ISSN 1239-6095 (print),   ISSN 1797-2469 (online)
© Boreal Environment Research 2015

Contents of Volume 20 no. 6

Saltikoff E., Lopez P., Taskinen A. & Pulkkinen S. 2015: Comparison of quantitative snowfall estimates from weather radar, rain gauges and a numerical weather prediction model. Boreal Env. Res. 20: 667–678.
Abstract
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Denfeld B.A., Wallin M.B., Sahlée E., Sobek S., Kokic J., Chmiel H.E. & Weyhenmeyer G.A. 2015: Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice-cover dynamics. Boreal Env. Res. 20: 679–692.
Abstract
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Kaila A., Laurén A., Sarkkola S., Koivusalo H., Ukonmaanaho L., O’Driscoll C., Xiao L., Asam Z. & Nieminen M. 2015: Effect of clear-felling and harvest residue removal on nitrogen and phosphorus export from drained Norway spruce mires in southern Finland. Boreal Env. Res. 20: 693–706.
Abstract
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Huhtamaa H., Helama S., Holopainen J., Rethorn C. & Rohr C. 2015: Crop yield responses to temperature fluctuations in 19th century Finland: provincial variation in relation to climate and tree-rings. Boreal Env. Res. 20: 707–723.
Abstract
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Jukonienė I., Dobravolskaitė R., Sendžikaitė J., Skipskytė D. & Repečkienė J. 2015: Disturbed peatlands as a habitat of an invasive moss Campylopus introflexus in Lithuania. Boreal Env. Res. 20: 724–734.
Abstract
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Rasmus K., Kiirikki M. & Lindfors A. 2015: Long-term field measurements of turbidity and current speed in the Gulf of Finland leading to an estimate of natural resuspension of bottom sediment. Boreal Env. Res. 20: 735–747.
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Berninger F., Susiluoto S., Gianelle D., Bahn M., Wohlfahrt G., Sutton M., Garcia-Pausas J., Gimeno C., Sanz M.J., Dore S., Rogiers N., Furger M., Eugster W., Balzarolo M., Sebastià M.T., Tenhunen J., Staszewski T. & Cernusca A. 2015: Management and site effects on carbon balances of European mountain meadows and rangelands. Boreal Env. Res. 20: 748–760.
Abstract
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Saltikoff E., Lopez P., Taskinen A. & Pulkkinen S. 2015: Comparison of quantitative snowfall estimates from weather radar, rain gauges and a numerical weather prediction model. Boreal Env. Res. 20: 667–678.

Quantitative snowfall estimates are needed in hydrology and weather services. Snow measurements with weather radars and rain gauges are challenging, hence adjustment methodologies have been developed for them. Still, the accumulations from different data sources differ. We compared different data sets from radars, gauges and numerical weather prediction models, commonly used in operational or semi-operational applications with varying corrections applied. The mean ratio of radar-based quantitative precipitation estimates (QPE) to the reference data sets varied between 0.43 and 1.59. Variability of the microphysical properties of snow is so large that a perfect operational solution for all situations may be impossible to reach. However, much improvement could be achieved if the presently-known methods were applied to all snowfall measurements.
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Denfeld B.A., Wallin M.B., Sahlée E., Sobek S., Kokic J., Chmiel H.E. & Weyhenmeyer G.A. 2015: Temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice-cover dynamics. Boreal Env. Res. 20: 679–692.

Global carbon dioxide (CO2) emission estimates from inland waters commonly neglect the ice-cover season. To account for CO2 accumulation below ice and consequent emissions into the atmosphere at ice-melt we combined automatically-monitored and manually-sampled spatially-distributed CO2 concentration measurements from a small boreal ice-covered lake in Sweden. In early winter, CO2 accumulated continuously below ice, whereas, in late winter, CO2 concentrations remained rather constant. At ice-melt, two CO2 concentration peaks were recorded, the first one reflecting lateral CO2 transport within the upper water column, and the second one reflecting vertical CO2 transport from bottom waters. We estimated that 66%–85% of the total CO2 accumulated in the water below ice left the lake at ice-melt, while the remainder was stored in bottom waters. Our results imply that CO2 accumulation under ice and emissions at ice-melt are more dynamic than previously reported, and thus need to be more accurately integrated into annual CO2 emission estimates from inland waters.
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Kaila A., Laurén A., Sarkkola S., Koivusalo H., Ukonmaanaho L., O’Driscoll C., Xiao L., Asam Z. & Nieminen M. 2015: Effect of clear-felling and harvest residue removal on nitrogen and phosphorus export from drained Norway spruce mires in southern Finland. Boreal Env. Res. 20: 693–706.

