finland. We sampled 48 house mice (Mus musculus) and 48 brown rat (Rattus norvegicus) in farms and urban locations from southern Finland and here we report the identification of Vkorc1 polymorphisms linked to AR resistance. Two thirds of mice carried Vkorc1 polymorphisms. The most common was the type Y139C (resistance to first-generation ARs, bromadiolone and difenacoum), whereas the type L128S (resistance to FGARs and bromadiolone) was much less abundant. Only two rats tested positive, both with a rare type R33P (resistance probably to warfarin). No clear patterns based on subregion, sex and urban/rural division were seen. We suggest that the type Y139C polymorphism should be taken into account when planning control actions targeting house mice in Finland. The low number of AR resistant rats found suggests a low prevalence of resistance in rats. To fully understand the state of AR resistance in Finland, additional studies on yellow-necked mouse (Apodemus flavicollis) and bank voles (Myodes glareolus) are needed.

Changes in over-winter prey availability, rather than winter climate, are associated with a long-term decline in a northern Tawny Owl population

Although the associations between climate, food conditions and reproduction in the wild has been the focus of numerous studies in recent years, we still know little about population level responses to climate and fluctuating food conditions in long-lived species and during longer periods of time. Here, we assessed the relative importance of the abundance of the main prey in winter (small mammals), and winter climate on population size and productivity in a Tawny Owl (Strix aluco) population in southern Finland during a 40-year period. We studied how population trends changed over time and in relation to winter weather and small mammal abundance on three levels: total estimated population size, proportion of breeders and population productivity. We identified declining trends in each population parameter over time, as well as directional changes in climate variables and prey abundance. Overall, small mammal abundance was the foremost predictor in explaining the variation in the number of active territorial pairs (population size). Moreover, both prey abundance and winter temperature significantly affected the proportion of territorial pairs that attempted to breed and thereby total offspring production, which reveals the relevance of winter weather conditions for population productivity. These results provide additional support to the view that changes in climate can modify predator–prey interactions leading to functional changes in the food web.

Highly pathogenic avian influenza A (H5N1) virus infections in wild carnivores connected to mass mortalities of pheasants in Finland.

Highly pathogenic avian influenza (HPAI) has caused widespread mortality in both wild and domestic birds in Europe during 2020-2022. Virus types H5N8 and H5N1 have dominated the epidemic. Isolated spill-over infections in mammals started to emerge as the epidemic continued. In autumn 2021, HPAI H5N1 caused a series of mass mortality events in farmed and released pheasants (Phasianus colchicus) in a restricted area in southern Finland. Later, in the same area, an otter (Lutra lutra), two red foxes (Vulpes vulpes) and a lynx (Lynx lynx) were found moribund or dead and infected with H5N1 HPAI virus. Phylogenetically, H5N1 strains from pheasants and mammals clustered together. Molecular analyses of the four mammalian virus strains revealed mutations in the PB2 gene segment (PB2-E627K and PB2-D701N) that are known to facilitate viral replication in mammals. This study revealed that avian influenza cases in mammals were spatially and temporally connected with avian mass mortalities suggesting increased infection pressure from birds to mammals.

Adverse Events After Surgical Treatment of Adult Diaphyseal Forearm Fractures: a Retrospective Analysis of 470 Patients.

