Törnblom, K., Bergström, H. & Johansson, C. 2007: Thermally driven mesoscale flows — simulations and measurements. Boreal Env. Res. 12: 623–641.

The wind climate shows often large local variations in coastal areas. The present study was based on measurements at several sites on the island of Gotland in the Baltic Sea and on simulations with a numerical meso-[gamma]-scale atmosphere model (the MIUU model). It is common for thermally driven flows, e.g. sea breezes and low level jets, to evolve resulting in supergeostrophic winds. The most important parameters affecting these flows were found to be temperature and roughness differences between the land and sea. Although the wind speed increases climatologically over a see, a case where the wind speed decreased when advected out over a cold sea was investigated. This happens if the stable boundary layer (SBL) over the sea is deep enough. A deep SBL is favoured by strong thermal winds in combination with large temperature differences between the land and sea. With a shallow SBL the wind speed increases over the sea.

Stankunavicius, G., Valiuskevicius, G., Rimkus, E., Bukantis, A. & Gulbinas, Z. 2007: Meteorological features behind spring runoff formation in the Nemunas River. Boreal Env. Res. 12: 643–651.

This paper is concerned with atmospheric circulation as the central factor influencing snow melting conditions and consequently the spring runoff characteristics of the Nemunas River. The analysis includes snow water equivalent (SWE) accumulated before the start of snowmelt runoff and its relationship with maximal water discharge and flood volume. The results show that the relationship has a dipolar character. The cohesion between SWE and the maximal runoff was divided into two different groups: A and B. The increasing maximal values of SWE correspond to the rapidly increasing maximal water discharge during the runoff seasons in group A and slowly increasing discharge in group B. Intensive snow melting following significant warm advection in the lower troposphere or, conversely, dominant radiative snow melting despite the high values of snow water equivalent, cause the high magnitude spring floods of the Nemunas River. The importance of atmospheric circulation increases during the beginning of the spring runoff in particular.

Kont, A., Endjärv, E., Jaagus, J., Lode, E., Orviku, K., Ratas, U., Rivis, R., Suursaar, Ü. & Tõnisson, H. 2007: Impact of climate change on Estonian coastal and inland wetlands — a summary with new results. Boreal Env. Res. 12: 653–671.

The natural environment of Estonia is sensitive to climate change due to its location in a transitional zone between areas with different bioclimatic conditions. We studied the NAO index and data on temperature, moisture, wind, and sea level regimes in Estonia and the Baltic Sea region. We also looked at the relationships between meteorological forcing time series and changes in wetlands. The effects of changing climatic conditions are clearly reflected in the data from the station at Tooma mire, where we identified shorter snow-cover duration, decreased soil-frost depth and changed groundwater levels in the bog. In comparing various types of Estonian wetlands under such changing climatic conditions, we also identified greater instability in the character of coastal wetlands compared to that of the inland bogs. We found that the most marked coastal changes in Estonia result from a combination of strong storms, high sea levels induced by storm surge, ice free seas and unfrozen sediments. Finally, we also found that a significant trend in the development of seashore grasslands is the replacement of former meadows by reed beds, shrubberies or woodland.

Vehniäinen, E.-R., Häkkinen, J. M. & Oikari, A. O. J. 2007: Responses to ultraviolet radiation in larval pike, Esox lucius, of two origins and ages. Boreal Env. Res. 12: 673–680.

Ultraviolet radiation (UVR)-induced mortality and behavioural disorder were studied in larval northern pike of two origins and ages. Newly hatched larvae of two differently coloured populations and six-day-old larvae of one population were exposed to four fluence rates of UVR, resulting in total doses from 11.5 to 63 kJ m^–2, and monitored for mortality and behaviour. The rate of mortality and the severity of behavioural disorder differed by origin and age of the animals, but the effect was fluence-rate dependent. Total melanin concentration of newly hatched larvae was measured to assess if sensitivity to UVR correlated with pigmentation, but no differences in melanin concentration between larvae from different origins were found.

Callesen, I., Raulund-Rasmussen, K., Westman, C. J. & Tau-Strand, L. 2007: Nitrogen pools and C:N ratios in well-drained Nordic forest soils related to climate and soil texture. Boreal Env. Res. 12: 681–692.

Relationships between soil nitrogen (N) pools, climate, and soil-texture class in well-drained Nordic forest soils may be used for upscaling of regional N budgets. Total soil N pools and C:N ratios were studied in forest soils in Fennoscandia and Denmark (55–70°N, 5–27°E) in boreal pine and spruce forest, boreal mixed forest, and nemoral forest types (beech, oak, mixed). Total N pools in 198 forest soil profiles were calculated from horizon thickness, bulk density, stone content and nitrogen concentration and related to climate and soil texture through multiple linear regressions. The top 100 cm of the mineral soil and the organic layer were included. C:N ratios were calculated from C and N concentrations in 10-cm depth sections. Total soil N pools ranged from 0.05 to 1.65 kg N m^–2 and were positively correlated with mean annual temperature (MAT) and mean annual precipitation (MAP). The range of mean annual temperatures was –2 °C to 8.4 °C, and the range of mean annual precipitations was 282 to 2270 mm y^–1. Soil N pools were highly variable and related to climate and soil texture class. The total soil N pools in coarse textured soils changed more with changing MAT and MAP than those in medium textured soils due to lower N pools in coarse soils in the northern part of the study area. C:N ratios were negatively correlated with temperature and precipitation in the uppermost mineral soil layers and the organic layer. C:N ratios of soil organic matter in the organic layer or top mineral soil are indicators of litter quality and degree of humification, but also reflect ecosystem N status in high N deposition areas.

Renou-Wilson, F. & Farrell, E. P. 2007: Phosphorus in surface runoff and soil water following fertilization of afforested cutaway peatlands. Boreal Env. Res. 12: 693–709.

This study retraced the fate of phosphorus (P) applied to various types of afforested cutaway peatlands and examined the spatial and temporal trends in the concentration of soluble molybdate reactive phosphorus (MRP) in surface runoff water and soil water. Edaphic characteristics had a critical role to play in the occurrence of P loss. The occurrence and magnitude of P loss also depended on the rate and method of application of the fertilizer and transport factors such as surface runoff, which is directly related to hydrological processes and climatic conditions. Due to low P-binding capacity, immediate P loss is inevitable from newly fertilized deep peat unless edaphic properties can be altered, e.g. by mixing the peat with calcareous sub-peat mineral soil. P loss can be reduced by (1) applying the initial fertilizer in band rather than broadcast, (2) splitting in two applications and applying the minimum rate of fertilizer necessary at planting, and (3) establishing a vegetation cover. The fate of lost P is still unknown as low MRP concentrations were recorded in the drain water two years after fertilization. Finally, P losses have been confirmed to be temporary as no P losses were recorded in plantations which had been established and fertilized ten years previously.