bluuebunny/crossref_metadata_2025_split huggingface dataset:
The local climate of the Øvre Heimdalen valley
Authors: Johannessen T. Werner 
Published: July 2006

Owing to the high altitude of Øvre Heimdalen and the complex topography within the valley, climatic conditions are complicated. The valley is situated in a mountain region with a subarctic or tundra macroclimate, which exists over the lake itself and on the SSW‐valley side. However, the favourable combination of slope angle and exposure of the NNE‐valley side gives a radiation or continental type of local climate on this side.The large net input of radiant energy onto the NNE‐valley side during the summer results in higher air temperatures, greater precipitation and higher air humidity than elsewhere in the valley. This is clearly reflected in the luxuriant vegetation on this side. Thus, the climate of the Øvre Heimdalsvatn area is strongly influenced by terrain irregularities and shows how fundamentally different growth possibilities due to local climates may be over short distances in the uppermost valleys on the eastern side of the central mountain chain.
The invertebrate fauna of the streams in Øvre Heimdalen
Authors: Lillehammer Albert , Britain John E. 
Published: July 2006

The lotic communities in Øvre Heimdalen were completely dominated by insects. The species distribution of stoneflies (Plecoptera), mayflies (Ephemeroptera) and caddisflies (Trichoptera) is given together with autecological notes on the Plecoptera and certain other major species. The species distribution of these groups, especially the Plecoptera, was clearly related to the deciduous vegetation along the streams. There was a reduction in species parallel to a reduction in Salix vegetation.The main inlet stream to the lake, Øvre Heimdalsvatn, the outlet and the outlet stream had different faunal compositions. The inlet fauna consisted to a large extent of winter growing species, mainly detritus feeders, while the outlet and outlet stream had a fauna dominated by summer growing species, several of which were filter feeders.
Laboratory energetics of larvae of Sericostoma personatum (Trichoptera)
Authors: Iversen Torben Moth 
Published: July 2006

The energetics of the shredder Sericostoma personatum Spence were studied in the laboratory at 3,8, 13 and 18°C using conditioned leaves of Fagus sylvatica L. as food. Ingestion (I), growth (G) and respiration (R) were dependent on larval size and temperature. Estimated assimilation (G + R) varied between 4.2–5.7%. Gross growth efficiency (G/I × 100) varied between 0.4–3.4% and was dependent on temperature. Growth rates estimated from field and laboratory data were in the same order of magnitude.The low assimilation is discussed in relation to the life cycle pattern of the species and its ecological role in the stream community.
Reproduction of the bank vole, Clethrionomys glareolus, in northern and southern Sweden during several seasons and in different phases of the vole population cycle
Authors: Nyholm N. Erik I. , Meurling Patrick 
Published: July 2006

The breeding biology of the bank vole was studied in northern and southern populations in Sweden in the years 1973–76. Trapped specimens supplied organ weights and histological data, which were utilized to describe the breeding season, number and size of litters, reproductive losses, spermatogenesis, and sexual maturation. In the north the populations are cyclic. During the increase phase of the cycle the breeding season was long, litter sizes and gonad weights were large, and there was maturation of yearlings in the summer. During the peak phase reproduction was impaired in all these respects. In southern Sweden there was no cyclicity, and the reproductive events varied less, but in 1976 the litters were larger than usual and the season was much extended.In the south the voles born during the early part of the season regularly became sexually mature during their first summer. The differences in reproductive biology are related to population dynamics and discussed in terms of different hypotheses concerning vole population cyclicity.
Biological nitrogen fixation in coniferous forest watershed areas in Central Sweden
Authors: Rosén Kaj , Lindberg Torbjörn 
Published: July 2006

