South-central Norway Research Articles

DOES TREE AGE PREDICT THE OCCURRENCE AND ABUNDANCE OF USNEA LONGISSIMA IN MULTI-AGED SUBMONTANE PICEA ABIES STANDS?

In boreal Scandinavia Usnea longissima is a rare epiphytic lichen associated with old spruce (Picea abies) forests. To test whether tree age was an important determinant of the occurrence and abundance of U. longissima at the scale of a forest stand we estimated thallus numbers on 1008 trees within three submontane spruce stands in south-central Norway. The stands were of all ages and multi-layered and had been selectively cut previous to the 1940s. There was no relationship between number of U. longissima thalli and tree age among trees with dbh of ≥10cm. The most consistent pattern was a positive relationship between occurrence and number of thalli and stem diameter. After controlling the covariance of stem diameter, there was a tendency for a negative relationship between number of thalli and tree age. The results suggest that in old-growth resembling stands, with already established U. longissima populations, tree size (here measured as stem diameter) is a better predictor of thallus number than tree age. This does not contradict the possibility that other environmental characteristics, associated with stands of older age, may be important for the establishment and growth of U. longissima populations.

Does Tree Age Predict the Occurrence and Abundance of Usnea Longissima in Multi-Aged Submontane Picea Abies Stands?

In boreal Scandinavia Usnea longissima is a rare epiphytic lichen associated with old spruce (Picea abies) forests. To test whether tree age was an important determinant of the occurrence and abundance of U. longissima at the scale of a forest stand we estimated thallus numbers on 1008 trees within three submontane spruce stands in south-central Norway. The stands were of all ages and multi-layered and had been selectively cut previous to the 1940s. There was no relationship between number of U. longissima thalli and tree age among trees with dbh of ≥ 10 cm. The most consistent pattern was a positive relationship between occurrence and number of thalli and stem diameter. After controlling the covariance of stem diameter, there was a tendency for a negative relationship between number of thalli and tree age. The results suggest that in old-growth resembling stands, with already established U. longissima populations, tree size (here measured as stem Diameter) is a better predictor of thallus number than tree age. This does not contradict the possibility that other environmental characteristics, associated with stands of older age, may be important for the establishment and growth of U. longissima populations.

Late Sveconorwegian monzonitic dykes in the Setesdalen area of Central South Norway: Examples of structures in dykes and their indications of accumulated strain

In the Setesdalen area, Central South Norway, a large number of monzonitic dykes and other minor bodies were intruded during the late stages of emplacement of Sveconorwegian magmatic complexes. Some of the dykes define cone sheet and bell-jar sheet systems. The dykes possess internal linear and planar fabrics, which are not seen in any of the host rocks. Also, cross-cutting granitic veins within the dykes are deformed and may show ptygmatic folds, whereas in the host rocks these same veins appear undeformed. The internal strain in the dykes was determined from vein deformation to be mainly simple shear with or without a volume reduction. The strain preferentially accumulated in the ductile monzonite dykes while the more rigid host rock blocks were passively displaced. In some cases, an additional minor component of flattening affected both the dykes and their host rocks.

Drainage, Liming and Fertilization of Organic Soils. I. Long-term Effects on Acid/Base Relations

Long-term changes of the acid/base relations of organic soils after drainage, fertilization and/or liming at three experimental sites—two ombrogenous and one soligenous—in south central Norway are discussed. These sites were drained, fertilized and/or limed in 1953–1956 and sampled in 1991–1992. Drainage at the ombrogelious sites caused: insignificant shifts of pH, higher bulk densities to 40 cm depth, higher ash percentage, higher contents of N and P to 20 cm depth and reduced concentrations of total Ca, K, Mg, Na, A1 and Fe in soil layers deeper than 20 cm. The soligenous site was not effectively drained; despite this, pH dropped about 0.5 unit in the surface and subsurface soil layers of the control plots, while small changes were measured for most other soil variables. The suggested reason for the pH drop is limited sulphide oxidation in the upper 20 cm drained layer. Base saturation at actual soil pH, when all treatments were included, was estimated with good precision by four regressors: pH, extractable Al, extractable Fe and extractable Ca (R2=0.90–0.95). Similar models explained 97–99”” of the variation in base saturation at soil pH=7.0. The lime effects at the properly drained oligotrophic sites were proportional to applied doses; for pH to 40 cm, base saturation to 60 cm, and Ca concentration to 60 cm depth. At the less well-drained soligenous site, effects were limited to the upper 30 cm layer. Both drainage and liming caused higher cation exchange capacities and proper drainage seems to be a prerequisite for the liming effect. Estimated recovery of calcium to 60 cm depth was 64–79% at the ombrogenous sites and 42–46% at the soligenous site.

