bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wood decomposition in an abandoned beech and oak coppiced woodland in SE England
Authors: Boddy Lynne , Swift M. J. 
Published: July 2006

Stand structure and rates and patterns of wood litterfall, between 23 June 1977 and 27 June 1979, are described for two sites In a coppiced beech Fagus sylvatica L. and oak Quercus petraea (Mattuschka) Liebl. woodland in south‐east England.Total wood fall (excluding trunks) was estimated at 1264 kg ha−1 and 593 kg ha−1 for the two years of sampling at one site and 776 kg ha−1 during the second year on the other site. The majority of leaf fall occurred in autumn; the maximum twig (wood < 1 cm diameter) and branch (wood ≥ 1 cm diameter) fall, occurred in winter at times generally corresponding with high wind speeds. Many oak twigs, however, abscissed in early November irrespective of wind speed.Branch characteristics at fall (size, state of decay and bark cover) were documented. The most significant feature observed was that a large amount of decay frequently occurred in branches whilst still in the canopy.
Variations in litter size and reproductive effort within and between some populations of Lacerta vivipara
Authors: Pilorge Thierry , Xavier Francoise , Barbault Robert 
Published: July 2006

We studied the relationships between litter size, litter weight, newborn weight, relative clutch mass and the female snout‐vent length in some Lacerta vivipara populations over a period of three years.Litter size and litter weight were positively correlated with female snout‐vent length in all the populations for all the years, as in most other lizard species. Relative clutch mass generally increased with female size, though correlations appear not to be very tight.Considering the two best studied populations suggests that montane females invest less in reproduction than lowland ones.The main reproductive traits of the species appeared highly variable between as well as within the different populations hitherto studied.We argue that current theory about lizard reproductive strategy requires, first to work out a good estimate of reproductive effort, and second to get more information about the relations between the species and their environmental, biotic and abiotic conditions.
Effect of habitat, date of laying and density on clutch size of the Great Tit Parus major in northern Finland
Authors: Orell Markku , Ojanen Mikko 
Published: July 2006

The sizes of 1034 Great Tit clutches were studied at the Oulu area (c. 65°N, 25°30′E) in northern Finland. The average size was 9.86 eggs in the first clutch and 7.51 in the second in 13 study areas. The decrease in clutch size from the first to the second laying was most pronounced in those females laying the largest first clutches.Irrespective of habitat, the clutch size was larger in the sparsely populated areas than in the densest area (Taskila). The clutch size decreased according to the season in all the areas, but this was not as pronounced in Taskila as in the other areas.The annual average size of the first clutches was inversely related to the breeding density and pronouncedly so to the mean dale of laying. The latter was suggested to be an adaptation to the short season in the northern areas.An analysis of data from 27 study areas in Europe, north of the Mediterranean region, suggests that the clutch size does not vary with latitude or longitude.
Species richness and succession of aquatic beetles in some kettle‐hole ponds in northern Sweden
Authors: Nilsson Anders N. 
Published: July 2006

Ten closely‐located kettle‐hole ponds in northern Sweden were ordered along a vegetational, successional gradient from the present‐day representation of the six vegetational units distinguished. Different rates of vegetational development caused by differences in depths of basins have made possible the long‐term existence of early successional stages. A fact that has offered the possibility of studying most of the vegetational succession of these habitats.The number of water beetle species inhabiting each pond were correlated to successional stage and area of pond. Mean species numbers decreased from 34 to 14 per pond with increasing maturity of the vegetational succession. This decrease in species richness of water beetles is caused by a decrease in number of habitats or vegetational units present. The increased floral conformity is mainly due to a more stable water‐level caused by lower rates of bottom seepage from the accumulation of organic deposits. Besides the extended zonation of littoral vegetation, a high water‐amplitude is also connected with recurrent nutrient pulses caused by the faster detritus composition during drought periods. Thus the changing water‐levels contribute to a high water beetle diversity through the maintenance of both a high habitat complexity and a high production.A positive correlation between pond size and number of water beetle species were only found if the fen ponds were excluded. From this it is concluded that the area effect is here a good predictor of species richness only within ponds of a similar successional stage.
Influence of velocity and food availability on catchnet dimensions of Neureclipsis bimaculata (Trichoptera: Polycentropodidae)
Authors: Petersen Robert C. , Petersen Lena B.‐M. , Wallace J. Bruce 
Published: July 2006

