bluuebunny/crossref_metadata_2025 huggingface dataset:
Communicating With and Motivating High Fatalists
Authors: Nielsen Richard P.
Published: July 2006

Abstract. In three studies responses of high and low fatalists to five different types of communications messages were compared. The five types of information considered were single reward, multiple reward, reward explanations, conformity, and nonsense information. Nutritional, political, and reading behaviors were considered. Two field experiments were conducted with male heads of households and a laboratory experiment was conducted with students. The high fatalists were motivated by reward explanation information. The low fatalists were motivated by single and multiple reward information more than the high fatalists. Responses of the high and low fatalists converged, at the highest motivation level, in response to reward explanation information. Fatalism accounted for more response variance than income, education, or race characteristics. The social significance of these findings is discussed in terms of: the need to motivate the high fatalists; who the high fatalists are; the growth of high fatalism; and the transferability of this paper's communication content findings to organizations dealing with problems of high fatalism.
Role of Consumer Preferences in an Economic System*
Authors: Zinam Oleg
Published: July 2006

Abstract. This article provides a theoretical model for systematic analysis of interaction of consumer preferences with preferences of producers and of government. The central question of the study is whose preferences are rendered effective and to what extent. A theoretical framework for analysis of diverse economic systems is used to derive preference and opportunity functions of decision‐making units on consumption, production, and government sides. This model is broadened by introduction of elements of a theory of change based on the postulates of necessary and sufficient conditions. Galbraith's model is placed analytically between the two extreme ideal types and subjected to a critical analysis.
Racial Differences in Returns to Educational Investment in the South
Authors: Niemi Albert W.
Published: July 2006

Abstract. The paper calculates rates of return to educational investment in the South and highlights differences in returns according to race and sex. The results of this investigation are compared with the results of earlier studies, and it appears that there has been a relative increase in the returns to Black education in the South. For most education levels, Blacks still earn lower returns than Whites, but the recent narrowing of earnings rates suggests that southern Blacks have made significant progress in their drive for equality of opportunity.
The Relation of ‘Human Capital’ Preservation to Health Costs*
Authors: Spratt John S.
Published: July 2006

Abstract. The concept of 'human capital' has evolved in economics as a way of measuring the value society places on an individual. This value, it is argued, constitutes a real but seldom discussed limit on how much money either an individual or society will pay for the health costs of an individual. Conversely, it can be argued that the capacity of the health system to preserve ‘human capital', as created by nature and nurture and by ‘investments’ in education and training, is an economic justification for health costs, just as military costs are justified for the defense of the population. In the latter instance, the greatest public health benefit for the dollar would be obtained by Pareto optimal expenditures. Similarly a microeconomic model for the clinical process involved in diagnosing, treating and rehabilitating the diseased individual is suggested that relates the time consumed by the elements of the clinical process to the probabilities of maximizing the preservation of the greatest number of functional man‐days obtainable for an aging individual's cohort. For the model to work there would have to be an economic incentive for the health provider to engage in objective‐oriented, interdisciplinary, cost‐effective actions in the clinical process that would minimize the diseased individual's downtime and maximize his functional longevity in an operations research framework.
Taxation for Low Cost Wood Fiber*
Authors: Lindholm Richard W.
Published: July 2006

Abstract. If forest industry taxation is to be put on a sound economic basis, the Federal Government, the largest land owner, should pay the same taxes as any other landowner, so that the social and economic effects of taxation are realized. Specialists report that the form of the property tax preferred for the taxation of the property of the forest industry, under most circumstances, is land value taxation, not the property tax based on income realized at some point In the future which presumed the continued existence of virgin forests. This paper recognizes that the forest industry now is based on harvests of tree crops and proposes a further development of the land value taxation principle in the form of a forest tax composed of a land value tax combined with a tax on tree growth which increases as growth as a percentage of volume growth decreases with the tree's increasing age.
Microdistribution of butterflies in a mosaic‐like habitat: The role of nectar sources
Authors: Loertscher Mathias , Erhardt Andreas , Zettel Juerg
Published: July 2006

The microdistribution of five butterfly species through their flying season was analyzed in a mosaic‐like habitat, brought about by secondary succession In order to explain the patterns observed, activity patterns and the use and distribution of nectar sources were determined Emphasis was laid on the changing allocation of visits to flower species and changing abundances of flowers during the season The use of nectar sources was basically limited to three flower species,Centaurea scabiosa, C bracteataandSerratula tinctoriaAs a consequence, niche breadth values were generally low and niche overlaps generally high Some butterflies changed their patterns of flower visits during the season and therefore reduced niche overlap with the other butterfly species The microdistribution ofMelanargia galathea, Lysandra condon, Ochlodes venatusandLictoria achilleaewas strongly influenced by the distribution of their preferred nectar sources as well as by areas generally rich in flowers Changing flower preferences ofMelanargia galatheaandLysandra coridonmales during the course of the season were also expressed by changes in the correlations between the distribution of these butterflies and their nectar plants The distribution of nectar sources was not found to be of importance forCoenonympha arcanta,a species which rarely visited flowers
Bird species turnover and stochastic extinction in woodland fragments
Authors: Hinsley Shelley A. , Bellamy Paul E. , Newton Ian
Published: July 2006

