Abstract: The utilization of microhabitat and food resources by Triturus vulgaris and T. cristatus was studied in an upland pond in mid-Wales. From April to June T. vulgaris was more evenly distributed across the pond than T. cristatus, which showed a preference for the middle of the pond and the bottom of the water column. From July to September however, when most T. vulgaris had left the pond, T cristatus was evenly distributed within the water column and a much higher proportion was captured around the shorelines. Both species appear to be generalist predators with diets limited by prey size. Zooplankton were the most important prey for T. vulgaris, while leeches formed the bulk of the diet of T. cristatus. However, T. cristatus did not select larger-sized zooplankton than T. vulgaris. Large body size therefore enables T. cristatus to consume a wider range of prey sizes than T. vulgaris. Microhabitat niche overlap was greater than feeding niche overlap between the species.

Abstract: Stoat Mustela erminea body size shows remarkably great variation over the species' European range. The pattern of this variation is opposite to that suggested by Bergmann's rule, i.e., stoats in central Europe are significantly larger than those in southern Sweden which, in turn are considerably larger than their conspecifics in northern Sweden. Neither winter temperature nor the length of snow cover shows any consistent correlation with stoat body size variation, and the larger body size of the southern populations could not be related to a widening of the stoat's feeding niche. A positive correlation was found between the frequency distribution, by size, of available prey and stoat body size in the different areas examined. This supports the hypothesis that body size variation in the stoat, especially females, is an adjustment to regional variations in the sizes of their available prey.

Abstract: Variation in reproductive traits (sexual maturity, clutch size, clutch weight, mean egg mass, newborn weight) was studied during a four year period in a population of the live-bearing lizard Lacerta vivipara. Sexual maturity was associated with attaining a minimum body size. Clutch size increased with female body length and litter weight increased with clutch size. A major component of the within year variation in these reproductive traits was attributable to female size. Analysis of successive clutches in individual females indicated that a significant fraction of the variation in litter size, adjusted for female length, was due to consistent differences between individuals. Newborn weight varied within and among litters, but no relations between hatchling mass or mean egg mass in a litter and other traits were detected. Size-adjusted reproductive performances remained constant during the course of this study, even though environmental conditions (weather factors, food availability) varied annually. Observed among year variations in reproductive characteristics were attributable to differences in the body size distributions of the adult females.

Abstract: We have investigated environmental factors influencing the choice of breeding pools by Bufo calamita in two different habitat types in Britain, using a number of methods including the construction of artificial pools and the translocation of spawn laid by competitively superior anuran species. On heathland, major determinants were aspects of pond chemistry especially pH, Na and SO4. On coastal dunes other criteria were important, notably maximum water temperatures achieved the day prior to spawning. These in turn related to the precise shape and size of the pond. In addition, natterjacks were able to discriminate against ponds which already contained large numbers of competitor species Rana temporaria and Bufo bufo larvae. Possible mechanisms underlying site choice by B. calamita are discussed.

Abstract: Composition of the winter diet, habitat selection and population fluctuations in the mountain hare Lepus timidus were studied in the Viirri6tunturi fell area, Eastern Finnish Forest Lapland, during the winters 1968/69-1984/85. The three population lows recorded during this 17-year period followed each other at intervals of 4 and 8 years. During the lows the hares occurred only in the most favoured (forest-covered) habitats and in two of them they behaved according to the concept of the refuge theory. The mountain birch Betula pubescens ssp. tortuosa appeared to be the most important, but not the most favoured winter food item. When the population crashed, the proportion of birch in the diet decreased, and was replaced especially by juniper which is one of the secondary food items (and is for this reason often discarded although cut). It is suggested that the quality and/or quantity of the winter food (i.e. winter pastures) are one of the driving forces in the population fluctuation of the mountain hare in this area.

