bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photosynthetic characteristics and leaf carbon economy of a deciduous and an evergreen dwarf shrub: Vaccinium uliginosum L. and V. vitis‐idaea L.
Authors: Karlsson P. Staffan 
Published: July 2006

The seasonal course of photosynthetic rate, and light and temperature relations were studied in the dwarf shrubs Vaccinium uliginosum L., deciduous, and Vaccinium vitisidaea L., evergreen, at a subarctic site in northern Sweden, Using the photosynthetic characteristics and meteorological data from the site, the seasonal and life‐span carbon dioxide gain was estimated.The photosynthetic capacity of V. uliginosum was at a maximum one month after the start of leaf expansion and declined rapidly in the beginning of September. The old V. vitis‐idaea leaves needed about 2 wk to recover full photosynthetic capacity after snow‐melt; the current‐year V. vitis‐idaea leaves needed the same time after bud‐break to reach full capacity. The leaves of V. vitis‐idaea showed no seasonal trend in photosynthetic capacity after the first two wk of recovery, but their capacity decreased by one third after the first winter and by approximately 10% yr−1 over the following two yr. The seasonal variation in the photosynthetic response to temperature was more marked in V. uliginosum than in V. vitis‐idaea. Light saturation occurred at approximately 3000 μmol m−2 s−1 in V. uliginosum and at 60 μmol m−2 s−1 in one‐year‐old V. vitis‐idaea leaves. The leaves of both species had a positive carbon balance at photon flux densities above 5 μmol m−2 s−1.The calculated seasonal CO2 gain was 21 g CO2 g−1 leaf in V. uliginosum and 6–8 g CO2 g−1 in V. vitis‐idaea leaves. Life‐span CO2 gain for leaves of V. vitis‐idaea was the same as in V. uliginosum, viz. 21 g CO2 g−1. One fifth of the CO2 gain of V. vitis‐idaea was assimilated during periods when V. uliginosum was leafless.
The effect of microhabitats on the leaf litter decomposition and on the distribution of soil animals
Authors: Szlavecz Katalin 
Published: July 2006

Earthworm burrows as microhabitats for other soil fauna were studied in a hornbeam‐oak mixed forest in Hungary. Comparative chemical analysis and feeding experiments were carried out to find out whether the leaves in the burrows of large‐bodied earthworms are more decomposed than those from the surrounding areas. The total organic matter content, the C/N ratio, the stability coefficient and the percentage of tannins and lipids indicate that the chemical breakdown of the litter material is more advanced in the burrows than on the other parts of the forest floor especially in autumn. No consistent differences were observed in the amounts of other organic components. Feeding experiments showed that three species of the fauna preferred the leaves pulled into the burrows to those from the surrounding areas and the preference was greater in autumn than in spring.It is suggested that the high density of some soil animals in the burrows in autumn is due to the more palatable food there; in summer the microclimate of the burrows is favoured, whereas spring can be considered as a transition period.
Lichen communities and the associated fauna on a rocky sea shore on Bornholm in the Baltic
Authors: Søchting Ulrik , Gjelstrup Peter 
Published: July 2006

Thirty‐three sampling sites representing 11 lichen dominated plant communities on maritime rocks on Bornholm were analysed with respect to composition of the vegetation, number of animals present and gross taxonomic composition of the fauna. The specific fauna of one moss and seven lichen species was examined.The lichen communities studied were largely the same as those found in similar studies in NW Europe, except for the recognition of a distinct Ramalina cuspidata community. The highest average number of animals per area was found in the Schistidium maritimum and the Ramalina siliquosa communities, whereas the highest average number of animals g−1 dry plant biomass was recorded in the Parmelia saxatilis community. Among the species examined Anaptychia fusca contained the highest average number of animals g−1 dry thallus and Ramalina cuspidata the lowest number, 114 and 7, respectively. Collemboles appeared to dominate in the moss Schistidium maritimum and in foliose lichens, whereas mites dominated in crustose and fruticose lichens.
Life history of the moose Alces alces: relationship between growth and reproduction
Authors: Sæther Bernt‐Erik , Haagenrud Hans 
Published: July 2006