Year‐to‐year turnover in bird species composition was recorded across, the whole size range (0 02‐30 ha) of 146 woods studied The mean number of resident breeding species both lost and gained per wood between consecutive breeding seasons was 2 (range 0‐8) No relationship was found between this absolute turnover rate and woodland area, or any other of 24 predictor variables (describing woodland structure, isolation, connectedness and surrounding land use) Extriction and colonisation rates (in terms of numbers of species lost and gained) were also unrelated to woodland area In all sizes of woods, the species most likely to show local extinctions and colonisations were those with small populations within those woods, but the identity of the species concerned changed as woodland area increased In the smallest woods, the majority of turnover involved common species, such as wren and dunnock, which occurred in only small numbers in these small woods As woodland area increased, these species attained sufficient numbers to usually avoid stochastic extinction The majority of turnover was then due to more specialist (and less numerous) woodland species, such as great‐spotted woodpecker and marsh tit, which were usually lacking in small woods In Britain, much existing broadleaved woodland falls within the size range studied Thus the numbers of many bird species are liable to be small enough for yearly turnover in woodland bird communities to be appreciable, and for the long‐term persistence of individual species in particular woods to depend on dispersal
Habitat preferences of sub‐montane spiders in northem England
Authors: Downie I. S. , Butterfield J. E. L. , Coulson J. C.
Published: July 2006

Thirteen study sites were selected to cover the dominant vegetation types on the plateaux of three summits in the North Pennines, England The spider community of these sites were sampled by pitfall trapping between April and October 1991 Several environmental variables were collected for each site, including local topography, soil characteristics and vegetation structure Multivariate methods were used to classify the sites based on their spider species composition Canonical correspondence analysis was used to assess the influence of the external factors on the distribution of the species The results suggest that vegetation density is the major factor influencing spider distribution on the summit plateaux with slope and soil depth also contributing to the variation Three spider associations for the plateaux are proposed based on their common species composition Two shortFestucagrassland assemblages and aNardus/ Ertophorumspp assemblage associated with higher vegetation density The habitat preferences of some species common to the plateaux are discussed in light of the results, and compatisons are made with studies from other upland areas
Ground‐dwelling spiders (Arachnida, Araneae) in fragmented old forests and surrounding managed forests in southern Finland
Authors: Pajunen Timo , Haila Yrjö , Halme Eero , Niemelà Jari , Punttila Pekka
Published: July 2006

We studied the structure of spider assemblages in fragments of old coniferous forest in the southern Finnish taiga We sampled spiders with pitfall traps in the interiors and in the edges of the old‐forest patches and in the surrounding managed forests We surveyed assemblages of ground‐dwelling spiders and the relation of species to formerly mentioned three forest‐habitat categories We analysed spider assemblages in relation to vegetation structure as well As in forest spiders there are no habitat specialists, no strict old‐forest species were found However, the spider assemblages of old forests were different from those in the surrounding managed forests The difference was attributable to habitat differences, mainly to reduced tree‐canopy cover in managed forests Large hunting‐spider species (Gnaphosidae, Lycosidae) benefitted from clearcutting and other management measures, whereas the catches of small forest‐living species (Linyphiidae) decreased in plantations and open forests The hunters colonized the edges of old‐forest fragments, and were seldom found in the interior of old forest Size of old‐forest fragment did not affect significantly the spider assemblage The results indicate that a buffer zone of mature forest with closed canopy should be left to surround the old‐growth reserves in order to minimize the edge effect in the fragments
Seed bank build‐up in small disturbances in a Mediterranean pasture: the contribution of endozoochorous dispersal by rabbits
Authors: Malo Juan E. , Jiménez Betsabé , Suárez Francisco
Published: July 2006