The incidence of and risk factors for adverse events after internal fixation of diaphyseal forearm fractures have not been well defined in the current literature. The objective of this study was to estimate the incidence of adverse events after diaphyseal forearm fracture surgery in adults and explore potential risk factors for adverse events. We conducted a retrospective, multicenter, cohort study in which we evaluated all diaphyseal forearm fractures between 2009 and 2019 in patients presenting to 4 trauma hospitals in southern Finland. Patients <16 years of age and fracture-dislocations were excluded. There were 470 patients included in this study. Patient records were evaluated to identify and analyze adverse events. There were 202 patients with both-bone fractures, 164 patients with isolated ulnar fractures, and 104 patients with isolated radial fractures. In total, 146 patients (31%) experienced an adverse event; 83 (18%) had major adverse events (persistent or requiring surgical intervention). The patients underwent procedures performed by 185 different surgeons. The median number of operations for a single surgeon was 2 (range, 1 to 12). The most common major adverse events were plate and screw-related issues (6%), nonunion (5%), persistent nerve injuries (4%), and refractures (4%). Higher body mass index, Gustilo-Anderson type-II open fractures, both-bone fractures, isolated radial fractures, and operations performed by junior residents were found to be risk factors for adverse events in the multivariable analysis. Adverse events after diaphyseal forearm fracture surgery are common. We recommend concentrating these operations in a limited team of surgeons and restricting inexperienced surgeons from operating on these fractures without supervision. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Regional background and donor-language fluency as predictors of Finnish loanword frequency in Finland-Swedish

Aims and objectives: This study examines fennicisms (i.e., Finnish loanwords and calques) in Finland-Swedish, a Swedish variety spoken in Finland. We investigate how fennicism frequency relates to speakers’ regional backgrounds and fluency in Finnish. Methodology: 134 participants from four regions in Finland performed a picture-naming task designed to elicit fennicisms. The participants also rated their own fluency in Finnish. Data and analysis: A regression analysis with the outcome variable of fennicism frequency and the predictors of region, fluency in Finnish, and gender was performed. Findings: Results show that speakers from the more bilingual regions of Southern Finland and Helsinki used significantly more fennicisms than speakers from Ostrobothnia or Swedish-speaking Åland. The study suggests that fluency in Finnish was a strong predictor for fennicism use, as speakers with low or moderate knowledge of Finnish used fewer fennicisms than speakers with high or native(-like) fluency. No significant effect of gender was found. Originality: While fennicisms are considered widespread in Finland-Swedish, there is little previous research on their use and distribution. Implications: The results demonstrate that while many of the fennicisms are well-established in the Finland-Swedish variety, their use is limited to certain groups and communities.

Stronger negative priming effect and lower basal respiration rates in nutrient-poor as compared to nutrient-rich forestry-drained peatland.

Land-use changes, e.g., forestry drainage, modify the characteristics of peatland soil and affect the peatland carbon (C) balance. Peat soil nutrient status, related mainly to the original peatland type, also has an impact on the C balance after drainage, as observed earlier at the ecosystem scale for two forestry-drained sites in Southern Finland. Here the aim was to compare the soil CO2 fluxes from the two sites, nutrient-poor and nutirent-rich forestry-drained peatlands, and study the effect of plant photosynthates on the decomposition of peat C. Therefore, the respiration rates and priming effect (PE) of peat soils with variable nutrient status were examined in the laboratory. Half of the samples were labelled with 13 C-glucose to study the effect of fresh C addition on the soil decomposition. The 13 CO2 -samples were analysed with isotope ratio mass spectrometry. A two-pool mixing model was applied to separate the soil- and sugar-derived respirations and to determine the PE. The nutrient-rich peat soil respired generally more than the nutrient-poor peat. A negative PE was observed in both peat soils, suggesting that the addition of fresh C did not increase the soil decomposition, but on the contrary decreased it. The negative PE was significantly more pronounced in nutrient-poor peat soil than in the nutrient-rich peat treatments, suggesting that the higher nutrient availability suppresses the negative PE. These results imply that microbes prefer utilizing fresh C instead of old C in the short term and that the peat decomposition is suppressed in the presence of fresh C inputs from vegetation at forestry-drained peatlands. These effects are even stronger in peat soils with less nutrients available. Ecosystem scale and soil process models could be improved with the help of these results.

