bluuebunny/crossref_metadata_2025_split huggingface dataset:
Revisiting Bergmann's rule for saguaros (Carnegiea gigantea (Engelm.) Britt. and Rose): stem diameter patterns over space
Authors: Drezner Taly Dawn 
Published: June 2010

AbstractAim The influence of winter temperatures and other climate variables are explored to determine which variables are associated with saguaro stem diameter and to determine if Bergmann's rule is applicable to saguaros.Location The northern Sonoran Desert in Arizona, USA.Methods Thirty saguaro populations were sampled (height, diameter, number of branches), and after adjustment for population height structure, mean relative thickness of saguaros was calculated for each plot (population). Fifty‐seven climate variables were calculated for the thirty populations. Regression was run to determine which variables (cold winter, hot summer and precipitation) best predict relative thickness. Previous studies have demonstrated a significant positive relationship between winter precipitation and saguaro branching (Drezner, 2003, Ecography, in press). To determine if relative thickness may be an artefact of branching (branches), partial correlation analysis was employed.Results Mean March precipitation best predicts relative thickness. When only winter temperature variables are considered, none are significantly related to relative thickness. Relative thickness is not an artefact of branches.Main conclusions  (1) Rainfall, not temperature, best predicts saguaro stem thickness. In addition, despite the focus on summer rains in the literature, winter precipitation is the best predictor of thickness. (2) Bergmann's rule is not applicable to saguaro populations as has been previously suggested [e.g. Niering et al. (1963)Science142, 15], as thickness does not increase significantly with latitude. In addition, the suggested mechanism for Bergmann's rule, cold winter temperature, does not significantly predict saguaro stem diameters over the area studied. In some populations that experience high winter rainfall as well as cold temperatures, individuals likely derive thermal benefits from a larger stem diameter; however, the trend is not observed over the area studied and it does not appear to be adaptive.
Exotic plant species of the St Lawrence River wetlands: a spatial and historical analysis
Authors: Lavoie Claude , Jean Martin , Delisle Fanny , Létourneau Guy 
Published: June 2010

AbstractAim To evaluate the importance (number of species, plant cover) of the exotic flora in seven well‐defined sectors of one of the most important transportation waterways in North America. To determine the impact of exotic species on wetland plant diversity and reconstruct the spread of some invasive species.Location St Lawrence River, southern Québec.Methods The exotic flora (vascular plants) of wetlands bordering the St Lawrence River was studied using 713 sampling stations (25 m2) along a 560‐km long corridor.Results Exotic species represent 13.7% of the vascular flora of the St Lawrence wetlands. The relative plant cover occupied by exotic species is high in some of the fluvial sectors (42–44%), but low (6–10%) in the estuarine sectors. Wetlands (marshes) surrounding islands were particularly susceptible to invasion by exotic plants. Historical, abiotic and landscape factors may explain the differences observed between sites. Purple loosestrife (Lythrum salicariaL.) is the most common exotic species of the St Lawrence wetlands, but other species, namely flowering‐rush (Butomus umbellatusL.) and reed canary grass (Phalaris arundinaceaL.) are much more invasive. There is no linear relationship between the exotic species cover and the diversity of wetland plants; low diversity sites can be dominated by either exotic or native plant species. In the other sites, exotic species generally have little impact on plant communities and can contribute to increase diversity. Common reed (Phragmites australis(Cav.) Trin. ex Steudel) and reed canary grass, both considered as exotic species in this study, clearly have a stronger impact on plant diversity than flowering‐rush and purple loosestrife.Main conclusions This study shows that the global impact of an invader cannot be adequately evaluated with only a few highly invaded sites. While nationwide strategies have been developed to control exotic species, large surveys are essential to adapt them to regional particularities.
Real vs. artefactual absences in species distributions: tests for Oryzomys albigularis (Rodentia: Muridae) in Venezuela
Authors: Anderson Robert P. 
Published: June 2010