Dietary and Reproductive Responses of Arctic Foxes to Changes in Small Rodent Abundance

Between 1988 and 1995, dens in three adjacent arctic fox (Alopex lagopus) territories were monitored in an alpine environment in south-central Norway (the Snøhetta plateau). A total of 675 scats were collected at dens in both winter and summer, and the numbers of resident adults and pups at emergence were counted each summer. Small rodents (mainly Lemmus sp. and Microtus sp.) were the most frequently consumed prey and made up the greatest volume within scats, in all seasons and at all stages of the rodent cycle. Small rodents were followed in frequency by reindeer (Rangifer tarandus), hares (Lepus timidus), birds, and vegetation. Birds and vegetation were more common in the summer diet than in the winter diet, reflecting their seasonal availability. The relative volume of reindeer and birds in the diet decreased with increasing rodent abundance. Increased pup production was associated with years of high rodent abundance and a high occurrence of rodents in the diet. Adult numbers were not associated with rodent abundance.

Home-range sizes and altitude selection for arctic foxes and wolverines in an alpine environment

We compared the use of space and habitat by wolverines, Gulo gulo, and arctic foxes, Alopex lagopus, on the Snøhetta plateau and surrounding mountains in south-central Norway. The arctic foxes used smaller annual home ranges than the wolverines, whose home ranges were among the largest yet reported for the species. In both species, resident males used larger home ranges than resident females. Arctic foxes used a much narrower, and higher, range of altitudes than wolverines, always above the tree line. Wolverines used lower altitudes in winter than in summer. Female wolverines showed pronounced seasonal peaks in their use of the peripheral areas of their home ranges. Both species showed an ability to cross at least some transportation corridors (road, rail, human settlements) in the area. The habitat available at Snøhetta appears suitable for arctic foxes and does not explain the failure of the population to recover during 67 years of protection. Because of predation on domestic sheep, wolverines will probably be confined to a series of core conservation areas (CCA). At present densities (0.28-0.36 wolverines per 100 km2), the CCA surrounding Snøhetta can contain from 36 to 50 wolverines.

The tectonic significance of pre-Scandian 40 Ar/ 39 Ar phengite cooling ages in the Caledonides of western Norway

Pre-Silurian continental-margin deposits in western Norway, non-conformably overlying allochthonous continental orthogneisses retain Ordovician 40 Ar/ 39 Ar cooling ages for phengites, implying either rapid cooling immediately after a Late Ordovician orogenic event, or less likely, a slow cooling following an Early Ordovician or older orogeny. The Dalsfjord Suite–Høyvik Group basement–cover pair are probably a lateral equivalent to Late Proterozoic sandstones (‘sparagmites’) covering the Jotun Nappe gneisses of the Middle Allochthon in central-south Norway. The Høyvik Group underwent polyphase deformation, greenschist-facies metamorphism ( T max <450°C) and exhumation prior to deposition of the unconformably overlying Wenlockian continental-margin deposits of the Herland Group. The Høyvik Group was only weakly metamorphosed during obduction of the Solund–Stavfjord Ophiolite and the Scandian continental collision between Baltica and Laurentia. Phengitic white micas from the Høyvik Group yield cooling ages of 446.1± 3.0, 449.1±2.2 and 447.5±4.0 Ma, respectively, identical within experimental error. One sample gives a plateau over 72% of the gas analysed, whereas the other samples were slightly disturbed after initial cooling, as indicated by systematically lower apparent ages at low experimental extraction temperatures. Minor 40 Ar loss probably occurred during subsequent Scandian deformation and late to post-orogenic extension.The Høyvik Group rocks were unroofed before the Wenlock time (423–428 Ma) and cooled through the temperature for argon retention in phengite at c . 447±4 Ma, indicating a maximum cooling rate between 14 and 22C/Ma- 1 through Ashgill and Llandovery times before being subjected to low-grade metamorphism during the Scandian orogeny. Rapid pre-Scandian cooling, combined with peak metamorphic conditions of 450C or less, may indicate that the Dalsfjord–Høyvik basement–cover pair were aVected by an orogenic event during the Late Ordovician (Caradoc) time. The data also suggest that the Caledonian margin of Baltica may have experienced a more protracted tectonism during the Caledonian cycle than previously models focusing on Early Caledonian and Tremadoc (or older) ophiolite obduction and the Scandian continental collision between Baltica and Laurentia.

