bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term effect of the combined use of powered toothbrush and triclosan dentifrice in periodontal maintenance patients
Authors: Bogren Anna , Teles Ricardo P. , Torresyap Gay , Haffajee Anne D. , Socransky Sigmund S. , Jönsson Kerstin , Wennström Jan L.
Published: August 2010

Aim: To test the hypothesis of a superior clinical and microbiological effect of the combined use of powered toothbrush+triclosan‐containing dentifrice compared with manual toothbrush+regular fluoride‐containing dentifrice in periodontal maintenance patients.

Material and Methods: A total of 128 periodontitis subjects involved in recall programmes were randomized to use either powered toothbrush with triclosan‐dentifrice (test) or manual toothbrush and standard dentifrice (control). Supportive periodontal treatment was provided at baseline and every 6 months. Plaque, bleeding on probing (BoP), probing pocket depth (PPD) and relative attachment level (RAL) were scored at baseline, 1, 2 and 3 years. Subgingival plaque samples were taken and analysed for their content of 40 bacterial species at each examination interval. All analyses were performed by “intention‐to‐treat” protocol.

Results: Both groups showed significant reduction in BoP, PPD and in mean total counts of the 40 bacterial species between baseline and 3 years, while plaque score and RAL remained almost unchanged. No significant differences between the two prevention programmes were found for any of the clinical outcome variables or in mean counts of the various bacterial species.

Conclusions: The study failed to demonstrate superior clinical and microbiological effects of powered toothbrush+triclosan dentifrice compared with manual toothbrush+standard fluoride‐dentifrice in periodontitis‐susceptible patients on regular maintenance therapy.
The distribution of Epichloe typhina in natural plant populations of the host plant Calamagrostis purpurea
Authors: Wennstróm Anders
Published: August 2010

The distribution of the systemic fungus Epichloe tvphina was studied in natural populations of the host grass Calamagrostis purpurea By searching for stroma in field and dissecting and staining plant parts in the lab I found that E typhina was only present in nutrient rich and more wet habitats and totally absent from nutrient poor areas A greenhouse experiment showed that under high nutrient conditions infected plants produced significantly more shoots than did healthy plants, while no difference was found when plants were grown m low nutrient conditions Thus, the results suggest that the occurrence as well as the effect of E typhina is strongly affected by environmental factors similar to the case of other systemic diseases, such as rusts and smuts
Ecological implications of a latitudinal gradient in inter‐annual climatic variability: a test using fractal and chaos theories
Authors: Ferguson Steven H. , Messier François
Published: August 2010

Although measures of seasonality are common, ecologists have seldom measured inter‐annual variation or tested for the presence of a latitudinal gradient Yet, species diversity and range size may be influenced by latitudinal gradients in climatic variability Fractal and chaos theories offer new techniques to measure climatic unpredictability by analyzing the dynamics of nonlinear time‐series data We analyzed data on the number of freezing degree‐days and date of first permanent ice from 12 weather stations (43–83°N) in Canada to describe latitudinal gradients in the timing of seasonal events Time‐series (ca 30 yr) of climatic variables were found to be nonlinear dynamic systems that were neither stochastic nor cyclic The analyses reveal a latitudinal gradient m system memory length, with high latitude locations displaying shorter memory length (R/S fractal analysis and Lyapunov exponent) This latitudinal gradient is also characterized by more random and irregular fractal patterns (Hurst exponent) associated with higher latitudes Both of these patterns may be due to the simpler climatic systems in high latitudes as indicated by fewer dynamic variables (lower correlation dimension) Application of fractal and chaos theories show that the timing of seasonal events (i e inter‐annual variation) comprises a chaotic‐dynamic system of comparatively low dimension
Variation in physical, chemical and biological components in the subantarctic lakes of South Georgia
Authors: Hansson L.‐A. , Dartnall H. J. G. , Ellis‐Evans J. C. , MacAlister H. , Tranvik L. J.
Published: August 2010

Physical, chemical and biological variables were quantified in 19 subantarctic lakes (South Georgia) as a prelude to comparing these pristine systems with temperate lakes and to improve the knowledge of spatial and temporal variation in water chemistry and abundances of organisms Lakes close to the sea had higher phosphorus concentrations, contained higher abundances of most organisms, and had higher number of invertebrate species than lakes situated further from the sea. Differences were attributed to higher nutrient input from marine organisms, such as penguins seals and petrels and probably also to a somewhat longer ice‐free period Since the lakes of South Georgia lack fish, the pelagic invertebrate fauna is dominated by herbivorous macrozooplankton Rotifers are rare in the open water and are restricted to the vegetation (mainly mosses) in shallow areas and to the sediment surface Generally, the algal abundance at the sediment surface is high in subantarctic lakes, indicating that the main part of the primary production is provided by benthic algae, which is in contrast to what is normally the case in temperate waters
Estimation of the primary productivity of Spartina alterniflora using a canopy model
Authors: Dai Ting , Wiegert Richard G.
Published: August 2010