An investigation on biological nitrogen fixation in the forest floor was carried out in five watershed areas in Central Sweden during the summers 1978 and 1979. Five different types of bottom layers with underlying soil horizons were investigated for nitrogen fixation. An inventory on the occurrence of potential nitrogen fixing lichens and alder trees was also carried out.Low fixation rates were determined in mesic‐soil mosses, F/H,layers and mineral soil. Though two orders of magnitude higher than in mesic‐soil mosses, the nitrogen fixation in the investigated Sphagnum mosses must be considered as low, probably due to absence of blue‐green algal associations. The contribution to total nitrogen fixation by lichens is low, but Alnus incana may play an important role. The estimated biological nitrogen fixation calculated as a weighted mean over the five watersheds is in the order of 0.5 kg N ha‐1 yr‐1.
Habitats, life histories, migration and dispersal by flight of two water‐beetles Helophorus brevipalpis and H. strigifrons (Hydrophilidae)
Authors: Landin Jan 
Published: July 2006

Populations of two Helophorus species from a Swedish lake were sampled during the ice‐free periods of two years. Dispersing beetles were (rapped in light‐reflecting glass traps. Both species are univoltine and breed in the spring. The populations of adult H. brevipalpis are largest during the summer when great numbers emerge and migrate. Very few H. strigifrons adults emerge before spring. Its adult populations are largest in the spring, and small numbers of mature individuals fly with mature H. brevipalpis specimens. This is discussed in relation to their habitat utilization: H. sirigifrons inhabits permanent waters only and is dimorphic for flight musculature. H. brevipalpis inhabits both permanent and ephemeral waters and is always equipped with a functioning flight apparatus. H. brevipalpis is an effective colonizer of ephemeral waters due to its large dispersal capacity and to the fact that the habitat of juveniles differs from that of adults.Age, sexual maturation and feeding in flying and non‐flying groups are compared. Food is seldom found in the gut of fliers of either species. In the spring flying H. brevipalpis females have larger oocytes than non‐flying ones; flying H. strigifrons females have smaller oocytes than non‐fliers. It is possible that the summer migrations of H. brevipalpis favour outbreeding since fliers are sexually immature; spring fliers, being sexually mature, are more efficient as colonizers.
The ecological requirements of Hierochloë odorata in Nova Scotia
Authors: Goldsmith F. Barrie , Murphy Susan L. 
Published: July 2006

Hierochloë odorata (L.) Beauv. is restricted to the upper zone of salt marshes and rarely becomes dominant.In the field, the species was found not to have strict N, P, K requirements. It grew in a range of pH values from 4.3 to 7.9, tolerated salinities up to 500 mhos and favoured soils with a moisture content from 25 to 30%. It grew in situations with a mean water table between 14 and 28 cm below the surface. Natural shading in the field was found to increase the heights of plants by about 30%. The application of fertilizer in the field increased the height of sweet grass but also stimulated the growth of associated species. In the greenhouse, the effects of different soils and fertilizers on plant growth were assessed. Inorganic fertilizer (12:18:12) application produced more leaves and tillers than organic fertilizer (6:2:0).Sweet grass grows in a zone of reduced competition between the dune species and the salt‐marsh species. Near the salt‐marsh, the species may be limited by high salt concentration. The low levels of competition offered by cultivation and the responsiveness of the species to fertilizer suggests that cultivation of Hierochloë odorata may be successful.
Daily flight activity of moths in the continuous daylight of the arctic summer
Authors: Dreisig Hans 
Published: July 2006

The daily onset of flight and the lime of activity of moths were studied at an arctic and a subarctic locality in midsummer under natural light conditions but with all other factors kept constant. The daily variation of light intensity is much smaller than at temperate latitudes, and the illumination is continuously at levels that normally inhibit the activity of moths. In spite of this, the investigated species showed a distinct daily periodicity with the activity occurring at about the same time of day as in the same or related species from lower latitudes. It is suggested that this is the result of a process of acclimatization to high light intensities.A number of species show a diurnal activity pattern, and it is suggested that this is connected with their high temperature requirements. In the field, Anarta zetterstedti Staud. thermoregulates by settling frequently on dark rocks which can reach high temperatures when the sun is shining. This species can not fly unless its body temperature is above 30°C and it prefers an ambient temperature of about 36°C.
An analysis of an adult Trichoptera community in the Laurentian highlands of Quebec
Authors: Roy D. , Harper P. P. 
Published: July 2006