The morphostratigraphic imprint of the Baltic Ice Lake drainage event in southern Finland

Digital elevation models, based on laser scanning imageries (LiDAR-DEM) and aided by ground penetrating radar (GPR) data, were used to study glaciofluvial Gilbert-type ice-contact deltas in the Younger Dryas Salpausselkä end-moraine zone in southern Finland. The geomorphological data analysed were used to reconstruct the water-level drop of the late glacial Baltic Ice Lake to the early Holocene Yoldia Sea and tie these changes to a wider stratigraphic context. The results indicate that the sudden drainage event at around 11 650 cal. yrs BP left its imprint not only on the varved sediments but also on ice-contact glaciofluvial deltas in the Second Salpausselkä zone throughout southern Finland. This morphostratigraphic boundary can be placed at locations where the ice-contact deltas occur at two different levels; the higher-level deltas formed during the Baltic Ice Lake B III water-level stage and the lower-level deltas during the Yoldia Sea Y I water-level stage. This morphostratigraphically defined boundary in southern Finland marks the Pleistocene/Holocene chronostratigraphic boundary in southern Finland and shows the corresponding positions of the Scandinavian Ice Sheet’s Finnish Lake District Ice Lobe and the Baltic Sea Ice Lobe.

Multiscale mapping and scaling analysis of the censored brittle structural framework within the crystalline bedrock of southern Finland

Fracture studies commonly lack data for the length range between 10 m to 1 km. For this reason, scaling laws are required to extrapolate fracture properties, for example in discrete fracture network models. This study focused on analysis and correlation of topology, orientation and length distribution of multiscale fracture datasets to assess their scalability. The used datasets comprise UAV-derived photogrammetric models from natural outcrops and lineaments mapped using airborne LiDAR, bathymetry and aerogeophysical data, in several contrasting scales and resolutions. This study highlights challenges in acquiring uncensored and coherent brittle structural datasets from source data characterized by a large span of resolutions between the remote sensing datasets and models of the fractured outcrop. In specific, collected data was found to be potentially biased and affected by uncertainties related to both the censoring by sedimentary cover and the scale of observation. Our results revealed differences between lineament and outcrop fracture orientations, as well as difficulties in assessing topological parameters from lineament datasets. The 1:200000 resolution was found best suited to the mapping of lineament length and resulted in a length distribution power law exponent of -1.92. For outcrop fractures that are less than 2 m long, the lognormal length distribution provided the only good fit to our data, while the longer outcrop fractures fitted relatively well with a power law exponent of -2.26.

Statistical approach to identify variables predicting sulphide clay occurrence in southern Finland

Acid sulphate soil and sulphide-bearing sediments cause various challenges in construction projects and land use planning, as well as harmful environmental effects. Fine-grained sulphide sediments were mainly formed in coastal areas during the Litorina Sea water phase at approximately 7000 BP in the capital region of Finland, but not all these sediments contain sulphide clay. In this study, environmental and material property variables related to the depositional conditions of sulphide clay were selected for statistical analyses to find their association with the occurrence of sulphide. The datasets consisted of sulphide investigations by the City of Espoo, the City of Helsinki, and the Geological Survey of Finland. Statistically significant associations were found in the study area between the occurrence of sulphide and enumerative variables (i.e., sediment organic content, total clay depth, topographic class in the Litorina Sea phase, and water depth) in the Litorina Sea phase. Locations where sulphide clay is especially likely to occur consist of organic-rich (≥ 2%) thick clay (≥ 15 m) deposits in a topographically narrow depression with deep Litorina water (≥ 30 m), or where there is a moderate depth clay (3–5 m) in a local depression with shallow Litorina water (10–20 m). The best individual predictor for sulphide clay occurrence in the study area was found to be the sediment organic content, and, together with sediment water content, these variables very accurately predicted the occurrence of sulphide clay. In addition, clay depth is a very good predictor and, together with the topographic class narrow depression and the Litorina water depth or current elevation, can be used to predict sulphide occurrence.

Prescribed fire is an effective restoration measure for increasing boreal fungal diversity.

