bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypsography, meteorology and hydrology of the Øvre Heimdalen catchment
Authors: Grøterud Olav , Kloster Asbjørn Elias
Published: July 2006

The Lake Øvre Heimdalsvatn is greatly affected by wind. Precipitation, especially heavy rainfall, has probably a good possibility of eroding and leaching material into the lake. The mean annual temperature is −1.2°C, and the estimated mean annual evapo‐transpiration is about 200 mm. The lake is covered by ice from late October to the beginning of June. Run‐off, lake level and precipitation are well correlated, indicating that the influence of the catchment is large and rapid.
The post‐glacial sediments of Øvre Heimdalsvatn
Authors: Kloster Asbjørn Elias , Hongve Dag
Published: July 2006

Two sediment cores, 143 cm and 268 cm in length, have been investigated. The oldest dating is 8240 ± 500 radiocarbon years B.P. The variation in the composition of the sediments is probably caused solely by climatic changes. The organic fraction is small, never exceeding 20%, reflecting the low primary production and rapid decomposition of allochthonous organic matter within the lake. The proportions of inorganic constituents indicate that the mineral fraction consists of clay and silt particles flushed into the lake from the drainage area.
Phytoplankton and pelagic primary productivity in Øvre Heimdalsvatn
Authors: Tangen Karl , Brettum Pål
Published: July 2006

A phytoplankton investigation was carried out in the subalpine, low‐productive Norwegian lake Øvre Heimdalsvatn in 1969–70 and 1972. This paper describes the temporal and spatial distribution of the standing stock of phytoplankton, and phytoplankton primary productivity. The annual average primary productivity in 1972 was 4.0–4.9 mg C m−3d−1; the annual average standing stock varied from 120 mg m−3(freshweight) in 1969–70, to 250 mg m−3in 1972. Phytoplankton species composition and size distribution is discussed. Throughout the year the phytoplankton is dominated by small (ultraplankton) species; μ‐algae (< 5 μm) showed cell concentrations up to 15 mill. cells 1−1. The dominating group was chrysophytes; cryptophytes, dinoflagellates or green algae were at times abundant. A phytoplankton monthly budget and a diagram showing annual average carbon flow through the standing stock of phytoplankton are presented; the phytoplankton dynamics in Øvre Heimdalsvatn is compared to that of other low‐productive lakes.
Periphytic and drifting microalgae in a tributary stream of Øvre Heimdalsvatn
Authors: Tangen Karl , Müller Christer , Brettum Pål
Published: July 2006

Samples of drifting and periphytic microalgae were collected during 1972 from a fast‐flowing, stony stream (Brurskardsbekken) in the Jotunheimen mountain area, central southern Norway. The predominant algal groups in the drift and the periphyton were diatoms and green algae, while only a few species were recorded in both communities. A considerable number of species from Chrysophyceae, Cryptophyceae and other algal classes were also recorded in the drift samples. The species composition was in good agreement with microalgal communities earlier described from mountain areas in Scandinavia, although species which probably are new to Norway, were also recorded. A quantitatively important fraction of planktonic species in the drift is interpreted as a contribution from lacustrine habitats in the watercourse. A general change in the periphyton during the summer, from green algae to diatoms, was observed, Altitudinal differences in the periphyton included a delayed green algal maximum at higher altitudes compared to lower. In the zone around the upper birch limit, a transition in species composition as one goes up stream, described in other investigations, was not observed.
An annotated check‐list of microalgae from Øvre Heimdalsvatn and its tributaries
Authors: Tangen Karl , Haworth Elisabeth Y. , Brettum Pål , Müller Christer
Published: July 2006

About one hundred genera with more than 300 species have been identified in water samples, net haul material, periphyton samples from artificial substrate, and benthos and sediment samples collected during 1969–1972. More than 40 taxa of lower rank (subspecies, varieties, forms) were recorded. The most prominent algal groups were diatoms with 138 taxa, and green algae with 122 taxa of which the majority was desmids. The material from the epipelic and epilithic communities in the lake is very scarce, while the list of plankton species is relatively complete, with the exception that a large number of small flagellates could not be identified to species level. The taxa which were identified, are presented in a list with additional notes on occurrence.
The benthos of Øvre Heimdalsvatn: Introduction
Authors: Aarefjord Finn , Brittain John E. , Lillehammer Albert
Published: July 2006

For the purpose of benthic studies Øvre Heimdalsvatn was divided into three depth zones. These were the exposed zone (from the shore down to 1–2 m depth), the macrophytic zone (1–2 m to 5–5.5 m depth) and the non‐macrophytic zone (5–5.5 m to 13 m). The reasons for this division and the main characteristics of each zone, including the substrata present, are given.
The fauna of the exposed zone of Øvre Heimdalsvatn: Methods, sampling stations and general results
Authors: Brittain John E. , Lillehammer Albert
Published: July 2006