The adult Trichoptera communities of a small watershed in the Québec Laurentian Hills were studied during two years with emergence and light traps.Some 180 species and more than 164500 specimens were collected, belonging mainly to the families Hydropsychidae, Polycentropodidae and Leptoceridae; the Limnephilidae with 41 species were the most diverse family.A comparison of catches in emergence and light traps revealed the importance of species from distant or specialized habitats in the composition of local communities. Two series of light trap catches show little similarity (Sanders index) although the traps were only some 60 m apart; this is in accordance with the suspected limited range of efficiency of light traps.The Shannon‐Wiener diversity index, the Simpson dominance index as well as the Lloyd and Ghelardi equitability index have been used to describe community structure; our four data series have also been shown to conform to the log‐normal frequency distribution of Preston.The sex‐ratios of the abundant species are given. In most light trap series and in half the emergence trap series, the ratio differs significantly from 50:50; there is however no overall dominance of one sex. Differences exist between the ratios obtained for the same species in the two types of traps and probably reflect sexual differences in behaviour at light.
Rotifer communities of ponds supplied with post‐waste water
Authors: Klekot Liliana , Klimowicz Henryk 
Published: July 2006

The studies concern the changes in communities of rotifers in a model system of 4 through‐flow ponds linked in a row and constantly supplied with waste‐water after mechanical‐biological treatment. Studies were carried out from the spring of 1977 to the spring of 1978 – i.e. during the first year the ponds were used.Twenty‐four species of rotifers, forming three cenotic communities differing in number of species, dominance structure and abundance, were found. Gradually increasing similarity of communities with the distance from the source of post‐waste water reflects the increasing stability of physico‐chemical and biological conditions in the examined model ecosystem.Maximum biocenotic stability was observed in the last pond with the highest specific differentiation, and also considerable share of oligo‐ and β‐mesosaprobionts, the highest frequency of species and slight differences in abundance between the dominant and accompanying species.The role of trophic factor in formation of rotifer communities in the successive links of the presented model pond system is pointed out.
Growth and tillering patterns within tussocks of Eriophorum vaginatum
Authors: Fetcher Ned , Shaver Gaius R. 
Published: July 2006

Growth patterns were investigated for Eriophorum vaginatum tussocks from disturbed and undisturbed tussock tundra at two sites in Alaska. Total basal area of tussocks decreased with increased cryoturbation but mean basal area per tussock did not. Flowering was observed in tussocks of significantly smaller size on disturbed compared to undisturbed tundra. For tussocks with < 10% cover by shrubs and moss, number of tillers per tussock was linearly related to tussock diameter in most disturbed and undisturbed sites. Exceptions occurred in an area that had been bladed with a bulldozer 7 yr before our survey where tiller number increased as the square of diameter and in an area with much frost activity where tiller number was not emulated with diameter. The ratio of daughter tillers to adult tillers decreased with diameter in disturbed tundra, whereas the trend was less pronounced in undisturbed tundra.Microsuccession in undisturbed tussock tundra was investigated by sampling tussocks with different amounts of shrub and moss cover for number of daughter tillers per adult tiller, weight per tiller, percent nitrogen, and percent phosphorus. Small tussocks without cover by other species and large, partially covered tussocks were not significantly different by any measures, but tussocks that were almost completely buried had significantly (p < 0.05) lower values of tillering index, weight per tiller, and percent phosphorus.
The structure of carrion fly communities: the size and the type of carrion
Authors: Kuusela Seppo , Hanski Ilkka 
Published: July 2006

Species composition and abundance relations of flies attracted to and bred from different sizes (20‐100 g) and types of carrion (small mammal, cow liver, bird, and fish) were studied experimentally in natural breeding conditions in South Finland. Large pieces of carrion did not attract significantly more individuals or species than did small ones, but there was a positive correlation between size of carrion and numbers of flies bred, apparently because of competition. Altogether 10 species emerged from 50 cultures, and on average 2.78 ± 1.22 (SD) species emerged from one culture. The number of co‐occurrences among the emerging flies indicated random colonization. Variation in species composition between like pieces of carrion was not less than variation between carcasses of different size or type; hence, size and type of carrion are not important determinants of community structure within the size and type ranges used. Lucilia illustris (Meig.) was the predominant species, comprising 50% of flies trapped and 85% of flies bred. The difference indicates changing species composition in the community. Two sets of cultures were left open for egg‐laying for 2 and 7 d. Competition was less Intensive in the former cultures, which produced 4.0 individuals per gram of carrion, contrasting with only 1.4 individuals per gram in the latter cultures. Competition delayed development in all species, but least in L. illustris, which suggests that fast developing species are at a competitive advantage. In agreement with this, abundance was positively correlated with the rate of development.
Fluctuations in some small rodent populations in Norway 1971–1979
Authors: Christiansen Erik 
Published: July 2006