Intensive forestry practices have had a negative impact on boreal forest biodiversity; as a consequence, the need for restoration is pressing. Polypores (wood-inhabiting fungi) are key decomposers of dead wood, but, due to a lack of coarse woody debris (CWD) in forest ecosystems, many species are under threat. Here, we study the long-term effects on polypore diversity of two restoration treatments: creating CWD by felling whole trees and prescribed burning. This large-scale experiment is located in spruce-dominated boreal forests in southern Finland. The experiment has a factorial design (n = 3) including three levels of created CWD (5, 30, and 60 m3 ha-1 ) crossed with burning or no burning. In 2018, 16 years after launching the experiment, we inventoried polypores on 10 experimentally cut logs and 10 naturally fallen logs per stand. We found that overall polypore community composition differed between burned and unburned stands. However, only red-listed species abundances and richness were positively affected by prescribed burning. We found no effects of CWD levels created mechanically by felling of trees. We show, for the first time, that prescribed burning is an effective measure for restoring polypore diversity in a late-successional Norway spruce forest. Burning creates CWD with certain characteristics that differ from what is created by CWD restoration by felling trees. Prescribed burning promotes primarily red-listed species, demonstrating its effectiveness as a restoration measure to promote diversity of threatened polypore species in boreal forests. However, because the CWD that the burning creates will decrease over time, to be functional, prescribed burns need to be applied regularly on the landscape scale. Large-scale and long-term experimental studies, such as this one, are invaluable for establishing evidence-based restoration strategies.

Input data resolution affects the conservation prioritization outcome of spatially sparse biodiversity features.

Detailed spatial data are an essential part of land use planning and decision-making. Their spatial resolution sets limitations to their use, as coarse datasets are not suitable for detecting small-scale phenomena. In this study, we explored the effects of spatial resolution on the ecological outcome of a conservation prioritization process in Zonation software. Our study area was in Evo, southern Finland, covering a mosaic of managed and conserved forests. We produced the feature layers describing the forest characteristics using high-resolution remote sensing datasets, object-based mapping methods, and forest site type data. We found that increasing the resolution above the 16 m baseline resolution resulted in substantial errors. The conservation errors were the highest for rare features related to European Aspen, whereas the common features related to dominant tree species could benefit from the growth of cell size. We conclude that adequate spatial resolution is a prerequisite for efficient conservation prioritization, and that the size and spatial distribution of the features affect the resolution requirements.

Transitioning beyond urban green space accessibility indicators: Case illustration of a novel diversity planning tool applied to Vantaa, Finland

Current urban green space planning processes are typically guided by greenspace-to-residence proximity indicators. Alone, these indicators are unable to assess, and respond, to the growing socio-spatial polarisation of environmental risks, impacts, and benefits among distinct societal groups within a city. In this research, we present a municipal green space planning tool for measuring the spatial distribution of urban green space diversity within a city, developed using a novel spatial application of the Shannon diversity index to urban green spaces. We illustrate the use of this planning tool in the case of Vantaa, a city in Southern Finland, and examine the association of this diversity indicator with three spatially polarising socio-demographic factors in the region. Contrary to the dominant environmental distributive justice narrative, and stark trends towards socio-spatial polarisation observed in many cities internationally, our findings reveal that urban green space diversity does not currently correlate with income, age structure, or share of population with a foreign background in Vantaa. However, given the changing social dynamics present in our case city, ongoing monitoring and evaluation of who benefits and how from ecosystem service benefits of a diverse urban green space network is necessary. This research offers a practical tool for urban green space planners in European cities facing similar periods of significant differential spatial expansion and changing social dynamics.

Latitudinal origins of Fragaria vesca show adaptive variation in phenological, morphological and ecophysiological leaf traits associated with winter climate