The importance of endozoochorous dispersal in seed bank build‐up is analyzed in artificial 40 x 40 cm disturbances in a Mediterranean pasture The top 10 cm of soil in the disturbances was replaced by sterile soil, and the excrement laid m half of them was removed fortnightly The seed banks of the disturbances subjected to the two treatments was quantified by germination of soil samples (n = 44) gathered at the start of the following growth season Rabbit droppings were collected fortnightly to quantify their seed content and the pasture seed production was estimated Seed bank regeneration takes place early in the disturbances The main source of qualitative variation in seed banks is their position on the slope, while endozoochory lacks a characteristic qualitative effect However, endozoochorous dispersal is responsible for a significant increase in the number of germinable seeds, the richness and diversity of the seed bank samples with respect to those lacking it The importance of endozoochorous dispersal by rabbits in grassland dynamics is suggested to be its effect on the colonization of small disturbances, where species dispersed with dung are found to be favoured This aids the maintenance of grazing‐tolerant communities
Small‐scale dynamics and species richness in successional alvar plant communities
Authors: Pärtel Meelis , Zobel Martin
Published: July 2006

Species richness and small‐scale spatial dynamics (turnover) were compared in four sites during 1990‐1993 1) former alvar grassland, now young Pinus sylvestris forest, 2) clear‐cut in 1990, 3) clear‐cut and grazed by sheep, 4) nearby grassland It was hypothesized that in communities which show large‐scale dynamics, small‐scale dynamics is also more rapid to support succession Area‐based species richness and shoot density increased in the cut and grazed site No significant dynamics was found in shoot‐based species richness Therefore the forest was considered to be stable and the cut and grazed site large‐scale dynamical (successional) Almost equally high small‐scale turnover values were found in all sites, which supports the carousel model for successional communities, but means we had to reject the initial hypothesis The successional and intrinsic small‐scale dynamics of the communities studied were two separate processes which acted at different scales, but the scale could not be only spatially determined, it depended also on the shoot density The overgrowing of this former alvar grassland has resulted in the decrease of shoot density and thus the decrease of species richness per unit area, but the total number of species has not changed much Consequently the possibility to restore grassland communities remains
Distribution and abundance of butterflies in a mountain area in the northern Iberian peninsula
Authors: Gutiérrez David , Menéndez Rosa
Published: July 2006

The effect of alutudinal range, distance to the latitudinal boundary of geographical range, body size and larval food plant on both the distribution and abundance of butterflies have been studied in a mountain area along a marked altitudinal gradient Multiple regression analysis revealed that distribution was positively related to altitudinal range and abundance Altitudinal range accounted for a great part of vanance in species distribution Altitudinal range increased as both distance to latitudinal boundary of geographical range and body size increased Abundance was not affected by altitudinal range, body size or distance to latitudinal boundary Larval food plants family was related to the abundance of butterflies, but not to distribution or altitudinal range These results suggest that regional distributions of butterflies are likely to be limited by climatic tolerances of species, while local abundance might be influenced by local resource levels
Trophic niche, age structure and seasonality in Dolichopoda cave crickets
Authors: de Pasquale Luigi , Cesaroni Donatella , Russo Claudio di , Sbordoni Valerio
Published: July 2006

Shifts in feeding habits are expected to occur during adaptation to cave life Doltchopoda cave crickets inhabit both natural and artificial caves showing differences in population size, fecundity, phenology and age structure Compared to artificial caves, typically holding a seasonal age structure, populations from natural caves maintain a constantly heterogeneous age structure Faecal content analysis of 605 individuals from 24 natural and artificial cave populations, enabled us to characterize their trophic niche and to investigate its variation The results of multivariate analyses and measures of niche breadth and niche overlap outlined differences in trophic resource exploitation between natural and artificial cave populations Seasonal variation in diet occurred in both types of caves, and it was greater in artificial cave populations However, within any season, differences in feeding habits between individuals were much greater in natural caves resulting in a wider heterogeneity in trophic resources exploitation. Such heterogeneity appears to be mainly due to differences in diet between individuals of different developmental stages In fact, in a sample of 15 populations we found a positive, statistical significant correlation between niche breadth and heterogeneity in age structure These data are discussed in a broader evolutionary context in order to understand the role of limited resources availability in shaping and maintaining heterogeneity in age structure of Dolichopoda populations
Body morphology of crucian carp Carassius carassius in lakes with or without piscivorous fish
Authors: Poléo Antonio B. S. , Osxnevad Sigurd A. , Össtbye Kjartan , Heibo Erik , Andersen Ronny A. , Vøllestad L. Asbjøm
Published: July 2006

Crucian carp Carassius carassius was sampled during 1993 and 1994 in 21 lakes and ponds in east Norway In 10 of these lakes and ponds no piscivorous fish species was present, and in the remaining 11 lakes and ponds predators such as perch Perca fluvtalilis. pike Esox lucius, and trout Salmo trutta were common In general, crucian carp was larger in the lakes with predators than in those without predators The relative body depth (body height/body length) of crucian carp was significantly deeper in populations sympatric with predators (mean 0 358), compared to allopatric populations (mean 0 286) The variation in relative body depth was larger among the sympatric populations than among the allopatric populations The observed difference in relative body depth may be due to 1) predator induced changes m body morphology, 2) increased growth rates in lakes containing predator due to reduced intraspecific competition, and 3) size‐selective predation
Primary and secondary seed dispersal by wind and water in Spergularia salina
Authors: Redbo‐Torstensson Peter , Telenius Anders
Published: July 2006