A comprehensive canopy productivity model was built to study the productivity of a primary salt marsh grass, Spartina alterniflora. in Georgia, USA The canopy model was unique in employing plant demographic data to reconstruct canopy profiles and dynamics, which showed many growth processes that are otherwise difficult to discern in the field By linking canopy dynamics and leaf photosynthesis, the net total primary productivity of S alterniflora m a Georgia salt marsh was estimated to be 1421, 749, and 1441 g C m‐2 yr‐1 for the tall, short, and N‐fertilized short populations respectively These estimates are reasonable in terms of the physiological capacity of S alterniflora and well below the range of 3000–4200 g C m‐2 yr‐1 as reported by some recent harvest studies Our detailed analysis suggested the net total productivity of S alterniflora might be greatly overestimated in the past This is mainly because of 1) failure to consider the translocation of photosynthate between aboveground and belowground parts, and 2) possible overestimates of belowground production We estimated the net belowground production to be 872, 397, and 762 g C m‐2 yr‐1 for the tall, short, and N‐fertilized populations respectively

After receiving nitrogen fertilizer, the net leaf carbon fixation in the short population increased from 1489 to 2487 g C m‐2 yr‐1, and our simulation showed the contribution of elevated leaf N to this increase was small, 21%, compared with that of increased leaf area, 79% Both tall and short populations allocated ca 48‐49% of their annual gross leaf carbon fixation to belowground structures Nitrogen enrichment caused more allocation to aboveground parts in the short population, mainly for increasing leaf area The canopy model assumed that there was no leaf photosynthesis under tidal submergence, but if this assumption was relaxed, then leaf carbon fixation might increase 7–13% for different S alterniflora populations

Although this research focused only on a salt marsh species, our general approaches, especially the coupling of leaf physiology with the reconstructed canopies, should be applicable to the study of production processes of many other plant populations
Dynamics of voles and small mustelids in the taiga landscape of northern Fennoscandia in relation to habitat quality
Authors: Oksanen Tarja , Henttonen Heikka
Published: August 2010

In the forests of northern Fennoscandia during the 1980's, the dynamics of microtine rodents changed from multiannual high amplitude fluctuations (cycles) to, depending on species, fluctuations with a strong seasonal component or fluctuations with smaller amplitude and lower frequency Microtine and predator data from the Pallasjarvi area, Finnish Lapland, suggest that this transition took place at different rates in different parts of the taiga landscape Generally, densities m forest habitats have been primarily seasonal since 1985‐86 In mesic spruce taiga and m drier forest habitats microtmes had a prolonged peak in 1981‐83 and a crash in 1984–85 At the timberline, however microtme populations dropped from peak to low densities already in 1982‐83 but the final crash did not occur until spring 1985 The synchronous decrease in microtmes densities m all habitat types in 1984‐85 coincided with increase in weasel activity Activity of other carnivores was consistently high in mesic lowland habitats The data support following three conjectures 1) Periodic abundance of least weasels is crucial for sustained vole cycles 2) Predominance of stoats and other generalist predators lead to less regular fluctuations with a strong seasonal component where density declines occur in autumn and early winter 3) In barren tundra areas, the vegetation cannot sustain high densities of microtmes and, consequently, predation is not a necessary condition for population crashes
Ambient ultraviolet‐B radiation reduces hatchling size in the common frog Rana temporaria
Authors: Pahkala Maarit , Laurila Anssi , Merilä Juha
Published: August 2010

Effects of ambient UV‐B radiation and pH on hatchability and early development of Rana temporaria embryos were studied in field experiments conducted at two sites in Sweden. In neither of the populations did we find clear evidence for reduced hatchability or increased frequency of developmental anomalies of embryos exposed to ambient UV‐B levels. However, in both populations hatchling size was significantly larger UV‐B blocked as compared to control treatments, suggesting that ambient UV‐B levels had a negative effect on early growth of embryos. This result is consistent with the hypothesis that the cellular UV‐B damage repair mechanisms are costly and trades‐off against early growth. Alternatively, UV‐B induced photoproducts inhibiting DNA‐transcription and thereby protein synthesis may directly reduce growth rate. Although low pH (5.0) had negative effects on hatchability and early embryonic growth, there was no evidence for synergistic effects of pH and UV‐B on hatchability, frequency of developmental anomalies or early growth. The results suggest that increased levels of UV‐B radiation may cause fitness loss in natural populations of the common frog.
Responses of alpine shrubs to simulated environmental change during three years in the mid‐latitude mountain, northern Japan
Authors: Suzuki Shizuo , Kudo Gaku
Published: August 2010