Abstract: The effects of temperature, oxygen and substrate on growth rates of three tubificid oligochaetes were examined in the laboratory. Two species Tubifex tubifex and Limnodrilus hoffmeisteri (Tubificidae, Oligochaeta) had similar narrow temperature ranges over which growth occurred, from 10–13°C and both showed a considerable tolerance to extended periods of anoxia, of at least 16 and 10 weeks respectively. However no growth was observed under anoxic conditions. A third common species Ilyodrilus templetoni was sensitive to anoxia and could not survive more than four weeks. There was no evidence of differences in substrate quality affecting growth rates of either T. tubifex or L. hoffmeisteri. The temperature and oxygen responses of these three species may explain their distribution in some lakes of the English Lake District.

Abstract: The seed banks in the soils of seven mature beech forests in southern Sweden were examined using the seedling-emergence method. Seedling emergence in the field was also studied. In the studied forests, covering a wide range of vegetation and soil types, between 1020 and 4500 germinating seeds m−2 were found in the seed bank. Seed abundance showed no apparent relationship with the type of soil or vegetation at the sites, but the highest number of species in the seed bank was found on the mull sites. The species diversity of germinative seeds increased strongly with increasing soil fertility. Only a minor part (10–35%) of the species in the germinable part of the seed bank were represented in the vegetation. Soil samples from the oligotrophic sites mainly contained graminoids, notably Carex spp., while herbs dominated the seed banks of the rich mull sites. Seeds of e.g. Stellaria nemorum, Oxalis acetosella, Moehringia trinervia, Viola rivinianalreichenbachiana, Melica uniflora, and Milium effusum were especially abundant in the mull soils. Woody species were infrequent on all sites, and no representatives of the early spring flora were noted in the germination tests. In the mor and moder soils most seeds were recovered from the mineral soil, and they were believed to originate from early stages in the succession of the forest. Several sites had comparatively large seed banks of species that typically occur in disturbed forests, e.g. Juncus effusus and Rubus idaeus, but very few germinating seeds belonged to species restricted to non-forest habitats. Emerging seedlings in the field were only observed on the mull and moder sites. With few exceptions they belonged to species, which were common both in the seed banks and in the vegetation.

Abstract: Habitat composition of 39 capercaillie Tetrao urogallus display grounds was compared with available and unused habitats in two coniferous forest areas in southeastern Norway. Macro-habitat was described with respect to forest successional stage and topography. Micro-habitat was described with respect to microtopography, plant association, and forest stand structure. Totally, 28 variables were measured. A pronounced macro-habitat preference was found for elevated areas with forests older than 60-70 years. Micro–habitat composition varied considerably. However, a slight but significant preference was found for heterogeneous, open-spaced understory, and for visibility of more than 30 m. Suitable micro-habitats were abundant, and distribution of display grounds were mainly limited by macro-habitat characteristics, i.e. elevated, old forest areas.

Abstract: Seasonal changes of bird communities and use of foraging substrates by the birds were studied in two forests with contrasting vegetation structure in montane and subalpine levels of central Spanish mountains throughout complete annual cycles. Common factors contributing most to foraging segregation among species were found to be the foraging on the ground vs that on vegetation and use of proximal vs distal tree parts. A complete dissimilarity exists between the composition of the respective foliage-gleaning guilds, the converse being true for the trunk-searchers. Temporal distribution of bird species is to a great extent determined by their use of space, thus existing a gradient of seasonality with maxima for ground-searchers, minima for trunk-gleaners and intermediate positions for foliage-gleaners. A close relationship among temporal variability, mean annual density and niche breadth is found for the subalpine pinewood community, but not for that from the montane oakwood, this being related with their contrasting migratory patterns and the structural stability of vegetation in each wood. The pattern of covariation in community parameters mirrors the summed response of individual bird species to the changing environmental conditions. Increases in community richness, density and diversity are related to temporal invasion by ground and foliage-gleaners of these highly seasonal Mediterranean habitats.