The patterns of repositioning by wind and water following their initial dispersal from the parent plant, of winged and unwinged seeds of the heteromorphic halophyte Spergularia salina were Investigated experimentally in both dense vegetation and bare ground under field conditions in a sea shore meadow in eastern Sweden Seeds were placed in situ in the field, and after four days with wind as the sole dispersing agency, 19% of the seeds were repositioned After another 11 days, during which both wind and water acted as dispersing agencies, all seeds of both types had either become repositioned and were still visible (1/3 of the seeds), had penetrated into the ground at the point of release or after dispersal (1/3), or were not recovered (1/3) The probability to become lifted secondarily by water was similar in both seed types Of those seeds repositioned and recovered on the ground, more of the winged type had been transported any distance horizontally than the unwinged type The seed dispersal curve was strongly skewed to the left, and the winged seed type was transported slightly further than the unwinged type, both during primary and secondary dispersal All seeds were transported further when placed on bare soil than when placed in dense vegetation Vertical transportation was quicker in dense vegetation, and unwinged seeds disappeared more quickly into the ground In dense vegetation, unwinged seeds were more frequently encountered in the seed bank than winged seeds, whereas in the absence of vegetation cover, seeds of both types recovered in the soil were found in equal shares
Long–term responses to factorial, NPK fertilizer treatment by Alaskan wet and moist tundra sedge species
Authors: Shaver G. R. , Chapin F. Stuart
Published: July 2006

At thirteen sites in northern and central Alaska, full factonal and partial factonal NPK fertilizer experiments were completed in wet and moist tundras The effects of the fertilizers on N and P concentrations in leaves, leaf mass per tiller, tilling, and flowering of the dominant sedge species (Eriophorum vaginatum. E angustifolium, and Carex aquatilis) were documented for 3–10 yr at each site Almost all sites showed at least some response to the fertilizer treatment, but the specific treatments and elements that caused the responses varied greatly among sites There also was no consistent difference in responses between wet and moist sites There was, however, a consistent temporal pattern to the responses observed, starting with increases in N and P concentration in leaves in the year that fertilizer was added, followed by growth and tilling responses in the second year, and increased flowering in the third year The increases in N concentration generally only appeared in the first year, while increased P concentrations were sustained for 3–4 yr Effects of fertilizer on flowering were still significant after 6 years in some cases Results are discussed in terms of the role of “nutrient limitation” arctic plant communities and detemuning their productivity following disturbance or fertilization
The structure of allozyme and leaf shape variation in isolated, range‐margin populations of the shrub Hippocrepis emerus (Leguminosae)
Authors: Lonn Mikael , Prentice Honor C.
Published: July 2006

We investigated allozyme variation and phenotypic variation in leaf shape in 15 populations of the shrubHippocrepis emerus(Leguminosae) from the three isolated, regional populations in Scandinavia and analysed patterns of differentiation and the hierarchical structuring of diversity on different geographic scales There are pronounced geographic differences between the Norwegian and Swedish isolates of the species and most of the polymorphic allozyme loci show reciprocal fixation in the two isolates The Scandinavian populations ofH emerusare not only disjunct on a macrogeographic scale but also show considerable disjunction within regions Within the Oland regional population, a central group of populations shows low levels of Inter‐population differentiation the Gotland group of populations is related to this core group of Oland populations The geographically marginal populations on Oland are spatially isolated and show a higher degree of divergence between populations than does the central group of Oland populations We interpret genetic divergence between the marginal populations in terms of genetic drift ‐ as a result of historical fluctuations in habitat availability and population size
Species abundance patterns of plants in Swedish semi‐natural pastures
Authors: Eriksson Åsa , Eriksson Ove , Berglund Hans
Published: July 2006

This investigation is based on a species inventory m semi‐natural pastures, remnants of an “old” traditional landscape, in Sweden The aim was to examine relationships between species richness and pasture area, neighbour pasture area, distance to nearest pasture, pasture heterogeneity and fertilization Species occurrences were also investigated individually for the same parameters Pasture area, neighbour pasture area and distance to nearest pasture were not found to influence species richness Habitat heterogeneity and indications that pastures had been influenced by fertilization were however associated with both species richness and species occurrences Heterogeneity had only positive effects whereas the effects of fertilization were only negative Species regional abundance pattern tended to be bimodal, as predicted by the core‐satellite hypothesis No correlation between abundance and plant height, or seed size was found, as would have been expected if competitive dominance effects determined species regional abundance There was a close to significant tendency that pasture area was positively associated with occurrences of species with features favouring a high seed dispersal capacity We suggest that the previous history of pasture distribution and management may be of vital importance for present day species abundance pattern, even though this remains obscure in the recent landscape
Global scale patterns of fish species richness in rivers
Authors: Oberdoff Thierry , Guégan Jean‐François , Hugueny Bernard
Published: July 2006