Larvae of Neureclipsis bimaculata (Trichoptera: Polycentropodidae) construct elaborate catchnets in lotic habitats to trap small drifting invertebrate prey. Three populations located at two oligotrophic and one eutrophic site were studied in southern Sweden. Measurements were made of larval weight, net size, seston quality and quantity, and stream velocity. Neureclipsis larvae alter their net dimensions in response to both velocity and seston concentration. This was determined by comparing net structure and seston at the three locations. Larvae from the eutrophic, high quality seston site attain a significantly (P < 0.001) heavier instar V dry weight, spin a smaller catchnet, filter a volume of water dependent on body size, and slightly alter their catchnet dimensions with velocity. Larvae from the two oligothrophic sites are significantly smaller than those from the eutrophic site, spin a larger net at comparable velocities, filter a larger volume of water at comparable weights, and alter net dimensions with velocity.Estimates of silk production indicate that the net cost is minimized by spinning a very fine silken strand and by adding silk over a period of time. The cost while large is offset by a large capture rate of prey.The structure of Neureclipsis nets appears to be the result of a trade‐off between maximizing food capture and minimizing hydraulic stress on the net.
The life‐cycles of four amphipod species in the Kattegat
Authors: Leineweber Peter 
Published: July 2006

Populations of four species of Gammaridae (Crustacea, Amphipoda) were sampled over 15 months in the south‐western Kattegat at Sangstrup Klint (Denmark). Chaetogammarus marinus, C. stoerensis and Gammarus oceanicus had annual life‐cycles, while G. salinus most likely had two generations per year. Mature C. marinus females were found from March to July, mature C. stoerensis females from March to June, mature G. oceanicus females from December to early June and mature G. salinus females from late November to late July. The theoretical maximum number of clutches were estimated at five for C. marinus, five plus for C. stoerensis, and six for G. oceanicus and both winter and summer reproducing G. salinus. Spring was the period of main recruitment in all populations, with additional recruitment during summer in G. salinus.The geographical patterns of the reproductive strategies are discussed in relation to environmental factors and interspecific competition.
Clutch size and breeding success in relation to nest‐box size in Tengmalm's owl Aegolius funereus
Authors: Korpimäki Erkki 
Published: July 2006

Clutch size and breeding success was related to nest‐box size in 215 nests of Tengmalm's owl in the Kauhava region, western Finland in 1966–82. In vole peak years, but not in other years, mean clutch size was positively correlated with the bottom area of the nest‐box, increasing on average by 0.005 eggs cm−2. In successful nests there were fewer nestlings in small and medium‐sized than in large boxes. Breeding was most successful in thick‐walled boxes with a small entrance diameter. The optimal box for Tengmalm's owl has the following dimensions: bottom area 20 × 20 cm, entrance diameter 8 cm, and wall thickness at least 3 cm.Hypotheses suggested to explain the “area effect” based on breeding data of hole‐nesting passerines do not hold good for Tengmalm's owl. Since there were more stored prey animals in medium‐sized and large boxes than in small boxes, I suggest that the “area effect” is related to food availability, which may determine how sensitive the species is to different bottom areas of the boxes, at least in areas with cyclic food (e.g. northern Europe).
Growth analysis of presmolt Atlantic salmon Salmo salar at three sections of a small Norwegian stream
Authors: Lund Roar A. , Heggberget Tor G. 
Published: July 2006

The growth of Atlantic salmon parr was investigated at three different sections of the small stream Levangerelva and its tributary during the period October 1978 to October 1979.Mean growth varied significantly between the sampling sites studied. The growth was found to be density dependent at all the sampling stations. Faster growth in the tributary was considered to be related to warm water draining from the epilimnion of a lake situated 2 km above the sampling site and a greater supply of alloctonous food from the alder wood covering parts of the stream banks. Differences in nitrogen and phosphorus content, conductivity, pH, total hardness and humus content of the stream water did not show any relation to growth variations in the different parts of the stream.
The chironomid fauna of North Norwegian lakes, with a discussion on methods of community classification
Authors: Aagaard Kaare 
Published: July 2006

The chironomid communities of fifty lakes in northern Norway are presented and briefly described. A limnological classification of the communities is given, together with remarks on the methods used.The interrelationships are given of the chironomid communities and such lake‐water parameters as the minimum oxygen content, Secchi disc values, conductivity, total hardness and calcium content, total nitrogen, total phosphorus, chlorophyll a, and estimated fish yield. The best predictive and monitoring value of the chironomid communities, as classified by the above system, was obtained for the organic parameters. Compared with other indices used for estimating fish yields, the present method is as reliable as the better ones.
Longitudinal zonation and food of larval chironomids (Insecta: Diptera) along the course of a river in temperate Canada
Authors: Ward Angela F. , Williams D. Dudley 
Published: July 2006

