bluuebunny/crossref_metadata_2025_split huggingface dataset:
Moms are better nurses than dads: gender biased self‐facilitation in a dioecious Juniperus tree
Authors: Montesinos Daniel , Verdú Miguel , García‐Fayos Patricio 
Published: February 2009

AbstractQuestions: Can gender of nurse plants affect regeneration patterns and spatial population structure? Is there a seed‐seedling conflict in the regeneration process? What factors are responsible for the clumped spatial population structure observed for adult trees?Location: Mediterranean cold semi‐arid high mountains in Spain.Methods: The spatial pattern of adult Juniperus thurifera trees was studied by means of Ripley's K‐analysis. χ2 analyses were used to test for natural seedling frequency in each of three main microhabitats: (1) under female and (2) male tree canopies and (3) in open interspaces. The observed pattern was explained experimentally by studying seed and seedling survival for two years. Survival probabilities were calculated across life stages for each of three main microhabitats.Results: Adult J. thurifera trees were aggregated in space. Most seedlings were found underneath female J. thurifera trees. Experimental studies demonstrated that from seed dispersal to seedling survival all life stages showed the same positive or negative trend within a given microhabitat, indicating stage coupling and no seed‐seedling conflicts. Attraction of frugivo‐rous birds by reproductive female junipers and improvement of environmental conditions beneath tree canopies were the main factors responsible for the variation in seedling density among microhabitats; highest underneath female trees and lowest in open interspaces.Conclusions: In dioecious species, the gender of nurse plants can significantly determine the spatial population structure. In J. thurifera forests, facilitation beneath female trees occurs among all life stages without any sign of seed‐seedling conflict. The most critical factors shaping the spatial population structure were directed seed dispersal and environmental amelioration beneath female conspecific trees.
Factors affecting the invasion success of Senecio inaequidens and S. pterophorus in Mediterranean plant communities
Authors: Caño L. , Escarré J. , Sans F.X. 
Published: February 2009

AbstractQuestion: Plant invasions result from complex interactions between species traits, community characteristics and environmental variations. We examined the effect of these interactions on the invasion potential of two invasive Senecio species, S. inaequidens and S. pterophorus, across three Mediterranean plant communities in a natural park.Location: Catalonia, NE Spain.Methods: We carried out two series of experimental seedling transplantations, in the spring and fall of 2003, in grassland, shrubland and Quercus ilex forest. Competition with neighbouring plants and water availability were manipulated. We evaluated the survival, growth and reproduction with respect to each treatment combination.Results: Any habitat can be colonised if disturbance occurs. In the absence of disturbance, shrubland enhanced the survival of seedlings. Competition with resident vegetation dramatically reduced survival in grassland and forest when establishment occurred in the spring. However, establishment in the fall promoted invasion in grassland and shrubland, even in the undisturbed treatment. Grassland allowed the highest growth and reproductive performance of both species while forest was the most resistant habitat to invasion. S. inaequidens had a higher growth rate and a shorter pre‐reproductive period than S. pterophorus. S. pterophorus produced more biomass and was more dependent on water availability than S. inaequidens.Conclusions: In the light of our results, we recommend surveying open shrublands and grasslands after periods of rainfall. Special attention should be paid to S. pterophorus, which is currently spreading. A preliminary assessment of the invasive‐ness of this plant is given in this study.
Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland‐shrubland ecotones
Authors: Bestelmeyer Brandon T. , Khalil N.I. , Peters Debra P.C. 
Published: February 2009

AbstractQuestion: Does shrub invasion at ecotones indirectly limit grass establishment by increasing mammalian seedling herbivory?Location: Chihuahuan Desert, New Mexico, USA.Methods: We tested the hypothesis that herbivore‐related mortality of seedlings of the dominant perennial grass Bouteloua eriopoda would be highest in shrub‐dominated portions of grassland‐shrubland ecotones. We tested the hypothesis in two Chihuahuan Desert sites featuring similar shrub encroachment patterns but different shrub species, grass cover, and different abundances of small mammals. Within each site we transplanted B. eriopoda seedlings to grass‐dominated, middle, and shrub‐dominated positions of replicate ecotones during the time of year (mid‐summer) when they would naturally appear and monitored seedling fates. We estimated population size/activity of putative small mammal herbivores.Results: Seedlings were killed by mammals in greater numbers in shrubland than in grassland or middle ecotone positions at the site with large herbivore numbers. At the site with low herbivore numbers, most seedlings were killed in middle ecotone positions. The abundance patterns of herbivores did not parallel patterns of seedling herbivory across the ecotones or between sites.Conclusions: Seedling herbivory is an important process and is related to vegetation composition, but the mechanisms underlying the relationship are not clear. We speculate that variation in small mammal foraging behavior may contribute to seedling herbivory patterns. Restoration strategies in the Chihuahuan Desert need to account for the abundance and/or behavior of native herbivores.
Quantitative prediction of the distribution and abundance of Vaccinium myrtillus with climatic and edaphic factors
Authors: Coudun Christophe , Gégout Jean‐Claude 
Published: February 2009