AbstractAim  Numerous geographical information system (GIS)‐based techniques for estimating a species’ potential geographical distribution now exist. While a species’ potential distribution is more extensive than its documented range, the lack of records from some suitable regions may simply derive from inadequate sampling there. Using occurrence records of both the study species and the more inclusive overall target group, I propose a progression of statistical models to evaluate apparent absences in species distributions.Location  Northern Venezuela.Methods  Employing data from the Smithsonian Venezuelan Project (a large set of standardized mammalian inventories undertaken across Venezuela), I tested distributional hypotheses for the sigmodontine rodent Oryzomys albigularis (Tomes, 1860). Those inventories collected O. albigularis in two of the five major montane regions of northern Venezuela (the Cordillera de Mérida/Macizo de El Tamá and Cordillera de la Costa Central). I used the Genetic Algorithm for Rule‐Set Prediction (GARP) to estimate the species’ potential distribution in northern Venezuela. Then, based on all collection localities from the Smithsonian Venezuelan Project, I determined the probability that the absence of O. albigularis from the three regions of potential presence where it was not documented (the Serranía de Perijá, Lara–Falcón highlands, and Cordillera de la Costa Oriental) could be the result of inadequate sampling.Results and main conclusions  All statistical models indicated that the sampling efforts of the Smithsonian Venezuelan Project were insufficient to demonstrate conclusively the absence of O. albigularis from any of the three regions lacking records. Indeed, a subsequent compilation of specimens from ten natural history museums confirmed its presence in the Serranía de Perijá and the Lara–Falcón highlands. Tests using empirical sampling effort and taking human modification of the landscape into account most closely fulfilled the assumptions required for the tests. By providing a framework for bringing additional quantitative rigour to studies of species distributions, these methods will probably prove of wide applicability to other systems.
Effects of forest fragmentation on European birds: implications of regional differences in species richness
Authors: Tellería José Luis , Baquero Rocío , Santos Tomás 
Published: June 2010

AbstractAim In this paper, we adopted a large‐scale approach to evaluate the effect of regional richness of forest birds on the number of bird species retained by forest fragments in several localities across Europe.Location We studied bird assemblages in fourteen forest archipelagos embedded in agricultural matrices from southern Norway to central Spain. Tree composition varied from oak and beech forests of the northern localities to oak and pine xerophitic woodlands of the southern ones. The number of fragments in each forest archipelago ranged from eighteen to 211.Methods We used the Gleason equation (s = a + z  log  A; wheresandAare, respectively, the species richness and size of forest fragments andzthe rate of species loss) to estimate the species richness for 1‐ and 15‐ha fragments in each archipelago. The regional richness of forest birds was estimated by modelling the geographical distribution of species richness in the European atlas of breeding birds.Results The latitudinal distribution of regional richness displayed a convex form, with the highest values being in central Europe. Along this gradient, the number of species retained by fragments and the rate of species loss was positively related to regional richness. In addition, the percentage of the regional pool of species sampled by fragments decreased in the southern localities.Main conclusions Relationships between regional richness of forest birds and richness in fragments seem to explain why fragments in central Europe shelter more species than their southern counterparts. The decreased ability of southern forest fragments to sample the regional richness of forest birds, could be explained as an effect of the low abundance of many species in the Mediterranean, which could depress their ability to prevent extinction in fragments by a rescue effect. Alternatively, high beta diversity in the Mediterranean could produce undersampling by fragments of the regional pool of species. These regional differences in the response of bird assemblages to forest fragmentation are used to discuss the usefulness of large‐scale, biogeographical approaches in the design of conservation guidelines.
Representation of tundra vegetation by pollen in lake sediments of northern Alaska
Authors: Wyatt Oswald W. , Anderson Patricia M. , Brubaker Linda B. , Hu Feng Sheng , Engstrom Daniel R. 
Published: June 2010

AbstractAim  To understand better the representation of arctic tundra vegetation by pollen data, we analysed pollen assemblages and pollen accumulation rates (PARs) in the surface sediments of lakes.Location  Modern sediment samples were collected from seventy‐eight lakes located in the Arctic Foothills and Arctic Coastal Plain regions of northern Alaska.Methods  For seventy of the lakes, we analysed pollen and spores in the upper 2 cm of the sediment and calculated the relative abundance of each taxon (pollen percentages). For eleven of the lakes, we used 210Pb analysis to determine sediment accumulation rates, and analysed pollen in the upper 10–15 cm of the sediment to estimate modern PARs. Using a detailed land‐cover map of northern Alaska, we assigned each study site to one of five tundra types: moist dwarf‐shrub tussock‐graminoid tundra (DST), moist graminoid prostrate‐shrub tundra (PST) (coastal and inland types), low‐shrub tundra (LST) and wet graminoid tundra (WGT).Results  Mapped pollen percentages and multivariate comparison of the pollen data using discriminant analysis show that pollen assemblages vary along the main north–south vegetational and climatic gradients. On the Arctic Coastal Plain where climate is cold and dry, graminoid‐dominated PST and WGT sites were characterized by high percentages of Cyperaceae and Poaceae pollen. In the Arctic Foothills where climate is warmer and wetter, shrub‐dominated DST, PST and LST were characterized by high percentages of Alnus and Betula pollen. Small‐scale variations in tundra vegetation related to edaphic variability are also represented by the pollen data. Discriminant analysis demonstrated that DST sites could be distinguished from foothills PST sites based on their higher percentages of Ericales and Rubus chamaemorus pollen, and coastal PST sites could be distinguished from WGT sites based on their higher percentages of Artemisia. PARs appear to reflect variations in overall vegetation cover, although the small number of samples limits our understanding of these patterns. For coastal sites, PARs were higher for PST than WGT, whereas in the Arctic Foothills, PARs were highest in LST, intermediate in DST, and lowest in PST.Main conclusion  Modern pollen data from northern Alaska reflect patterns of tundra vegetation related to both regional‐scale climatic gradients and landscape‐scale edaphic heterogeneity.
Modelling space use and dispersal of mammals in real landscapes: a tool for conservation
Authors: Macdonald David W. , Rushton Stephen 
Published: June 2010