We studied the relationship between increase in body weight and reproductive performance in different populations of Norwegian moose to evaluate costs associated with early onset of reproduction, viz. whether early onset of reproduction was correlated with low adult body weight or reduced adult fecundity.The mean carcass weight of non‐ovulating yearlings was significantly lower than for ovulating yearlings. However, those 2.5 yr old females that conceived as yearlings were lighter than non‐reproducing females of the same age. Thus, to begin to reproduce as a yearling was assumed to be expensive because it reduces the possibilities for further growth. The cost associated with reproduction was further illustrated by the fact that the difference in mean carcass weight from age 2.5 to 3.5 yr of females that produced calves in both years, was less for the females from regions with lowest mean yearling weights, i.e. regions with probably the lowest resource availability.In populations with high mean yearling carcass weights, the proportion of cows with calf and the number of calves per pregnant female in the early reproductive phase (2.5 or 3.5 yr old) were higher than in populations in which the mean yearling weights were low. There was a negative correlation between growth rate in the population after 1.5 yr of age and the mean yearling carcass weight. Thus, low yearling weight was associated with a prolonged period of growth and thereby a reduced reproductive output during the first year of the female's life.For old females (≥ 9.5 yr old) the number of calves produced per pregnant female was highest in populations where yearling carcass weights were highest. Furthermore, mean yearling weight and the mean adult female weight were positively correlated in those regions. This relationship suggests that within this species early onset of reproduction is not related to retarded reproduction or lower weight later in life. We suggest that the moose has been selected for an early onset of reproduction.
Incubation rhythm in the great snipe Gallinago media
Authors: Løfaldli Lars 
Published: July 2006

The incubation rhythm of four female great snipe was monitored with telemetric equipment. The mean daily incubation constancy was 90.3 ± 2.0 (SD) per cent, and the mean daily time off the nest amounted to 139.8 ± 28.8 min. The number of recesses per day averaged 8.7 ± 1.9, with a mean duration of 15.7 ± 6.1 min. Generally, the birds incubated for long bouts during the night, and left the nest frequently during the daylight hours.Recesses were concentrated in the warmest part of the day in cool periods, but were more evenly distributed throughout the day in warmer periods. Recess duration decreased with decreasing temperature. These adjustments minimize egg cooling when the bird is off the nest, and thus allow the incubating bird more time to feed without lowering the mean egg temperature.Calculations of the cooling rates of eggs indicate that the bird minimizes incubation energy expenditure as far as possible, but without letting the eggs cool beyond the temperature of no embryonic development.
Associations between corticolous microarthropod communities and epiphytic cover on bark
Authors: André H. M. 
Published: July 2006

The discontinuous bark cover formed by epiphytic lichens and algae provides a mosaic of microhabitats for the fauna. Multivariate analyses applied to 1800 samples collected in Belgian Lorraine (southern Belgium) during each of the four seasons has made it possible to distinguish five major classes of arthropod microcommunities. Two of them are confined to special habitats or places at certain seasons, viz.

a Pseudochermes fraxini (Homoptera) community found on Fraxinus during the summer, and “trophically” different from others;
a Vertagopus arborea (Collembola) community observed in foliose lichens in St. Mard mainly in winter.

The three other classes are directly related to the epiphytic cover, viz.

a Dometorina plantivaga (Oribatida) community found in crustose epiphytes;
an Eueremaeus oblongus/Trichoribates trimaculatus (Oribatida) community sheltered by foliose lichens;
an Entomobrya nivalis (Collembola)/Cerobasis guestfalicus (Psocoptera) community observed in fruticose lichens.