Explanations of spatial and temporal variation in species richness is a central theme in community ecology Until recently, most research has focused on small‐scale phenomena, often emphasizing on local environmental factors and, thus, poorly reflecting large‐scale processes that organize species richness In this paper, we analyze variations in species richness of indigeneous freshwater fish on a worldwide scale We show that factors related to species‐area and species‐energy theories statistically explain most of the variation in freshwater fish species richness across continents Historical events supposed to influence present distributions offish are of little assistence in explaining variations in fish species richness at the global scale Our model, which uses easily measured factors, should also be of practical value to aquatic conservation biology and natural resource management
The effect of water and mycorrhizal infection on the distribution of Carlina vulgar is on sand dunes
Authors: de Jong Tom J. , Klinkhamer Peter G. L. , de Heiden J. L. H.
Published: July 2006

On sand dunes at Meijendel (the Netherlands) the thistle Carlina vulgaris grows almost exclusively near shrubs of willow (Salix repens) and more rarely near shrubs of sea buckthorn (Hippophaë rhamnoides), although both scrubs occur in similar frequency The critical stage in the life cycle is the phase of establishment of seedlings, which is better in Salix than in Hippophae Once established, the performance of plants IS better under buckthom than willow Watering greatly improved seedling establishment and subsequent growth, especially under sea buckthom As a result, after watering the total biomass of C vulgaris became even higher in buckthom scrub than in willow Because of its higher humus content, the water content of the top 10 cm of the soil was consistently higher (c 55%) under willow than buckthom Apparently low water availability prevents C vulgaris from establishing outside willow scrub but once this limitation has been overcome, other habitats are entirely suitable for growth Roots of C vulgaris plants in unwatered plots in willow were less colonized by mycorrhiza than in buckthom plots Our results do not indicate that mycorrhiza helps seedling establishment
Granivory in the Chilean matorral: extending the information on arid zones of South America
Authors: Vásquez Rodrigo A. , Bustamante Ramiro O. , Simonetti Javier A.
Published: July 2006

Comparative studies of granivory intensity across different arid and semi‐and regions of the world have assumed homogeneity of conditions over large geographical areas, despite the existence of evident heterogeneities at local and regional scales For South America, previous evidence from the Monte desert, Argentina, showed that granivory intensity is low compared with other continents and that seed removal rates by taxon (granivore ranking) are in decreasing order ants > birds = small mammals In this work, we examined the assumed generality of this pattern for another South American region, the Chilean matorral We studied the differences between sparse and dense habitats of the matorral in granivory intensity throughout the year Although total seed removal did not differ between habitats, differences among granivores did occur Ants were the most important seed removers in both habitats, although they did not differ from birds in the sparse habitat Further, ants were the most important seed consumers during summer, but their seed removal rate is almost negligible the rest of the year Birds maintained an intermediate rate of seed consumption through the year Granivory intensity by small mammals was very low in both habitats during the whole year The granivory ranking obtained for the Chilean matorral was ants > birds > mammals, in dense habitat, and ants = birds > mammals, in sparse matorral Am abundance is correlated with seed removal throughout the year This relationship was not found in the other taxa We discuss possible causes for the differences among habitats, taxa, and seasons, as well as distinct granivore rankings from different continents
Diatom, chrysophyte and protozoan distributions along a latitudinal transect in Fennoscandia
Authors: Pienitz Reinhard , Douglas Marianne S. V. , Smol John P. , Huttunen Pertti , Meriläinen Jouko
Published: July 2006

Diatoms, chrysophyte scales and cysts, and the siliceous plates of thecoamoebae were studied from the surface sediments of 20 freshwater habitats in Fennoscandia The study sites are distributed along a latitudinal transect extending from southern Finland to northern Norway, spanning boreal forest through arctic tundra vegetational zones Diatom assemblages were usually dominated by acidophilic, periphytic members of the genera Achnanthe, Fragilaria and Navicula Marked shifts in diatom assemblage composition were recorded along the latitudinal transect, whereas scaled chrysophytes were rare in all study sites Meanwhile, siliceous protozoa were common, but did not exhibit any noticeable trends in assemblage composition with changing latitude A comparison of the Fennoscandian diatom assemblages with those recorded from freshwater sites near Yellowknife (central Northwest Territories, Canada) revealed similar trends in diatom assemblage composition with changing ecoclimatic zones in both regions Moreover, canonical correspondence analysis showed that diatom assemblages in cold, dilute tundra sites were effectively separated from sites with forested catchments from both the Fennoscandian and Canadian transects The general similarity between the two regions suggests that autecological data and the resulting environmental transfer functions based on diatom assemblages may eventually be joined from North American and European regions
Effects of woodland modification by African elephant Loxodonta africana on bird diversity in northern Botswana
Authors: Herremans Marc
Published: July 2006

