Yang, Y., Cheng, B., Kourzeneva, E., Semmler, T., Rontu, L., Leppäranta, M., Shirasawa, K. & Li, Z. J. 2013: Modelling experiments on air–snow–ice interactions over Kilpisjärvi, a lake in northern Finland. Boreal Env. Res. 18: 341–358.
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Saarinen, T. & Celebi, A. & Kløve, B. 2013: Links between river water acidity, land use and hydrology. Boreal Env. Res. 18: 359–372.
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Rankinen, K., Granlund, K., Futter, M. N., Butterfield, D., Wade, A. J., Skeffington, R., Arvola, L., Veijalainen, N., Huttunen, I. & Lepistö, A. 2013: Controls on inorganic nitrogen leaching from Finnish catchments assessed using a sensitivity and uncertainty analysis of the INCA-N model. Boreal Env. Res. 18: 373–386.
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Peltomaa, E., Ojala, A., Holopainen, A.-L. & Salonen, K. 2013: Changes in phytoplankton in a boreal lake during a 14-year period. Boreal Env. Res. 18: 387–400.
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Symonds, J., Morris, D. M. & Kwiaton, M. M. 2013: Effect of harvest intensity and soil moisture regime on the decomposition and release of nutrients from needle and twig litter in northwestern Ontario. Boreal Env. Res. 18: 401–413.
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Mörsky, S. K., Haapala, J. K., Rinnan, R., Saarnio, S., Kyrö, E., Silvola, J., Martikainen, P. J. & Holopainen, T. 2013: Effects of elevated UV-B radiation on UV-absorbing pigments and leaf anatomy of a sedge, Eriophorum russeolum. Boreal Env. Res. 18: 414–424.
Abstract
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Yang, Y., Cheng, B., Kourzeneva, E., Semmler, T., Rontu, L., Leppäranta, M., Shirasawa, K. & Li, Z. J. 2013: Modelling experiments on air–snow–ice interactions over Kilpisjärvi, a lake in northern Finland. Boreal Env. Res. 18: 341–358.

The evolution of snow and ice thicknesses and temperature in an Arctic lake was investigated using two models: a high-resolution, time-dependent model (HIGHTSI) and a quasi-steady two-layer model on top of a lake model (FLake). In situ observations and a Numerical Weather Prediction model (HIRLAM) were used for the forcing data. HIRLAM forecasts, after orography correction, were comparable with the in situ data. Both lake-ice models predicted the ice thickness (accuracy 5 cm), surface temperature (accuracy 2–3 °C in winter, better in spring), and ice-breakup date (accuracy better than five days) well. HIGHTSI was better for ice thickness and ice-breakup date, while FLake gave better freezing date. Snow thickness outcome was worse, in particular for the melting season. Surface temperature was highly sensitive to air temperature, stratification and albedo, and the largest errors (positively biased) resulted in strongly stable conditions.

Saarinen, T. & Celebi, A. & Kløve, B. 2013: Links between river water acidity, land use and hydrology. Boreal Env. Res. 18: 359–372.

In western Finland, acid leaching to watercourses is mainly due to drainage of acid sulphate (AS) soils. This study examined how different land-use and land-cover types affect water acidity in the northwestern coastal region of Finland, which has abundant drained AS soils and peatlands. Sampling conducted in different hydrological conditions in studied river basins revealed two different catchment types: catchments dominated by drained forested peatlands and catchments used by agriculture. Low pH and high electric conductivity (EC) were typical in rivers affected by agriculture. In rivers dominated by forested peatlands and wetlands, EC was considerably lower. During spring and autumn high runoff events, water quality was poor and showed large spatial variation. Thus it is important to ensure that in river basin status assessment, sampling is carried out in different hydrological situations and in also water from some tributaries is sampled.

Rankinen, K., Granlund, K., Futter, M. N., Butterfield, D., Wade, A. J., Skeffington, R., Arvola, L., Veijalainen, N., Huttunen, I. & Lepistö, A. 2013: Controls on inorganic nitrogen leaching from Finnish catchments assessed using a sensitivity and uncertainty analysis of the INCA-N model. Boreal Env. Res. 18: 373–386.