Small rodent populations were monitored by autumn snap trapping in 22 localities of Norway during the years 1971–979. A total of 105528 trap days yielded 7987 small mammals, out of which the bank vole Clethrionomys glareolus and the short‐tailed vole Microtus agrestis made up 52.3 and 29.0%, respectively. Third in abundance was the wood mouse Apodemus sylvaticus.Both M. agrestis and C. glareolus fluctuated fairly regularly, with general peak years of abundance in 1973 and 1977. Other Microtidae, such as M. oeconomus, C. rutilus and Lemmus lemmus apparently also exhibited cyclic fluctuations. In Arvicola terrestris, Apodemus, and in Sorex shrews, regular fluctuations could not be demonstrated, although the abundance varied considerably.The body weights of sub‐adult C. glareolus cycled in accordance with the fluctuations in abundance; the highest weights being recorded in peak years. In M. agrestis, this correlation was less obvious.
The lizards Lacerta agilis and L. vivipara as hosts to larvae and nymphs of the tick Ixodes ricinus
Authors: Bauwens D. , Strijbosch H. , Stumpel A. H. P. 
Published: July 2006

In this paper we provide quantitative information on the occurrence of larvae and nymphs of the tick Ixodes ricinus in populations of the lizards Lacerta agilis and L. vivipara. Levels of infestation were rather low, at least when compared with those of small mammals and sheep. Hence we suppose that lizards feed only a minor fraction of the total tick population.Differences in tick loads among lizard subpopulations are probably attributable to difference in body size and mobility among the host groups.Ticks exhibit a markedly clumped distribution on the lizards. This distribution pattern fits with the negative binomial distribution. The overdispersed distribution of tick larvae in the field and aspects of the lizards' behaviour are considered as factors which contribute to the observed infestation patterns.Tick larvae were active throughout summer, with peak levels occurring during June‐July. Nymphs were most numerous during May‐June but almost absent during the summer months. Almost always ticks were attached near the lizards' forelimbs. Possible mortality resulting from tick infestation does not contribute significantly to the overall lizard mortality. Hence, these ectoparasites seem to have but a minor impact on the lizard populations.
The life history of Glyphopsyche irrorata (Trichoptera, Limnephilidae): A caddisfly that overwinters as an adult
Authors: Berté Stephen B. , Pritchard Gordon 
Published: July 2006

Glyphopsyche irrorata has adapted to live in ponds with fluctuating water levels and ponds exhibiting winter drought by passing the winter as an adult in the terrestrial environment.Larvae, which hatch in May and pupate in late August, are detritivorous shredders. Males and females emerge in September, with a sex ratio of one and commence mating in the autumn. The entire population has mated by May at which time females oviposit in the water. Adult males and females are present in equal numbers in the spring and have similar longevities approaching a maximum of 8 to 9 months.
Influence of woodlot floor topography on microbial decomposer distribution
Authors: Dwyer L. M. , Ivarson K. C. 
Published: July 2006