Extensional tectonics in the Caledonides of southern Norway, an overview

The extensional collapse of the Scandinavian Caledonides resulted in rapid tectonic denudation of the orogen, exhumation of high- and ultra-high-pressure metamorphic rocks and provided a structural template for the formation of Devonian supra-detachment sedimentary basins. The geometry and intensity of the extensional deformation show considerable variation vertically in the crustal section as well as horizontally from east to west across the orogen. The most prominent structural feature related to the extension in central-south Norway is the change in the direction of tectonic transport, from the easterly directed nappe translation during the Silurian Scandian Orogeny, to top-westerly directed sense of shear during the extension. The Fennoscandian basement was little affected by extension in the eastern Caledonides. In the west, however, top-to-the-west shear zones are commonly observed in basement windows. Deformation affecting the Cambrian to Late Silurian rocks in the Caledonian foreland developed a typical of foreland fold and thrust belt geometry. Deformation in the foreland was apparently contemporaneous with the extension-related decompression of the high-pressure rocks in the hinterland. Thrusting in the foreland may thus have been driven by gravitational collapse, and as such have important similarities to the foreland-hinterland relationships of the Himalayan-Tibetan region. The basal contacts of the Jotun and other major nappes constitute prominent shear zones in which fabrics related to thrusting have been mostly destroyed by extensional shearing. The high structural levels of the Western Gneiss Region, adjacent to the western margin of the Jotun Nappe, were only moderately affected by the extensional deformation. Consequently, the Proterozoic orthogneiss complexes are generally well preserved in this area. The westernmost and structurally lowermost parts of the Western Gneiss Region have, however, been subjected to extreme overburden during the Caledonian continental collision. Initial, near-isothermal decompression of the high-pressure rocks occurred by non-rotational vertical shortening-horizontal stretching at eclogite- to amphilbolite-facies conditions; at a later stage, decompression and cooling from amphibolite to greenschist facies occurred by rotational deformation associated with the large-scale extensional detachments. The initial extensional deformation in the hanging wall of the detachments in western Norway commenced at greenschist-facies conditions, and became progressively more brittle and localised as the complexes were exhumed in the Late Silurian to Middle Devonian. Major syn-depositional normal faults in the hanging wall of the extensional detachments eventually controlled sedimentation in the Devonian supra-detachment basins.

Responses of the Norwegian alpine Betula nana community to nitrogen fertilization

The effect of nitrogen fertilization on species cover, increment of shrubs, tissue nitrogen, and soil parameters was tested during a 3-year experiment in a low alpine plant community dominated by Betula nana in the Dovre mountains, south-central Norway. The doses used were 1.2 and 6.1 g N/m2, corresponding to 0.72 and 3.6 times, respectively, the annual deposition of nitrogen in southwest Norway. Statistical analysis using SAS ANOVA and GLM procedures were applied to different types of models. The cover of species and growth forms showed no significant response to additional nitrogen supply. The increment of shrubs was not significantly affected by the fertilization, except for the year factor. Incorporation of nitrogen into plant tissue was not evident. No effects were found on soil parameters. Key words: fertilization, alpine tundra, shrubs, nitrogen.

What's a "Year's Work" Worth? The Influence of the State on Cultural Constructs of Farming in Norway

Based on fieldwork conducted in a rural community in south-central Norway from 1988-1990, I provide ethnographic insight into the state agricultural bureaucracy, the influence of the state on agricultural conditions and local cultural constructs of farming, and the interplay between community-based notions of rural identity and modern farming. Drawing on participant observation, interviews, and surveys among farmers and state agricultural organizations, I show how the state and its policies create conditions within which farmers make operating decisions and shape their conceptions of farming.

The provenance of pre-Scandian continental flakes within the Caledonide Orogen of south-central Norway

Abstract A significant portion of the Caledonian nappe pile of south-central Norway is composed of tectonic flakes of continental crust older than the arkosic sediments of the Upper Precambrian-Lower Cambrian Hedmark and Valdres Groups. Models deriving these flakes from a suture zone S and SE of the Western Gneiss Region have found less favour than those deriving them from a root zone lying off the present-day coast line to the NW. Recent models propose that the largest flake, the Jotun-Valdres Nappe Complex, is a microcontinental suspect terrane structurally bounded above and below by ophiolitic sutures. The pre-Caledonian geological evolution of the Jotun-Valdres Nappe Complex and the Bergen Arcs is shown to be comparable to that of adjacent parts of the autochthonous Fennoscandian Shield, and to a putative root zone along strike from the Lofoten-Vesterålen Province. It is concluded that the Jotun-Valdres Nappe Complex and, by implication, related units in the Bergen Arcs and elsewhere, are not ‘suspect’ and are portions of the Mid to Late Proterozoic Baltoscandian crust, detached and thrust into position during the c. 390 Ma Scandian (= late-Caledonian) orogenic event.