Twenty stations were sampled monthly during the Ice free period (June‐September) in 1972. Emergence traps, emptied daily, were also employed. The major macroinvertebrates in the exposed zone were Ephemeroptera, Gammarus lacustris, Trichoptera, Chironomidae, Plecoptera and Coleoptera, and these constituted over 90% of total numbers. Densities of G. lacustris, Ephemeroptera, Tipulidae and Plecoptera showed a positive correlation with detritus. No significant relationship was found for the other taxa. Nearly 70% of the fauna emerged, and did so during the period from June to September. Chironomidae, Ephemeroptera, Plecoptera, Trichoptera and Tipulidae accounted for nearly all emergence and their total average annual emergence was 372 cal m−2. Of this total, Chironomidae constituted 28%, Ephemeroptera 28%, Plecoptera and Trichoptera 15% each and Tipulidae 4%.
The Ephemeroptera of Øvre Heimdalsvatn
Authors: Brittain John E.
Published: July 2006

The species composition, distribution, seasonal variations in abundance, life cycles, emergence periods, length‐weight relationships and biomass of the Ephemeroptera of Øvre Heimdalsvatn were investigated. Detritus was a significant factor in explaining the variation in total ephemeropteran numbers around the lake. Numbers in the exposed zone reached a maximum during July due to emergence activity. The ephemeropteran biomass at emergence, to which Leptophlebia vespertina (L.), L. marginata (L.) and Siphlonurus lacustris Eaton were the main contributors, was estimated to be 0 02g dw m−2. Other species recorded from the lake were Baëtis macani Kimmins, B. rhodani Pictet, Siphlonurus aestivalis Eaton and Ameletus inopinatus Eaton. All species were univoltine, but differences in ability to grow during ice cover and in life cycle timing resulted in a succession in emergence during the ice free period.
The Chironomidae of the exposed zone of Øvre Heimdalsvatn
Authors: Aagaard Kaare
Published: July 2006

A total of 67 species of chironomids were caught in emergence traps placed at the shoreline. Additional larval records increase the number of species to be at least 75, a high number of species possibly explained by the exposed nature of the lake, which also provides habitats for lotic forms.

The species composition and relative abundance of the four main groups of Chironomidac indicate that Øvre Heimdalsvatn is a subarctic lake, with a strong oligotrophic character. The emergence period starts in mid‐June and lasts to mid‐September. Diversity studies show similarity with mountain lakes in France and with the Bodensee, but the equilability in Øvre Heimdalsvatn is lower.

The chironomid faunal composition of Øvre Heimdalsvatn seems to be determined by abiotic ecological factors and not the history of distribution.
The lake ecosystem of Øvre Heimdalsvatn
Authors: Larsson Petter , Brittain John E. , Lien Leif , Lillehammer Albert , Tangen Karl
Published: July 2006

The Norwegian subalpine lake. Øvre Heimdalsvatn, has a surface area of 0.78 km2and a maximum depth of 13 m. It is ice‐covered for 7.5–8 months, has a marked spring spate and a mean annual renewal period of about two months. The water is poor in electrolytes. Intensive studies have been made by an interdisciplinary team of the lake's physical and chemical properties, primary production and secondary production under the auspices of IBP/PF from 1969 to 1973, Allochthonous material accounted for 1/3 of utilized plant input. The major lake predator, the brown trout, fed largely on benthic organisms and did not exploit the zooplankton biomass. On account of the long period of ice cover and the rapid rise in temperature after ice break, many organisms (both planktonic and benthic) showed synchronous development. Abiotic conditions, such as the nature of the spring spate and the temperature rise, strongly affect species and community development.
Phytoplankton of shallow lakes: Seasonal succession, standing crop and the chief determinants of primary productivity, 1. Cooking Lake, Alberta, Canada
Authors: Hickman Michael
Published: July 2006

Cooking Lake (113°02′W, 53°26′N), a well‐mixed, shallow (mean depth (1.59 m), eutrophic lake in Alberta, Canada, is characterized by eutrophic chlorococcalean and cyanophycean phytoplankton associations, and little change in standing crop with increasing depth. Standing crop and primary productivity are low during the winter but pronounced spring and summer maxima occur. Mean yearly areal standing crop (ΔB) and primary productivity (ΔA) were 212.4 mg m−2 chlorophyll a and 301.8 mg C h−1 m−2 respectively. Annual productivity was estimated at 1322 g C m−2. The mean increase in the extinction coefficient (ɛ) per unit increase in standing crop (B) was 0.03 In units m−1. High non‐algal light attenuation (ɛq) occurred avenging 41 which prevented the ratio B/ɛ from attaining more than 65% of the theoretical maximum except once when algal self‐shading occurred. Close correlations existed between B (mg m−3 chlorophyll a) and A max (mg h−1 m−3) ΔA and ΔB, ΔA and B, Amax, and Amax/ɛ, and ΔA and Io′, (W m−2). The depth of the euphotic zone (Zeu) varied between 0.5 and 1 25 m; the average relationship between zeu and E was Zeu= 3.74/ɛ, and the mean standing Crop found in the euphotic zone represented 55.2% of the theoretical maximum, The high ɛq, values made the model of Tailing (1957) inapplicable to Cooking Lake. The Q10 value for the lake was 2.2. The maximum rate of photosynthesis per unit of population per h. Ømax, (mg C sag chlorophyll a−1 h−1) was more closely related to temperature than irradiance and ma depressed by pH values greater than 9.1. Growth of the phytoplankton was not nutrient limited: instead irradiance and temperature were more important. Indirect evidence that free CO2 limited photosynthetic rates, is provided by the Ømax: pH relationship.
Habitat distribution and conservation of land bird populations in northern Norway
Authors: Järvinen Olli , Väisänen Risto A.
Published: July 2006

About 300 km line transect censuses of breeding land birds were made in northern Norway in 1974–76. The data (1020 pairs in 26 samples) were grouped into seven major habitats: stony ground and oceanic heath (C1), continental dry heath (C2). “′2Calcarius heath”, dry peatland, wet peatland (C5), meagre and average birch forest, and rich birch forest (C7). Bird density ranged from 22 pairs km−2 (C2) to 364 pairs km−2 (C7), but most habitats had 67–96 pairs km−2. The bird communities are described.