AbstractQuestion: Can the distribution and abundance of Vaccinium myrtillus be reasonably predicted with soil nutritional and climatic factors?Location: Forests of France.Methods: We used Braun‐Blanquet abundance/dominance information for Vaccinium myrtillus on 2905 forest sites extracted from the phyto‐ecological database EcoPlant, to characterize the species ecological response to climatic and edaphic factors and to predict its cover/abundance at the national scale. The link between cover/abundance of the species and climatic (65 monthly and annual predictors concerning temperature, precipitation, radiation, potential evapotranspiration, water balance) and edaphic (two predictors: soil pH and C:N ratio) factors was investigated with proportional odds models. We evaluated the quality of our model with 9830 independent relevés extracted from Sophy, a large phytosociological database for France.Results: In France, Vaccinium myrtillus is at the southern limit of its European geographic range and three environmental factors (mean annual temperature, soil pH and C:N ratio) allow prediction of its distribution and abundance in forests with high success rates. The species reveals a preference for colder sites (especially mountains) and nutritionally poor soils (low pH and high C:N ratio). A predictive map of its geographic range reveals that the main potential habitats are mountains and northwestern France. The potential habitats with maximal expected abundance are the Vosges and the Massif central mountains, which are both acidic mountains.Conclusions: Complete niche models including climate and soil nutritional conditions allow an improvement of the spatial prediction of plant species abundance at a broad scale. The use of soil nutritional variables in distribution models further leads to an improvement in the prediction of plant species habitats within their geographical range.
Climate and pH as determinants of vegetation succession in Central European man‐made habitats
Authors: Prach Karel , Pyšek Petr , Jarošík Vojtech 
Published: February 2009

AbstractQuestions:(1) What are the most important abiotic environmental variables influencing succession in central European man‐made habitats? (2) How do these variables interact with one another and with variation in community properties?Location:Central, western and southern parts of the Czech Republic. Habitats included old fields, urban sites, spoil heaps after coal mining, sites at water reservoirs, extracted sand pit and peatland and reclaimed sites in areas deforested by air pollution.Methods:We investigated vegetation patterns on 15 succes‐sional seres, sampled by the same methods. Time of succession over which the data were available ranged from 12 to 76 years. The cover of vascular plant species (in %) was estimated in 5 m × 5 m plots. The relationships between vegetation characteristics (species composition, total cover, cover of woody species, species number and rate of dominant species turnover) and 13 abiotic site factors, including climatic and soil variables, were tested using CCA ordination and regression models.Results:Substratum pH, the only substratum characteristic, and climate were the environmental variables significantly affecting the vegetation patterns in the course of succession. The rate of succession, measured as the turnover of dominant species, was significantly more rapid in lowland than in mountain climates. On alkaline soils, species numbers in succession increased towards warmer climates. However, acid soils prevented any increase in species numbers, regardless of the climate. Surprisingly, forms of nitrogen and contents of C, P and cations did not exhibit any significant effect on the vegetation characteristics studied.Conclusions:Our approach, to compare a number of seres, can contribute not only to our understanding of succession, but also to help restoration projects to predict vegetation change because the crucial environmental variables, as identified by this study, are easy to measure.
A quick and robust method for biomass estimation in structurally diverse vegetation
Authors: Radloff Frans G.T. , Mucina Ladislav 
Published: February 2009

AbstractRationale: Few techniques exist for non‐destructive measurement of the biomass of different co‐occurring growth forms in a similar manner, and the available techniques tend to be tedious and time consuming.Aim: This paper provides an alternative technique for the measurement of components of biomass (defined in terms of growth forms) and describes an apparatus effective to perform these measurements in samples of vegetation stands up to 1.5 meter tall.Approach: The technique is based on a regression relationship between a number of probes [multiple height measurements of targeted growth forms with the help of mini disks (3 cm in diameter)] taken in a given area, and the dry biomass of these growth forms within that area.Test: We tested the method in a multi‐layered shrubland composed of three major growth forms (shrub, stoloniferous grass and tussock grass) to: (1) establish how accurate the new method predicts the biomass of different plant growth forms, and (2) determine the sampling intensity necessary for reliable results. The technique proved to be very effective in terms of predicting the biomass of the respective growth forms within sample plots, even at a very low density of probes.Conclusion: The Multipoint Minidisk Meter method provides a good alternative biomass estimation method for vegetation composed of diverse growth forms, especially where sampling time is of essence. It will be especially useful to closely track changes in biomass within the same plot over time.
Interactive effects of grazing and shrubs on the annual plant community in semi‐arid Mediterranean shrublands
Authors: Osem Yagil , Perevolotsky Avi , Kigel Jaime 
Published: February 2009