Effects of artificial warming on phenology, individual leaf traits, vegetative growth, and reproduction of five alpine species (two deciduous and three evergreen shrubs) were investigated during three years in the mid‐latitude alpine, northern Japan. Eleven open‐top chambers (OTCs) were set up on a fellfield (1680 m a. s. l.) in the Taisetsu Mountains by which air temperature at plant height was increased by ca 2°C. Vaccinium uliginosum (deciduous shrub) showed earlier leaf emergence in every season and earlier flowering only in the first season in the OTCs. By contrast, acceleration of leaf emergence in the OTCs was not clear for other species, i.e. Arctous alpinus (deciduous shrub). Ledum palustre. V. vitis‐idaea, and Empetrum nigrum (evergreen shrub). Both deciduous species showed longer leaf life‐span in the OTCs every season. All evergreen species had higher leaf survival rates in the OTCs. indicating extension of leaf life‐span. Leaf nitrogen concentration and leaf mass per unit leaf area (mg cm −2) generally tended to decrease in the OTCs. Relationships between the individual leaf traits and cumulative air temperature during the leaf developing period were not clear. Total leaf production during the three seasons increased in the OTCs in A. alpinus. L. palustre. V. vitis‐idaea, and E. nigrum. All evergreen shrubs showed larger shoot growth in the OTCs but both deciduous shrubs did not show significant changes. In contrast to the vegetative growth, deciduous shrubs produced more flowers in the OTCs. Fruit production was not influenced by the OTCs for all species. The extension of photosynthetic period in the OTCs may contribute to the larger vegetative growth or flower production.
Flexibility, efficiency, and accountability: adapting reserve selection algorithms to more complex conservation problems
Authors: Rodrigues Ana S. , Orestes Cerdeira J. , Gaston Kevin J.
Published: August 2010

Flexibility, efficiency and accountability are considered key attributes of good reserve selection methods. Flexibility, the ability to incorporate all the diversity of considerations, concerns and information that typically impinge on real conservation problems, is fundamental if the particulars of any given situation are to be addressed and land use conflicts are to be effectively resolved. High efficiency, the representation of the maximum diversity of the relevant features (e.g. species) at the minimum cost, is important because reserves will commonly be in direct competition with other forms of land use. Accountability means that the solutions are obtained in a transparent way. allowing others to understand why and how the result was arrived at. Because of the robustness of the general integer linear model, a remarkably rich variety of problems concerning the management and efficient use of scarce resources can be represented as problems of this type. This study starts by analysing a simple representation problem and then develops more general problems that can be applied to a variety of conservation planning exercises. It is illustrated how high flexibility can be attained, while simultaneously addressing efficiency and accountability, by modelling reserve selection questions as integer linear problems.
Modified dispersal‐related traits in disjunct populations of bird‐dispersed Frangula alnus (Rhamnaceae): a result of its Quaternary distribution shifts?
Authors: Hampe Arndt , Bairlein Franz
Published: August 2010

Many European tree species survived Pleistocene glaciations in Mediterranean refugia and rapidly recolonized temperate Europe afterwards. Inter‐ and postglacial migration processes are assumed to have catalized evolutionary optimizations of dispersal‐related traits, but up to now empirical evidence is lacking in vertebrate‐dispersed plants. We investigated if south Iberian glacial relict and central European “colonizer” populations of the bird‐dispersed treeFrangula alnushave experienced differentiations of dispersal‐related traits which increase the mobility of northern populations. A comparison of lifetime reproductive strategy, disperser guilds, ripening phenology, and fruit design revealed considerable differences. Compared to south Iberian conspecifics, central European plants were considerably smaller and experienced a highly accelerated generation turnover. In south Iberian populations seed dispersal was carried out almost completely by resident birds which occurred in constant abundances throughout the ripening season. In contrast, central European seeds were dispersed by migrants whose abundances changed considerably during the ripening season. Several bird species were involved in both study areas but rendered different importance for seed dispersal. The fruit ripening pattern was highly asynchronous throughout the ripening season in south Iberia, while central European trees showed a complex ripening sequence which resulted in a significant correlation between fruit abundance and changing disperser availability. Central European fruits were smaller and showed a considerably smaller seed load than south Iberian fruits, thus presumably being more attractive for their small‐sized main dispersers (Sylvia warblers). Chemical analyses revealed significant differences in contents of water, glucose, fructose, proteins, ash. and phenolic compounds. The extensive differentiation of dispersal‐related traits inF. alnussuggests that even weak selective pressures by frugivores may induce evolutionary adjustments of dispersal traits over large time scales. We suggest that the differences we observe today evolved during the species' distribution shifts in the Quaternary.
Scale of habitat connectivity and colonization in fragmented nuthatch populations
Authors: van Langevelde Frank
Published: August 2010