Defining the Optimal habitat for a species as the maximum‐density habitat, the 43 species observed were found to comprise three major groups: tundra species (optimal habitat C1), peatland species (C5) and forest species (C7). Species whose central range includes northern Norway had a broader habitat amplitude than those with a southern or a very northern distribution. A new index was devised for the evaluation of the conservational importance of a habitat or a species. From the North European standpoint. C1 is certainly the most important habitat in northern Norway, as C1 supports many species which are rare in other parts of North Europe. However, population trends should also be taken into account when conservational preferences are judged.
Light penetration in different types of lakes in Central Finland
Authors: Eloranta Pertti
Published: July 2006

Light penetration measurements of blue (Schott filter BG 12), green (VG 9), and red (RG 630) light was made in 30 Finnish lakes with different degree of humus content and eutrophy for the comparison of the structure of phytoplankton communities and the light environment in the waters.

The relations between Secchi disc visibility and the penetrations of different spectral regions and relations between the light conditions and the colour of the water was examined.

The increase of ɛmin m−1 caused by humus material is 0.008 In units per colour unit (mg Pt l−1). The optical depth was especially in brown waters smaller than calculated by Formula after Talling (1965).
Bird community energetics in a boreal coniferous forest
Authors: Alatalo Rauno V.
Published: July 2006

The annual minimum energy consumption of the bird community was 2524 × 103 kcal km−2, of which 44% was consumed by wintering species and 73% by passerines. The daily energy consumption was in summer 14–16 × 103 and in winter 1–2 × 103 kcal km−2. In spruce forests and in afforested swamps birds required approximately 0.12% of the net primary production. Their total annual energy consumption was covered by invertebrates (59%), vertebrates (2%) and vegetable matter (39%); the food derived from the ground (55%), from trees (44%) and from the air (1%). Arboreal insectivorous passerines, ground passerines and gallinaceous birds were the most important ecological guilds. Among passerines existence metabolism accounted for 73% of the annual energy consumption, extra activity for 17%, breeding activity for 1%, moult for 4% and nestlings for 4%.
The epifaunal communities of Pelvetia canaliculata and Fucus spiralis
Authors: Dunstone M. A. , O'Connor R. J. , Seed R.
Published: July 2006

The distribution, size and abundance of Pelvetia canaliculata (L.) and Fucus spiralis L. and the epifaunal communities associated with these two high shore fucoid algae have been studied at several contrasting sites in North Wales. Several environmental parameters were measured at each site and correlated with the distribution of the algae and their associated fauna. These weeds, which occur in perhaps the harshest zone of the shore, support exceedingly impoverished epifaunal communities in which the amphipod Hyale nilssoni (Rathke), small littorinids and acarines predominate. This contrasts markedly with the extremely diverse epifaunal communities associated with algae situated lower in the intertidal zone.
A carbon budget for nematodes, rotifers and tardigrades in a Swedish coniferous forest soil
Authors: Sohlenius Björn
Published: July 2006

Nematodes, rotifers and tardigrades from a Swedish pine forest soil were investigated in a monthly sampling programme lasting for one year. The monthly mean values of number, biomass and oxygen consumption were estimated. All groups fluctuated rather much over the year with a summer minimum (1.1 ˙ 106 animals m‐2) and a winter maximum (6.3 ˙ 106 animals m‐2) for the nematodes. The reasons for these fluctuations are discussed in relation to fluctuations of water content and temperature of the soil. On an annual basis a carbon budget was calculated which gave the following values for this fauna; consumption 4.3, production 0.6, respiration 0.9 and defecation 2.8 g carbon m‐2.
Pupation, emergence and fecundity of phoretic Epoicocladius ephemerae (Chironomidae)
Authors: Svensson Björn S.
Published: July 2006

The importance of the presence of nymphs ofEphemera danicafor the emergence and survival of phoreticEpoicocladius ephemeraewas tested in the laboratory. Only a few midges survived when hosts were absent. The synchronization of emergence of the host and its associate was examined in the field. Fecundity and total egg volume per unit wing length was compared betweenE. ephemeraeand several free‐living chironomids. The number of eggs was about the same inE. ephemeraeas in the other species, but total egg volume was comparatively large. A comparison is also made between the host‐related adaptations and feeding habits ofE. ephemeraeand of the parasiticSymbiocladius rhithrogenae.Some larvae ofE. ephemeraeuse the fullgrown nymphs as pupation sites, probably because the emerging hosts carry the pupae to the water surface. The reason why not all midge larvae make use of nymphs for this purpose is probably because they are unable to adapt to the exact emergence time of the nymphs. Analysis of the emergence data of the midge and of the mayfly support this hypothesis.
A comparison of carbon dioxide production and oxygen uptake in sediment cores from four south Swedish lakes
Authors: Granéli Wilhelm
Published: July 2006