The ecological meaning of those microcommunities (mosaic and stratification patterns, seasonal variation, succession) is discussed. The results support the hypothesis that corticolous microcoenoses are associated with the epiphyte type and that their composition is greatly affected by the vegetation stratification pattern on bark.
Frugivory of transient and wintering European robins Erithacus rubecula in a Mediterranean region and its relationship with ornithochory
Authors: Debussche M. , Isenmann P. 
Published: July 2006

Stomach contents of 209 dead and droppings of 57 mist‐netted migrating or wintering European robins Erithacus rubecula in a Mediterranean area in southern France showed the following seasonal trends: (1) a dominance of invertebrates in early autumn, (2) a dominance of fruits in mid‐autumn, (3) acorns being important in midwinter, and (4) a strong dominance of invertebrates at the end of winter and in early spring.The fruits of 23 plant species had been consumed. The most widespread and abundant ones were also the most commonly taken (Rubia peregrina at the regional level and Viburnum tinus at a local one). The size of these fruits ranged from 4 to 12 mm. mostly between 6 and 8 mm. Owing to the amount of fruits consumed and the numbers of birds involved, the European robin is one of the few main dispersers of the numerous fleshy‐fruited plant species of the Mediterranean area. Nevertheless, a correct evaluation of its role is only possible within the dense network existing between these plant species and all their dispersers (mainly birds but also mammals).
Effect of lake acidity and morphometry on the distribution of aquatic birds in southern Quebec
Authors: DesGranges J.‐L. , Darveau M. 
Published: July 2006

More than half the lakes in the deciduous and boreal forest regions of southern Quebec harbour at least one aquatic bird species during the nesting period. Although the number of nesting pairs per lake is generally small, those pairs are most commonly seen on lakes with a surface area of more than 15 ha, a winter pH lower than that of normal rain (i.e. < 5.6), an irregular shore configuration marked by abundant riparian vegetation, and islands.In a correspondence analysis, the first axis, representing lake acidity, explains 68% of the total variance. The common goldeneyeBucephala clangula, which is frequently seen on the most acidic lakes, and the American black duckAnas rubripes, which tends to avoid acidic lakes, show the largest contributions to that axis. The second axis describes an altitude/surface area gradient and brings the cumulative percentage of explained total variance to 94%; the great blue heronArdea herodiasand the common loonGavia immerprimarily use large, low‐altitude lakes, whereas the ringnecked duckAythya collarisand the American black duck are often found on the smaller, higher‐altitude lakes. Those results are discussed as they relate to the feeding requirements of the various species of bird and the biology of their main prey. The ecological segregation of the three waterfowl species is attributed to interspecific competition.
Diel activity patterns of South Scandinavian high mountain ground beetles (Coleoptera, Carabidae)
Authors: Ottesen Preben S. 
Published: July 2006

Fourteen species of carabids were studied throughout the snowfree season in outdoor arenas above the timberline at Finse, South Norway (60°36′N, 7°30′E). Ten species were nocturnal. Onset of nocturnal activity occurred after termination of twilight with peak activity before midnight, but in June, with less than 1 h of darkness, activity was extended into evening twilight, the peak being around midnight. Linear regressions between ground surface temperature and nocturnal activity predicted zero activity in the range −2.0 to0.8°C, mean −0.5°C, indicating that activity is possible on most nights throughout the snowfree season. Two diurnal species had activity threshold temperatures at 4 and 8°C, respectively, the former with a peak at 16°C and an upper threshold at 28°C.The proportion of nocturnal species in the study area was significantly greater than in lowland open fields. Large and common species were mainly nocturnal, while small and rare species were mainly diurnal. It is suggested that nocturnalism in the South Scandinavian high mountains is a response to avoid bird predation and desiccation.
Annual activity and life cycles of carabid beetles in two forest communities
Authors: Loreau Michel 
Published: July 2006

The annual activity and life cycles of thirteen species of carabid beetles coexisting in two forests in Belgium were studied by recording above‐ground activity of adult and larval populations, and by examining the reproductive condition of adults in the course of the year. The cycles were far more complex and diversified than suggested by previous works. Besides typical “spring breeders” and “autumn breeders”, species were found

with a continuous reproductive period from spring to autumn,
with several variable breeding periods, part of the population overwintering as adults, part as larvae,
with a breeding period that begins facultatively in autumn and continues the next spring,
with a winter reproduction.