AbstractQuestion: We studied the interactive effects of grazing and dwarf shrub cover on the structure of a highly diverse annual plant community.Location: Mediterranean, semi‐arid shrubland in the Northern Negev desert, Israel.Methods: Variation in the biomass and plant density of annual species in the shrub and open patches was monitored during four years, inside and outside exclosures protected from sheep grazing, in two contrasting topographic sites: north and south‐facing slopes that differed in their dominant dwarf shrubs species: Sarcopoterium spinosus and Corydothymus capitatus, respectively.Results: Above‐ground biomass, density and richness of annual species were lower under the canopy of both shrub species compared to the adjacent open patches in the absence of grazing. Grazing reduced the biomass of annuals in open patches of both topographic sites, but not in the shrub patches. On the north‐facing slope, grazing also reduced plant density and richness in the open patches, but increased plant density in the shrub patches. At the species level, various response patterns to the combined effects of grazing and patch type were exhibited by different annuals. Protection against the direct impacts of grazing by shrub cover as well as species‐specific interactions between shrubs and annuals were observed. A conceptual mechanistic model explaining these interactions is proposed.Conclusion: In semi‐arid Mediterranean shrublands grazing and dwarf shrub cover interact in shaping the structure of the annual plant community through (1) direct impacts of grazing restricted to the open patches, (2) species‐specific facilitation/ interference occurring in the shrub patches and (3) subsequent further processes occurring among the interconnected shrub and open patches mediated through variation in seed flows between patches.
Fire disturbance and forest structure in old‐growth mixed conifer forests in the northern Sierra Nevada, California
Authors: Beaty R. Matthew , Taylor Alan H. 
Published: February 2009

AbstractQuestion:This study evaluates how fire regimes influence stand structure and dynamics in old‐growth mixed conifer forests across a range of environmental settings.Location:A 2000‐ha area of mixed conifer forest on the west shore of Lake Tahoe in the northern Sierra Nevada, California.Methods:We quantified the age, size, and spatial structure of trees in 12 mixed conifer stands distributed across major topographic gradients. Fire history was reconstructed in each stand using fire scar dendrochronology. The influence of fire on stand structure was assessed by comparing the fire history with the age, size, and spatial structure of trees in a stand.Results:There was significant variation in species composition among stands, but not in the size, age and spatial patterning of trees. Stands had multiple size and age classes with clusters of similar aged trees occurring at scales of 113 ‐ 254 m2. The frequency and severity of fires was also similar, and stands burned with low to moderate severity in the dormant season on average every 9–17 years. Most fires were not synchronized among stands except in very dry years. No fires have burned since ca. 1880.Conclusions:Fire and forest structure interact to perpetuate similar stand characteristics across a range of environmental settings. Fire occurrence is controlled primarily by spatial variation in fuel mosaics (e.g. patterns of abundance, fuel moisture, forest structure), but regional drought synchronizes fire in some years. Fire exclusion over the last 120 years has caused compositional and structural shifts in these mixed conifer forests.
Quantifying patterns and controls of mire vegetation succession in a southern boreal bog in Finland using partial ordinations
Authors: Tuittila E.‐S. , Väliranta M. , Laine J. , Korhola A. 
Published: February 2009

AbstractQuestion: How do we distinguish between concurrent allogenic and autogenic forcings behind changing patterns in plant community structures during mire development?Location: Lakkasuo raised bog, southern Finland.Methods: Two radiometrically dated peat profiles were studied using high resolution plant macrofossil analysis. A combination of partial direct and indirect gradient analyses (CCA and DCA) was applied to quantify the role of different drivers of vegetation changes.Results: Autogenic hydroseral succession explained 16% of the compositional variation in the vegetation. Disturbance successions initiated by fire explained 15% of the variation in the hummock, but only 9% in the wetter lawn. The early post‐disturbance successional stages were characterized by Eriophorum vaginatum. After partialling out the effects of peat depth and time since fire, a moisture gradient explained 29% of variation in the hummock core and 26% in the lawn. The analyses also indicated alternation between species with a similar niche. This interaction gradient explained 26% and 31% of the compositional variation in the hummock and lawn, respectively. The similar order of species replacement from both cores supported the existence of general directional succession in mire vegetation, both during the mire development and after fire events. The autogenic succession was slow and gradual while the disturbance successions were episodic and fast.Conclusion: Our results support the paradigm of the complex nature of mire vegetation dynamics where several interlinked agents have simultaneous effects. The approach of combining partial ordinations developed here appeared to be a useful tool to assess the role of different environmental factors in controlling the vegetation succession.
17β‐Hydroxysteroid Dehydrogenases in Human Breast Cancer
Authors: Nagasaki Shuji , Miki Yasuhiro , Akahira Jun‐ichi , Suzuki Takashi , Sasano Hironobu 
Published: February 2009