Carbon dioxide production and oxygen uptake were measured in undisturbed sediment cores taken during winter from four lakes of different trophic state. Respiration was measured at 5, 10, 15 and 20°C at high oxygen saturation (75–100%). The respiratory quotient, calculated from the mean values of carbon dioxide production and oxygen uptake at each temperature for each lake, was 0.83–0.96 with a mean value for the four lakes of 0.90. At very low oxygen saturations (<10%) carbon dioxide production was 21–42% of the production at 20°C and high oxygen saturations. The results indicate that under aerobic conditions, oxygen uptake and carbon dioxide production are closely‐coupled processes in these lake sediments.
Chironomid communities as water quality indicators
Authors: Saether Ole A.
Published: July 2006

Recent mathematical indices summarizing biological communities of indicators are recapitulated. Improvements of these indices based on weighting according to width of trophic ranges of each species are suggested. Their principle deficiencies, however, are pointed out.

Revised lists of characteristic profundal as well as littoral and sublittoral chironomids in Nearctic and Palearctic lakes show that at least 15 characteristic chironomid species communities can be delineated, 6 in each of the oligotrophic and the eutrophic ranges and 3 in the mesotrophic range. It is proposed that these communities be lettered consecutively in the Greek alphabet from α (alpha) to o (omikron). A key to the 15 divisions based on the species associations in the profundal zone of harmonic lakes is put forward. There is very good correlation between the 15 divisions and the ratios of average total phosphorus to mean lake depth and average chlorophyll a to mean lake depth.

The ratio of chironomids to oligochaetes and the distribution patterns of single species have proven useful in pin‐pointing localized areas of pollution. The primary mechanism governing the distribution of chironomid communities in oligotrophic and mesotrophic lakes appears to be the availability of food materials rather than the annual hypolimnetic oxygen concentration. In eutrophic lakes the relationships between organic matter accumulation and oxygen levels are so interdependent as to be inseparable.
The breeding biology of the starling Sturnus vulgaris in northern Finland
Authors: Ojanen Mikko , Orell Markku , Hirvelä Juhani
Published: July 2006

The breeding biology of the starling Sturnus vulgaris was studied in three populations in northern Finland, with additional reference localities in nearby areas. Results from a total of 329 nests are presented from years 1962‐1976.

The onset of laying in the Oulu area took place on 5 May, the median date being 10 May, about one week later than in southern Finland and 2–3 weeks later than in central Europe. The clutch‐size was 5.29 ± 0.05 in the first nests and 5.06 ± 0.26 in later ones. Incubation time was 12.1 ± 0.6 d. An average of 3.31 ± 0.10 fledglings was produced per pair, 3.69 ± 0.08 in succesful clutches, which is significantly less than usually reported from central Europe. Most of the losses were due to starvation of the young.

No second broods were observed in the Oulu area, and repeated nesting was not common, probably because of the general late start of laying.

The reasons for the recent decline in several Finnish starling populations do not lie in the production capacity but must be sought for elsewhere.
Benthic resting periods of pelagic cyclopoids in an oligotrophic lake
Authors: Sarvala Jouko
Published: July 2006

The benthic resting stages of pelagic cyclopoids were studied in the oligotrophic lake Pääjärvi (maximum depth 87 m), southern Finland. Stage 5 copepodids of Thermocyclops oithonoides were found in the bottom from September to April, with highest abundances in the littoral at 1–2 m. Dormant Mesocyclops leuckarti (mainly stage 5 copepodids) were found from mid‐August so April, with a strong concentration at the depth of 1.5 m, and resting stage 4 copepodids of Cyclops kolensis from mid‐summer to late winter at the depths of 1–13 m. Single stage 4 and 5 copepodids of C. strenuus and C. lacustris were also found in the bottom during autumn and winter. Available information on the periodicity of these species conforms well with the hypothesis of a temperature‐adjusted photoperiodic control of diapause.

In the sediment, the resting stages of pelagic cyclopoids were confined to the uppermost 2–3 cm, C. kolensis penetrating slightly deeper than the smaller Thermocyclops and Mesocyclops species.

Losses during the resting period were highest in T. oithonoides, in which the seasonal mortality rates were significantly correlated with temperature. Its overall mortality was slightly lower at 2 m than at 13 or 40 m. C. kolensis had the lowest mortality, with no clear relation to temperature.