Bird diversity was assessed by point‐transect‐count sampling during the dry and the wet season in riverine gallery woodland and in Colophospermum mopane woodland with different levels of elephant impact Dramatic woodland degradation did not result in a dramatic overall reduction m bird diversity, but resulted in substantial changes in bird species composition and capacity for migrant birds Less affected, more dense woodlands functioned as dry season refuges for‘resident’Afrotropical species, but this function was lost in degraded woodlands In contrast, secondanzed habitat had a much higher capacity for long distance migrants in the wet season Species endemic to the sub‐region and subspecies with restricted ranges centred in the area were not negatively affected by woodland degradation The cumulative interference of past and current elephant numbers with the conservation of bird diversity appears to be insignificant in northern Botswana
Parasites and the regional distribution of bumblebee species
Authors: Durrer Stephan , Schmid‐Hempel Paul
Published: July 2006

Parasites and regional processes may be important to structure local species assemblages In particular, it has been hypothesized that widely distributed and abundant species should harbour more parasite species which could give them a competitive advantage in local species assemblages Empirical evidence bearing on these points are scarce and mainly restricted to vertebrate hosts or plants The aim of this study was to provide data in insect hosts and to test whether the patterns in field populations conform with those correlates expected from the parasite‐host distribution hypothesis We investigated species assemblages of bumblebees at 12 different sites in a mesoscale region with their parasites over two consecutive years Parasites included dipteran and hymenopteran parasitoids. nematodes, mites, and protozoa The mean number of parasite species per host species ranged from 1 to 8 To account for sampling effort, all data were corrected for sample size effects The number of parasite species per average host individual (parasite load) ranged from 0 09 to 0 75 In cross‐species comparisons, the number of parasite species per host species was positively correlated with regional distribution, i e the number of sites a host species occupied m the region, and with the average local host abundance The same relationships were found for parasite load In addition, parasite load correlated positively with average colony size of the host species, but not with body size of the individuals Bumblebee species were bimodally distributed When separated into widely‐distributed and locally‐occurring species, common hosts harboured more parasite species than rare ones Moreover, workers of common species individually had higher parasite loads From these results, we conclude that some of the necessary preconditions for parasites being able to affect the distribution and occurrence of their hosts are met in bumblebees The findings support a general pattern that parasite loads correlate positively with local abundance and geographical distribution of their hosts, also on mesoscales usually considered in ecological studies
Density dependent processes and the importance of periodic germination in the winter annual plant Saxifraga osloensis
Authors: Nilsson Thomas
Published: July 2006

Saxifraga osloensis is an allopolyploid plant, endemic to Scandinavia A field study of Its population biology was performed during two years, 1989‐90 and 1990‐91 The timing of different life stages in spring was correlated with weather conditions, mainly temperature Density effects were found on survival of rosettes in autumn and on capsule production in spring It seemed as if the density effects occurred only when the initial density was very high or when there was shortage of water Most plants emerged in autumn, but between 10% and 15% emerged m spring Spring gemunators were exposed to higher mortality risks in spring than autumn germinators Fitness, estimated as life‐time capsule production, was lower for spring cohorts both years Most plants in the spring cohorts produced no seeds Thus, spring germination should not be selected for in this population
Nutritional estimate of populations of some wild free‐ranging African ungulates in grassland (Nechisar national park, Ethiopia) in dry season
Authors: Abaturov Boris D. , Kassaye Fekadu , Kuznetsov German V. , Magomedov Magomed‐Rasul D. , Petelin Dmitry A.
Published: July 2006

