Nieminen, J. K. & Pohjola, P. 2014: Labile carbon addition affects soil organisms and N availability but not cellulose decomposition in clear-cut Norway spruce forests. Boreal Env. Res. 19: 257–266.
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Danielsson, Â 2014: Influence of hypoxia on silicate concentrations in the Baltic Proper (Baltic Sea). Boreal Env. Res. 19: 267–280.
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Sutinen, S., Roitto, M., Lehto, T. & Repo, T. 2014: Simulated snowmelt and infiltration into frozen soil affected root growth, needle structure and physiology of Scots pine saplings. Boreal Env. Res. 19: 281–294.
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Maljanen, M., Liimatainen, M., Hytönen, J. & Martikainen, P. J. 2014: The effect of granulated wood-ash fertilization on soil properties and greenhouse gas (GHG) emissions in boreal peatland forests. Boreal Env. Res. 19: 295–309.
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Stivrins, N., Kalnina, L., Veski, S. & Zeimule, S. 2014: Local and regional Holocene vegetation dynamics at two sites in eastern Latvia. Boreal Env. Res. 19: 310–322.
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Díaz-Gil, C., Werner, M., Lövgren, O., Kaljuste, O., Grzyb, A., Margoński, P. & Casini, M. 2014: Spatio-temporal composition and dynamics of zooplankton in the Kalmar Sound (western Baltic Sea) in 2009–2010. Boreal Env. Res. 19: 323–335.
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Nieminen, J. K. & Pohjola, P. 2014: Labile carbon addition affects soil organisms and N availability but not cellulose decomposition in clear-cut Norway spruce forests. Boreal Env. Res. 19: 257–266.

We assessed the effects of sucrose addition on the biological and chemical properties of organic soil in clear-cut Norway spruce forests managed with or without wood-ash fertilization and mechanical site preparation. Sucrose addition increased the abundances of enchytraeids and tardigrades and soil moisture percentage in the clear-cut areas. Sucrose also increased nematode abundance in the non-fertilized plots. Sucrose reduced the pool of water-extractable NH₄-N in the soil in the first year, but increased it in the second year. Sucrose addition did not affect the decomposition rate of cellulose strips. The biomass of ground vegetation was not affected by sucrose. Carbohydrate addition seems to enhance N immobilization in clear-cut areas in the short term, and it is suggested that aims at reducing N loss from disturbed forest soil do not necessarily accelerate carbon loss from the forest ecosystem.

Danielsson, Â 2014: Influence of hypoxia on silicate concentrations in the Baltic Proper (Baltic Sea). Boreal Env. Res. 19: 267–280.

Silica (Si) is a key nutrient for diatoms. Over the last century, Si concentrations within the Baltic Sea decreased significantly. This is mainly attributed to ongoing eutrophication, increased production and subsequent deposition and accumulation of organic matter including biogenic silica. As a consequence of the eutrophication, hypoxic and anoxic bottom waters have spread affecting nutrient cycling. This paper looks at the potential impact of oxygen on dissolved silica (DSi). It presents a statistical analysis of the relationship between DSi concentrations and oxygen conditions (O₂) in the deep water of the Baltic Proper. The idea is not new, but this is the first time it is studied in more detail in this area. Regression analysis shows that DSi concentrations decrease significantly with O₂ concentrations, and that the major intrusion of saline water in 1993 strengthened this relationship. Increased hypoxia will significantly affect the cycling of Si in the Baltic Sea.

Sutinen, S., Roitto, M., Lehto, T. & Repo, T. 2014: Simulated snowmelt and infiltration into frozen soil affected root growth, needle structure and physiology of Scots pine saplings. Boreal Env. Res. 19: 281–294.

Climate warming scenarios predict a decreased snow cover and more rain instead of snow in boreal areas in winter. These conditions may affect soil freezing processes. We studied how watering of the soil before and after soil thawing affects fine roots and shoots of Scots pine saplings during the follow-up season. A growth chamber experiment was carried out with four treatments. During the dormancy water was applied onto frozen soil three times (3xFROSOIL) or once (1xFROSOIL) whereas in the beginning of the growing season the watering was started when the soil temperature reached +9 (START+9) and +15 ²C (START+15). Fine root damage was noted in 3xFROSOIL, and on a smaller scale also in 1xFROSOIL. The root growth did not recover during the follow-up season. Due to the root damage, in 3xFROSOIL there was a reduced transport of water in the saplings, which induced xeromorphic features in the needles developed after the treatment. The fine root damage in 3xFROSOIL was most probably caused by mechanical breakage after the applied water froze in the soil. Our results suggest that even established saplings may suffer root damage if the climatic and soil conditions favour infiltration and freezing cycles of water, which induce frost heaving.

Maljanen, M., Liimatainen, M., Hytönen, J. & Martikainen, P. J. 2014: The effect of granulated wood-ash fertilization on soil properties and greenhouse gas (GHG) emissions in boreal peatland forests. Boreal Env. Res. 19: 295–309.

The amount of wood ash produced in power plants is increasing with increasing use of forest biomass in energy production. Wood ash can be recycled as fertilizer especially in boreal peatland forests naturally rich in nitrogen. Improved nutrient availability and increases in soil pH can enhance microbial activities, decomposition of organic matter and greenhouse gas (GHG) emissions. We studied the effects of granulated wood-ash on soil chemical properties, vegetation characteristics, decomposition rate and fluxes of nitrous oxide (N₂O) and methane (CH₄) in boreal peatland forests. In addition to the field measurements, we conducted laboratory experiments. Wood-ash fertilization changed soil chemical properties, altered understory vegetation, increased tree growth and decomposition rate but there were no significant changes in the N₂O and CH₄ fluxes in situ, whereas in laboratory incubations ash decreased the N₂O production rate. The results show that there is no major risk of increasing GHG emissions after granulated wood-ash fertilization in boreal peatland forests.

Stivrins, N., Kalnina, L., Veski, S. & Zeimule, S. 2014: Local and regional Holocene vegetation dynamics at two sites in eastern Latvia. Boreal Env. Res. 19: 310–322.

The study compares the local and regional Holocene vegetation dynamics of two sites in eastern Latvia. Both sites show similar trends in vegetation change. Differences were found in local abundances of Betula, Pinus and Picea. Lower amounts of Betula at the local site suggest stronger regional pollen influx into the regional site. The continuous presence of conifer stomata indicates the development of a stand-scale conifer forest at the local site since 5000 cal yr BP. Similar presence and dynamics in thermophilous tree species at both sites suggest that the pollen values of the regional site may truly show the local presence of thermophilous tree taxa. Apart from general vegetation succession, the strongest cause for the vegetation differences at both sites were water-level changes, as shown by the peat decomposition rate.

Díaz-Gil, C., Werner, M., Lövgren, O., Kaljuste, O., Grzyb, A., Margoński, P. & Casini, M. 2014: Spatio-temporal composition and dynamics of zooplankton in the Kalmar Sound (western Baltic Sea) in 2009–2010. Boreal Env. Res. 19: 323–335.

In pelagic food webs, zooplankton is the link between lower and higher trophic levels. It is thus essential to know how the zooplankton community structure varies with its environment. We investigated the seasonal and spatial variation in the zooplankton diversity and community structure during two consecutive years in the Kalmar Sound, along the Swedish east coast, an area with a strong bathymetric gradient and of high ecological importance for e.g. commercial fish species. Two zooplankton communities were identified in the area: a coastal/estuarine community in the south and an open-water community in the north. They were separated mainly by differing salinity and temperature conditions. Biodiversity increased from spring to autumn and was higher in the open waters.