Estrogen plays a pivotal role in development and progression of human breast carcinoma. Before menopause the main source of estrogen in women is circulating estrogen secreted from the ovary, but following menopause the source changes to the hormone that is converted from circulating adrenal androgens in peripheral tissues. Therefore, adrenal androgens have to be converted to estrogen to stimulate breast carcinoma cells. In these steps, several enzymes such as aromatase, steroid sulfatase, and 17β‐hydroxysteroid dehydrogenases (17β‐HSDs) are involved in the production of estrogens.The reaction related to 17β‐HSDs activity is one of the last steps of estradiol biosynthesis, and 14 isozymes of 17β‐HSD have been identified at this juncture. The balance of the relative expression levels of 17β‐HSD isozymes in human breast carcinomas is thought to play a pivotal role in supply of estradiol to estrogen receptor positive carcinoma cells. Understanding the character of 17β‐HSD isozymes in human breast carcinoma thus provides important information on the mechanisms of biosynthesis of estradiol in breast carcinoma and for development of a therapeutic agent targeted for inhibition of local estradiol synthesis in breast carcinoma cells. In the present review we summarize the roles played by 17β‐HSDs in human breast carcinoma to obtain a better understanding of the properties of 17β‐HSDs in human breast carcinoma.
From North‐South to ‘Global’ South? An Investigation of a Changing ‘South’ Using Airline Flows between Cities, 1970–2005
Authors: Taylor Peter J. , Derudder Ben , García Cándida Gago , Witlox Frank 
Published: February 2009

AbstractUsing a city‐centred approach to development issues, this article critiques the recent concept of ‘Global South’. With its provenance from the ‘South’ half of the 1970s ‘North‐South divide’, the concept recognizes the transformations of the world economy since the 1970s, latterly known as globalization, by adding the adjective ‘global’ but leaves the geography undisturbed: the map of ‘South’ in ‘Global South’ is the same as in the North‐South divide. The limitation of this static geography in dynamic times is explored using relational geographies based upon airline flights and passengers between cities. Flight patterns for 1970, 1991 and 2005 are used to show the prime finding that contrasts a dense Pacific Asian network with airline patterns in the rest of the ‘South’. In addition, there appears to be bifurcation of the ‘South’ with Latin America having less inter‐regional South‐South links than other regions. Specific origin/destination data for 2001 provide a cross‐sectional depiction of the details of this South geography and confirm the very large flows into, through and out of Pacific Asia. These results are interpreted using Jacobs’ work on economic change and moral syndromes. We conclude that ‘Global South’ is a geographical chaotic conception, which has possible implications for its major sponsor, the United Nations Development Programme, wedded to an old political geography while ‘real, existing’ economic development proceeds regardless.
Spaces and Networks of Musical Creativity in the City
Authors: Watson Allan , Hoyler Michael , Mager Christoph 
Published: February 2009

AbstractUrban geography, both material and imagined, is a crucial mediating factor in the production and consumption of music. The city provides the concrete places which offer spaces for musical creativity. While certain spaces such as recording studios are specifically organised for this purpose, music is produced in many spaces, from the bedroom, garage or home studio, to community and youth centres, to street corners and clubs. Cities also sustain networks that foster and support musical creativity. These networks come together in locales of creativity and production to find fixity in the concrete spaces of the city. At the same time the networks are fluid, with musical knowledge moving within and between cities through the mobility of skilled creatives and new technologies. A growing body of geographical literature is attempting to foreground the spatial in music studies by focusing on local scenes, musical production, and the particularity of certain places. This article aims to provide an overview of current geographical research and debates on music, with an explicit focus on the role of urban space in musical creativity, and on the musically creative networks at work within and between cities. We argue that there is a need to situate creativity more squarely in its material and embodied contexts of production and to consider the ways in which creative individuals interact in complex ways with urban physical form, technology, and other actors in networks of creativity and production.
International Council for Standardization in Haematology – the first 40 years
Authors: LEWIS S. M. 
Published: February 2009

SummaryThis brief history of the origin and development of ICSH must, inevitably, be selective as it has been extracted from the many pages of the records of the meetings of the ICSH board and its secretariat, the annual assembly and the reports of the various expert panels and working groups. It is hoped that it will give a picture of the way in which ICSH functioned and the many experts around the world who have contributed to its activities – but with an apology and appreciation, to other colleagues who have not been named in this annotation, but who made significant contributions to the activities that are described.