The mean winter biomass of the benthic resting stages of pelagic cyclopoids exceeded that of the true benthic copepods, and the winter losses of the former were equal to about one fifth of the total annual production of the true benthic copepods.
Population ecology of Trituras cristatus and T. vulgaris (Urodela) in SW Sweden
Authors: Hagström Torkel
Published: July 2006

The population ecology of newts was investigated between 1969 and 1974 in two localities near Gothenburg, SW Sweden: the Gunnebo park pond (about 300 m2) where Triturus cristatus Laurenti and T. vulgaris L. are sympatric, and a rock‐pool (6 m2) in Billdal with only T. vulgaris. At Gunnebo, a population of about 350 breeding T. cristatus was found with about as many males as females but males being more aquatic than females. An annual survival of 0.7–0.8 was estimated for the adults. The T. vulgaris population at the same locality was estimated to about 250–300 breeding adults with a sex ratio possibly in favour of males. The survival of adults was found to be extremely low and a very small percent of the adults seems to breed more than once. The Billdal T. vulgaris population was estimated to contain nearly 70 breeding adults with a sex ratio very near to 1:1. The annual survival of adults was found to be 0.5. The different survival of the two T. vulgaris populations are discussed with particular reference to predation. The age at which newts breed for the first time seems to vary; for T. vulgaris five years may well be the normal age. Factors that may limit the sizes of the populations, possible reasons for differences in frequency of occurrence in water, and possible predators are discussed.
Variation in body size, hair length, and hair density in the deer mouse Peromyscus maniculatus along an altitudinal gradient
Authors: Wasserman David , Nash Donald J.
Published: July 2006

Wasserman, D. and Nash, D. J. 1979. Variation in body size, hair length, and hair density in the deer mouse Peromyscus maniculatus along an altitudinal gradient. – Holarct. Ecol. 2: 115‐118.

Deer mice Peromyscus maniculatus were captured along an altitudinal gradient that extended from 1524 m up to 3353 m in central Colorado during August and early September 1976. No differences were found in mean body weight along the altitudinal, gradient. Mean hair length was found to increase along the gradient up to an altitude of 2438 m where it leveled off. Hair density was higher in mice captured at 3353 m than at 1524 m. This suggests that Bergmann's Rule was not found along the altitudinal gradient and that insulation was modified in response to the cooler conditions that exist at, high altitude.
Biometry and biology of Constempellina brevicosta (Chironomidae) in a subarctic lake
Authors: Grimås Ulf , Wiederholm Torgny
Published: July 2006

Grimås, U. and Wiederholm, T. 1979. Biometry and biology of Constempellina brevicosta (Chironomidae) in a subarctic lake. – Holarct. Ecol. 2: 119‐124.

Constempellina brevicosta Edw. made up about 50% of the chironomids emerging from the littoral of Lake Blåsjön. The lake is impounded for hydroelectrical purposes. Constempellina was less abundant at an earlier, smaller amplitude of water level fluctuations in the same lake and much less abundant in a nearby natural lake. The species is able to survive in a frozen substratum on ice‐covered bottoms. Records of early life stages and emergence data indicated a one‐year life cycle with peak emergence from the littoral zone occurring in mid July. Statistical comparisons were made of size characteristics with respect to time and site of emergence and swarming. Swarming individuals were found to be significantly larger than emerging ones as measured in length of body, wing, tibia, and tarsi. Individuals swarming from mid July to August were successively smaller in all characters except basal antennal segments. Individuals swarming in June were smaller than those occurring somewhat later. The changes in size seem to reflect differences in larval habitat, with early summer material emanating from areas exposed to winter freezing. Males swarming at different sites at the same date were similar in all respects except for body size. Individuals emerging from different depths within the littoral zone at a single date were different in most respects, those from more shallow areas being smaller. Linear regression of swarm material from different dates showed a positive correlation for most characters. The correlations were particularly strong, and applied to all characters, when the early summer material was excluded. Mean AR values were successively lower throughout the season and positively correlated with size. Mean LR values were slightly higher in early summer than later. The LR values varied independantly of size. AR and LR values in swarm material varied between extremes for single individuals which were usually within 20% of the arithmetic mean, or 0.92–1.36 for AR and 0.78–1.06 for LR. Confidence limits for population estimates were within 0.04 units of the means.
Nutrient cycling in two Danish beech forests growing on different soil types
Authors: Astrup Mette , Bülow‐Olsen Anne
Published: July 2006

In two mature Danish beech forests, one growing on fertile mull, the other on acid mor, cycles through vegetation of Ca, Mg, K, Na, Mn and P are followed. Nutrient content is measured in precipitation, throughfall, stem flow, litter and herbage as well as in soil pool (0–10 cm).

In both forests, Na is found to pass vegetation in highest rate compared to soil pool, On acid mor, trees accumulate amounts of nutrients comparable to the amounts falling in precipitation, but on fertile mull trees accumulate more of all nutrients than that which falls in precipitation, with the exception of Mn.

P seems to be the limiting growth factors for trees on acid mor, and none of the nutrients investigated seems to limit growth on fertile mull.
The rate of downstream displacement of macroinvertebrates in the upper Wye, Wales
Authors: Hemsworth R. J. , Brooker M. P.
Published: July 2006

Quantitative data describing drift rates and benthic density of macroinvertebrates are utilised to estimate the rates of downstream displacement of invertebrate populations in the Wye, Wales. Calculations are based upon two models, one a classical exponential relationship between drift catch and distance travelled and the other derived from a solute balance equation. Results from the two models were significantly correlated. Estimates of the rate of benthic community displacement ranged from 2.8 to 70.7 m d‐1, with highest rates recorded in she summer period. There were considerable differences in rates between taxa and between sites. It was estimated that a displacement of 10 km downstream could be achieved by certain taxa during a generation period.
Geolittoral extent of Vaccinium myrtillus and vegetational differentiation on a bank of the Muddusjokk River, North Sweden
Authors: Nilsson Christer
Published: July 2006