Abstract: Small mammals dispersing in habitat corridors to and from an abandoned field in south-central Sweden, at the forest edge and inside the forest, were continuously sampled during 1977–81. Altogether 967 specimens of ten species were obtained. Number and dynamics of grassland species were censused intensively in the centre of the abandoned field and extensively on other abandoned fields nearby. Numbers of resident and dispersing animals correlated positively. Grassland field voles Microtus agrestis were almost only obtained in the corridors and woodland bank voles Clethrionomys glareolus mainly in the forest and in narrow grassland corridors. Both these species are folivorous. Granivorous-insectivorous Apodemus and Sorex species moved more on a broad front through various habitats. Different population categories did not show any elear differences in dispersal routes. The findings of different dispersal strategies in a species gradient are discussed in relation to the local dynamics of subpopulations belonging to metapopulations inhabiting whole landscapes. Implications for pest management and conservation of endangered species are considered.

Abstract: The diel rhythm of juvenile (0+) Astacus astacus was studied experimentally with constant and dielly fluctuating water levels. In the first case the diel rhythm was mainly crepescular, but with tendencies of a phase shift towards diurnal rhythm during low light conditions. The locomotor activity increased with temperature and with the length of the dark period. In presence of a crepescular predator the crayfish decreased their light period activity. With fluctuating water levels the activity increased especially when the water level changes occurred during normal resting periods. Crayfish did not show any adaptation to fluctuating water levels by preferring covers constantly situated beneath the surface. The relative effect of the water level fluctuations increased with temperature. As the main part of the juvenile crayfish population is concentrated to the litoral zone, diel water level regulations are thought to be detrimental to crayfish populations even if the regulation amplitude is small.

Abstract: Larvae of the blackfly Simulium noelleri aggregated at very high population densities (up to 1.2 × 106 individuals m−2) at a lake outlet in Kent, United Kingdom. During 1983 and 1984 their first appearance in these large numbers was in late-June and they completed three summer generations before the overwintering larval generation appeared in October. It is not known where the larvae overwinter but they recolonized the concrete steps of this outlet in May, together with larvae of the S. ornatum group which, however, were not found after completing one generation at this location. Female flies from the overwintering generation oviposited en masse during late-June and the result was a well-synchronized growth of larvae in the first summer generation. Within this, and other generations, there was A wide range of emergence times for adults; they could emerge early and were then relatively small, or could emerge later and were then relatively large. Females were always larger than males and the emergence of flies was protandrous. A very similar pattern of growth and emergence times was found at a site in Finland. In all generations, sex ratio was biased to males and the sex ratio in each generation was inversely correlated with population density. This ensured that there were sufficient males emerging, and surviving adult mortality, to guarantee fertilisation of the females which were more expensive to produce.

Abstract: The distribution pattern of Calluna vulgaris on the ombrotrophic peat bog Akhultmyren, S. Sweden, was investigated. Calluna occurs primarily on hummocks, with its maximum biomass (ca 250 g m−2 above ground, and ca 300 g m−2 below ground) concentrated on hummock tops. Biomass decreased gradually along the hummock-hollow gradient to a level of ca 5 cm above the water level. This decreasing biomass was correlated with a decrease in the predominant age of the above ground shoots from 6–8 yr to 3–4 yr old shoots. Calluna is characterized by extremely slow diameter growth and biomass increment. There was, however, a poor relation between height above water level and stem thickness, assimilating biomass and total shoot weight, respectively.

Abstract: Slow release fertilizer pellets (NPK) were spread in June and July 1985, on the frost surface under an 8–20 cm thick layer of thawed tundra in the northern foothills of the Brooks Range, Alaska. The fertilizer was applied at a rate of 3.8 kg N, 1.2 kg P2O5, and 2.4 kg K to two, 10 × 0.75 m tussock bands. These bands were placed parallel to the contour lines in the middle of a uniform 10° slope. The purpose of the experiment was to test the hypothesis that fertilizer moves at a measurable rate downslope, affecting the vegetation in its course. The results support this hypothesis. One year after fertilizer application, plants collected 2 to 6 m downslope from the fertilizer band had significantly larger leaves and significantly higher nitrogen and phosphorus concentrations than those upslope from fertilizer application. It is concluded that nutrient-releasing tundra perturbations affect the downslope tundra vegetation.