Comparison of life cycles in Scandinavia and In Belgium also shows their variability in relation to climate. More flexible and varied cycles are made possible by the milder winters further south. Existing classifications of life cycles of carabids appear unable to account for such a diversity and variability.
Life history variation in Pisidium (Bivalvia: Pisidiidae)
Authors: Holopainen Ismo J. , Hanski Ilkka 
Published: July 2006

Intraspecific variation in the maximum shell length ofPisidiumis small in comparison with variation in the life span of the clams, from 4 mo to 4 yr. The use of shell length as a measure of size is complicated by large intraspecific variation in the weight‐length relationship, a possible reflection of resource availability on the weight of the soft parts. Maximum embryo length is relatively constant (1 mm) in the majority of species but litter size is variable (1 to 40), generally increasing with parent size. The time of egg‐laying is determined by the size of the clam, season, and previous episode of reproduction, while the timing of the release of embryos, depending also on embryonic growth rate, is additionally affected by temperature and oxygen conditions. In brief, the maximum adult and embryo lengths are relatively conservative traits while growth rates vary by an order of magnitude.Reproductive effort, when measured by the ratio of litter weight to parent weight, may increase or decrease with parent length and age. Both semelparous and iteroparous populations are known in several species. We suggest that if maximum adult length can be reached by the first reproductive season (in a favourable environment) the population is semelparous, otherwise (in an unfavourable environment) the population is iteroparous. Gravid clams in semelparous populations continue to grow, and thus assimilation cannot be meaningfully partitioned into reproduction, somatic growth and maintenance.Along a depth gradient from 8 to 65 m, maximum and mature shell lengths, embryo length and litter size varies significantly inPisidium conventussubpopulations not distinguishable electrophoretically. Large clams in deep water produce large embryos but small litters, which is contrary to the general trend of increasing litter size with parent length. Low food availability that decreases juvenile growth rate may restrict litter size in this case.
The effect of temperature on the egg incubation period of Capnia bifrons (Plecoptera: Capniidae) from Windermere (English Lake District)
Authors: Elliott J. M. 
Published: July 2006

Gravid females of Capnia bifrons (Newman) from Windermere (English Lake District) were almost completely ovoviviparous, the eggs hatching within 15 min after oviposition in the water. When kept in the laboratory at constant temperatures between 3.8 and 19.8°C, few females survived to lay eggs at temperatures above 12.1°C. The relationship between air temperature (T°C) and the egg incubation period (Y days between fertilisation and oviposition) was given by the regression equation: Y = 316.4 T−0.9996 (r2= 0.957, p < 0.001). This equation successfully predicted egg incubation periods for gravid females kept in cages in the field.Comparisons with similar studies on four non‐ovoviviparous species of Plecoptera showed that egg development was rarely more rapid in C. bifrons. It was also shown that the hypothesis of ovoviviparity being an adaptation to combat low water temperatures could be rejected for C. bifrons from Windermere.
Seasonal colonisation and effects of salinity and temperature on species richness and abundance of fish of some brackish and estuarine shallow waters in Sweden
Authors: Thorman Staffan 
Published: July 2006