The numbers, densities and mean heights of the above‐ground shoots of Vaccinium myrtillus growing in the geolittoral on a bank of the Muddusjokk river, N Sweden, were studied in relation to the position of the seasonal high‐water level. V. myrtillus was constantly present in the upper half of the geolittoral belt, with its lower limit about 50 cm below the drift‐line and its lowermost occurrence of all at 82 cm below. The vertical extent of the whole transect was 1.3 m. The vertical extent of the entire geolittoral was assessed by studying the distributions of a range of vascular plants and bryophytes. The upper geolittoral subdivision had a greater vertical extent (0.68 m) than the middle and lower ones (together 0.60 m). V. myrtillus does not appear to be a suitable indicator species for determining the local high‐water levels along watercourses in N Sweden.
Distribution patterns of morph frequencies in the snail Cepaea hortensis in Iceland
Authors: Bengtson Sven‐Axel , Nilsson Anders , Nordström Sten , Rundgren Sten
Published: July 2006

In Iceland Cepaea hortensis Müll. reaches its northern limit of distribution occurring in restricted areas along the south coast. Samples of snails collected along steep cliffs in two such restricted areas were effectively monomorphic for shell colour (yellow), but were polymorphic for banding pattern and revealed strong area effects. In both localities samples from sites facing east contained varying frequencies of unbanded snails whereas in ecologically similar sites facing south unbanded were absent. In an experimental population released at a south‐facing site unbanded snails failed to become established whereas banded individuals survived and bred. It is suggested that the area effects are maintained through non‐visual (most likely climatic) selection though other possibilities cannot be ruled out.
Phytoplankton diversity in Lake Norrviken 1961–1975
Authors: Tinnberg Lena
Published: July 2006

Five common indices were compared to see which of them would be most suitable in the study of long time changes in a phytoplankton community.

Margalefs index d showed the same course during the year as did the number of species. This is also valid for Brillouin's, Shannon's, Simpson's and McIntosh's indices when based on number of individuals. Brillouin's and Shannon's indices based on cell number were found to differ from the diversity values obtained by Simpson's and McIntosh's indices depending on their different sensitivity to the two components of diversity, species richness and species evenness.

Diversity indices including species richness and evenness (e.g. all except Margalef's) are recommended, but their different sensitivity to their species richness and evenness component should not be overlooked.

A description of the phytoplankton composition should always be given together with diversity indices. This is very important since any index used gives no information on the species and their ecology.
Seasonal and annual variations in the prevalence of blood parasites in cyclic species of small rodents in Norway with special reference to Clethrionomys glareolus
Authors: Wiger Richard
Published: July 2006

An investigation of the blood parasites of Clethrionomys glareolus, Microtus agrestis and Apodemus sylvaticus from southern Norway revealed four genera, Trypanosoma, Babesia, Hepatozoon and Grahamella. C. glareolus and M. agrestis harbored all four genera, but Hepatozoon was not detected in A. sylvaticus. Babesia was fairly common in M. agrestis but rare in the other rodents. The peak prevalence of Grahamella and Hepatozoon in C. glareolus occurred in early summer whereas trypanosomes peaked near the end of the summer. Infections with trypanosomes and/or Grahamella in C. glareolus were associated with lowered hematocrit levels and enlarged spleens.
Seasonal and annual variations in the prevalence of helminths in a cyclic population of Clethrionomys glareolus
Authors: Tenora F. , Wiger R. , Baruš V.
Published: July 2006

Six cestode and two nematode species were recovered from a cyclic population of Clethrionomys glareolus in southern Norway. The cestode Aprostatandrya macrocephala and the nematode Heligmosomum glareoli were euconstant species which displayed late spring/early summer peaks in numbers after which they declined. This decrease in prevalence was correlated with decreasing mean age of the host population. Increases in the prevalence of infections with the nematode Syphacia nigeriana in bank voles were correlated to increasing numbers of Microius agrestis in the mixed woods. Cestode larvae were at maximum prevalence during peak years of bank vole abundance. Pathological conditions such as ascites and peritoneal adhesions, as well as splenic and adrenal hypertrophy, were associated with cestode larvae. There was no general trend of an increase in the prevalence of helminth infection with increasing population density of the bank voles.
Aspects of the breeding biology of the goldeneye Bucephala clangula
Authors: Eriksson Mats O. G.
Published: July 2006

Some descriptive data concerning a nest‐box breeding goldeneye population in SW Sweden is given. Clutch size and the proportion of breeding adults were not significantly correlated to proximate factors like food and air temperature. A relationship between population density and the proportion of breeding adults cannot be excluded. Predation was the most important nest mortality factor. There was a preference for nest‐boxes with successful breeding results in the previous year, while no preference for nest‐boxes at good feeding lakes for the ducklings was found. Duckling survival seems to be regulated in a brood size dependent way, and an important mortality factor is losses during travels between different lakes. A negative correlation between temperature and laying date was found, while the yearly variations of the laying date did not influence the proportion of breeding adults, clutch size or hatching success. Clutches which started later contained fewer eggs and produced fewer young than early ones from the same breeding season.
Microbial changes during oil decomposition in soil
Authors: Pinholt Yvonne , Struwe Sten , Kjøller Annelise
Published: July 2006

