Depositional history of peatland pines (Pinus sylvestris L.) in NW Enontekiö, Finnish Lapland: implications for Middle Holocene drought and temperature fluctuations

High altitude and latitude findings of subfossil peatland pine trees were unearthed from the region of NW Finnish Lapland and dated by ¹⁴C and tree-ring methods. The depositional history of the trees illustrated two distinct peatland pine phases dated to Middle Holocene intervals 4900–4400 and 4100–3400 cal. a BC. It seems evident that both thermal and hydroclimatic fluctuations have played roles of varying importance in the establishment of this pine population and its demise. The presence of these pines, from a site ~60 km north of the coniferous timberline and conditions ~1 °C and 100 degree-days colder than those at the present-day timberline, concurs with previous studies demonstrating the association between the high-latitude summer-temperature cooling and circumpolar timberline retreat since the Middle Holocene due to Milankovitch forcing. On the other hand, the peatland pine recruitment was made possible by drier than present surface conditions during the previously reconstructed Middle Holocene drought anomaly (Hyvärinen-Alhonen event). Our data suggest this event was not continuous but reached its two-phase climax during the peatland pine phases, with an interruption of several centuries with moister surface conditions between 4400 and 4100 cal. a BC. The findings highlight the sensitivity of well-dated peatland tree assemblages in terms of recording past climatic evolution and events and the need for new collections from north and south Fennoscandia and the Baltic region, for more detailed analyses over extended time intervals and regions.     

Ray asymptotic propagation of the spectra of elastic surface waves in a waveguide with laterally smooth inhomogeneities

Summary. A technique based on ray asymptotics has been developed to propagate complex spectra of elastic normal mode surface waves in a waveguide with material and geometrical properties varying smoothly in the lateral directions. In the technique, the original problem defined in the unstretched coordinates has been transformed into an eiconal equation as well as into a certain number of transport equations defined in stretched coordinates.
The solution of the eiconal equation is equal to the solution of the eigenproblem of the eiconal operator A₀. Due to the self-adjointness of A₀, in each of the relevant local inner product spaces, LIPS, the solution of the eigenproblem, A₀ψ= v ψ results in the set { v _t} of real local eigenvalues and in the orthonormal system {ψ_t} of local eigenvectors.
As the Hamiltonian function of an initial value problem, each eigenvalues gives birth to a bicharacteristic curve as well as to the related ray. The introduction of the rays induces connections between the vertical cross-sections of the waveguide.
Finally, for each asymptotic order j , the LIPS-valued transport equations are reduced to a set of matricial propagation equations in the local spectral amplitude vectors, LSAVs. Consequently, a knowledge of the initial conditions at a vertical cross-section makes it possible to propagate the LSAVs along the rays of the relevant modes. However, to complete the propagation one needs, in addition to the initial values, information about certain additional quantities, non-diagonal terms of order j , diagonal terms of orders lower than j and the auxiliary boundary terms of orders from 1 to j . The treatment has been completed by the propagation of the modal phases along the relevant rays.     

Herbivory-Mediated Responses of Selected Boreal Forests to Climatic Change

Recent efforts to project vegetationresponses to climatic warming have emphasized thetight linkages between climate and vegetationdistribution. Here we provide several examplesindicating that the direct effects of climatic warmingon boreal vegetation can be qualitatively differentthan the indirect effects mediated by climaticresponses of herbivores. These herbivore-mediatedvegetation responses to climatic warming will likelyvary regionally. In southern Fennoscandia, we projectthat the climatically induced changes in animalpopulations should enhance the density of spruce atthe expense of pine and broadleafed trees. In northernFennoscandia we project reduced herbivory onbroadleafed trees and increased herbivory on pine,leading to an increase in broadleafed trees and spruceand a reduction in pine. Climatic warming in interiorAlaska may reduce herbivory on broadleafed trees andincrease herbivory on evergreen spruce, thusreinforcing the impact of increased fire frequency.     

Contact zone interaction of metabasites with metapelites: Amphibolite facies mineral assemblages, chemical profiles and their origin, the Puolankajärvi Formation, Finland

The amphibolite facies, iron-rich metapelites (garnet-staurolite mica schists) of the early Proterozoic Puolankajärvi Formation are intercalated with metamorphosed basic rocks which vary from iron-rich amphibolites to magnesium-rich layered sills and serpentinites. Garnet-cummingtonite-hornblende assemblages are abundant at the contacts of the metapelites with amphibolites, while garnet-chlorite, garnet-gedrite±chlorite, garnet-gedrite-cummingtonite±chlorite and chlorite-cummingtonite-hornblende assemblages occur at their contacts with the layered magnesium-rich sill.

The bulk composition profiles of these contacts, normalised with respect to chromium and/or aluminium, show conspicuous enrichment in Fe, S, Ga and Co and depletion in Si, K, Ba and Rb. Some elements (e.g. Mg, Mn, Ni, P, Zr and Hf) are depleted or enriched in only small amounts, while others (e.g. Ca, Na, Sr and the rare earth elements) may show both enrichment and depletion in the course of a profile.

