Luoto, T. P. & Salonen V.-P. 2010: Fossil midge larvae (Diptera: Chironomidae) as quantitative indicators of late-winter hypolimnetic oxygen in southern Finland: a calibration model, case studies and potentialities. Boreal Env. Res. 15: 1–18.
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Paatero, J., Hämeri, K., Jaakkola, T., Jantunen, M., Koivukoski, J. & Saxén, R. 2010: Airborne and deposited radioactivity from the Chernobyl accident — a review of investigations in Finland. Boreal Env. Res. 15: 19–33.
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Maljanen, M., Alm, J., Martikainen, P. J. & Repo, T. 2010: Prolongation of soil frost resulting from reduced snow cover increases nitrous oxide emissions from boreal forest soil. Boreal Env. Res. 15: 34–42.
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Wannebo-Nilsen, K., Bjerke, J. W., Beck, P. S. A. & Tømmervik, H. 2010: Epiphytic macrolichens in spruce plantations and native birch forests along a coast-inland gradient in North Norway. Boreal Env. Res. 15: 43–57.
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Kaakinen, A., Salonen, V.-P., Artimo, A. & Saraperä, S. 2010: Holocene groundwater table fluctuations in a small perched aquifer inferred from sediment record of Kankaanjärvi, SW Finland. Boreal Env. Res. 15: 58–68.
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Heino, J., Erős, T., Kotanen, J. & Rask, M. 2010: Describing lake fish communities: Do presence–absence and biomass data show similar spatial and environmental relationships? Boreal Env. Res. 15: 69–80.
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Yrjälä, K., Mancano, G., Fortelius, C., Åkerman, M.-L. & Sipilä, T. P. 2010: The incidence of Burkholderia in epiphytic and endophytic bacterial cenoses in hybrid aspen grown on sandy peat. Boreal Env. Res. 15: 81–96.
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Luoto, T. P. & Salonen V.-P. 2010: Fossil midge larvae (Diptera: Chironomidae) as quantitative indicators of late-winter hypolimnetic oxygen in southern Finland: a calibration model, case studies and potentialities. Boreal Env. Res. 15: 1–18.

We examined the relationship between fossil chironomid assemblages and environmental variables in 30 lakes in southern Finland with particular attention to hypolimnetic oxygen. Ordination techniques (DCA, CCAs) and Monte Carlo permutation tests were used to identify the most important parameters controlling the chironomid distributions. Based on the λ₁:λ₂ ratios of the variables, the greatest potential for quantitative inferences was with hypolimnetic oxygen (λ₁:λ₂ = 0.767). Therefore, inference models for past late-winter hypolimnetic oxygen were developed using weighted-averaging partial least squares (WA-PLS) techniques. The best model used one WA-PLS component, with a cross-validated coefficient of determination (r²_jack) of 0.72 and a root-mean-squared error of prediction (RMSEP) of 2.351 mg l^–1. The model was tested on two short-core sediment sequences. The results indicated that quantitative estimations of hypolimnetic oxygen changes provide a useful tool for palaeolimnology and lake management in assessments of lake ecosystems, and in restoration projects in southern Finland.

Paatero, J., Hämeri, K., Jaakkola, T., Jantunen, M., Koivukoski, J. & Saxén, R. 2010: Airborne and deposited radioactivity from the Chernobyl accident — a review of investigations in Finland. Boreal Env. Res. 15: 19–33.

The Chernobyl nuclear accident happened in the former Soviet Union on 26 April 1986. The accident destroyed one of the RBMK-1000 type reactors and released significant radioactive contamination into the environment. At first the emissions were transported north-westwards over Poland, the Baltic States, Finland, Sweden and Norway. During 27 April 1986 emissions were spreading to eastern-central Europe, southern Germany, Italy and Yugoslavia. Radioactivity mapping over Finland between 29 April and 16 May 1986 showed that the ground deposition in Finland covered southern and central parts of the country but had an irregular distribution. The highest (over 100 µR h^–1 [1 µSv h^–1]) contamination disclosed by the mapping was around the city of Uusikaupunki in western Finland and the city of Kotka in southeastern Finland. The Uusikaupunki region was an area of heavy fallout associated with the air mass that was located in the Chernobyl area at the time of the accident. The fallout pattern of reftractory nuclides, e.g. plutonium isotopes, had their spatial maximum in this region. Medical consequences in Finland were luckily mild, the most important symptoms being psychological ones. No increase in thyroid cancer or birth defect occurrence has been observed. The Chernobyl accident boosted the radioecological research which had already been calming down after the last atmospheric nuclear test in China in October 1980. Important new results concerning e.g. hot particles have been achieved. The most important effects of the accident in Finland were, however, the increase of public awareness of environmental issues in general and especially of nuclear energy. In Finland, the nuclear energy programme was halted until 2002 when the Parliament of Finland granted a licence to build the fifth nuclear reactor in Finland.

Maljanen, M., Alm, J., Martikainen, P. J. & Repo, T. 2010: Prolongation of soil frost resulting from reduced snow cover increases nitrous oxide emissions from boreal forest soil. Boreal Env. Res. 15: 34–42.