The amount and nutritive value of forage plants, diet composition, digestibility of dry matter and nutrients were recorded for zebra. Grant's gazelle, Swayne's hartebeest and hippopotamus in November‐December 1991 Besides, daily egest of feces, the level of food and nutrient consumption, energy and protein requirements were recorded for zebra and Grant's gazelle The digestibility of pasture forage was determined as a ratio of lignin concentration in food to the concentration m feces (lignin tracer technique), a daily intake was calculated on the basis of the daily feces egest Protein percentage m the diet of zebra and hartebeest consuming dry parts of grasses did not exceed 5% Gazelle diet consists of green parts of plants and included 18% of protein The digestibility of dry matter in nonruminants (zebra, hippopotamus) was 40‐45%, in hartebeest ‐ 50%, in gazelle ‐ 60% Due to the abundance of dry grasses (3 7 ton ha‐1) the daily food consumption of zebra was high ‐ 7 2 kg ind‐1 (dry weight), the metabolizable energy intake (ME) being 51 MJ Adult gazelles consumed 15‐25 kg ind‐1 of food and 14‐24 MJ of ME The energy requirements of adult males and non‐lactating females of zebras and gazelles (48 and 13 MJ respectively) were met, the energy balance berig negative for lactating animals The daily protein requirement was not met in zebra (392‐704 g md‐1 vs 134 g ind‐1 of intake) and in lactating gazelles (250 g ind‐1 vs 197 g md‐1) Non‐lactating gazelles consume sufficient amount of both energy and protein due to the high feeding selectivity of the species and thanks to the abundance of burnt areas with young green after‐grass m the dry period
Testing for seasonal displacement in a dung beetle guild
Authors: Palmer Miquel
Published: July 2006

The temporal overlap between seasonal distribution of adults of 14 congeneric dung beetle species (Aphodius spp) was determined during one year, based on 11122 captures The mean seasonal distribution of adults (mean of the sampling dates weighted by the abundance value) was analyzed to elucidate deviations from ram‐domness In addition, the effect of the shape of seasonal distribution of adults was investigated In both analyses randomization methods were used A clear trend exists maximizing the temporal displacement between middle points of chronologically consecutive species newly emerging species appear every 26 ± 16 days This trend minimizes the number of species pairs with no or very little temporal overlap In contrast, the mean temporal overlap of the whole guild seems unaffected, with some species pairs showing a large temporal overlap Whether the observed pattern can be attributed to interspecific competition must be addresed experimentally
Use and improvement of Ellenberg's indicator values in deciduous forests of the Boreo‐nemoral zone in Sweden
Authors: Diekmann Martin
Published: July 2006

Ellenberg's indicator values for light, moisture and reaction were tested in deciduous hardwood forests of the Boreo‐nemoral zone m Sweden Weighted averages of indicator values were calculated and correlated with field measurements for two test sets of relevés The best, highly significant correlations were found for reaction, particularly for weighted averages based on vascular plant species Significant correlations were also found for light, whereas those for moisture were less good and only partly significant Weighted averages based on presence/absence values and those based on cover/abundance values were generally very similar to each other, but showed differences in their correlations with actual measurements

A training set of relevés was used to calculate optima and ecological amplitudes of the most common species Under certain conditions, the original indicator values were replaced by these optima in order to obtain improved indicator values for Swedish deciduous forests These were correlated with the same test sets of field measurements as the original values and clearly gave better results for light as well as for reaction regarding vascular plants No clear differences were found for moisture and reaction regarding bryophytes For the majority of species, the original indicator values also expressed the ecological optima in Swedish deciduous forests as determined by this study However, several species, most of them preferring more open habitats, showed ecological optima and amplitudes that considerably deviated from central European conditions In conclusion, Ellenberg's indicator values can successfully be used in south Swedish deciduous forests, particularly after calibration of the values according to regional deviations
Responses of vegetation to a changing regime of disturbance: effects of feral pigs in a Californian coastal prairie
Authors: Kotanen Peter M.
Published: July 2006

Disturbance can eliminate sensitive native species and facilitate invasions by exotics, but disturbance is also important in the maintenance of many native‐dominated ecosystems Because of this dual role, disturbance can have complex implications for biodiversity I have investigated the effects of an introduced agent of disturbance, the feral pig Sus scrofa L, in meadows in northern California Pigs were the principal agent of soil disturbance at this site, annually overturning an average of 74% of the total surface area Grubbed areas re vegetated rapidly, but grubbing bad significant effects on the composition of the affected vegetation Species richness was reduced in grubbed plots in the first year following disturbance, but rose thereafter, often exceeding the richness of undisturbed controls Disturbance did not exclusively benefit either native or exotic species Changes in richness primarily reflected the early colonization of disturbed plots by natives, particularly annuals, although alien annual grasses also increased in disturbed sites Consequently, though non‐natives did respond positively to disturbance, at least in the short‐term they did not simply replace natives Pigs' effects may typify the complicated events to be expected when an ecosystem's regime of disturbance is significantly altered, either by direct human intervention or as a consequence of a biological invasion
Seed production, predation and dispersal in the Mediterranean myrmecochore Euphorbia characias (Euphorbiaceae)
Authors: Espadaler X. , Gómez C.
Published: July 2006

