Nykänen, M., Kairesalo, T., Mäkelä, S., Huitu, E., Ala-Opas, P. & Mannio, J. 2005: A typology and ecological classification system for Finnish lakes: applicability of the ECOFRAME scheme. Boreal Env. Res. 10: 159–179.

A pan-European typology and ecological classification system for shallow lakes was developed by the EU-funded project ECOFRAME. Here, we tested how the ECOFRAME typology separates Finnish lakes. Without accounting for division by depth, six different ecotypes resulted, one of which included the majority of the lakes. Subdivision of typology appears necessary, especially for organic types. We also collected data on a set of lakes that were extensively studied for their chemical and biological elements and classified the lakes according to the ECOFRAME classification scheme. In general, the achieved ecological quality status for each lake was less favourable than we had expected. Inspection of individual variables used in the classification highlighted some characteristics of Finnish lakes that need to be addressed in the scheme. Macrophyte variables especially need revision to better reflect the state of Finland's humic waters. However, many of the ECOFRAME solutions and guidelines were directly applicable.

Clarke, N., Røsberg, I. & Aamlid, D. 2005: Concentrations of dissolved organic carbon along an altitudinal gradient from Norway spruce forest to the mountain birch/alpine ecotone in Norway. Boreal Env. Res. 10: 181–189.

Concentrations of dissolved organic carbon (DOC) in soil water from the base of the soil organic layer were determined at three forest plots along an altitudinal gradient in eastern Norway. The lowest plot, at 830 m above sea level (a.s.l.), was in Norway spruce forest and there were additional plots at the ecotone between Norway spruce and mountain birch at 925 m a.s.l. and at the forest line (1000 m a.s.l.). DOC concentrations in soil water did not decrease uniformly with altitude although tree biomass, above-ground litterfall and the soil C pool all did so. Significant correlations between DOC and {H⁺} or electrical conductivity may reflect the contribution of DOC to solution acidity and the anionic charge, respectively. If mean temperature during the growing season increases, tree growth at any given altitude will tend to increase and the spruce-birch ecotone may move to a higher altitude than at present. Increased C inputs as litter to the soil might then lead to increasing DOC concentrations and fluxes in surface waters.

Nieminen, M., Ahti, E., Nousiainen, H., Joensuu, S. & Vuollekoski, M. 2005: Does the use of riparian buffer zones in forest drainage sites to reduce the transport of solids simultaneously increase the export of solutes? Boreal Env. Res. 10: 191–201.

Riparian buffer zone areas (BZAs) effectively reduce sediment transport and are considered as the most important water protection method in forest drainage sites in Finland. However, it has been questioned whether BZAs are a significant source of nutrients and other dissolved constituents to water-courses. At seven locations in south-central Finland a buffer zone was created below a drainage site and the effects on the concentrations of dissolved organic carbon (DOC), dissolved P, Fe and Al in through-flow were studied for 4–7 years. The effect of the two smallest BZAs (< 0.1% of watershed area) on through-flow quality was negligible. The three medium-sized BZAs (0.15%–0.23% of watershed area) either had no effect on through-flow quality or slightly increased solute concentrations (3%–30%). At the two largest BZAs (> 1% of watershed area) the concentrations of Fe either increased or decreased and the concentrations of DOC, Al and P were either unaffected or decreased (15%–27%). It was concluded that, although increased leaching may occur from some individual sites, BZAs are unlikely to act as a general source of P, Al, Fe, or DOC to water courses.

Silvan, N., Sallantaus, T., Vasander, H. & Laine, J. 2005: Hydraulic nutrient transport in a restored peatland buffer. Boreal Env. Res. 10: 203–210.

The aim of this study was to investigate the hydraulic transport of nitrate (NO₃^–) and phosphate (PO₄^3–) in a restored peatland buffer by quantifying the nitrate and phosphate input–output balance and nutrient transport in the buffer. The area of the buffer was ca. 0.5 ha, and it amounted to ca. 15%–25% of the water catchment area above. Nitrate and phosphate were added continuously during June–July in 1999, applying Ca(NO₃)₂ (110 kg Ca, 90 kg N ha^–1) and K₃PO₄ (38 kg K, 30 kg P ha^–1) water solution in the experimental area. Nutrient transport and retention in the buffer were monitored in the site in 1998–2001. Only ca. 0.5% of added nitrate and ca. 7% of added phosphate was leached through the buffer during the period 1999–2001. Especially added nitrate was retained in a relatively small area in the upper experimental area, ca. 0.2 ha, whereas added phosphate spread out to a much larger area. The results obtained indicate that the buffer is capable of removing effectively especially nitrate but also phosphate from throughflowing water, if the buffer area is large enough, and if the slope of the buffer is suitable.

Hagen, E. & Feistel, R. 2005: Climatic turning points and regime shifts in the Baltic Sea region: the Baltic winter index (WIBIX) 1659–2002. Boreal Env. Res. 10: 211–224.

The derived climate index is based on monthly values of the first principal component of (i) winter anomalies (January–March) of air pressure difference between Gibraltar and Reykjavik to describe the North Atlantic Oscillation, (ii) sea level anomalies of Landsort (Sweden) to characterise the filling level in the Baltic Proper, and (iii) maximum Baltic ice cover to include the influence of continentally dominated alignments of atmospheric centres of action (1897–2002). Resulting time coefficients were regressively completed by corresponding winter anomalies in air temperature over central England (1659–1896). The power spectrum of the obtained index (WIBIX 1659–2002) exhibits five significant quasi-cycles (2.2, 3, 6, 8, and 14 years), but also suggests periods of about 40 and 100 years. Severe (continental, WIBIX < 0) and mild (maritime, WIBIX > 0) winter types alternate and associated turning points characterise regime shifts affecting the ecosystem. Consequences for the Baltic fishery are discussed.

Urpanen, O., Huuskonen, H., Marjomäki, T. J. & Karjalainen, J. 2005: Growth and size-selective mortality of vendace (Coregonus albula (L.)) and whitefish (C. lavaretus L.) larvae. Boreal Env. Res. 10: 225–238.

Vendace (Coregonus albula (L.)) and whitefish (C. lavaretus L.) larvae were sampled by stratified random sampling design in four Finnish lakes. Otolith microstructure analysis was used to investigate individual age, hatching time and growth rate of newly hatched larvae to reveal possible size-selective mortality during early life. The majority of the larvae hatched during a short period after the ice-off. Significant differences in hatching length between the lakes were found. Growth rate decreased when larvae became larger and the growth rate was slowest in the lake with the highest density of larvae. However, larger larvae were not relatively more abundant after first weeks and thus, size-dependent mortality was not evident. Hence, we observed that mortality of these two coregonid species during the first weeks was rather random in relation to size of the larvae. Overall, the mortality of vendace larvae with smaller hatching length was higher than that of larger whitefish larvae.