Abstract: The relationship between micro-site nitrogen status (total soil N conc., total vegetation N, and leaf N conc.) and performance (biomass) for two evergreen and two deciduous dwarf shrubs was studied in a subarctic heath. One deciduous species, Vaccinium uliginosum, dominated on sites having the highest vegetation nitrogen content and highest leaf nitrogen concentrations. The evergreen Empetrum hermaphroditum dominated on sites with a low total vegetation nitrogen content and low leaf nitrogen concentrations. Two other species, V. myrtillus (deciduous) and V. vitis-idaea (evergreen), showed intermediate patterns that were not clearly separated from either V. uliginosum or Empetrum. Soil nitrogen content showed no significant differences between micro-sites. Possible physiological reasons for the observed patterns are discussed.

Abstract: Winter activity patterns of 16 radio-marked capercaillie, Tetrao urogallus, were studied during 1981–83 at Varaldskogen, SE Norway. Activity was confined to the light hours of the day, closely following the photoperiod. Diel distribution showed a major peak near sunset during every month. A second peak was found in the morning. This peak was comparable to the evening peak in early and late winter, but nearly disappeared in midwinter. Ambient temperature rather than photoperiod seemed to be the important proximate factor responsible for the changes in morning activity. By postponing activity to the afternoon, capercaillie avoids energy expenditure during the coldest morning hours. Total daily activity (TDA) during the period November-April averaged about 3 h for both sexes. TDA of cocks was U-shaped with the lowest values (2.0 h) in December-January, whereas TDA of hens was fairly stable during November-March with mean value of 2.7 h, increasing abruptly to 4 h in April. TDA during December-January is believed to express the time used for feeding in pine trees. The significantly higher TDA of hens (26%) compared with cocks during this period may be explained by a higher relative heat loss of hens (body weights: hens 2.0 kg, cocks 4.3 kg). The increased level of activity during early and late winter among cocks was probably due to display and related territorial behaviour, whereas increased activity of hens during April probably was caused by a shift from feeding in pines to more time-consuming, selective feeding on the ground

Abstract: A breeding population of European common frogs Rana temporaria was studied during six springs. Male and female body length varied significantly between years. Females averaged 6 mm longer than males. Amplectant males did not differ significantly from non-amplectant males in body or leg length. No significant correlation was found in body or leg length between males and females in amplectant pairs at any time of the breeding season.

Abstract: Mountain hares in Scotland live on open tree-less moorland in a harsh winter environment with frequent high winds and drifting snow. By day they rest in forms in tall heather, seats in shorter heather or snow, or scrapes in snow or peat. All these reduce wind speeds by 84-90%, but vary in the degree of shelter and concealment. Forms afford the best concealment and shelter and occur as often on flat ground as elsewhere. Seats and scrapes are commoner on sheltered slopes. They command a wide field of view but offer little concealment. During snow-lie, when forms may be covered, hares move to seats and scrapes, often at the edge of snowfields and gather, sometimes in large groups, on sheltered slopes.

Abstract: The adult demography of a population of Speyeria mormonia (Lepidoptera: Nymphalidae) near Gothic, Colorado USA was studied for four years. Values of demographic parameters, including survival, dispersal and sex ratio, varied yearly, without major changes in density. Shift in sex ratio with constant population numbers entails variation in effective population size among years. Flight period, catchability, relationship between body size and eclosion date, and significance of correlation between weather and daily survival rates differed between the sexes. Sexual dimorphism in correlation of wheather with survival rate may partially explain the lack of yearly variation in total population size. There was no significant sexual dimorphism in large scale habitat use, or in dispersal, except in 1982. The demography of this insect is compared to that of related species of Argynnis and heliconiines, from the old world temperate zone and new world tropics, respectively. While some differences are observed which can be ascribed to differences in length of the growing season, many patterns are similar. This implies conservation of demographic traits, even across broad habitat and geographic areas.