Studies of effects of landscape pattern on population dynamics should consider the spatial scale at which habitat connectivity varies relative to the spatial scale of the species' behavioral response. In this paper, I investigate the relationship between the degree of connectivity of wooded patches measured at different spatial scales and the colonization of these patches by nuthatch Sitta europaea populations. I used different threshold distances to calculate the degree of habitat connectivity. A threshold distance is the distance beyond which the probability of successfully bridging the distance by dispersing individuals is assumed to decrease rapidly. The sum of the degree of connectivity over all patches in a region provides a measure for the overall degree of connectivity. Based on this measure, I could first give an indication under what conditions species may experience effects of constrained dispersal in that region. Second, the degree of connectivity of the individual patches was related with the observed colonizations of these patches. The degree of habitat connectivity measured for threshold distances of ea 2.4‐3 km best explains the colonization probability of unoccupied patches. These threshold distances give an indication of the distances covered by dispersing nuthatches that led to successful colonizations.
Browsing in a heterogeneons savanna
Authors: Skarpe C. , Bergström R. , Bråten A. L. , Danell K.
Published: August 2010

Large herbivores generally depend on and interact with a food resource that is heterogeneous at different spatial scales. Plants allocate resources to rapid growth or to defence mechanisms depending on the availability of resources relative to loss of resources from herbivory. Herbivores select food and feeding habitats in order to maximize intake rate of nutrients and digestible energy, while avoiding chemical and structural deterrents. To optimize foraging, herbivores select habitats and food items in a hierarchical way, and different attracting and deterring factors may govern selection at different scales. We studied the impact of twig biting by a guild of indigenous browsers in three vegetation types in a semi‐arid savanna in Botswana. The heaviest browsing pressure was in the vegetation type richest in preferred plant species, although that type was also richest in defended species. There were large differences in relative utilization between plant species, and ranking of species was roughly similar in the different vegetation types. Browsing pressure varied between species from almost 0‐30%. Overall, spinescent trees were less browsed than non‐spinescent ones, and evergreen species were less browsed than deciduous ones. In two of the three vegetation types there was a negative correlation between browsing pressure on a species and its frequency. There was a high incidence of rebrowsing, and once a tree had been browsed, the probability that it would be browsed again increased. The results largely agree with predictions based on the resource availability hypothesis, the scarcity accessibility hypothesis and recent theories on the significance of plant defences and on plant's response to browsing and the subsequent response by herbivores on the plant's responses.
Functional significance of emergence timing in bats
Authors: Duvergé P. Laurent , Jones Gareth , Rydell Jens , Ransome Roger D.
Published: August 2010

We investigated intraspecific differences in evening emergence time of northern bats Eptesicus nilssonii, greater horseshoe bats Rhinolophus ferrumequinum and lesser horseshoe bats R. hipposideros. Significant differences in emergence time were associated with presumed variation in predation risk, related to light intensity, and energetic benefits of early emergence, caused by differences in age, reproductive state (energetic demands), and body condition. Females of both species emerged progressively later as pregnancy advanced, perhaps because of decreased flight performance, and earlier as lactation proceeded, probably because of increased energy demands and low reserves. Bats under energetic stress, due to persistent low ambient temperatures during pregnancy, or when body reserves were low, emerged relatively early, and hence appeared to take higher risks, than other bats. Young bats emerged much later than the adults at first, but progressively earlier as their flight skills improved. Lesser horseshoe bats emerged later at exposed roost exits than in more protected situations. The results largely corroborate the hypothesis that emergence time, and therefore feeding performance, of insectivorous bats is constrained at bright light conditions, possibly by predation risk (from birds), and modified by energetic considerations.
Relationships between body size and geographical range size among Australian mammals: has human impact distorted macroecological patterns?
Authors: Murray Brad R. , Dickman Chris R.
Published: August 2010

Extinction and artificial reduction in the size of geographical ranges of many species have occurred extensively across the globe because of human activities. In particular, Australian mammals have suffered heavily in the last two hundred years, with the highest number of reported cases of mammal extinctions anywhere. In the present study, we investigated the extent to which human impact has affected contemporary macroecological patterns in Australian terrestrial mammals. After examining patterns relating to body size and range size among the contemporary mammal fauna, we removed the effects of the last two hundred years of human impact by exploring patterns in the pre‐European assemblage. This permitted us to determine whether contemporary macroecological patterns are distortions of pre‐European patterns. In contrast to the expected pattern of a significant positive relationship between body size and range size, our results showed no significant association for the complete fauna in both cross‐species and phylogenetic analyses, even when data were corrected for species extinctions and range reductions. Analyses within families and among species with the same dietary strategy revealed three significant positive relationships (Macropodidae, Peramelidae, and herbivores) and one significant negative relationship (insectivores) within the contemporary assemblage that disappeared when the pre‐European assemblage was analysed. A positive relationship also emerged in the pre‐European assemblage for the Vombatidae that was not apparent in the contemporary fauna. Thus, correcting for human impact revealed important distortions among contemporary macroecological relationships that have been brought about by human‐induced range reduction and extinction. These findings not only provide further evidence that the Australian continent presents a unique and valuable opportunity with which to test the generality of macroecological patterns, but they also have important ramifications for the analysis and interpretation of contemporary macroecological datasets.
Red‐shifts and red herrings in geographical ecology
Authors: Lennon Jack J.
Published: August 2010