The decline of a brown bear Ursus arctos L. population in central South Norway

The brown bear Ursus arctos L. was studied in the Vassfaret area of Norway for the 40-year period 1949–1988. More than 800 bear reports, mostly from untrained observers, were analysed, critically evaluated and 35 verified as true. During the whole period there was a clear concentration of observations in a core area of about 1300 km2 and a less dense and more patchy occurrence in the surrounding area of about 25 000 km2. Reproduction was unconfirmed, as no observations of females with cubs or young could be verified. Results from tracking and other special studies suggested that the population consisted of only a few individuals. A tracking study during 1970–1972 showed at least one bear to be present, but a similar study in 1991 found none. There was a clear tendency of a decline, probably caused by heavy hunting before the study, and habitat deterioration by human intrusion during the study period.

Homeostatic Behavioural Responses in a Changing Environment: Brown Trout (Salmo trutta) become Nocturnal during Winter

Behaviour and microhabitat selection by brown trout in two streams presenting severe winter conditions, were investigated in south-central Norway. Fish were studied by direct underwater observation in different habitat types, during day and night, and with simultaneous sampling for dietary analysis and invertebrate drift. During the day in winter, brown trout exhibited two different behavioural strategies, depending on fish size. Smaller fish (<25 cm) sheltered passively in the substrate or in submerged vegetation, and were almost never active during daylight hours. This behaviour was consistent throughout the winter until water temperatures rose in spring. Larger trout (25-60 cm) were actively aggregating in deep-slow stream areas during the day. During the night the trout exhibited a third behavioural strategy. The trout were active throughout the night from dusk to dawn, and this behaviour was consistent throughout the winter

Food habits and foraging of the brown bear Ursus arctos in central south Norway

Analysis of 134 excrement samples from the brown bear Ursus arctos L in boreal forests m central south Norway found volumes to be largest for Vaccinium spp, herbage Empetrum spp, and Formicidae The most important plant material in volume uptake were herbage, leaves, and mosses, closely followed by berries and seeds All together, plant material amounted to c 85% by volume, Formicidae to c 8%, and domestic sheep to c 7% These values were radically changed by applying correction factors for different nutritional value of food items The importance of large mammals then increased substantially, while the importance of herbage was reduced There was a drastic shift in food composition through the seasons Formicidae and flowers of deciduous trees were prevalent in spring, herbage in early summer, Vaccinium spp and sheep in late summer, and Vaccinium spp and Empetrum spp in autumn

Structure and Meaning in a Norwegian Couple Dance

The term Valdres-sprinyar refers to a traditional couple dance from the mountain valley region of Valdres, located in central South Norway. From the national point of view the Valdres-springar is today considered to be a 'dialect' of dancing within the genre of sprinyar dances known to be in 3/4 meter. In turn this category is part of the genre of folk-dances called byydedans (lit. countrsr dance), consisting also of dances conventionally described to be in 2/4 and 6/8 meters: ganyar, rqxll, halliny/la?s. Taken together these dances are viewed as the indigenous or national dances of Norway as opposed to the historically younger 'waltz-polka comples' of the 19th (Sentury called gammaldans (lit. old dance). The classification of the 'Valdres-springar' as a single dance dialect overlooks the a rangie of individual as well as local varieties in form and style of performances. This is due to the fact that dancers within the region respond in synchrony to the springar music, i.e. making homologous metricaUl inferences of the fiddlers performances, and that they, in spitn of differences in sequences of cooperational interchanges within couples, still have no difficulty in maintaining the ring formation. By implication, dancers of the region must shars some basic structural knowledga in order to attain the necessary degree of coordination and coop3ration. In contrast the Valdres dancars find it difficult to aUttain synchronization and cooperation with dancers from surrounding districts. This exp3rience, along with dialectal features of speech and costumes, seetn to reenforce their sense of loca.l cultural unity and sha.ring. It is possible for the trained observar to show that the various loca.l varieties of couple dances within the genre of bygdedanser have a series of common characteristics:

Coexistence with similar life cycles in two species of freshwater copepods (Crustacea)

Two species of freshwater cyclopoid copepods, Cyclops scutifer Sars and Mesocyclops leuckarti (Claus), with different ecological requirements, coexist in three humic ponds near the timberline in boreal forests in south-central Norway. The life cycle in both species is basically regulated by complete depletion of oxygen during the long winter. There is a short period of reproduction in spring followed by a rapid development during summer and autumn to advanced instars, capable of diapause when oxygen depletion starts in early winter. Both species have an exclusive 1-yr cycle.