The chironomid larvae of the Rouge River, Ontario, Canada, showed a longitudinal zonation which may have been influenced by water temperature and substrate composition. Species of Orthocladiinae predominated in the cooler headwaters while species of Chironomini dominated the comparatively warmer water near the estuary. In the middle section the chironomid assemblage was of a more mixed nature.Differences occurred in both food availability and feeding between sites along the river. Within genera, there were differences in the proportions of major food items between the larval guts and the available food material sampled from the same area. In most cases (e.g. Cryptochironomus, Polypedilum and Orthocladius) larvae selected detritus over diatoms. Some genera (e.g. Microtendipes) changed the proportions of food items ingested seasonally, while others (e.g. Psectrocladius) exhibited a more stable diet throughout the year. Second instar larvae appeared to seasonally adjust their diet most often (e.g. Cricotopus. Tanytarsus and Eukiefferiella), however these changes were not just in the types of food eaten, but also in the proportions of food types consumed. Larvae of all genera continued feeding throughout the cold water conditions (<5°C) of winter. Incidence of predation was very low, for example <10% in the Tanypodinae. In the laboratory, species of Chironomini ingested and assimulated, to varying degress, isolated populations of diatoms, detritus and bacteria.
Utilisation of different ages of heather on three Scottish moors by red grouse, mountain hares, sheep and red deer
Authors: Savory C. John 
Published: July 2006

Utilisation of heather at three Scottish moors, by red grouse, mountain hares, sheep and red deer, was measured by collecting their faecal droppings regularly from plots on heather patches of different ages. Rates of heather growth differed between moors, and preferences of the four species, all grazers of heather, were related more closely to its height than to its age. Thus hares spent most time on ground with heather less than 15 cm high, sheep less than 20 cm, grouse preferred heather 10–30 cm high and deer spent most time on heather over 25 cm high.Differences between outer, middle and inner plots on patches at one of the moors in dicated that grouse are reluctant to move far from cover into areas of newly burned ground, and reluctant to move far into patches of tall, dense heather, when these are next to shorter material. Hares preferred the middle of patches on newly burned ground and very young heather.At two of the moors, but not the third, there was evidence that heavy grazing by hares in winter reduced the amount of young heather available to hares and grouse in spring. This potential reduction in the quality of the spring diet of grouse is discussed In relation to previously reported associations between numbers of hares and grouse at those two moors.
Density dynamics of bumblebees in subalpine meadows: competition and resource limitation
Authors: Bowers Michael A. 
Published: July 2006

Densities of Bombus flavifrons and B. rufocinctus were measured over one summer in 23 and 11 discrete subalpine meadows, respectively. I assessed the relation between observed bee densities and meadow size, elevation, floristics, temperature, and time of day by multiple regression. Multivariate regression solutions for each week of observation accounted for 38 to 61% of the variation in density for B. flavifrons and 47 to 87% for B. rufocinctus. Temperature or time of day consistently accounted for the most variation in density of the two species. In early summer meadow size or elevation also accounted for a large proportion of explained variation in B. flavifrons density; as the summer progressed meadow floristics increasingly contributed to the explanation of variation in both species.In mid‐ to late summer a statistically significant portion of the variation in densities not explained by habitat characteristics was accounted for by densities of congeners: i.e., densities of B. flavifrons and B. rufocinctus were negatively related in eight meadows where they co‐occurred. In experimental meadows where all Bombus but one of the two target species were removed. B. rufocinctus underwent significant positive density compensation but B. flavifrons did not. To the extent that B. flavifrons appeared to limit the density of B. rufocinctus these statistical and experimental results are consistent with the hypothesis that competition limits local bumblebee densities.
Shrews on small islands: epigenetic variation elucidates population stability
Authors: Hanski Ilkka , Kuitunen Juhani 
Published: July 2006