I draw attention to the need for ecologists to take spatial structure into account more seriously in hypothesis testing. If spatial autocorrelation is ignored, as it usually is, then analyses of ecological patterns in terms of environmental factors can produce very misleading results. This is demonstrated using synthetic but realistic spatial patterns with known spatial properties which are subjected to classical correlation and multiple regression analyses. Correlation between an autocorrelated response variable and each of a set of explanatory variables is strongly biased in favour of those explanatory variables that are highly autocorrelated ‐ the expected magnitude of the correlation coefficient increases with autocorrelation even if the spatial patterns are completely independent. Similarly, multiple regression analysis finds highly autocorrelated explanatory variables “significant” much more frequently than it should. The chances of mistakenly identifying a “significant” slope across an autocorrelated pattern is very high if classical regression is used. Consequently, under these circumstances strongly autocorrelated environmental factors reported in the literature as associated with ecological patterns may not actually be significant. It is likely that these factors wrongly described as important constitute a red‐shifted subset of the set of potential explanations, and that more spatially discontinuous factors (those with bluer spectra) are actually relatively more important than their present status suggests. There is much that ecologists can do to improve on this situation. I discuss various approaches to the problem of spatial autocorrelation from the literature and present a randomisation test for the association of two spatial patterns which has advantages over currently available methods.
Are macroinvertebrate communities influenced by seagrass structural complexity?
Authors: Attrill Martin J. , Strong James A. , Rowden Ashley A.
Published: August 2010

A study was undertaken within a sub‐tidal Zostera marina seagrass bed (Devon, U.K.), with the aim of elucidating the relationship between seagrass structural complexity and the size and composition of the associated macroinvertebrate community. Samples of macroinvertebrates were recovered from three designated areas of shoot density. Various physical characteristics were measured for individual plants, and an a priori complexity index was determined relevant to the associated target organisms. Resulting data were analysed using linear regression and multivariate techniques. Significant relationships were found between shoot density and number of leaves/shoot, leaf length, stem length and algal epiphyte biomass. Neither the number of species nor abundance of macroinvertebrates was significantly related with the derived complexity index. Multivariate analysis indicated that macroinvertebrate communities from the three areas of shoot density were significantly different, the pattern of macroinvertebrate community composition being best explained by sea‐grass biomass. Linear regression of seagrass biomass with macroinvertebrate number of species and abundance revealed significant positive relationships. Regression also indicated that there was no significant increase in complexity with increasing seagrass biomass. The results suggest that within a seagrass bed the size and composition of the associated macroinvertebrate community is not determined by the structural complexity of the plants, but by the amount of plant available. This finding indicates a simple species‐area relationship, and arguably one brought about as a result of a sampling artefact. Thus, the current paradigm that structural complexity of seagrass is responsible for increased species diversity, can only be justifiably applied to comparisons between seagrass and other habitats, and not within a seagrass bed itself.
Body size and host range in European Heteroptera
Authors: Brändle Martin , Stadler Jutta , Brandl Roland
Published: August 2010

We used data on body size and host range of phytophagous Heteroptera in central Europe, an inverse measure of specialisation, to analyse the relationship of body size vs specialisation: 1) we found a clear positive relationship between body size and host range using species as independent data points. 2) However, a nested analysis of variance shows that most of the variance in body size occurred at higher taxonomic levels whereas most of the variance in host specialisation occurred between species. This suggests different phylogenetic inertia of body size and specialisation. Nevertheless, using means of different higher taxonomic levels there is still a significant positive correlation between body size and host range. 3) With more sophisticated methods of correcting for the phylogenetic relatedness between species, the positive correlation between body size and host range still holds, despite the different assumptions of each method. Thus, the relationship between body size and host range is a very robust pattern in true bugs.
Effect of nest and nest site characteristics on the risk of cuckooCuculus canorusparasitism in the great reed warblerAcrocephalus arundinaceus
Authors: Moskát Csaba , Honza Marcel
Published: August 2010