Ongoing climate change is affecting vascular plants, but it is uncertain how plant species will react to the environmental changes, and therefore detailed understanding of adaptive phenotypic variation is needed. Woodland strawberry (Fragaria vesca L.) has a large geographical range, thus having great phenotypic variation and ability to adapt to different climates. One adaptive trait that allows F. vesca to continue photosynthesis through an extended growing season is the production of two morphologically distinct sets of leaves – summer leaves, produced in the spring and summer, and winter leaves produced in the autumn. However, to date it was unknown whether F. vesca genotypes from warmer European countries produce winter leaves, and whether they could survive cold winter conditions. To test for local adaptation in F. vesca, we studied variation in phenology, morphology and ecophysiology among ten European F. vesca genotypes from populations extending over the natural latitudinal range of the species. All genotypes survived a harsh winter in a common garden in southern Finland and produced winter leaves. These leaves acclimated well to the winter climate, as the maximum capacity of photosystem II (Fv/Fm) remained high from late autumn to spring despite low temperatures. We found a latitudinal pattern in phenology with the northern European genotypes producing their first winter leaves earlier than the genotypes of southern European origin. This indicates that winter leaf phenology and climate acclimation are under genetic control and express local adaptation. In contrast, cessation of stolon production in the autumn did not show a latitudinal cline. Our finding that local adaptation causes clear differences among populations in functional traits in F. vesca provides a foundation for future studies to explore underlying genetic variation and molecular processes affecting these traits that might improve the resilience of plant populations in a changing climate.

Fish muscle mercury concentration and bioaccumulation fluctuate year-round - Insights from cyprinid and percid fishes in a humic boreal lake

Boreal lakes demonstrate pronounced seasonality, where the warm open-water season and subsequent cold and ice-covered season dominate natural cycles. While fish muscle total mercury concentration (mg/kg) [THg] is well documented in open-water summer months, there is limited knowledge on the ice-covered winter and spring mercury dynamics in fish from various foraging and thermal guilds. This year-round study tested how seasonality influences [THg] and its bioaccumulation in three percids, perch (Perca fluviatilis), pikeperch (Sander lucioperca), ruffe (Gymnocephalus cernua), and three cyprinids, roach (Rutilus rutilus), bleak (Alburnus alburnus), and bream (Abramis brama) in deep boreal mesotrophic Lake Pääjärvi, southern Finland. Fish were sampled and [THg] was quantified in the dorsal muscle during four seasons in this humic lake. Bioaccumulation regression slopes (mean ± STD, 0.039 ± 0.030, range 0.013–0.114) between [THg] and fish length were steepest during and after spawning and shallowest during autumn and winter for all species. Fish [THg] was significantly higher in the winter-spring than summer-autumn in all percids, however, not in cyprinids. The lowest [THg] was observed in summer and autumn, likely due to recovery from spring spawning, somatic growth and lipid accumulation. Fish [THg] was best described by multiple regression models (R2adj: 52–76%) which included total length and varying combinations of seasonally changing environmental (water temperature, total carbon, total nitrogen, and oxygen saturation) and biotic factors (gonadosomatic index, and sex) in all species. The seasonal variation in [THg] and bioaccumulation slopes across multiple species suggests a need for standardized sampling seasons in long-term monitoring to avoid any seasonality bias. From the fisheries and fish consumption perspective in seasonally ice-covered lakes, monitoring of both winter-spring and summer-autumn would improve knowledge of [THg] variation in fish muscle.

Comparison of four alternative survey methods in assessing dead wood at the stand level

ABSTRACT Many forestry practitioners need information on the amount of dead wood for various purposes, often at the level of individual stands. Our aim was to compare four simple dead-wood inventory methods of which systematic circular plot inventory is a well-known method, while relascope plot inventory (using the ordinary horizontal angle relascope also for downed trees), diameter class counting and total inventory are new methods. Seven surveyors tested the methods in four stands in southern Finland. All the methods produced rather accurate volume estimates. Mean percent error was the smallest (−5.7%) in total inventory and the largest (−12.4%) in diameter class counting. Precision differed significantly between the methods. Variation among individual measurements, expressed as percentage SD, was 15.9% in total inventory, 24.8% in diameter counting, 36.6% in relascope inventory and 43.0% in circular plot inventory. Diameter counting was by far the fastest method. Relascope inventory and circular plot inventory took about twice as much time, and total inventory over three times as much time as diameter counting. In conclusion, diameter class counting is a cost-effective dead-wood assessment method, if the purpose is to get an estimate of the total volume of dead wood within a forest stand with a reasonable precision.

