bluuebunny/crossref_metadata_2025_split huggingface dataset:
Life course dental caries determinants and predictors in children aged 12 years: a population‐based birth cohort
Authors: Peres Marco Aurélio , Barros Aluisio J , Peres Karen Glazer , Araújo Cora LP , Menezes Ana MB 
Published: February 2009

Abstract – Objective: To investigate the main dental caries life course determinants and predictors of dental caries at age 12.Methods: This study was nested in a population‐based birth cohort started in 1993 in Pelotas, Brazil. A sample of 359 children was followed‐up. Dental examinations and interviews were performed at 6 and at 12 years old. Dental caries (DMFT) at 12 years old was the outcome. Exploratory variables included socioeconomic and demographic variables at birth, children’s nutritional and development characteristics, primary dental caries, oral health related behaviors and dental service use at age 6 and 12. Poisson regression was used in order to provide relative risk ratio estimates. Attributable risk or etiology fraction and population attributable risk for both main early life variables were calculated. Dental caries prediction (DMFT ≥ 1) at 12 years old was tested using logistic regression analyses.Results: Children who presented height‐for‐age deficit at 12 months (RR 1.50 CI: 95% = 1.03–2.18), children who showed a DMFT of 1–3 and 4–19 at 6 years (RR = 2.01; CI: 95% = 1.33–3.03, and RR = 2.66; CI: 95% = 1.81–2.53, respectively) and those children aged 12 in the highest tertile of proportion of teeth experiencing gingival bleeding (RR = 1.58; CI: 95% = 1.11–2.24) presented a higher level of dental caries at age 12. Attributable risk for dental caries at age 12 were 79.1% and 74.2% for deficit in height for age at 12 months and for primary dental caries at age 6 years respectively; population attributable risk for dental caries at age 12 were 3.1% for deficit in height for age at 12 months and 64.9% for primary dental caries at age 6. The level of accuracy in predicting dental caries at age 12 by using life course socioeconomic, behavioral and clinical data was modest.Conclusions: The results of this study support the hypothesis linking social, biological and behavioral exposures and dental caries at 12 years old. In addition, the findings reinforce the lack of accuracy of dental caries predictors therefore limiting the individuals high‐risk approach as a public health strategy.
Secondary succession on sandy old‐fields in Hungary
Authors: Csecserits Anikó , Rédei Tamás 
Published: February 2009

Abstract. Development of semi‐natural vegetation has recently been a primary concern of restoration efforts. A primary management question is whether active intervention is required or spontaneous secondary succession could suffice. We studied 54 old‐fields in central Hungary, which differed in time since abandonment but which had similar environmental conditions and management histories. The sites were grouped into four age groups according to the time elapsed since cultivation abandonment: 1–5, 6–10, 11–23 and 24–33 yr. In each old‐field we recorded the species and estimated their abundances. We grouped species in two ways: according to life form (annuals, biennials, perennials, woody plants) and according to coenological behaviour (weeds, sand and steppe generalists, specialists). We analysed the changes in species number and abundance in these categories as a function of site age.Contrary to other successional studies, the total number of species did not change significantly among the four age groups. A significant change was detected between the first two age groups as to life‐form composition. Species number and abundance of annuals decreased, while the perennials and woody plants increased. As to coenological behaviour, species number changed only in the first two age groups, while abundance changed in the first three. Weeds quickly disappeared and specialists established and spread, while the species number and abundance of generalists did not change significantly. We concluded that the basic shifts in species composition are almost completed within 10 yr. Most of the late successional species colonized and weeds disappeared. We conclude that there was no need for active intervention in this system: the spontaneous secondary succession leads to semi‐natural vegetation.
Directional and non‐directional vegetation changes in a temperate salt marsh in relation to biotic and abiotic factors
Authors: Schröder Henning K. , Kiehl Kathrin , Stock Martin 
Published: February 2009

Abstract. The effects of reduction and cessation of sheep grazing on salt‐marsh vegetation were studied on a formerly intensively grazed salt marsh in northern Germany. Plant species cover was recorded in 45 permanent plots from 1992 to 2000. In 1995, physical and chemical soil parameters were analysed. Results of Redundancy Analysis (RDA) indicated that salinity and the depth of anoxic conditions below the surface were the most important soil factors related to the spatial vegetation pattern. Furthermore, plant species distribution was influenced by present and past grazing intensity, by soil grain size and nitrogen content.Vegetation changes over 9 yr were analysed by non‐linear regression. The cover of Aster tripolium, Atriplex portulacoides, and, to a lesser extent, Artemisia maritima and Elymus athericus increased due to reduced grazing pressure, whereas the cover of Salicornia europaea decreased. After a strong increase in the first years Aster decreased 2 to 6 yr after abandonment. In the mid salt‐marsh zone Puccinellia maritima was replaced by Festuca rubra. The cover of Puccinellia, Festuca, Suaeda maritima, Glaux maritima and Salicornia fluctuated strongly, probably due to differences in weather conditions and inundation frequency. Species richness per 4 m2 generally increased while vegetation evenness decreased during the study period. Only in the high salt marsh abandoned for 9 yr did the number of species decrease slightly. Thus far, cessation of grazing did not lead to large‐scale dominance of single plant species.
Species spread and persistence: implications for experimental design and habitat re‐creation
Authors: Pakeman Robin J. , Pywell Richard F. , Wells Terry C.E. 
Published: February 2009