The risk of cuckooCuculus canorusparasitism for great reed warblerAcrocephalus arundinaceusnests was evaluated in respect to nest and nest site structure in the reedbeds along canals in central Hungary, In total 90 nests were analysed, from which 31 remained unparasitised. 37 were single parasitised and 22 multiple parasitised. Multiple discriminant analysis, based on eight structural variables, separated well the unparasitised clutches from the cases of single and multiple parasitism, but the latter two categories also showed a weaker separation. Nests close to cuckoo vantage points are most vulnerable to parasitism. The variable “distance from nest to closest available cuckoo perch site” (tree or electric wire) played the most important role in the risk of parasitism. It showed highly significant differences among the groups: lowest distances were found in the case of multiple parasitism, and the highest distances were measured when nests remained unparasitised. Additionally, “nest visibility” also showed significant differences among the three groups: a more visible nest is more likely to be parasitised. Risk of parasitism affects on the host on two levels: 1) female cuckoos search for nest‐building hosts from a perch site, but 2) when they are in the act of parasitism, they can find more visible nests in the reed. Besides the robust effects of the variables “distance to cuckoo perch site” and “nest visibility”, the variable “distance from nest to open water” may reduce, but “nest volume” increases the risk of multiple parasitism. Differences between cases of single and multiple parasitism are weak, mainly affected by chance. We explain it by the high abundance of the cuckoo, the parasitism rate was 65.6% (59/90), Cuckoos parasitised almost all of the available nests in the close vicinity of potential perch sites. There was no evidence that great reed warblers nested closer to each other when risk of parasitism was high.
Recolonization of breeding waterfowl communities by the whooper swan: vacant niches available
Authors: Pöysä Hannu , Sorjonen Jorma
Published: August 2010

Breeding population of the whooper swan Cygnus cygnus has increased dramatically in Finland during the last 50 yr, from ca 15 to 1500 pairs. We studied if the recent recolonization by the whooper swan into waterfowl communities in Finland has had negative effects on Anas species belonging to the same foraging guild. Using data of foraging behaviour and ecomorphology of the whooper swan and Anas species, we studied the position of the former in the dabbling guild. We used long‐term duck census data from different parts of Finland to study changes in breeding numbers of Anas species in lakes that have been recently colonized by the whooper swan and in control lakes that have not been colonized. Overall, foraging and ecomorphological similarity between the whooper swan and the other species decreased in the following order: pintail A. acuta (most similar), mallard A. platyrhynchos, shoveler A. clypeata, garganey A. querquedula. wigeon A. penelope. teal A. crecca (least similar). We did not find evidence of adverse impact by the whooper swan colonization on population densities of the other species. Neither did we find any indication that species relatively more similar with the whooper swan in terms of foraging ecology would show relatively more negative response to the whooper swan colonization. Our results suggest that whooper swans have occupied vacant niche space when colonizing boreal waterfowl communities.
A comparison of fine‐scale distribution patterns of four plant groups in an Amazonian rainforest
Authors: Vormisto J. , Phillips O. L. , Ruokolainen K. , Tuomisto H. , Vásquez R.
Published: August 2010

We carried out a comparison among the floristic patterns of four different plant groups (palms, trees, melastomes and pteridophytes) in a lowland rainforest site in Peruvian Amazonia. The study site consisted of a mosaic of edaphic patches reflecting the different geological formations that can be found on the surface. We collected the data along a linear transect (500 m long, divided into 20 × 20 m or 5 × 20 m subplots), and recorded of the four plant groups all individuals that exceeded a minimum size limit predefined for each plant group. We also recorded the drainage conditions and soil type classes in each subplot of the transect. The results indicated that different plant groups can produce similar floristic patterns in local spatial scales, and that these patterns reflect similarities in edaphic conditions. All matrix correlations calculated between pairs of the four plant groups were positive and statistically significant. Floristic composition in all plant groups correlated with soil class, and to a somewhat lesser degree with drainage. These results imply that any one of the four plant groups could serve as a rough indicator of more general floristic patterns, and that even the inventory of a limited part of the flora can shed light on the floristic variation found in Amazonian forests.
Endophytic fungi in wild and cultivated grasses in Finland
Authors: Saikkonen K. , Ahlholm J. , Helander M. , Lehtimäki S. , Niemeläinen O.
Published: August 2010

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species‐specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris. Festuca arundinacea. F. ovina. F. Pratensis. F. rubra and Phleum pratense (67%, 98%, 29%., 42%. 32% and 33%, respectively). Mean incidences were < 20% in Dactylis glomerata. Deschampsia flexuosa. D. cespitosa and Elymus repens. and no infections were detected in Calamagrostis lapponica. C. epigejos. Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte‐free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected eonspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. Pratensis and Lolium perenne. and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte‐free.
Local and regional species richness in communities of surface‐dwelling grassland Collembola: indication of species saturation
Authors: Winkler Henrike , Kampichler Christian
Published: August 2010