Seed production or a population of 193 reproductive individuals of Euphorbia characias from the north‐east Iberian peninsula was estimated at 155000 seeds per year. The dehiscence period lasts for four weeks. The timing of ballistic dispersal is uniformly distributed throughout the day. Seeds remain on the surface a mean time (±SE) of 52.3 ± 6.7 min. Several ant species take the seeds in varying proportions: Messor barbarus (0.225), a granivorous ant which eats the seeds; Aphaenogaster senilis (0.313), Pheidole pallidula (0.296) and Tapinoma nigerrimum (0.162) which take the seeds to their nests but do not eat them. Half a million ant foraging trips per day indicate a very strong short term influence of ants on fate of Euphorbia seeds. Ants as a group have a dual role of predation and dispersal of Euphorbia characias seeds. The characteristics of this Euphorbia (sclerophylly, diplochory, firmness of elaiosome, absence of subsidiary myrmecochorous features) better fit the syndrome described for Australian myrmecochores than the one proposed for European and North American myrmecochores.
Ant communities in taiga clearcuts: habitat effects and species interactions
Authors: Punttila Pekka , Haila Yijö , Tukia Harri
Published: July 2006

We surveyed the structure or ant communities in young taiga forests by pitfall trapping in southern Finland. The sampling sites were clearcut and planted with conifers 14–20 yr before the sampling. The results indicated that the structure of the ant communities was largely determined by the top competitors, the territorial species of the wood‐ant group (Formica aquilonia and F. lugubris) in the older, and the aggressive slavemaking ant (F. sanguinea) in the younger clearcuts. Species interactions resulted in distinct spatial distributions of individual species depending on the competitive status of the species concerned. Competition and slavemaking were the most important factors on larger spatial scales. The spatial scale of competitive structuring was determined by the territory and colony sizes of the top competitors. On a finer scale, variability in moisture and tree‐canopy shading seemed to have enhanced coexistence of some competing submissive species by alleviating the effects of nest‐site competition and slavemaking. Competition between the wood ants and the slavemaking ant affected indirectly the distribution and abundance of the species subject to slavemaking, F. fusca and F. lemani. Similarly, the top competitors presumably affected the distributions of other interacting subordinate species indirectly through differential competitive effects on them. Overall, species interactions seemed to have induced considerable determinism in ant‐community succession in young forests.
Food habits of the barbastelle bat Barbastella barbastellus
Authors: Rydell Jens , Natuschke Guenther , Theiler Alex , Zingg Peter E.
Published: July 2006

The diet of Barbastella barbastellus was investigated through analysis of droppings collected from three maternity roosts in Germany and Switzerland. The results showed a high dominance of moths (Lepidoptera), which accounted for 73–94% of the recovered items by volume. Flies (Diptera), ranging in size from blow flies (Calliphoridae) and large crane flies (Tipulidae) to small Nematocera, were the second most important prey items (4–17%). Prey types recovered also included small numbers of Trichoptera, Neuroptera, Homoptera, Hymenoptera, Coleoptera and spiders (Araneae). The diet of the barbastelle differs from that of most other bats in Europe in the predominance of moths and the corresponding virtual absence of dung beetles (Coleoptera; Scarabaeidae) and midges (Diptera; Chironpmidae). Conservation measures for barbastelles should therefore consider facilitation of the diversity and abundance of moths.
Habitat fragmentation reduces disperser success in juvenile nuthatches Sitta europaea: evidence from patterns of territory establishment
Authors: Matthysen Erik , Currie David
Published: July 2006

We studied establishment in summer territories by first‐year nuthatches Sitta europaea both in a large forest and in a set of small and isolated forest fragments (2 yr in each area). In the large forest, vacant territories were rapidly taken up by newly formed pairs of juveniles. In the fragments, settlers arrived at a slower rate, more of them remained unpaired, and more territories remained vacant at the end of the dispersal period. Furthermore, territories were taken up in a highly predictable order related to territory quality in the large forest, but not so in the fragments. We suggest that dispersal is more costly in a highly fragmented habitat, reducing the number of settlers at the population level, and reducing opportunities for pair formation and habitat selection at the individual level.
Predation on artificial ground nests in relation to forest fragmentation, agricultural land and habitat structure
Authors: Huhta Esa , Mappes Tapio , Jokimäki Jukka
Published: July 2006

The impacts of forest fragmentation, agricultural land and habitat structure on depredation of artificial ground nests were studied in the cultivated area in central Finland and in the forest dominated area in Finnish Lapland. The overall predation rate did not differ between the regions. The overall predation rate was also independent of landscape characteristics forest patch size and the distance to patch edge. However, nest predation was clearly affected by the agricultural land since the robbing rate in forest edges was higher near farmlands than further away. This effect was caused by avian predators which proportional importance in predation was higher in the agricultural landscape than in the forest landscape. In both regions, depredation correlated positively with high numbers of pine and spruce. This can be mainly explained by the preference of predators over coniferous forest habitat as a living or hunting area.