An examination has been made of the changes in bacterial and fungal populations during the decomposition of oil in contaminated soil. The number of aerobic and anaerobic bacteria and the length of mycelium increased in the oily soil whereas the number of CFU (= colony forming units) of fungi was highest in a control soil. The percentage of oil‐utilizing fungi increased from 60% to 82%, while the bacterial utilization figure increased from 3% to 50%. The important oil‐utilizing fungusScolecobasidiumappeared only in the oily soil, but otherwise the composition of the fungal flora changed only little after addition of oil. In laboratory experiments the chemical Pajab FI was shown to increase microbial activity.
The fruits available as food to small rodents in two woodland ecosystems
Authors: Smal C. M. , Fairley J. S.
Published: July 2006

The fruit fall from the canopy and the understorey in an oak Quercus petraea (Mattushka) Liebl. wood and in a yew Taxus baccata L. wood at Killarney, Ireland, were measured over a period of approximately 13 months; this included two complete fruit crops in each wood. Fruit represents the great bulk of the food of the small rodents present: wood mice Apodemus sylvaticus (L.) and bank voles Clethrionomys glareolus Schreber. From a knowledge of the particular fruits or their parts eaten, the amounts of available food, in kcal ha‐1 were derived. In each ecosystem the food potentially available to small rodents in one crop was five times that in the other.
Microfungi of a Danish Beech forest Microbiology of a Danish beech forest II
Authors: Holm Esther , Jensen Vagn
Published: July 2006

The fungal flora in different parts of a beech forest ecosystem was investigated through a four year period as part of an IBP project. Both colony counts and direct measurements of fungal mycelium indicated that a vast majority of the fungal biomass is concentrated in the upper horizons of the soil, especially in the mull layer. The litter also contained large amounts of fungi when calculated per g dry weight, but still the litter fungi accounted for only a quite small percentage of the total fungal biomass. The fungi growing in direct contact with the living plants, i.e. in the rhizosphere and phylloplane, also accounted for only a few per cent of the total amount of fungi in the ecosystem.

On basis of direct measurements of fungal mycelium the total biomass was estimated to be about 100 g dry wt per m2. However, no attempts were made to distinguish between living and dead hyphae, and a large proportion of the observed hyphae may very well be dead or inactive.

Qualitative studies revealed that the upper soil layers not only contained the largest amounts of fungal mycelium, but also by far the highest species diversity. Other parts of the ecosystem, e.g. the phylloplane, were often strongly dominated by one or a few species, whereas soil always contained a large variety of different types.
Reproduction in a population of the hooded crow Corvus cornix
Authors: Loman Jon
Published: July 2006

Nest density was stable during the 8‐year study period. The mean clutch size was 4.3, and the production of fledglings was 2.0 per pair. Incubation started, on average, when there were still two eggs to be laid and lasted for 18 days. Few eggs were lost but 23% of all broods of nestlings were lost to predators. Single nestlings in a brood were not lost to predators but often starved to death, this applied to 25% of all nestlings. A large proportion of the nestlings were probably infected by Syngamus tracheae, and some of these succumbed during the first weeks after fledging. A comparison with other studies of crow populations shows that the major causes of breeding failure are different in different populations. The causes of variation in breeding success between populations are discussed, especially considering the role of nonbreeding crows.
Attraction of wild ungulates to mineral‐rich springs in central Canada
Authors: Fraser D. , Reardon E.
Published: July 2006

Natural mineral‐rich springs which attract moose Alces alces and white‐tailed deer Odocoileus virginianus were studied in a small area in central Canada. The spring water was particularly rich in Na and Cl but also contained levels of K, Ca, Mg, HCO3 and Mn higher than nearby stream water. In a selection experiment near a natural spring, aqueous solutions of NaCl, NaHCO3 and Na2SO4 were consumed consistently by the animals while salts of K, Ca and Mg were not. Isotope analysis indicates that the spring waters are part of a modern and probably localized flow system. Evaporite minerals and extensive fractures in the local sedimentary bedrock appear to account for the salt content of the spring waters.
Summer food of the golden plover Pluvialis apricaria at Hardangervidda, southern Norway
Authors: Byrkjedal Ingvar
Published: July 2006

Golden plover stomachs were examined through the breeding season al Hardangervidda, southern Norway. The main foods were Diptera larvae (in particular Tipula excisa), adult Coleoptera (notably Otiorrhynchus dubius and Carabidae), and in May and August berries of Empetrum hermaphroditum. Also some larvae of Coleoptera and Lepidoptera were taken. Adult Coleoptera were considerably more common in the diet than expected from abundance data, while Araneae were unimportant as food in spite of a high abundance. The males take the major parental duties after hatching, allowing the females a more undisturbed feeding, supposed to be strongly advantageous for them due to close proximity of egg‐laying and the start of the postnuptial moult. This is reflected in the diet: in July males showed a larger tropic diversity, and ate more adult insects and less insect larvae than the females.
Production and population dynamics of Leptodiaptomus sicilis in a mountain lake in Alberta, Canada
Authors: Herzig Alois , Anderson R. Stewart , Mayhood David W.
Published: July 2006