Emission rates of the greenhouse gas, nitrous oxide (N₂O), from northern upland forest soils are generally low. According to recent climate scenarios, the snow cover in the boreal region is predicted to decrease and which will result in lower soil temperatures. In this study, we investigated whether lower soil temperatures during winter can also trigger N₂O emissions from boreal forest soils with originally low N₂O emissions, as has earlier been shown for northern agricultural soils with higher N₂O emissions. We measured the N₂O emissions from a spruce forest in eastern Finland where the soil temperature was changed by manipulating snow-pack thickness and using insulating covers. The effects of the treatments on methane (CH₄) and carbon dioxide (CO₂) fluxes were also studied for comparative purposes. The results show that there can be an increase in N₂O emissions and CO₂ production rate from boreal upland forest soils resulting from a thinner snow cover that causes a prolongation of soil frost. Reducing the snow pack thickness had only minor effects on the CH₄ fluxes.

Wannebo-Nilsen, K., Bjerke, J. W., Beck, P. S. A. & Tømmervik, H. 2010: Epiphytic macrolichens in spruce plantations and native birch forests along a coast-inland gradient in North Norway. Boreal Env. Res. 15: 43–57.

Around 10% of the natural coastal birch forest in North Norway has been converted to spruce plantations. However, little is known about the effects on the affected ecosystems. Our objective was to evaluate differences in macrolichen communities between spruce plantations and native birch-dominated forests. Canonical correspondence ordination shows that birch forests and spruce plantations host distinct macrolichen species compositions. Mean yearly temperature is the most important explanatory environmental variable. Sitka spruce plantations had the lowest recorded species number and diversity, which probably is a result of low-light conditions caused by very long branches. Mixed birch–Norway spruce stands had both highest species number and diversity. Oceanic sites generally have different species composition, and higher species number and bark pH than continental sites. Plantations cause changes in species compositions and partly also declines in species number and diversity, and hence, plantations are far from optimal for conservation of native epiphytic lichen communities.

Kaakinen, A., Salonen, V.-P., Artimo, A. & Saraperä, S. 2010: Holocene groundwater table fluctuations in a small perched aquifer inferred from sediment record of Kankaanjärvi, SW Finland. Boreal Env. Res. 15: 58–68.

Kankaanjärvi is a closed seepage lake controlled by groundwater flow within a perched aquifer. The results of this study indicate that its paleolimnological record forms a detailed groundwater table proxy covering the Holocene. Lake-level fluctuations were reconstructed from AMS-dated shifts in sediment properties, indicating marked natural changes of exceptional magnitude during the last 9000 years. The basin was more or less dry from 9000 to 6000 years ago. Since then, the water level gradually rose to its present limits of fluctuations about 3000 years ago. The record indicates that the water table of the associated perched aquifer is sensitive to precipitation changes, and that a decrease of 100 mm in annual precipitation may explain the low early Holocene level of the water system. The predicted climate change will likely keep the water table at a high, but stable level due to increased precipitation rates.

Heino, J., Erős, T., Kotanen, J. & Rask, M. 2010: Describing lake fish communities: Do presence–absence and biomass data show similar spatial and environmental relationships? Boreal Env. Res. 15: 69–80.

We examined if community–environment and community–geographical-location relationships differ between presence–absence and biomass data of lake fishes. Our study lakes ranged across very long gradients of the features of boreal lakes in the ecoregions of Finland, providing an excellent opportunity to examine patterns in lake fish communities. Fish community structure responded to multiple environmental gradients, yet there was a clear pattern of succession from salmonids in oligotrophic lakes through European perch in mesotrophic lakes to cyprinids in eutrophic lakes. Such patterns prevailed especially in the biomass data. Partitioning of variation in the species matrix between environmental and spatial variables did not reveal clear differences between presence-absence and biomass data. Although slightly different combinations of environmental factors were included in the constrained ordination models, the relatively similar variation in presence–absence and biomass data along environmental and spatial gradients suggests that they may be used interchangeably to describe community–environment relationships at large geographical extents.

Yrjälä, K., Mancano, G., Fortelius, C., Åkerman, M.-L. & Sipilä, T. P. 2010: The incidence of Burkholderia in epiphytic and endophytic bacterial cenoses in hybrid aspen grown on sandy peat. Boreal Env. Res. 15: 81–96.

Endophytic bacteria are not known from woody plant seedlings. Endophytic and epiphytic bacteria were isolated from leaves, stems and roots of hybrid aspen (Populus tremula x Populus tremuloides) seedlings. The uncultured 16S rRNA rhizospheric bacterial community was cloned from pristine and polyaromatic hydrocarbon polluted rhizosphere soil. The isolates were subjected to restriction fragment length polymorphism analysis and partial 16S rRNA of selected strains was sequenced for phylogenetic identification. The bacteria could be classified into 16 different genera, showing that epiphytes from plant surfaces were most often Gammaproteobacteria, which composed 47% of the isolates. Endophytes from plant tissue were most frequently Betaproteobacteria (45%). Polyaromatic hydrocarbons caused a shift in the cultured bacterial community in the rhizosphere soil to a Betaproteobacteria dominated one. The root bacterial community showed a strong association of Burkholderia bacteria with hybrid aspen. Over 50% of all isolated strains grew on benzoic acid, but only 16% of benzoic acid degraders grew on m-toluate.