Multivariate mixed-effects models for stand characteristics of hybrid aspen plantations in southern Finland and southern Sweden

Hybrid aspen, a hybrid between the European aspen and North American trembling aspen (Populus tremula L. × P. tremuloides Michx.), is a promising species because of its fast-growth and its suitability for multi-purpose use. However, models for predicting the age-dependent development of stand characteristics are still missing. The main objectives of this study were therefore to develop the models for predicting stand characteristics of hybrid aspen plantations and to validate the model applicability. The target response variables were stand basal area (BA), basal area-weighted mean diameter (DG) and basal area-weighted mean height (HG). Data were obtained from clonal hybrid aspen trials in southern Finland and southern Sweden. Multivariate mixed-effects modelling was used to estimate the parameters of seemingly unrelated regression for BA, DG, and HG. Model fit provided the following predictor variables: stand age (AGE), the number of trees per hectare (TPH), site index (SI), growing degree-days (GDD5), soil and site type, and thinning treatment. The chosen predictors differed slightly by response variable, but all parameters were highly significant (P < 0.0001), and model goodness-of-fit statistics presented high accuracy: RMSE of 2.59 m2 ha−1 for BA, 1.21 cm for DG, 1.05 m for HG in arithmetic scale. The applied simulations illustrated clear differences in the predicted development of stand characteristics when input variables SI, TPH or GDD5 changed. The developed models were assessed to be easily applicable and useful for predicting the stand and tree characteristics of clonal hybrid aspen plantations, especially for the stands with AGE ≤ 30 years and TPH ≤ 2000 trees ha−1.

Tree regeneration potential in urban spruce-dominated forests is shaped by management history

With projected climate change, urban spruce-dominated forests are facing increasing risks of forest damages, encouraging management for mixed stand structures. In the major cities of southern Finland, forests are preferentially maintained continuously covered, and tree regeneration is mostly reliant on naturally emerging sapling stock. To understand the role of forest management in shaping natural tree regeneration in urban forests, we studied the occurrence and abundance of tree saplings in spruce-dominated tree stands on a management continuum ranging from partially logged to undisturbed near-natural stands. Study sites (N = 74) were located in three urban centers in southern Finland: Tampere, Lahti and Helsinki region. We analyzed the data by comparing tree regeneration potential between management classes reflecting the timing and intensity of past logging, and by relating the occurrence of saplings with current structures of the living tree stand.Compared to undisturbed stands, partially logged sites had increased regeneration of broad-leaved trees and repressed regeneration of spruce, while the most abundant sapling tree species across all management classes was rowan. We conclude that partial logging can be a successful way of directing tree regeneration towards lower dominance of spruce. However, when the canopy is only partially opened, created gaps may end up being filled primarily by rowans that are comparatively shade-tolerant. Because the ingrowth of rowan and many other broad-leaved tree species is strongly restricted by dense populations of large browsing animals in non-urban areas, urban forests may develop stand structures and tree species composition that are otherwise rare in the Fennoscandian boreal forests.

Soil organic carbon sequestration potential for croplands in Finland over 2021–2040 under the interactive impacts of climate change and agricultural management