Although early infiltration during the hydration of metabasites and tectonic reworking may have produced some interaction of the basites with the pelites, the major metasomatic event is considered to have bile elements. The composition of the metapelites, for example, approached that of magnesium-rich ultramafites through potassium depletion, while the ultramafites became markedly enriched in iron. To conserve the volume, silica was depleted from the contact which underwent iron enrichment.     

Surface Stokes drift in the Baltic Sea based on modelled wave spectra

The Stokes drift is an important component in the surface drift. We used the wave model WAM to evaluate the mean values and exceedance probabilities of the surface Stokes drift in the Baltic Sea. As there is no direct way to verify the accuracy of the modelled Stokes drift, we compared the bulk parameters calculated by the wave model against buoy measurements to ensure the quality of the wave hindcast. Furthermore, we evaluated the surface Stokes drift from measured wave spectra to assess the accuracy of the modelled surface Stokes drift. The importance of the Stokes drift as a component of the total surface drift was evaluated by calculating the hindcast mean values and percentiles of the surface Stokes drift. The mean values were between 0.08 and 0.10 ms^?1 in the open sea areas, thus being of the same order of magnitude as the mean wind shear currents. The highest values of the surface Stokes drift were slightly larger than 0.6 ms^?1. The comparison of modelled Stokes drift values to estimates obtained from measured spectra suggests that the mean values are well represented by the model. However, the higher modelled values are most likely slightly too large because the wave energy was overestimated during high wind situations in some of the sub-basins, such as the Gulf of Finland. A comparison to a drifter experiment showed that use of the Stokes drift improves the estimate of both the drift speed and the direction in the Gulf of Finland. Parameterised methods to evaluate the Stokes drift that are used, e.g. in currently available Baltic Sea drift models, overestimate the smaller values (under 0.3 ms^?1) and underestimate the larger values of the Stokes drift compared to the values calculated by the wave model. The modelled surface Stokes drift direction mostly followed the forcing wind direction. This was the case even in the Gulf of Finland, where the direction of the wind and the waves can differ considerably.     

Introducing run-size driven fisheries management for the coastal fishery of Atlantic salmon: Preseason forecasts for policy makers

The Finnish coastal fishery of Atlantic salmon (Salmo salar) in the northern Baltic Sea is regulated using multi-annual, pre-fixed, opening dates of harvests that aim to enhance spawning escapement of early migrating wild salmon. Such an inflexible management regime does not set regulations that track varying run sizes of salmon. We introduce an array of computational intelligence techniques to estimate and forecast coastal run size and escapement of salmon into three spawning rivers in the northern Baltic Sea. Our results indicated that the present management pattern, driven largely by regional fisheries policy, contrasts greatly with a “run-size driven” (i.e. abundance-based) management approach. Introducing run-size driven management, i.e. setting regulations annually by tracking preseason forecasts, would better ensure adequate escapement and at the same time allow the maintenance of coastal catch at sustainable level. Setting regulations annually would allow effective harvesting in years when the run is high, and would effectively restrict harvests when the run is low.     

Increased Carbon Sink in Temperate and Boreal Forests

An intense search is under way to identify the `missing sink' in the world carbon budget of perhaps 2 Pg year^–1 (petagrams, or billiontonnes) of carbon, but its location and mechanism have proved elusive. Here we use a new forest inventory data set to estimate the carbon sink and the carbon pool of woody biomass in 55 countries that account for nearly all temperate or boreal forests and approximately half the world's total forest area. In each country there was a net accumulation of biomass; together, the carbon sink of woody biomass was 0.88 Pg year^–1 during the 1990swith estimated uncertainty from 0.71 to 1.1 Pg year^–1. Thisestimate, already about half of the missing sink, would probably be even larger if carbon accumulation in soil and detritus were also accounted for, but we are unable to quantify that additional sink. The sink is twice that estimated for the woody biomass of these forests a decade ago due to higher estimates for tree growth throughout the region and decreased timber harvests in Russia. In contrast, the new data indicate a carbon pool that is smaller than earlier estimates because of improved data for Russia and Australia.     

Biochemical biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)

A battery of biochemical biomarkers and the SigmaPCB concentration in adult female perch (Perca fluviatilis) verified an aquatic pollution gradient with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included both an upstream gradient, 46 km westwards through Lake M?laren, and a downstream gradient, 84 km eastwards through the Stockholm archipelago. Besides the main gradient from Stockholm, there were strong indications of pollution coming from the Baltic Sea. The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch, characterised by increased specific EROD activity in the liver, increased liver EROD somatic index, decreased AChE activity in the muscle, increased amount of DNA adducts in the liver, and a high concentration of biliary 1-pyrenol. In addition, laboratory exposure to common EROD inducers elicited an abnormal response, suggestive of chronic intoxication.     

Amplifier arrays for CMB polarization

Cryogenic low noise amplifier technology has been successfully used in the study of the cosmic microwave background (CMB). Monolithic millimeter wave integrated circuit (MMIC) technology makes the mass production of coherent detection receivers feasible. We have produced large numbers of MMIC amplifiers for CMB measurements. We have also demonstrated the viability of multi-function multi-chip modules as sensitive receiver front-ends. MMIC integration makes it possible to realize massive arrays of receivers suitable for measurements of the polarization of the CMB. We describe the development of the unit cell of such an array and the development plans for implementation.