Abstract. The patterns of species establishment, persistence and spread in a long‐term experiment investigating the recreation of chalk grassland using different seed mixtures on ex‐arable land were analysed with the intention of providing enhanced re‐creation/restoration prescriptions and a critique of experimental designs. Species had a wide range of behaviours; (1) species that did not establish from seed e.g. Blackstonia perfoliata, (2) establishment but poor persistence in closed sward e.g. Hieracium pilosella, (3) establishment and persistence but little spread e.g. Onobrychis viciifolia and (4) good establishment and spread over all treatments e.g. Centaurea nigra and Trisetum flavescens. Persistence appeared greater in species with lower germination rates in both light and dark. Spread was greater in species with higher seed mass and lower dark germination rates.However, results from small‐plot experiments should be critically analysed. Though initial results show the potential for re‐establishment of vegetation, subsequent vegetation dynamics may be more closely related to the invasion of species from other treatments than the original species sown. Experimental designs should employ either large plots and/or wide guard rows to extend their useful life span. Long‐term data show which species are useful for cost‐effective restoration. Some species need to be sown over the whole area to provide cover (a ‘grass matrix’) and competition with arable weeds. Others need to be sown over wide areas as they spread poorly. Some species can be sown at low densities or in small patches as they have the ability to spread in closed vegetation.
Ecohydrology of saline grasslands: Consequences for their restoration
Authors: Beyen Wouter , Meire Patrick 
Published: February 2009

Abstract. By the approval of the European Bird Directive (79/409/EEC) in 1979 and the Habitat Directive (92/43/EEC) in 1992, nature protection has become an important part of European law with direct consequences for land use, industrial development and agriculture. If a member state reclaims an area that is protected by these directives, it has to take compensational measures. When such an area includes saline grasslands that require very specific abiotic conditions, a place with similar conditions must be available to re‐establish those grasslands at another location in a sustainable way. This will limit the number and extent of possible sites for compensation.In the conflict between economy and ecology in the Schelde polders, Flanders has chosen to expand the port of Antwerp in the polders at the left Schelde bank and destroy a protected saline grassland site. As a consequence, it has to compensate for this loss. Therefore, we made a detailed study of the hydrology, geology and soil conditions of the endangered saline grassland site. The same was done in four possible compensation sites, all situated in nearby polders. We found that the presence of upwelling groundwater flowing through a saline peat layer is necessary for the occurrence of saline grasslands. Only in one of the four possible compensation sites, called Muggenhoek, we found such conditions. So, we indicate this place as a possible site for the re‐creation of saline grasslands and give some recommendations for their development.
Restoration prospects of abandoned species‐rich sandy grassland in Hungary
Authors: Matus G. , Tóthmérész B. , Papp M. 
Published: February 2009

Abstract. Secondary succession and seed bank formation was studied in a formerly grazed, abandoned, eastern Hungarian sandy steppe‐meadow (Pulsatillo‐Festucetum). The vegetation was sampled at different elevations of a sand dune which became partly invaded by the tree Robinia pseudo‐acacia ca. 10 yr ago. Pre‐abandonment vegetation records were used as historic references. Though composition of the non‐invaded grassland only changed moderately, dominance of tall grasses (Elymus hispidus, Poa angustifolia) increased significantly at the cost of annuals and low stature perennials. In the stand invaded by Robinia most grassland species were lost and replaced by nitrophytes. Vertical position influenced species abundance, but affected the composition only moderately. Fine‐scale zonation of the vegetation also changed with time. Species richness of the above‐ground vegetation and the seed density of soil samples at the lower elevation were slightly greater than at the higher sites.Seed banks of sensitive grassland specialists (e.g. Pulsatilla pratensis subsp. hungarica) disappeared during grass encroachment. Following extinction from above‐ground vegetation, restoration must rely on dispersal from adjacent areas. In contrast, several annuals and perennials, which survived this degradation stage in the above‐ground vegetation, possessed seed banks. Many of these species became extinct from the vegetation during the Robinia invasion but left viable persistent seeds. This fact is promising for restoration of the Potentillo‐Festucetum sandy pasture. Competitive weedy species and sprouting Robinia can, however, limit seedling establishment.
Relative growth rate and hemerobiotic state in the assessment of disturbance gradients
Authors: Fanelli G. , De Lillis M. 
Published: February 2009