Calibration-period/control-area approach was used to study nitrogen and phosphorus export from drained and productive Norway-spruce-dominated peatland forests following conventional stem-only and whole-tree harvesting. The study indicated high nitrogen and particulate phosphorus exports and lack of significant differences between the harvest treatments during the first 3–4 years after harvesting. The high extra nitrogen exports, increasing to a maximum level of about 10 kg ha–1 during the third year after harvesting, were partly caused by the higher nitrate export than in previous studies. The study has a practical outcome that management of harvest residues (i.e. left on site or harvested) may not be an efficient means of mitigation of nitrogen and phosphorus exports. The high exports following harvesting underline the importance of using the best available water protection methods, such as sufficiently large wetland buffer areas, to decrease nutrient exports to watercourses from productive Norway spruce dominated peatland catchments.
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Huhtamaa H., Helama S., Holopainen J., Rethorn C. & Rohr C. 2015: Crop yield responses to temperature fluctuations in 19th century Finland: provincial variation in relation to climate and tree-rings. Boreal Env. Res. 20: 707–723.

Past agricultural responses to climate variability can helps us to better understand the current and future impacts of climate change on agricultural production. We studied rye (Secale cereale) and barley (Hordeum vulgare) yield responses to temperature fluctuations in Finland during the period 1861–1913. Our analyses demonstrate the high sensitivity of non-industrialised northern agriculture to temperature anomalies. We found evidence of a strong relationship between monthly and seasonal mean temperatures and crop yields. In particular, high spring temperatures were associated with higher yields. Additionally, we tested temperature-sensitive tree-ring series for their value in indicating previous agricultural outputs. The results imply that tree-ring proxies (in particular, maximum latewood density) can provide novel material for studies of historical periods and locations where instrumentally measured climate and harvest data are not available.
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Jukonienė I., Dobravolskaitė R., Sendžikaitė J., Skipskytė D. & Repečkienė J. 2015: Disturbed peatlands as a habitat of an invasive moss Campylopus introflexus in Lithuania. Boreal Env. Res. 20: 724–734.

Distribution of Campylopus introflexus in disturbed peatlands was investigated throughout Lithuania in 2010–2011. Frequency and abundance of the invasive moss species were evaluated according to the parameters of peat (pH, total nitrogen, phosphorus, potassium and organic matter), prevailing herb-layer species, percentage of cover of herb and tree layers, amount of litter, and time since the abandonment of the area. Campylopus introflexus was recorded in 68.7% of the investigated disturbed peatlands, of these, 63.8% had recently been managed. The cover of the invasive moss did not correlate with most parameters of peat, but it differed significantly among the plots (1) with different prevailing herb-layer species, (2) abandoned for different lengths of time, (3) with developed and undeveloped tree layer, and (4) with different pH.
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Rasmus K., Kiirikki M. & Lindfors A. 2015: Long-term field measurements of turbidity and current speed in the Gulf of Finland leading to an estimate of natural resuspension of bottom sediment. Boreal Env. Res. 20: 735–747.

Long-term current and turbidity measurements were carried out at two locations in the northern Gulf of Finland using bottom-mounted, automatic turbidity and current meters. An uninterrupted three-year time series of current speeds and turbidity was obtained for the years 2009–2012. The data were originally collected for the NordStream project. The first location was in the western Gulf of Finland (59°44.0´N, 23°29.2´E), where an average turbidity close to the bottom (at a depth of 41 m) was 1.58 nephelometric turbidity units (NTU), and an average current speed 5.5 cm s–1. The second location was in the eastern Gulf of Finland (60°10.6´N, 26°45.1´E) where an average turbidity close to the bottom (at a depth of 44 m) was 0.67 NTU, and an average current speed 4.45 cm s–1. The Rouse profile for the vertical distribution of sediment in water was then used to calculate the amount of sediment in the water column from the measured turbidity and current speeds. Consecutive hourly values were then compared to see whether resuspension had occurred. The resuspension values were then summed up to get yearly values of natural resuspension. These were found to be approximately 10–20 kg m–2 for the western location and 5–10 kg m–2 for the eastern location.
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Berninger F., Susiluoto S., Gianelle D., Bahn M., Wohlfahrt G., Sutton M., Garcia-Pausas J., Gimeno C., Sanz M.J., Dore S., Rogiers N., Furger M., Eugster W., Balzarolo M., Sebastià M.T., Tenhunen J., Staszewski T. & Cernusca A. 2015: Management and site effects on carbon balances of European mountain meadows and rangelands. Boreal Env. Res. 20: 748–760.

We studied carbon balances and carbon stocks of mountain rangelands and meadows in a network of 8 eddy covariance sites and 14 sites with biomass data in Europe. Net ecosystem exchange of pastures and extensively managed semi-natural rangelands were usually close to zero, while meadows fixed carbon, with the exception of one meadow that was established on a drained peatland. When we accounted for off-site losses and inputs also the carbon budget of meadows approached zero. Soil carbon stocks in these ecosystems were high, comparable to those of forest ecosystems, while carbon stocks in plant biomass were smaller. Since soil carbon stocks of abandoned mountain grasslands are as high as in managed ecosystems, it is likely that the widespread abandonment of mountain rangelands used currently as pastures will not lead to an immediate carbon sink in those ecosystems.
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