The distribution of microbial populations that decomposed sugar, cellulose and lignin‐related substrates was examined in a beech Fagus grandifolia Ehrh. and maple Acer saccharum Marsh. dominated woodlot developed on glacial till. The topography of the woodlot, characterized by rises, depressions and more extensive level areas about 1 m in diameter with a 0.5 m vertical maximum, produced a mosaic of decomposer habitats designated as high, level and low sites.In general, populations of sugar, cellulose and lignin decomposing organisms (based on ten estimates made from April to October) were two to four times higher in litter and soil samples from low sites than those from high sites. Sugar decomposing bacteria in litter were most abundant at all topographic sites. 135 × 106 g−1 dry litter at high sites, 396 × 106 g−1 at level sites and 456 × 106 g−1 at low sites; lignolytic fungi were least abundant, 391 × 102 g−1 dry litter at high sites. 700 × 106 g−1 at level sites and 954 × 102 g−1 at low sites. Numbers of microbial decomposers in the topographic sites were correlated with organic matter content. Distribution of fungal genera did not appear to be related to topographic site. Most populations examined showed two numerical peaks, one in late May or June and one in late September or October. It is suspected that these peaks were influenced by the coincident timing of favourable physical conditions and priming by soluble nutrients leached from litter.
Chemical composition of reindeer forage plants in Svalbard and Norway
Authors: Staaland Hans , Brattbakk Ingvar , Ekern Karen , Kildemo Kjetil 
Published: July 2006

Several of the most important reindeer forage plants in Svalbard were analysed for content of minerals (Na, K, P, Ca, Mg, S, Cl, Fe, Cu, Mn, Zn, Mo and Co) and for content of ash, crude protein, crude fiber, ether extracts and nitrogen free extracts. Some forage plants were also examined in in vitro digestibility trials. The results were compared with results from similar analyses of alpine mountain plants from southern Norway. Also freshly voided fecal samples were analysed for the same components as the forage plants.The Svalbard vegetation had a higher content of Na, Ca, Mg, Cl, Fe and Co, than similar plants from Southern Norway. The content of other elements examined seemed to be more equal in Norway and on Svalbard. Within the Svalbard area plants growing in limestone areas had the highest content of calcium and magnesium. Also plants growing on manured soil below bird cliffs appeared to have high nutritional value. It is furthermore concluded that the closeness to the sea as well as the occurrence of several plants with high mineral content, gave the Svalbard reindeer the possibility to further improve their mineral balance compared with continental reindeer. Also the dietary shift from lichens as a major dietary component in Norway, to mosses on Svalbard, may increase mineral intake, but may also have an inferior effect on digestibility.Although balance experiments and carcass analyses of minerals in Svalbard reindeer are missing, it is concluded that Svalbard reindeer apparently had adequate intake of most mineral elements. In spite of low standing biomass of reindeer forage plants, the quality of the vegetation seemed to compare favourably with continental reindeer pasture.
Longitudinal patterns of production, food consumption, and seston utilization by net‐spinning caddisflies (Trichoptera) in a southern Appalachian stream (USA)
Authors: Ross Douglas H. , Wallace J. Bruce 
Published: July 2006

Larval production of ten species of Hydropsychidae and Philipotamidae was studied at six stations along 6.4 km of a southern Appalachian stream, encompassing stream orders 1–4 and a 600 m elevation change. Species‐specific production estimates ranged from 23–983 mg AFDM m−2 yr−1 These low values are attributed to the paucity of nutrients in these undisturbed headwater streams which reduces detrital food quality, algal growth, and production of smaller invertebrates eaten by hydropsychids. Animal food supported the majority of hydropsychid production (72%); philopotamids relied primarily on fine detritus (80%) and diatoms (15%). The contribution of animal food to caddisfly production decreased downstream, while the relative importance of filamentous algae and diatoms increased. These changes reflect the downstream decline of more carnivorous species, as well as increased primary production which accompanies the shift in lotic community metabolism from heterotrophy towards autotrophy with increasing stream order.Net‐spinning caddisflies had a minor impact on seston quantity, consuming only 0.0003%‐0.005% of the total seston (including invertebrate drift) passing over a m2 of substrate annually. In contrast, the percentage of invertebrate drift consumed was, on the average, > 400 × higher than total seston consumption. These insects influence seston quality rather than quantity. The percentage of total seston and animal drift consumed declined downstream, indicating that turnover lengths of these materials increase with stream order. Longer turnover lengths or “spirals” result from changes in the physical characteristics of the stream, i.e., increasing discharge and stream power and decreasing numbers of retention devices (i.e., organic debris dams), which increase the downstream transport velocity of seston. Higher transport velocities reduce the rates at which these filter feeding caddisflies can process the organic inputs to a given reach of stream. Small streams (orders 1–3) appear to be most responsible for efficient processing of a stream's energy inputs.