Abstract: Inter- and intra-specific differences in survivorship of Nephelopsis obscura and Erpobdella punctata under anoxic conditions were examined. Two types of experiments were used. In the closed (static) experiments the leeches faced three stresses – anoxia, build-up of metabolites and starvation, while in the flow-through experiments only anoxia was experienced. The results obtained from the two types of experiments indicate that survival times are longer in the flow-through experiments. Inter- and intra-specific differences in survivorship under anoxic conditions correlate well with the patterns of reproduction observed for field populations of N. obscura and E. punctata.

Abstract: The relative success of a sample of 99 immigrant dispersers was studied in a population of Peromyscus leucopus in deciduous forest from 1980 to 1985. Dispersers were identified in two ways; (1) as immigrants to a natural dispersal sink and (2) as individuals that relocated their center of activity more than one home range diameter within a large live-trapping system. Female immigrants were significantly less likely to be pregnant or lactating than philopatric residents; males showed no significant difference. Reproductive immigrants were more likely than non-reproductive immigrants to establish residency after dispersal. There was no difference in survivorship of philopatrie residents and those dispersers that successfully immigrated.

Abstract: The pelagic amphipod, Hyalella montezuma comprised nearly 90% of the diet of the leech, Erpobdella montezuma in the near thermally constant environment of Montezuma Well, Arizona. This restricted diet, confirmed by both gut content and serological analyses, occurred even though other potential prey were abundant throughout the year in the pelagic column, littoral vegetation and sediments. Seasonal electivity indices for this pelagic prey species were ≥0.9. It is suggested that the highly predictable environmental conditions in Montezuma Well have contributed to this very close predator–prey relationship.

Abstract: Unisexual populations were found largely at the periphery of the geographic range of the mayfly Eurylophella funeralis in eastern North America. Bisexual populations generally had a normal sex ratio but at least two populations were observed with only about 2–11% males. Hatch success for unfertilized eggs depended on temperature but in general averaged >61% in unisexual populations and < 14% in bisexual populations. Eggs took about 65 d to hatch at 10°C and 19 d at 25°C; no hatching occurred at 5 or 30°C. Successful oviposition was observed for about 97% and 20% of unmated female adults from unisexual and bisexual populations respectively. The hatch success of unfertilized eggs for three geographically distinct bisexual populations was in versely correlated with the proportion of males in the populations. The genetic structure of bisexual and unisexual populations was very similar. Unisexual populations consists of clones, with as few as four recognizable phenotypes being present at a given location. All offspring had the same phenotype as the mother. Tychoparthenogenesis is suggested as the most reasonable working hypothesis concerning the origin of unisexual populations in E. funeralis.

Abstract: The objectives of this study were to assess the roles of plant species, time, and site on competition for tracer 15N (without carrier) in tussock tundra ecosystems. Six experimental sites were located in northern Alaska. After one year across the experimental sites, the recovery of 1N by litter (11.3-16.3%) and mosses (5.4-16.4%) was significantly greater than for aboveground vascular plants (2.6-5.0%). 15N recoveries by tundra vascular plants (2.6-5.0%) were low when compared to forest trees (9-25%) which suggest that competition for nitrogen is particularly severe in these colddominated tundra ecosystems. There were no significant differences among sites in 15N recoveries by vascular plants, by mosses, or by litter. There was a statistically significant decline in '5N recovery with time for Vaccinium vitis-idaea and Eriophorum vaginatum between the second and third year. The shallow rooted Vaccinium vitisideae was more highly labeled than the deep rooted Eriophorum vaginatum. Nearness to the source of the applied "1N played a critical role in competition for surface applied nitrogen.

Abstract: The diet of dippers in south west Norway was investigated by faecal analysis during the 1985 breeding season. Overall, the diets of adults and nestlings were similar and consisted mostly of nymphs and larvae of Baetidae (mayflies). Leuctridae/Nemouridae (stoneflies). Hydropsychidae, Limnephilidae and Rhyaeophilidae (caddisflies). However, strong trends were apparent with nestling age: large items such as caddisflies declined in adult diet but increased in nestling diet as the chicks grew. The pattern probably reflected the growing energy demands of the brood in a central-place. Because some of the items of dietary importance are scarce in acidic streams, we stress the need for research on the influences of acidification on the ecology of Scandinavian dippers.