Leptodiaptomus sicilis(S. A. Forbes 1882) in Pyramid Lake, Alberta, Canada, has only one main generation per year. A small summer generation probably does not survive. Adults may persist for 7 to 12 months, and individual copepods may live for up to 17 months. Retardation of the development of copepodid C4 and C 5 seems to be food linked. The high percentage of survivors (up to 97%) from the first egg pulse of the main generation, and the low percentage of survivors (as low as 3%) from the second egg pulse, is likely due to the absence of cyclopoid adults and copepodids in spring, and to both cyclopoid predation and a poor food regime in summer. Production estimates by several methods gave closely comparable results. Mean daily production byL. sicilisis 0.29 mg dry weight m‐3, and the annual P/B ratio is 2.63.
Densities and energetics of two streamliving larval populations of Sericostoma personatum (Trichoptera)
Authors: Iversen Torben Moth
Published: July 2006

Two populations of Sericostoma personatum Spence were studied during one year in two first order woodland streams, varying in water flow and temperature regime. The life cycles look two and three years, respectively.

Numbers in drift varied with water flow, and daily elimination rates of about 1% due to catastrophic drift were found in one of the streams. Differences in elimination rates between the two populations are discussed in relation to predation, catastrophic drift, and quantity of food present during the year.

The production was about 0.9 g AFDW m‐2 yr‐1 in both streams, 20–22% of which was production of cases. P/B ratios were 2.4 and 3.8, and reflect differences in life cycle.

Total potential leaf consumption was estimated to about 50 g AFDW m‐2 yr‐1 in both streams, which makes up about 10% of yearly leaf input. The seasonal pattern of the consumption is discussed in relation to biomass, temperature and leaf input. There was little agreement between the patterns of leaf input and leaf consumption.
Growth and body weight of European hares in southern Sweden
Authors: Frylestam Bo
Published: July 2006

Body weight and growth of European hares Lepus europaeus Pallas in relation to environmental conditions, population density, age, sex, and reproduction were studied in three populations in southern Sweden on the basis of hares shot during October‐December. There were no significant differences in mean body weight of juveniles in the three areas. Differences in juvenile growth, as indicated by the correlation between eye lens weight (age indicator) and body weight, between areas and years were related to variations in nutrient conditions, in an island population it was probably also related to population density. Adult body weights did not differ between two mainland areas despite differences in food supply and population density, whereas island adult hares were, on average, significantly lighter than mainland hares. Also this difference was ascribed to nutrient conditions and/or population density. There were no significant differences in body weight between adult hares of different age classes. But reproductive females showed a significant positive correlation between number of litters produced annually and body weight. This relation indicates that reproduction is favoured by large body size and body weight, which also might explain the average higher mean body weight in females than in males. Juvenile hares showed no clear tendency in sex dimorphism of body weight.
Climatic fluctuations and forestry in Lapland
Authors: Pohtila Eljas
Published: July 2006

Climatic fluctuation is a serious problem for forestry in Lapland. Some indications about the nature and causal relationships of such fluctuation have been discussed. Cyclic variation can be explained by a “memory” in the atmosphere, variation in the Moons's gravitation, and solar activity.

The index of atmospheric circulation over the northern hemisphere was the most effective climatic parameter in explaining the growth variation of Scots pine.
Differences in drifting of larval stages of Rhyacophila nubila (Trichoptera)
Authors: Fjellheim Arne
Published: July 2006

Larval drift of the trichopteran Rhyacophila nubila (Zett.) was studied in a West Norwegian river. The frequency distribution of different instars in the drift samples was significantly different compared with the benthic samples. The drift, measured as the number which passed a transect of the river, rised markedly in periods of high water discharge. Different instars can be arranged according to the extent in which they are drifting: 2>3>4>1>5. Instar 1 and 2 shared a neutral phototaxis. From the 2nd instar and on, the larvae became increasingly night‐active with a culmination in the last instar which was highly night active, also confined by laboratory studies. It is suggested that changes in activity patterns is associated with a shift towards a more carnivorous way of life.
Release of plant nutrients from decomposing leaf litter in a South Swedish beech forest
Authors: Staaf Håkan
Published: July 2006

Weight loss and dynamics of plant nutrients (N, P, K, Ca, Mg, S, Fe, Mn, Na, Zn and Cu) in leaf litter were studied in a mature beech forest in South Sweden, using the litter bag technique. An initial decomposition period of about 12 to 18 months was characterized by an absolute net increase of N, P, and S contents in litter, followed by a period of net release of these elements. This development, which was most obvious for N and P, was interpreted as a change from a phase where decomposer activity was limited by the availability of nutrient elements to an energy‐limited phase. A net release of nitrogen did not occur until after two years of decomposition, and a transfer of nitrogen and phosphorus between different litter layers is here proposed to work as a retention mechanism.

Potassium and sodium were quickly leached from the litter, while release of magnesium, calcium, and initially also manganese, was more associated to organic matter weight loss. Iron, zinc and copper were all strongly accumulated in the litter material. This is explained by mineral soil admixture for the former element and by atmospheric fall‐out in combination with the chemical complex formation character for the latter two elements.

Finally, the importance of the different release processes in the total nutrient recycling of the forest is discussed.