CONTEXTCropland soil organic carbon (SOC) stock can be increased by agricultural management, but is subject to various factors. The extent and rates of SOC sequestration potential, as well as the controlling factors, under different climate and management practices across a region or country are important for policy-makers and land managers, however have been rarely known. OBJECTIVEWe aim to investigate the extent and rates of SOC sequestration potential over 2021–2040 under different scenarios of climate change and Sustainable Soil Management (SSM) practices, and quantify the impacts of climate change and SSM practices on the SOC sequestration potential, for croplands across Finland at a spatial resolution of 1 km. METHODSRothC model is run iteratively to equilibrium to calculate the size of the SOC pools and the annual plant carbon inputs. Then, it is applied to investigate the SOC sequestration potential over 2021–2040 under different scenarios of climate change and SSM practices. Finally, facorial simulation experiments are conducted to quantify the impacts of climate change and SSM practices, alone and in combination, on SOC sequestration potential. RESULTS AND CONCLUSIONUnder the combined impacts of climate change and SSM practices, the SOC sequestration potential during 2021–2040 relative to 2020 will be on average − 0.03, 0.007, 0.05, and 0.13 t C ha−1 yr−1, respectively, with carbon input being business as usual, 5%, 10%, and 20% increase. This is equivalent to an annual change rate of −0.04%, 0.009%, 0.07%, and 0.17%, respectively. Therefore, a 20% increase in C input to soil will not be enough to obtain a 4‰ increase per year over the 20-year period in Finland. Carbon input will promote SOC sequestration potential; however, climate change will reduce it on average by 0.28 t C ha−1 yr−1. Across the cropland in Finland, on average, the relative contributions of C input, temperature, and precipitation to SOC sequestration potential in 2021–2040 will be 56%, 24%, and 20%, respectively, however there is a spatially explicit pattern. The SOC sequestration potential will be relatively high and dominated by C input in west and southwest Finland. By contrast, it will be relatively low and dominated by climate in north and east Finland, and the central part of southern Finland. SIGNIFICANCEOur findings provide the information as to where, how much, and which SSM practices could be applied for enhancing SOC sequestration at a high spatial resolution, which is essential for stakeholders to increase cropland SOC sequestration efficiently.

The Urheilupuisto House and Other Corded Ware Houses from Finland

Although numerous settlement sites of Corded Ware culture have been discovered in Finland, only a few houses have been identified. This is in stark contrast to the abundant number of pithouses of local hunter-gatherers. This paper takes a closer look at the houses associated with Corded Ware culture, first, by introducing a recently excavated Corded Ware house from southern Finland and other houses connected to Corded Ware culture from Finland and the Karelian Isthmus, Russia, and second, by outlining the various types of Corded Ware houses around the Baltic Sea. After that, the emerging picture suggesting interaction between the regional variants of Corded Ware culture as well as between Corded Ware cultures and local hunter-gatherers will be discussed. Even if the remains of Corded Ware houses are few and often quite ambiguous, it will be concluded that several types of houses have existed in the area north of the Gulf of Finland, and the contacts between cultural traditions affected settlement types and house structures in each party involved in the process.

Hydraulic conductivity of the crystalline crust: Insights from hydraulic stimulation and induced seismicity of an enhanced geothermal system pilot reservoir at 6 km depth, Espoo, southern Finland

We analyze hydraulic stimulation data from the St1 Deep Heat Project, which comprised drilling wells to >6 km depth in crystalline rock in southern Finland with an aim to study the conditions for an Enhanced Geothermal System. Combining the stimulation and borehole logging data with induced seismicity results allows for a comprehensive analysis of hydraulic conductivity at rarely tested depths of 5 – 6 km. Hydraulic conductivity was observed to be pressure-dependent, heterogeneously distributed and affected by pre-existing fractures and lithological variation. The pre-stimulation formation fracture frequency is in the range of 0 – 8 m−1 with an average of 1.9 m−1. Only a small fraction of the fractures were open and conductive implying a hydraulically heterogeneous medium. The average natural hydraulic conductivity derived from leak-off tests and well tests before stimulation and from cross-hole pressure data is of the order of 5 0·10−10 - 5 0·10−9 m/s (permeability 1· 10−17 – 1·10−16 m2), which is in agreement with permeability models for the brittle crystalline crust at this depth. Hydraulic stimulation increased conductivity to 10−8 – 10−7 m/s, but it gradually decreased back to the natural level after pressure release. Stimulation generated five micro-earthquake clusters at 4.8 – 6.3 km TVD depth. Hydraulic connections between clusters were apparently not attained. The project generated extensive experience and data sets regarding deep drilling, hydrogeological properties, and seismic response to stimulation of crystalline rock in the upper continental crust. Hydraulic conductivity turned out to be the most challenging issue for the St1 EGS development and the EGS project is not continued at the moment.