In this study two questions concerning the structure and organisation of shallow brackish and estuarine fish assemblages are: (1) Does the species number decline with lower salinity as found for the macrofauna invertebrates? (2) Does the water temperature during the year influence the abundance of fishes along the Swedish coast?In a west coast estuary salinities were higher but fluctuated more than in the Bothnian Sea. Days with temperatures exceeding 15°C were up to twice as many in the west coast estuary as in the Bothnian Sea. In spring the species number increased, but later on in summer it declined to increase again in autumn, but declined once again as winter approached. Fish density in the west coast estuary increased gradually to a maximum in late summer and then declined, while in the Bothnian Sea there was often a decline during summer. Positive correlations were found between observed minimum salinities and average species number, and between number of days with temperatures exceeding +15°C and both yearly average and maximum fish densities. Juveniles (0+) were present for longer periods in the west coast estuary than in the Bothnian Sea and reproduction of the common species started earlier in the former area. In winter the shallow areas are devoid of fish because of ice and so are re‐colonised each spring. The study demonstrates that water salinity limited the species number, and water temperature the abundance of fish.
Ectoparasites on small mammals in Iceland: Origin and population characteristics of a species‐poor insular community
Authors: Bengtson S.‐A. , Brinck‐Lindroth G. , Lundqvist L. , Nilsson A. , Rundgren S. 
Published: July 2006

The Icelandic small mammal fauna is depauperated as is the associated ectoparasite fauna. Three small mammal species occur, viz. Apodemus sylvaticus L., Mus musculus L., and Rattus norvegicus Berk. (R. rattus is probably not a regular member). The mice supposedly came to the island by settlers from the 10th century and onwards. Apodemus and Mus from five localities altogether had seven ectoparasite species, five mites and two fleas. All species occurred on Apodemus whereas Mus was infested by four. Compared with the numbers of ectoparasite species recorded in similar studies in the Nordic countries, there are conspicuously few species in Iceland. Further, Apodemus had an overall higher infestation frequency than Mus (90% and 30%, respectively) and a higher total density of ectoparasites (3.3–20.3 and 0.5 inds/host, respectively). The density figures were high compared with those for mainland Apodemus. Especially the mite Laelaps agilis C. L. Koch and the flea Ctenophthalmus agyrtes (Heller) were common on Icelandic Apodemus. Reduced competition among parasites and/or low predator pressure on small mammals may explain the density figures obtained.The ectoparasite species compositions on small mammals in Scandinavia and Iceland have many features in common that renders it probable that Apodemus originate from Scandinavia.
The life‐cycle and productivity of Tibifex tubifex (Oligochaeta; Tibificidae) in the Moat‐Feeder Stream, Cardiff, South Wales
Authors: Lazim M. N. , Learner M. A. 
Published: July 2006

A population of Tubifex tubifex in an organically rich stream was found to have an annual life‐cycle with a prolonged period of reproductive activity throughout the winter and spring. Cocoons were produced mainly during the late winter and early spring. No cocoons were found during August and September, and there were few mature worms at this time.The population density ranged between 5420 m−2 in mid‐September and 613000 m −2 in mid‐May. The maximum population biomass (Bmax) recorded was 106 g dry wt m−2 (March) and the minimum was 10 g dry wt m−2 (September). Total annual production (P) was 139 g dry wt m−2 and the average annual biomass (B) was 46 g dry wt m−2 giving an annual P/B ratio of 3.0, and a P/Bmax ratio of 1.3.
Pitfall trapping within enclosures: a method for estimating the relationship between the abundances of coexisting carabid species (Coleoptera: Carabidae)
Authors: Desender Konjev , Maelfait Jean‐Pierre 
Published: July 2006

Pitfall trapping within enclosures is proposed as a method to get a reliable impression of the relationship between the abundances of a number of coexisting carabid species. The investigations were performed during two years in a heavily grazed pasture at Melle (Belgium). On a rather large scale soil samples could be compared with both enclosed and open pitfall catches.In all cases fenced pitfalls gave ratios between the catches of the different species showing a much better correlation with those from soil samples than the catch ratios from open pitfalls. This method seems especially suitable to compare the relative abundances of a number of carabid species in short term investigations during periods of peak activities.
Seasonal crayfish activity as influenced by fluctuating water levels and presence of a fish predator
Authors: Hamrin Stellan F. 
Published: July 2006

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.