Abstract. A method is discussed for describing the intensity of disturbance, based on the floristic composition of vegetation types. It includes the development of a hemerobiotic scale (from hemeros= cultivated). We attempted to relate this scale based on floristic patterns with functional parameters.Following a large phytosociological survey of the Roman area, we selected 19 species of herbs and grasses, widely differing in ‘hemeroby’, and measured their Relative Growth Rate (RGR). RGR varies between 0.13 and 0.21 d‐1. A significant correlation between mean hemerobiotic value, resulting from the phytosociological study, and measured RGR of juvenile plants emerges. Although Specific Leaf Area (SLA) is highly correlated with RGR, and thus explains most of its variations, as previously found in other studies, it is only weakly related to hemerobiotic state. An additional data set with 78 species from the literature supports the conclusions. This approach allows a functional quantification of hemeroby which enables useful applications, for instance in cartography. A biotope map showing a steep gradient of disturbance impact in the city of Rome is presented as a preliminary test.
Impact of management and habitat on demographic traits of Primula vulgaris in an agricultural landscape
Authors: Endels Patrick , Jacquemyn Hans , Brys Rein , Hermy Martin 
Published: February 2009

AbstractQuestion: Is demographic performance of Primula vulgaris correlated with habitat characteristics of the small landscape elements in which it occurs? Can we use this species as an indicator for species‐rich semi‐natural habitats?Location: Flanders, Belgium.Methods: To capture differences in demographic traits and habitat characteristics, both within and between populations, a two‐level survey was carried out. Population size and structure of 89 P. vulgaris populations in different types of small landscape elements was recorded in 1999. At plot level, densities of different life stages were determined and these were related to edaphic conditions and vegetation structure and composition.Results: Three different population types were distinguished: (1) dynamic populations, characterized by seedling and juvenile proportions, (2) normal populations with relatively more adults, but with considerable numbers of seedlings and juveniles and (3) senescent populations, mainly consisting of adults. Senescent populations were significantly smaller than populations with a dynamic demographic structure. At plot level, comparison of demographic characteristics between different management regimes revealed that recruitment rates and total plant density of P. vulgaris were highest in plots that received a regime that included mowing and clearing of ditch banks whereas densities were lower along forest edges. For these plots, it was shown that nutrient levels were higher. Densities of adults as well as juvenile and seedling densities were negatively correlated with vegetation height.Conclusions: Local disturbance and heterogeneity may mask the relationship between unfavourable conditions and demographic characteristics at population level, but it is clear that in small populations recruitment needs to be lifted to guarantee its persistence. Performance of P. vulgaris in small landscape elements can be a first indication of plant species diversity in small landscape elements.
Vegetation ofSphagnumbogs in highly disturbed landscapes: relative influence of abiotic and anthropogenic factors
Authors: Lachance Daniel , Lavoie Claude 
Published: February 2009

AbstractQuestion:Has the vegetation ofSphagnumbogs been affected by more than 200 years of human activities?Location:Bas‐Saint‐Laurent region, southeastern Québec, Canada.Methods:Data (species assemblages, abiotic and spatio‐historical variables) were collected in 16 bogs ranging from 2 to 189 ha, and incorporated in a geographical information system. Major gradients in vegetation composition were identified using DCA. CCA was used to relate vegetation gradients to abiotic and spatio‐historical variables.Results:A clear segregation of species assemblages was observed, from open and undisturbed bogs to forested and highly disturbed sites. Among abiotic factors, tree basal area, water table level and peat thickness had a significant influence on plant species composition. Among spatio‐historical factors, disturbance level, area loss and fire were the most influential factors. Variance partitioning between these groups of factors suggests that spatio‐historical factors had a major influence on peatlands, representing 22% of the variation observed in the plant species assemblages while abiotic factors represent only 17% of the variation.Conclusions:The results highlight the influence of agricultural and other anthropogenic activities on plant assemblages and suggest that even wetlands apparently resistant to disturbances, such as peatlands, can be severely affected by anthropogenic factors. Plant species assemblages of ombrotrophic peatlands of the Bas‐Saint‐Laurent region were, and still are, largely influenced by human activities.
A test of the use of NDVI data to predict secondary productivity
Authors: Posse Gabriela , Cingolani Ana María 
Published: February 2009