The semi-distributed, dynamic INCA-N model was used to simulate the behaviour of dissolved inorganic nitrogen (DIN) in two Finnish research catchments. Parameter sensitivity and model structural uncertainty were analysed using generalized sensitivity analysis. The Mustajoki catchment is a forested upstream catchment, while the Savijoki catchment represents intensively cultivated lowlands. In general, there were more influential parameters in Savijoki than Mustajoki. Model results were sensitive to N-transformation rates, vegetation dynamics, and soil and river hydrology. Values of the sensitive parameters were based on long-term measurements covering both warm and cold years. The highest measured DIN concentrations fell between minimum and maximum values estimated during the uncertainty analysis. The lowest measured concentrations fell outside these bounds, suggesting that some retention processes may be missing from the current model structure. The lowest concentrations occurred mainly during low flow periods; so effects on total loads were small.

Peltomaa, E., Ojala, A., Holopainen, A.-L. & Salonen, K. 2013: Changes in phytoplankton in a boreal lake during a 14-year period. Boreal Env. Res. 18: 387–400.

Climate-induced changes in phytoplankton were examined over a 14-year period in a remote humic headwater lake recovering from acidification. The time series analysis revealed that the total biomass as well as the biomass of the two dominant taxa — the raphidophyte Gonyostomum semen and Peridinium dinoflagellates — decreased (changes as indicated by trends –0.014 g m^–3 yr^–1 and –0.006 g m^–3 yr^–1, respectively), whereas the biomass of the subdominant Cryptomonas spp. did not change. The timing of ice-out, the extent of the spring circulation or the length of the stratification period could not be firmly connected to the phytoplankton phenology. Concentrations of major nutrients decreased during the period, whereas the dissolved organic carbon (DOC) and water colour increased. These changes probably led to the decrease in the biomass of the dominant G. semen and Peridinium spp., and thus in the total phytoplankton biomass.

Symonds, J., Morris, D. M. & Kwiaton, M. M. 2013: Effect of harvest intensity and soil moisture regime on the decomposition and release of nutrients from needle and twig litter in northwestern Ontario. Boreal Env. Res. 18: 401–413.

A four-year fine litter decomposition study was established at black-spruce dominated forest sites following harvesting that included a range of biomass removals (uncut stand, stem only, full-tree, and full-tree + bladed). The current study was designed to address the following questions: (1) does an increase in biomass removal alter the decomposition rates and nutrient release in fine litter, and (2) do these patterns differ across site types that vary in soil moisture regime? Orthogonal contrasts revealed that: (1) conditions following harvesting (all biomass removal treatments combined) slowed the decomposition of both needle and twig material as compared with that of the uncut controls, (2) removal of the forest floor further reduced needle decomposition as compared with the other harvest treatments, and (3) decomposition rates did not differ between stem-only and full-tree harvest treatments. The wet mineral sites showed a more rapid rate of decomposition within the first two years.

Mörsky, S. K., Haapala, J. K., Rinnan, R., Saarnio, S., Kyrö, E., Silvola, J., Martikainen, P. J. & Holopainen, T. 2013: Effects of elevated UV-B radiation on UV-absorbing pigments and leaf anatomy of a sedge, Eriophorum russeolum. Boreal Env. Res. 18: 414–424.

Long-term effects of elevated ultraviolet-B (UV-B) on the sedge Eriophorum russeolum were studied in a subarctic fen at Sodankylä in northern Finland for three consecutive growing seasons (2003–2005). Supplemental UV-B exposure (63%, 37% and 21% above ambient in 2003, 2004 and 2005, respectively) was conducted using fluorescent UV-lamps. The experimental plots were divided into three treatments (n = 10): ambient control, UV-A control and elevated UV-B. Elevated UV-B transiently increased the amount of cell-wall bound UV-absorbing pigments in E. russeolum leaves during the first exposure year, but the concentrations of soluble UV-absorbing compounds, total chlorophyll and carotenoids were not affected. Enhanced UV-B did not affect the leaf anatomy or senescence of E. russeolum. Additionally, there were no changes in carbon or nitrogen content and decomposition rate of E. russeolum leaves. These results show that E. russeolum responds to elevated UV-B radiation primarily by producing UV-absorbing compounds. Hence, projected UV-B radiation levels in the near future will not reduce vitality of E. russeolum.