Three large (4 to 8 ha) and 14 small islands (0.3 to 2 ha) in a lake in eastern Finland, all situated less than 0.5 km from the mainland, were surveyed for small mammals. Three species of shrew and two species of vole were resident in July 1982:Sorex araneuson 10,S. caecutienson 2,S. minutuson 5,Microtus agrestison 12 andClethrionomys glareoluson 4 islands. Immigrants were trapped from tiny islets, and the data indicate thatS. caecutiensandM. agrestisare better dispersers thanS. minutusandC. glareolus, respectively.Microtus agrestis, S. araneusandC. glareolusoccurred non‐randomly, on subsets of the larger islands, while the two smallSorexspecies occurred more erratically, possibly because of competition withS. araneus. Juvenile sex ratio was male‐biased on the mainland but female‐biased on large islands, possibly because juvenile males move more and are more likely to emigrate from an island than juvenile females.Metrical and non‐metrical (epigenetic) cranial traits gave similar patterns of population differentiation inS. araneus. Two of the three large‐island populations have differentiated from the mainland populations and from each other, suggesting that the populations are relatively stable. Small‐island populations, which are often less than 10 individuals in size, showed little differentiation but had more epigenetic traits fixed than large‐island and mainland populations (founder effect). This suggests that the small‐island populations are unstable, have a high extinction rate.
The spider communities on peat and upland grasslands In northern England
Authors: Coulson J. C. , Butterfield Jennifer 
Published: July 2006

Between midsummer 1976 and November 1977 some 29000 spiders belonging to 168 species were caught in pitfalls on 42 peat and upland grassland sites covering an altitude range of 11–827 m in the north of England. The similarities between the spider faunas of each site have been assessed using a modified form of Sørensen's Index and the sites clustered according to their similarities. The sites divided into two major groups; (1) mineral soils where grasses are dominant or shallow peat soils where Juncus squarrosus is dominant and (2) peat soils where Eriophorum vaginatum and Calluna vulgaris are dominant. It is suggested that this major division is the result of the plant “architecture” rather than the species composition of the vegetation. Direct comparison between paired peat and grassland sites at the same altitudes shows no marked separation in the spider species composition on the two soil types but there are differences in abundance of individual species. The three peat site clusters form an altitudinal sequence which is not the result of the decline in numbers of non‐linyphiid species with increase in altitude as the cluster formation is largely dependent on the linyphiid species which dominate the catches.Twenty one common species have been used lo identify the communities. Many of these species are often found together and form associations. Typically, a number of associations contribute to each community. Only 19 species contribute more than 4% to the numbers of individuals caught in any one community.Diversity declines with increase in altitude, as does the number of species caught. The decline in the number of species caught is the effect of a decrease in non‐linyphiid species with increasing altitude. There is no significant decline in the numbers of species of linyphiids with increase in altitude.
Feeding by geese on the Filsø Farmland, Denmark, and the effect of grazing on yield structure of spring barley
Authors: Lorenzen Bent , Madsen Jesper 
Published: July 2006

From the end of August to early May on average 506400 goose days were spent on the farmland of Filsø, 92% by pink‐footed geese, 7% by greylag geese and 1% by bean geese. 36% of the goose days were spent on stubbles (autumn), 38% on stubbles with undersown seed grass (autumn‐spring), and 21% on new‐sown barley fields (spring).Geese feeding on spring barley consume kernels left on the surface or in the upper surface layers. In 1982 and 1983 trials were set up to quantify the effect of grazing. The effect on yield and plant structure was measured by comparing ungrazed (exclosures) and grazed plots. Grazing by geese significantly reduced the grain yield (7‐20%), but the reduction was not proportional to goose usage. The maximum reduction in sprout density was observed in 1982 in an area with heavy goose usage; sprout density was reduced by 72%, but the subsequent yield in the same area was only reduced by 8%. Plants on grazed plots compensated for the reduced sprout density by having more tillers with ears and grains of higher weight. The effect of grazing on stubble, seed grass, and winter cereals on Filsø is discussed.
Ecology of heath communities dominated by Cassiope tetragona at Alexandra Fiord, Ellesmere Island, Canada
Authors: Nams Margorie L. N. , Freedman Bill 
Published: July 2006

At a high arctic lowland on Ellesmere Island, heath communities dominated byCassiope tetragonawere 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, notablyCassiope tetragonaandDryas integrifolia. TheCassiope‐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 amongCassiope‐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 ofCassiope‐dominated heaths reflects the conservative, stress tolerant growth strategy of the dominant species,Cassiope tetragona.
Lake outlet blackflies ‐ the dynamics of filter feeders at very high population densities
Authors: Wotton R. S. 
Published: July 2006

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.