AbstractAimTo explore the usefulness of Spatially Explicit Population Models (SEPMs), incorporating dispersal, as tools for animal conservation, as illustrated by the contrasting cases of four British mammals.MethodsFor each of the four species (American mink,Mustela vison,pine marten,Martes martes,dormouse,Muscardinus avellanariusand water vole,Arvicola terrestris) a spatial dynamics model was developed based on an integrated geographical information system (GIS) population model that linked space use to the incidence of the species. Each model had, first, a GIS, which stored environmental, habitat and animal population information, and secondly, an individual‐based population dynamics module, which simulated home range formation, individual life histories and dispersal within the GIS‐held landscape.ResultsThe four models illustrated different interactions between species life‐history variables and the landscape, particularly with respect to dispersal. As water voles and dormice occupy home ranges that are small relative to blocks of their habitat, they were most effectively modelled in terms of the dynamics of local populations within habitat blocks but linked by dispersal. In contrast, because the home ranges of American mink and pine marten are large relative to blocks of habitat, they were best modelled as individuals moving through a landscape of more or less useful patches of habitat. For the water vole, the most significant predictors of population size were the carrying capacity of each habitat and the annual number of litters. For the dormouse, the likelihood of catastrophe and the upper limit to dispersal movement were the key variables determining persistence. Adult mortality and home‐range size were the only significant partial correlates of total population size for the American mink. Adult mortality was also a significant correlate of total population size in the pine marten, as were litter size and juvenile mortality. In neither the marten nor the mink was dispersal distance a significant factor in determining their persistence in the landscape.Main conclusionsAt a landscape scale it is difficult to measure animal distributions directly and yet conservation planning often necessitates knowledge of where, and in what numbers, animals are found, and how their distributions will be affected by interventions. SEPMs offer a useful tool for predicting this, and for refining conservation plans before irreversible decisions are taken in practice.
Persistence on inselbergs: the role of obligate seeders and resprouters
Authors: Hunter John T. 
Published: June 2010

AbstractAim  To investigate if the current theories associated with recruitment strategies are sufficient to explain differences in the proportions of obligate seeders and resprouters on inselbergs and in the matrix.Location  The New England Batholith of eastern Australia.Methods  The importance of life form and regenerative response of flora species are compared for twenty‐four archipelagos of inselbergs habitat islands and for their adjacent matrix. Forward stepwise multiple linear regression is used to correlate measured and modelled variables with differences in the proportional abundance of obligate seeders on inselbergs at three levels of sampling.Results  A total of 216 inselbergs were surveyed and information on 826 vascular plant species was collated. Herbs were the most common life form both on and off inselbergs. There were generally more shrubs on inselbergs than in the matrix. Resprouters were more common everywhere. However, obligate seeders were proportionately more common on inselbergs. The degree of insularity of outcrop floras accounted for 23–37% of the variance in the proportional abundance of obligate seeders at three sampling scales.Main conclusions  A model is proposed whereby the mechanisms that influence the abundances of obligate seeders and resprouters are different on inselbergs and in the matrix. Inselberg environments are harsh, arid, have limited safe recruitment sites and below ground resources, but are not light limited. In such habitats, obligate seeders with persistence life‐history traits are favoured. Within the matrix in eastern Australia frequent biomass removal disturbances occur (such as fire) and resprouting is advantageous. High turnover obligate seeders with no persistence life‐history traits can be favoured in the matrix with a reduced disturbance regime and where competition for light still occurs. Some of these matrix obligate seeders occur on inselbergs due to their infrequent disturbance regimes.
THE EUROPEANIZATION OF PORTUGAL
Authors: Goucha Soares Antonio 
Published: June 2010

ABSTRACT
The article aims to explore Portugal's performance in some areas that can be included in a wide concept of Europeanization: the state of the economy, the rule of law, and education. It starts with a brief reference to the evolution of the Portuguese economy since the European accession to conclude that with the adoption of the single currency Portugal entered into a phase of clear economic divergence, making it an exception within the EU. Section 2 is devoted to the rule of law. It highlights how a modern and updated legal system can have an outcome that threatens some basic foundations of the rule of law, and can also contribute to increasing social inequality. The last section focuses on some problems affecting education. Particular attention is drawn to the performance of the secondary education system and to issues related to the quality of higher education institutions.
WHO DOES NOT PARTICIPATE IN ELECTIONS IN EUROPE AND WHY IS THIS?
Authors: Hadjar Andreas , Beck Michael 
Published: June 2010