The relationship of local (LSR) versus regional species richness (RSR) provides an insight into patterns of species diversity. We examined communities of surface‐dwelling Collembola in ten differently sized, temperate dry grasslands. To register genuine manifestations of saturation or proportional sampling, accurate determination of species pools is essential. Therefore. we applied the first‐order jackknife as a species‐richness estimator for LSR and introduce here a method for defining a range within which the real RSR probably lies. Our data exhibited similar levels of local Collembolan species richness across all regions, largely independent of regional richness. This curvilinear relationship between LSR and RSR indicates that a limit is present for the number of species that can locally coexist, suggesting local interactions and community saturation. We discuss several conditions that may cause pseudo‐proportionality or pseudosaturation, i.e. artificial relationships between LSR and RSR, Furthermore, we test the LSR‐RSR relationship for possible effects of autocorrelation.
Genet age in marginal populations of two clonal Carex species in the Siberian Arctic
Authors: Jónsdóttir Ingibjörg S. , Augner Magnus , Fagerström Torbjön , Persson Helena , Stenström Anna
Published: August 2010

During a Swedish‐Russian expedition to northern Siberia 1994, we sampled two marginal populations of two Carex species at two high arctic sites (C, stans Drej. on Faddeyevsky Island and C. ensifolia V. Krecz ssp. arctisibirica Jurtz. at north‐eastern Taymyr Peninsula), both north of previously documented localities in that areas for the two species. These populations were composed of a few distinct patches of ramet colonies, some of them shaped like fairy rings with dead centres. We measured the size of all colonies and collected samples for detailed morphometric analyses of rhizome growth. By using RAPD (random amplified polymorphic DNA) analysis we established that the largest colony at each site consisted of a single genet, based on 41 polymorphic bands amplified with three primers. Pooled samples from each of two additional colonies of C. stans on Faddeyevsky Island were analysed and showed that clones of the same species at the same site were relatively dissimilar (Dice's similarity index 0.26 0,43), We then assumed that each ramet colony represented a single genet. Based on the morphometric data, we developed a deterministic growth model that simulates the clonal growth of these species and enabled estimates of the time since establishment of the genets. The estimated age of the five C. Stans clones varied from 17 to 154 yr and the age of the two C. ensifolia ssp, arctisibirica clones was well over 3000 yr.
Diversity and structure of turtle assemblages: associations with wetland characters across a floodplain landscape
Authors: Bodie J. Russell , Semlitsch Raymond D. , Renken Rochelle B.
Published: August 2010

We studied 24 wetlands along a 296‐km portion of the lower Missouri River floodplain, USA during 1996–1998. Our goal was to examine relationships between wetland characters and freshwater turtle diversity. We collected data on a total of 2201 individual captures of six freshwater turtle species. Ten species variables (richness, evenness, proportion of lentic species combined, proportion of lotic species combined, and proportions of six individual species) described the turtle assemblage structure and were associated with six broad wetland categories (remnant oxbow, remnant slough, connected scour, isolated scour, temporary farmed, and temporary not farmed) as well as with six abiotic (water depth, distance from the river, duration dry, duration flooded, size, and turbidity) and two biotic (primary and secondary productivity) wetland characters. Repeated‐measures MANOVA and ANOVA revealed highest diversity in remnant sloughs and oxbows as well as in newly created scour wetlands and lowest diversity in temporary wetlands. Multiple regressions and correlations indicated that the single most important wetland characteristic for high turtle diversity was a low annual duration of drying. Oxbows supported the highest proportions of lentic turtles; while connected scours supported the highest proportions of lentic turtles. Lentic species proportions were highest in wetlands that were frequently flooded, relatively distant from the Missouri River, and insect rich, while lotic species proportions were highest in wetlands that were turbid, close to the river, and relatively insect poor. The cohabitation patterns of several turtle species suggest that direct or indirect interactions between species may affect assemblage structure. Based on our broad array of wetlands, we identified crucial wetland types and characteristics that were associated with maximum diversity for freshwater turtles. Empirical studies similar to ours across broad landscapes are needed for a variety of wetland floral and faunal groups before sound conservation and management recommendations can be formulated.
Plasticity in age and size at metamorphosis inRana temporaria‐ comparison of high and low latitude populations
Authors: Merilä Juha , Laurila Anssi , Laugen Ane Timenes , Räsänen Katja , Pahkala Maarit
Published: August 2010

