Pumpanen, J., Westman, C. J. & Ilvesniemi, H. 2004: Soil CO₂ efflux from a podzolic forest soil before and after forest clear-cutting and site preparation. Boreal Env. Res. 9: 199–212.

The effect of forest harvesting and subsequent site preparation on soil CO₂ efflux was studied on a clear-cut site with five soil treatments, including mounding, exposed E- and C-horizons, and undisturbed soil with and without logging residue left on soil. Site preparation accounted for over 75% of the total variance in soil CO₂ effluxes. Clear-cutting and removal of logging residue decreased instantaneous CO₂ effluxes from the soil surface by 40%, whereas the highest instantaneous effluxes were measured from mounds and from undisturbed soil with logging residue. These sampling points showed effluxes twice as high as those in the control forest or in places where the logging residue was removed. The lowest instantaneous effluxes, about 18% of those in the control forest, were measured from the exposed C-horizon. Annual effluxes in the forest were 1900 g CO₂ m^–2 before harvesting and 3242, 2845, and 2926 g m^–2 in the three successive years after harvesting in places with logging residue, but when logging residue was removed, the annual efflux decreased to pre clear-cutting levels. Annual CO₂ efflux from the logging residue was 1423 g m^–2 during the first year after clear-cutting equaling 388 g m^–2 of C assuming even distribution of logging residue on the site. Thus, some 23% of the total C pool in the above-ground logging residue was released during the first year after clear-cutting. The estimated annual C emissions from the O-, E- and B-horizons were 352 g m^–2 during the first year after clear-cutting. Assuming that this compounded emission originated from the decomposition of roots, this would make about 20% of measured root biomass on the site. The decomposition rate was also fastest during this period, slowing in subsequent years. Based on the measured CO₂ evolution rate, the reduction observed in the decomposition rate, and the aging of decomposing material, we believe that the decomposition of logging residue is a slow process. Consequently substantial amounts of non-decomposed material still may remain at the time point when the developing new forest starts to function as a carbon sink. The carbon pool of the soil may therefore increase in the long run as a result of intensive forest management.

Fischer, P. 2004: Effects of intraspecific competition and predation risk in the littoral-benthic community: a case study of juvenile burbot (Lota lota). Boreal Env. Res. 9: 213–225.

The diel activity pattern and substratum preferences of juvenile burbot (Lota lota) were investigated in mesocosm experiments. Single specimens as well as groups of six burbot fed ad libitum, starved and with a predator present, were continuously monitored over 24 hours. The diel pattern of activity did not change among treatments but absolute activity levels were significantly different. High levels of activity were observed in solitary and starved fish, intermediate when conspecifics were present but significantly lower in the presence of a predator. Solitary specimens preferred stones while fish in a group showed a size dependent use of the substratum. The results classify the crepuscular to nocturnal behaviour of burbot as stenotype behaviour with little modulation due to external stimuli. The absolute levels of activity as well as the substratum selection however seem to be dominated by individual decisions based on a specimen's environment and predation risk.

Helmiö, T. & Järvelä, J. 2004: Hydraulic aspects of environmental flood management in boreal conditions. Boreal Env. Res. 9: 227–241.

In environmental flood management, an essential task is to improve channel conveyance using environmentally preferable methods, which aim to preserve natural morphological and hydraulic characteristics of a river. This requires a reliable channel design method that accounts for complex hydraulics, i.e. two-stage channel or considerable bank vegetation. Hydraulic field measurements were carried out in two rivers to find out how different factors affected flow resistance. In one of the study reaches, the effects of bioengineering on channel hydraulics were investigated under boreal climatic conditions. The Darcy-Weisbach friction factor, the Manning coefficient and the roughness height were related to the characteristics of channel geometry and flow. Comparison between the field data and the investigated channel design methods gave accurate results only in reaches having simple hydraulic properties. In reaches with complex hydraulics the results were poor.

Helmiö, T. 2004: Hydraulic geometry of cohesive lowland rivers. Boreal Env. Res. 9: 243–251.

Natural recovery may be extremely slow in cohesive, low-energy, lowland rivers. Therefore, a detailed understanding of the hydraulic properties of the channel is essential when designing restoration or environmental flood management measures. The aim of this study was to increase understanding on the channel size and geometry of cohesive rivers and channels. At-a-site hydraulic geometry of 34 cohesive river and channel reaches in Finland were determined from the field measurements and compared to those determined elsewhere. The computed values of the exponents of the hydraulic geometry were within the range of those presented in the literature and similar between natural and man-made channels. The results indicated that longitudinal channel variation had significant resistance effects during low water.

Rusanen, K., Finér, L., Antikainen, M., Korkka-Niemi, K., Backman, B. & Britschgi, R. 2004: The effect of forest cutting on the quality of groundwater in large aquifers in Finland. Boreal Env. Res. 9: 253–261.

The effects of forest cuttings on the level of the groundwater table and the quality of groundwater in large aquifers in Finland were studied by interpreting the long-term data from three groundwater monitoring stations together with information about the forest management history. Groundwater nitrate concentrations increased after clear-cuttings and thinnings for several years after the operations. However, the nitrate concentrations remained low (< 2 mg l^–1) even after the treatments. None of the changes in the groundwater level or in the other studied variables (electrical conductivity, alkalinity, pH, ammonium, chloride, sulphate, sodium, potassium, calcium and magnesium) could be attributed to the forestry operations.

Raateoja, M. P. 2004: Fast repetition rate fluorometry (FRRF) measuring phytoplankton productivity: A case study at the entrance to the Gulf of Finland, Baltic Sea. Boreal Env. Res. 9: 263–276.

The fast repetition rate (FRR) fluorometry, based on variable fluorescence of chlorophyll a, has been introduced as a potential tool to evaluate the primary productivity (PP) in aquatic systems. I measured PP in situ with both the ¹⁴C and the FRR techniques at the entrance to the Gulf of Finland, Baltic sea, and noticed that the relation between the ¹⁴C-based (P_b) and the FRR-based (P_f) estimates of PP was non-linear. This discrepancy between P_f measuring the rate of linear photosynthetic electron flow, and P_b measuring the rate of C fixation should be resolved before the PP can be reasonably estimated with the FRR technique. The deviation from linearity took place at irradiances above 200 µmol quanta m^–2 s^–1, since P_b reached light-saturation at lower irradiances than did P_f. Within the regression fits, the daily variability in P_b explained at least 85% of the daily variability in P_f (a total of four days, n = 11 on each day). The period of time over which PP was determined was substantially different for the two approaches; over 2 h for P_b, and approximately 10 s for P_f. Consequently, most of the deviation around the resulting fits was caused by the sensitivity of the FRR technique to the momentary incident irradiance at the time of the measurement. The FRR-based photosynthetic efficiency of phytoplankton in the upper parts of the water column could be divided into three layers: reduced levels in the near-surface layer due to inhibiting effect of supraoptimal irradiance, the layer beneath this having the highest levels, and the deepest layer inhabited by a senescent algal population characterized by lowered levels.