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

Contents of Volume 20 no. 1

Stenberg L., Finér L., Nieminen M., Sarkkola S. & Koivusalo H. 2015: Quantification of ditch bank erosion in a drained forested catchment. Boreal Env. Res. 20: 1–18.
Abstract
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Kallio-Nyberg I., Saloniemi I. & Jutila E. 2015: Growth of hatchery-reared sea trout (Salmo trutta trutta) on the Finnish coast of the Baltic Sea. Boreal Env. Res. 20: 19–34.
Abstract
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Aldvén D., Degerman E. & Höjesjö J. 2015: Environmental cues and downstream migration of anadromous brown trout (Salmo trutta) and Atlantic salmon (Salmo salar) smolts. Boreal Env. Res. 20: 35–44.
Abstract
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Morris D.M., Wiebe S.A., Luckai N.J. & Reid D.E.B. 2015: Nutrient retention and leaching potential of coarse wood bolts collected from logged and burned upland boreal sites: a greenhouse misting experiment. Boreal Env. Res. 20: 45–61.
Abstract
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Lundberg P. 2015: "O that awful deepdown torrent". Boreal Env. Res. 20: 62–74.
Abstract
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Miettinen H., Pumpanen J., Heiskanen J.J., Aaltonen H., Mammarella I., Ojala A., Levula J. & Rantakari M. 2015: Towards a more comprehensive understanding of lacustrine greenhouse gas dynamics — two-year measurements of concentrations and fluxes of CO2, CH4 and N2O in a typical boreal lake surrounded by managed forests. Boreal Env. Res. 20: 75–89.
Abstract
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Futsaether C.M., Vollsnes A.V., Kruse O.M., Indahl U.G., Kvaal K. & Eriksen A.B. 2015: Daylength influences the response of three clover species (Trifolium spp.) to short-term ozone stress. Boreal Env. Res. 20: 90–104.
Abstract
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Pirjola L., Virkkula A., Petäjä T., Levula J., Kukkonen J. & Kulmala M. 2015: Mobile ground-based measurements of aerosol and trace gases during a prescribed burning experiment in boreal forest in Finland. Boreal Env. Res. 20: 105–119.
Abstract
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Aronsuu K., Marjomäki T.J., Tuohino J., Wennman K., Vikström R. & Ojutkangas E. 2015: Migratory behaviour and holding habitats of adult river lampreys (Lampetra fluviatilis) in two Finnish rivers. Boreal Env. Res. 20: 120–144.
Abstract
Full text (pdf format)


Stenberg L., Finér L., Nieminen M., Sarkkola S. & Koivusalo H. 2015: Quantification of ditch bank erosion in a drained forested catchment. Boreal Env. Res. 20: 1–18.

In boreal areas where forestry extends to drained peatlands, erosion and sediment transport from ditch networks are among the most harmful effects of forestry. To explore and quantify the initial bank erosion processes at their source area, topography of a 3.8-metre-long section of a newly cleaned ditch bank was measured at different times with a pin meter. The risk of erosion in the ditch bank was increased by generating elevated water table conditions using artificial irrigation. Erosion and soil deposition were estimated by calculating the changes in the bank topography between the sequential measurements. The total erosion was 41 kg m–1 within the studied stretch. The eroded material was deposited at the bottom of the ditch and exposed to transportation only later during greater discharge events. The pin meter was found to be a workable device for detecting the erosion-induced changes (1–15 cm) in the ditch dimensions.
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Kallio-Nyberg I., Saloniemi I. & Jutila E. 2015: Growth of hatchery-reared sea trout (Salmo trutta trutta) on the Finnish coast of the Baltic Sea. Boreal Env. Res. 20: 19–34.

The marine growth of approximately 20 000 tagged and recaptured sea trout (Salmo trutta trutta) smolts was examined following Finnish releases into the Baltic Sea from 1980 to 2010. All these trout smolts were hatchery reared. Due to the low catch length and intensive fishing, a high proportion of the trout were captured in their first and second sea year, i.e. before spawning. Sea trout grew better in the southern Finnish sea area (59°30'–60°30'N) than in its northern parts (60°30'–66°N). The marine growth rate increased in both sea areas from 1980 to 2010, but relatively more in the northern than the southern one, especially among the northern two-sea-winter-old trout. Better annual marine growth was associated with an increase in the sea surface temperature in April, or a high abundance of Baltic herring (Clupea harengus membras). The condition factor of trout was higher in the southern than the northern sea area and was positively linked to herring abundance.
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Aldvén D., Degerman E. & Höjesjö J. 2015: Environmental cues and downstream migration of anadromous brown trout (Salmo trutta) and Atlantic salmon (Salmo salar) smolts. Boreal Env. Res. 20: 35–44.