ABSTRACT
This paper focuses on the research question ‘Who does not vote and why?’ regarding national elections in 24 European countries. We analyse determinants of non-voting both on the individual and the societal level employing a multilevel design. On the micro level, the sociological determinants under consideration are education, cohort and gender. Regarding psychological or motivational factors, we include in the analyses political efficacy, political interest, political trust and satisfaction with politics. On the macro level, we analyse characteristics of the electoral system, including opportunities for ‘direct democracy’, maturity of democracy, disproportionality factor, and if the participation in elections is compulsory. The data source of the analyses is the European Social Survey 2006. A first main finding is the fact that the probability of non-voting is higher among people with a low level of education and among younger cohorts. The motivational factors have similar impacts on non-voting across all analysed societies. Lack of political efficacy, lack of political interest, lack of political trust and dissatisfaction with politicians and the political system increase the probability of non-voting. Regarding macro influences, countries with compulsory voting and ‘old democracies’ turn out to have a lower rate of non-voting, although these effects vanish when simultaneously modelled with the social psychological micro level indicators.
Institutions, Geography, and Market Power: The Political Economy of Rubber in the Brazilian Amazon, c. 1870–1910
Authors: Fernandes Felipe Tamega 
Published: June 2010

The thesis applies a political economy approach to the study of how institutions and geography explain the development of a commodity chain. Focusing on the Brazilian Amazon from 1870 to 1910, the analysis develops a new theoretical framework constructed by combining standard trade models with institutions and economic geography. There are two levels of analysis: interactions among and within different nodes of the commodity chain. A quantitative-driven analysis from macroeconomic data supports inferences from microeconomic behavior. The thesis provides new information on rubber prices and exports, trader ledgers, estate accounts, newspapers, traveler accounts, and official documents.The research develops a demand- and supply-side analysis of the history of rubber, from tappers to manufacturers. It features the main rubber manufacturing countries, Britain and the U.S.A., and shows how competition prevailed along the chain, translating into a struggle for rubber supply. Rubber was not a homogeneous product. Due to a combination of quantity and quality, the Brazilian Amazon possessed significant market power, market power that shaped the rubber chain. In this light, the thesis investigates how the Brazilian rubber supply chain was organized and how agents profited from its monopolistic position. It also shows that taxation increased the regional welfare and allowed the government to support two related activities: telegraphs and shipping.The thesis proves that violence and coercion were not necessary features of rubber production, as argued by much of the literature. Through a game theoretic approach, the thesis demonstrates conditions under which production could have occurred without exploitation. In a context of high price inelasticity of demand and rising prices, production was driven by market forces. Inelasticity of demand was indeed one of the main features of the rubber boom. It shaped production, bargaining power between different nodes of the chain and competition within them, defining the distribution of profits along the rubber chain.
Pollinator‐mediated selection and experimental manipulation of the flower phenotype inChloraea bletioides
Authors: Cuartas‐Domínguez Marcela , Medel Rodrigo 
Published: June 2010

Summary1. While many studies of flower evolution have relied on the assessment of selection coefficients, these estimates represent correlative evidence of selection. Few studies have combined correlative with experimental evidence, and hence the mechanisms underlying selection processes are not well understood.2. In this study we quantified the magnitude, direction and form of pollinator‐mediated selection acting upon morphological traits in the Chilean endemic orchidChloraea bletioides. Results revealed strong selection differentials for plant height and flower number, and absence of total selection for morphological flower characters. Multivariate analysis of selection revealed a strong and positive directional selection gradient for flower number.3. The labellar lobe and flower tube were under negative correlational selection, indicating that selection promoted alternative combinations of traits. Plants with long floral tubes and small labellar lobes, and short floral tubes with large labellar lobes were selected for. Interestingly, selection on flower number increased at a higher rate through the female function than through the male function, which suggests that size‐dependent resource limitation may be more important than pollinator‐mediated selection for fruit set.4. In addition to estimates of phenotypic selection, we evaluated through phenotype modification the impact of pollinators on the correlation and potential integration of flower traits coming from different whorls. We removed the tip of the lateral sepals and the labellar lobe in a 2 × 2 factorial design.5. Results revealed that phenotypic modification had no effect on male and female fitness. The absence of effect was consistent with the low and non‐significant selection coefficients. Nevertheless, the observation of significant correlational selection for labellar lobe and flower tube suggests that experimental studies performed on these characters may be of interest to evaluate the functional and adaptive integration of flower design in orchids.