Platinum-group mineral inclusions in chromitite from the Osthammeren ultramafic tectonite body, South Central Norway

Fourteen different platinum-group minerals (PGM) have been found in massive chromitite from the Osthammeren ultramafic tectonite (serpentinite) body, Norway. The PGM-inclusions occur in two distinctly different textural groups. 1. Os, Ir, Ru and minor Pt occur in euhedral-subhedral, small (< 5–20 , µm), mainly single-phase inclusions of Os-free laurite, Os-laurite, osmiridium and Pt2 (Ir, Os)Fe0,65. They are totally enclosed in fresh chromite. A few PGM-inclusions are however associated with small blebs of Na-bearing hornblende and phlogopite, included in the chromite, indicating that the presence of volatiles at an early stage (i.e. preceding chromite crystallization) may have influenced the formation of these PGM. The occurrence of PGM within unaltered chromite suggests a primary magmatic origin of these. 2. Purely secondary PGM occur as anhedral-(subhedral), texturally often very complex grains or grain-aggregates of varying size (5–70 µm) and consisting of from one to eight PGM-phases plus Ni-sulphide and Ni-arsenide. These PGM always occur within, or in contact with, late formed cataclastic cracks or very fine fissures, in the primary magmatic chromite grains. The finer fissures are generally tightened by ferrit-chromite, a hydrothermal alteration product of chromite. The wider cracks are usually serpentineand chlorite-filled and are rimmed by ferrit-chromite against the chromite. Os, Ir, Ru, Rh, Pt and minor Pd are represented in grains of this group, and the secondary PGM—association found consists of Os-free laurite, Os-laurite, erlichmanite, Ir-rich erlichmanite, native Os, iridosmine, osarsite, irarsite, hollingworthite, Rh-rich platarsite (?), Ru-rich platarsite, sperrylite, (Ir, Rh)SbS, IrSbS, (Ir, Pt, Pb)S2 (new?), Pd-antimonide (probably stibiopalladinite) plus the associated phases pentlandite, heazlewoodite and niccolite.

New evidence for Preboreal deglaciation of south-central Norway

Mapping and detailed morphological evidence suggests that mounds and ridges at 1200 to 1350 m in upper Breiseterdalen, western Jotunhcimen probably represent Rogen moraines, ice sheet marginal moraines and a cirque moraine. 14C dates from an intermoraine hollow suggest that peat development began about 8800 BP, confirming a Preboreal age for deglaciation. A need for a revised deglaciation chronology is suggested, with evidence for active ice present comparatively close to the present glacier limits until a late stage of deglaciation. A possible correlation of the Breiseterdalen moraines with similarly dated marginal moraines in southwest Norway is discussed.

Lake survival of hatchery and pre-stocked pond brown trout, Salmo trutta L.

Abstract. A comparison was made of lake survival, after 2 years, of hatchery and pre-stocked pond brown trout, Salmo trutta L., (age 0+) in two small mountain lakes in south-central Norway, one which contained a resident population of brown trout. There was a significantly higher recapture of pond fish in both lakes. The mortality rate for the stocked fish was significantly higher in the lake which contained a resident population of brown trout. The competitiveness of the stocked fish is discussed in relation to foraging success, predation and stress.

Effects of logging on capercaillie (Tetrao urogallus) leks

Display activity and population size of 2 experimentally logged leks were compared with 7 untreated control leks in a coniferous area in southcentral Norway, during 1974–87. Leks were treated by thinnings and small‐scale seed‐tree‐ and clearcuttings. Number of displaying cocks increased on all leks, but the experimental lek populations increased more than the controls. Displaying cocks were either indifferent to or preferred the logged areas, and recruiting cocks established display sites at newly created group selection cuts and at the edge of seed‐tree and clearcuts. The findings indicate that moderate thinnings, leaving >500 stems/ha, and clearcuts <50 m in diameter, are acceptable cutting methods within T. urogallus leks, with the reservations that lek populations should not be smaller than 5 displaying cocks, and that surrounding habitats should contain >50% old forest.