Effects of different combinations of stressors (viz. temperature, food level) on growth, developmental and survival ratesof Rana temporariatadpoles from two geographically widely (∼ 1500 km) separated populations were studied in a common garden experiment. In both populations, low temperature and low food level lead to towered growth rates and delayed metamorphosis, whereas high temperature and high food level had the opposite effect. Tadpoles from north metamorphosed earlier and exhibited higher growth rates than tadpoles from south, suggesting local adaptation to shorter growth period and cooler ambient temperature in north. Size at metamorphosis did not differ between the two populations, but when the differences in metamorphic age were accounted for, then the tadpoles from north were larger than those from south. These results suggest considerable adaptive genetic differentiation in growth rates, size and timing of metamorphosis between northern and southernR. temporariapopulations. In both populations, high food levels tended to reduce tadpole survival rates and there was a negative correlation between growth and survival rates across different treatments in both populations. In general, tadpoles from north experienced high mortality rates in high food level ‐ low temperature treatments, whereas southern tadpoles experienced high mortality in high food level‐high temperature treatments. This suggest that there may be genetic differences among different populations as how they would be influenced by high nutrient loads, such as brought along for example by fertilization of forest or agricultural soils.
Diversity of butterflies in the agricultural landscape: the role of farming system and landscape heterogeneity
Authors: Weibull Ann‐Christin , Bengtsson Jan , Nohlgren Eva
Published: August 2010

To examine the importance of management practices and landscape structure on diversity of butterflies 16 farms with organic or conventional management were censused during 1997 and 1998. On each farm a transect route was walked during July and the beginning of August, six times in 1997 and five times in 1998. The farms were located in the central part of Sweden in two adjacent regions with the same pool of species. The organic and conventional farms were paired with help of the Bray‐Curtis dissimilarity index according to land use to control for landscape structure on the farm level.

On each farm calculations were made of large‐ and small‐scale landscape heterogeneity with the help of GIS. A grid with a mesh size of 400 m was placed over each farm and the small‐scale heterogeneity was calculated as the mean habitat diversity of four squares. The large‐scale landscape heterogeneity described the landscape in which the farms were imbedded, and covered an area of 5x5 km.

No differences in butterfly diversity, number of species or number of observations were noted between organic and conventional farms. Butterfly diversity was positively correlated with small‐scale landscape heterogeneity while butterfly abundance was positively correlated with large‐scale heterogeneity. Both large‐scale and small‐scale heterogeneity were important for the composition of species. The landscape structure seemed to be more important for butterfly diversity and species composition than the farming system in itself.
Spatial dynamics in a metapopulation network: recovery of a rare grasshopper Stauvoderus scalaris from population refuges
Authors: Carlsson Allan , Kindvall Oskar
Published: August 2010

A characteristic feature of the spatial distribution of many species is patchiness. This spatial patchiness may be generated by very different processes, e.g. fragmentation, succession and extinction‐colonisation dynamics. In this study, we apply a spatial realistic metapopulation model to analyse the occupancy pattern of a rare and endangered grasshopper, Stauroderus scalaris. found in an extensive network of 158 patches. When the study was initiated in 1985 the regional occupancy was 9.3% declining down to 7.1% in 1989. Then there was a spatial expansion of the population and in 1993 as many as 27.3% of the patches were occupied and 32.9% in 1995. During this expansion phase, the dynamics obeyed metapopulation principles: large patches and less isolated ones were more likely to be colonised. In the beginning, local extinction risks were negatively related to patch size and positively influenced by isolation. However, later on neither area nor isolation affected extinction probabilities. Altogether, 20 extinctions and 56 colonisations were observed. The shift in regional occupancy, with a growth of ca 20%, coincides with perturbations to the patch network and the warmest summer in 140 yr. Our results suggest that S. scalaris persists on a dynamic habitat mosaic, where refuges are crucial during adverse periods, and stochastic environmental factors (disturbances and climate), that are correlated over large areas, are generating population dynamic patterns that are hard to predict using current modelling techniques.
Biogeography of the golden‐striped salamander Chioglossa lusitanica: a field survey and spatial modelling approach
Authors: Teixeira J. , Ferrand N. , Arntzen J. W.
Published: August 2010

Chioglossa lusitanica is A streamside salamander endemic to the northwestern corner of the Iberian Peninsula. In an extensive Held survey we found the species to be widely distributed across northwestern Portugal. The distribution data were used to identify macroenvironmental parameters related to the presence of the species in Portugal, and to produce a descriptive distribution model for C. lusitanica. We modelled the species distribution based on five environmental parameters (precipitation, relief, July temperature, number of frost months and hardness of water) selected by logistic regression analysis. The model yielded a high score of correct classification (95%). Excluding parameters unavailable for Spain the model included four parameters (precipitation, relief, July temperature and altitude) and had a 93% correct classification score. Extrapolation of the model to Spain yielded a correct classification of 92% and served as a validation of the modelling technique in an independent area. The models indicate the existence of several potentially suitable areas outside the known distribution of the species, providing clues about the species historical biogeography. The models, through the identification of highly suitable and stable protection regions, may contribute to informed conservation planning.