Several environmental cues have been suggested to govern the initiation of the downstream migration of smolts (e.g. light, temperature and discharge). Here we investigated the effect of these cues on the initiation of the downstream migration in anadromous brown trout and Atlantic salmon in a small river on the Swedish west coast during two consecutive years. The total smolt production was assessed using a smolt trap and by modelling data from standardized electrofishing. The results show that it is possible to estimate smolt numbers using electrofishing, but that the model had a tendency to overestimate the number of smolts from electrofishing as compared with that from captures with the smolt trap. Discharge had the greatest effect on downstream migration, but temperature was also important when there was no increase in discharge. These results reveal that discharge and temperature govern the initiation of downstream migration but their effect may depend on the amount of precipitation.
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Morris D.M., Wiebe S.A., Luckai N.J. & Reid D.E.B. 2015: Nutrient retention and leaching potential of coarse wood bolts collected from logged and burned upland boreal sites: a greenhouse misting experiment. Boreal Env. Res. 20: 45–61.

This 16-week, ex situ greenhouse misting trial was designed to isolate and compare the patterns of carbon and nutrient release from coarse woody debris (CWD). Comparisons included: hardwood (aspen) versus conifer (spruce); harvest- versus fire-origin; and among decay classes (DC1 to DC5). In terms of nutrient concentrations in the CWD bolts, with the exception of C and Mn, the aspen logs had significantly higher concentrations than the spruce logs and lower C:N ratios. The spruce logs did, however, contain six times higher levels of Mn as compared with those of aspen. In terms of origin, only Mn was altered (volatilized) as a result of being burned/charred, resulting in significantly lower concentrations levels. As decomposition progressed, there was a general increase in nutrient concentrations, and a reduction in C:N ratios. In all cases, the logs were a source of DOC for both species and decay class. In the case of decay class, DOC leachate was relatively low for the first three decay classes, peaked as a strong source for DC4, then a small, but significant reduction for the DC5 logs. The leachate pattern for N, however, differed in that both DC1 and DC2 logs had negative fluxes, indicating immobilization of N, but thereafter (DC3–5) the CWD leachate was an increasing source of N. For P, K, Ca, Mg, and Mn there was an overwhelming effect on the cumulative flux exerted by species, with significantly higher levels of P, K, Ca, and Mg from the aspen logs, but significantly lower levels of Mn. This pattern corresponds to the weighted concentrations in the logs, with aspen having three to four times higher concentrations of P, K, Ca, Mg, but six times lower levels of Mn. In light of initiatives calling for increased utilization of unmerchantable or low value wood within typical boreal harvesting systems, the current results suggest that careful consideration of the type and amount of CWD (species, decay class) that should be retained on site, as well as consideration for CWD "recruitment" (i.e., green tree retention) should be incorporated into biomass harvesting guidelines.
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Lundberg P. 2015: "O that awful deepdown torrent". Boreal Env. Res. 20: 62–74.

An overview of the deep-water flow from the Nordic Seas through the Faroe-Bank Channel and the Denmark Strait into the North Atlantic proper is given. These fluxes are of considerable importance for the global thermohaline circulation, and it is outlined how they can be modeled on the basis of rotating hydraulic theory for zero- as well as finite-potential-vorticity flow. The hydraulic framework is also shown to be useful for analyzing various dynamic features characterizing the deep-water flow.
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Miettinen H., Pumpanen J., Heiskanen J.J., Aaltonen H., Mammarella I., Ojala A., Levula J. & Rantakari M. 2015: Towards a more comprehensive understanding of lacustrine greenhouse gas dynamics — two-year measurements of concentrations and fluxes of CO2, CH4 and N2O in a typical boreal lake surrounded by managed forests. Boreal Env. Res. 20: 75–89.