Abstract: Trapping of frass-drop from needle-eating insects in three Scots pine stands, 18-, 55-and 120-yr-old, respectively, in three years, revealed that the consumption rate in the two older stands on average displayed three peaks: in July (consumption by Panolis flammea and a first wave of diprionids), late August/early September (lasiocampid/sphingids, a second wave of diprionids), and September/October (Bupalus piniarius). Annual consumption was the same in these two stands, on average 7 kg dw ha−1. In the young stand, there was no late season peak (due to the absence of B. piniarius,) consumption ceasing one month earlier, at 0.2 kg dw ha−1. Consumption intensity (consumption per needle biomass) corresponded to 0.05%, 0.5% and 1.2% of new needle production, respectively, in the three stands, and increased approximately linearly with the needle biomass of the tree. This increase with size (age) of the tree seems to be due to the multiplicative effect of a larger complexity of the grazer guild and a higher population density of single insect species.

Abstract: Due to high numbers of mountain hares in recent winters in northern Finland the barking of winter dormant Scots pines was widespread. The hares fed selectively upon upper crown bark of grafted pines, nitrogen fertilized trees and trees in poor condition. Bark of preferred upper crown branches and physiologically mature scions contained less total phenols than lower parts. However, there were no differences between total phenols concentrations of graft bark preferred by hares and nearby unbarked juvenile phase Scots pine. Neither decrease in resistance after nitrogen fertilization n- or stress was correlated with bark total phenolic concentration. Thus, total phenolic concentration is not a reliable predictor of the susceptibility of Scots pine to winter barking by the mountain hare.

Abstract: At a high arctic lowland on Ellesmere Island, heath communities dominated by Cassiope tetragona were widespread, and occurred in a variety of habitats that differred in time of snowmelt, relative site moisture, soil thaw depth, and air and soil temperature. Cover, standing crop, and production were dominated by woody plants, notably Cassiope tetragona and Dryas integrifolia. The Cassiope-dominated heaths were similar in composition to those at other Canadian high arctic localities, but were less similar to localities in Greenland and Spitzbergen. Compositional relationships among Cassiope-dominated heaths in different habitats at the study site may be largely determined by two interrelated environmental factors, time of snowmelt and site moisture. Aboveground vascular plant biomass was concentrated near the ground surface, resulting in simple vertical structure that takes advantage of relatively warm soil and air temperatures in summer, and a protective snow cover in winter. Aboveground vascular plant standing crop was largely comprised of attached dead tissue, and there were equal proportions of above- and belowground biomass. Low community production was due to dominance by long-lived, slow-growing species, and to short growing seasons and cold temperatures. Overall character of Cassiope-dominated heaths reflects the conservative, stress tolerant growth strategy of the dominant species, Cassiope tetragona.

Abstract: Ground-living spiders were studied, using pitfall traps, in six habitats between 580 and 960 m (deciduous forest, fir forest, forest-line and three alpine mountain top sites) on Mont du Lac des Cygnes. Altogether 88 species of spiders were found during the study summer (June-mid-September 1985), of which 51 belonged to Linyphiidae (s. lat.), 9 to Lycosidae and 8 to Gnaphosidae. The highest species number and diversity were found in the forest-line habitat, the highest individual number on the main summit and the lowest in deciduous forest, the lowest site. Lycosidae and Gnaphosidae species and individuals characterized the alpine habitats. Linyphiidae (especially Linyphiinae) the forested sites and Amaurobiidae and Agelenidae the deciduous forest site. Erigoninae occurred commonly at all sites; their individual numbers were very high at coniferous forest sites. The dominant species in all three alpine habitats was Pardosa concinna, on the forest-line Hybocoptus gibbosus, in balsam fir forest Sisicottus montanus and in deciduous forest Amaurobius borealis. The material included several (sub)arctic-alpine species.