Lakes emit terrestrially fixed carbon back to the atmosphere as carbon dioxide (CO2) and methane (CH4). Redox conditions in the water columns of lakes typically vary seasonally, and therefore lakes may also be sources of nitrous oxide (N2O). In this study, we measured the weekly water column concentrations of CO2, CH4 and N2O in a boreal lake and calculated the annual emissions of these gases for the years 2011 and 2012. We found that the emissions of all the gases studied were high right after the ice melt, CH4 most likely originating from the catchment. Bottom anoxia in summer induced maximum concentrations of CH4 and N2O near the sediment, but only elevated the emission of N2O in autumn 2012. Otherwise, the high concentrations near the sediment did not affect the surface concentrations. The unstable water column in summer 2012 increased the CO2 and N2O emissions, but prevented anoxia, and thus decreased the CH4 concentrations. From the perspective of global warming, the CO2 emissions were by far the most significant and the relevance of the N2O emissions was negligible.
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Futsaether C.M., Vollsnes A.V., Kruse O.M., Indahl U.G., Kvaal K. & Eriksen A.B. 2015: Daylength influences the response of three clover species (Trifolium spp.) to short-term ozone stress. Boreal Env. Res. 20: 90–104.

Long photoperiods characteristic of summers at high latitudes can increase ozone-induced foliar injury in subterranean clover (Trifolium subterraneum). This study compared the effects of long photoperiods on ozone injury in red and white clover cultivars adapted to shorter or longer daylengths of southern or northern Fennoscandia. Plants were exposed to 70 ppb ozone for six hours during the daytime for three consecutive days. Simultaneously, the daylength in the growth rooms was altered to long-day (10 h light; 14 h dim light) and short-day (10 h light; 14 h darkness) conditions. Thermal imaging showed that ozone disrupted leaf temperature and stomatal function, particularly in sensitive species, in which leaf temperature deviations persisted for several days after ozone exposure. Long-day conditions increased visible foliar injury (30%–70%), characterized by chlorotic and necrotic areas, relative to short day conditions in all species and cultivars independently of the photoperiod in the region they were adapted to.
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Pirjola L., Virkkula A., Petäjä T., Levula J., Kukkonen J. & Kulmala M. 2015: Mobile ground-based measurements of aerosol and trace gases during a prescribed burning experiment in boreal forest in Finland. Boreal Env. Res. 20: 105–119.

As a part of the EUCAARI and IS4FIRES projects, a prescribed burning experiment was conducted near the SMEAR II station in Hyytiälä, Finland, on 26 June 2009. The ground-level concentrations of the smoke at different distances from the burn area were measured by a mobile laboratory van "Sniffer". The maximum of the total particle number concentration, Ntot, was 2.7 x 106 cm–3 at a distance of around 180 m from the burn area. The number size distribution had two modes peaking at 12–16 nm and 90–100 nm during the flaming phase, and three modes peaking at 6–10 nm, 42–70 nm, and 260–460 nm during the smouldering phase. The accumulation and coarse mode particles dominated the volume size distributions. The emission ratios were calculated for Ntot, PM2.5, CO and NOx in regard to the excess CO2 concentration. The obtained emission factors EF (number or mass per kg fuel burned) were 18.4 x 1015 kg–1, 29.0 g kg–1, 52.1 g kg–1, and 2.7 g kg–1 for Ntot, PM2.5, CO and NOx, respectively.
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Aronsuu K., Marjomäki T.J., Tuohino J., Wennman K., Vikström R. & Ojutkangas E. 2015: Migratory behaviour and holding habitats of adult river lampreys (Lampetra fluviatilis) in two Finnish rivers. Boreal Env. Res. 20: 120–144.

The effect of environmental factors on migratory activity of adult river lampreys entering the Kalajoki and Perhonjoki, rivers in Finland, for spawning was studied using correlation and regression analyses. Telemetric tracking of 60 individuals was utilized to study the migratory patterns and holding habitat requirements of adult river lampreys. The increases in the river discharge, wind forcing towards the river mouth and speed and magnitude of river water cooling had positive effects on the numbers of lampreys entering the rivers whereas the increase in the illumination intensity of the moon had a negative effect on their migration activity. Radio-tagged lampreys typically passed slow-flowing river sections as well as steep riffles during one night, and were holding in runs, glides and the lowermost section of riffles. Substratum dominated by large boulders (> 256 mm) was preferred during winter holding behaviour. The migratory activity of lampreys released in low (< 2 °C) and high (> 16 °C) river water temperatures was low. Lampreys tended to halt next to illuminated bridges, and we suggest that this behaviour markedly shortened migration distances. The passage efficiency through a natural-like fish ramp in the low-head barrier was 100%. The results can be utilized in mitigation actions like river restoration, transplanting of adults, and improving passage and water flow regulation.
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