AbstractQuestion: How well does the use of NDVI predict secondary productivity at landscape scales? What is the influence of vegetation quality and phenology over secondary productivity?Location: Magellanic steppe in Tierra del Fuego, Argentina. (52°45’to 54° S, 68°15’to 67°30’W).Methods: Monthly and yearly integrated NDVI (NDVI‐I) were calculated from AVHRR/NOAA 14, as estimators of phenology and aerial net primary productivity respectively. From a vegetation map we obtained the proportional cover of different physiognomic types and calculated the palatable fraction (forage) productivity that were used as estimators of vegetation quality. Data were analysed through correlations and regressions.Results: NDVI‐I was not related with secondary productivity indices, while December and annual maximum NDVI, proportion of lawns and tussock grasslands and forage productivity were positively related with secondary productivity. A negative relationship was found between the proportion of heathlands and secondary productivity, but a positive relationship between heathland's proportion and NDVI‐I was found.Conclusions: NDVI‐I is not a good predictor of secondary productivity at the scale of our study. These results could be due to: (1) NDVI‐I is not related to primary productivity and (2) primary productivity is not related to secondary productivity.
Experimental restoration of a fen plant community after peat mining
Authors: Cobbaert D. , Rochefort L. , Price J.S. 
Published: February 2009

AbstractQuestion: Which restoration measures (introduction of donor diaspore material, application of straw mulch, alteration of residual peat depths) contribute to the establishment of a fen plant community on minerotrophic surfaces after peat mining?Location: Rivière‐du‐Loup peatland, southern Québec, Canada at 100 m a.s.1.Methods: The effectiveness of introducing fen plants with the application of donor diaspore material was tested. The donor diaspore material, containing seeds, rhizomes, moss fragments, and other plant propagules, was collected from two different types of natural fens. We tested whether the application of straw mulch would increase fen species cover and biodiversity compared to control plots without straw mulch. Terrace levels of different peat depths (15 cm, 40 cm, and 56 cm) were created to test the effects of different environmental site conditions on the success of re‐vegetation.Results: Applying donor seed bank from natural fens was found to significantly increase fen plant cover and richness after the two growing seasons. Straw mulch proved to significantly increase fen plant richness. The intermediate terrace level (40 cm) had the highest fen plant establishment. Compared to reference sites, the low terrace level (15 cm) was richer in base cations, whereas the high terrace level (56 cm) was much drier.Conclusions: The application of donor diaspore material was demonstrated as an effective technique for establishing vascular fen plants. Further re wetting measures are considered necessary at the restoration site to create a fen ecosystem rather than simply restoring some fen species.
Development ofBrachystegia‐Julbernardiawoodland after clear‐felling in central Zambia: Evidence for high resilience
Authors: Chidumayo E.N. 
Published: February 2009

AbstractQuestion:Does the development ofBrachystegia‐Julbernardia(miombo) woodland after felling, and under a variable fire regime, occur via a serai stage of fire‐tolerant species?Location:Four sites in central Zambia, Africa.Methods:Trees in replicate plots were clear‐cut and stumps and resprouts enumerated. Species recruited into the tree layer (> 2.0 m tall) were monitored for 11 years (1991–2001) and fire occurrence and herbaceous biomass assessed annually to determine fuel loads.Results:Fire frequency was variable at the study sites and fuel loads were generally too low to suppress woodland regeneration after felling. However, at one site a change from low to high fire frequency arrested woodland development and triggered a regression towards a ‘fire‐trap’ vegetation type in which a few fire‐tolerant species survived. There was no evidence to support the hypothesis that miombo woodland regeneration is facilitated by a sere of fire‐tolerant species. All regrowth after felling was from resprouting plants present before felling. Trees with a previous history of felling sprouted more vigorously than trees that had not been felled before. Species richness in the tree layer increased with time since felling because resprout species had different height growth rates.Conclusion:The resilience of miombo trees after clear‐felling is largely due to their capacity to regenerate vegetatively from resprouts and stumps after release from frequent fires. Coppicing is therefore recommended as a suitable management technique for miombo woodland in central southern Africa.
Effects of leaf litter and precipitation on germination and seedling survival of the endangered tree Beilschmiedia miersii
Authors: Becerra Pablo I. , Celis‐Diez Juan L. , Bustamante Ramiro O. 
Published: February 2009

AbstractQuestion: What effects do leaf litter and rainfall regime have on seed germination (time and probability) and seedling survival of the endangered tree species Beilschmiedia miersii (Lauraceae)?Location: The species is a native tree from the mediterranean climate region of Chile. Seeds were collected from La Campana National Park (Chile). The study was carried out under controlled conditions at the Laboratory of Ecology, University of Chile, Santiago, Chile.Methods: During April 2001,200 seeds were assigned to four experimental treatments: high precipitation, with and without litter and low precipitation, with and without litter. Each treatment had 50 individual seeds, each seed in an individual pot. For statistical purposes, we considered each seed as one replicate. High and low values of artificial rainfall corresponded to mean dry and wet years, respectively, for the period 1958–1993 in the central zone of Chile.Results: Seeds germinated earlier, and in higher proportion, in the presence of leaf litter, but only under low rainfall. Seedling survival was insensitive to both litter and precipitation.Conclusions: We conclude that the presence of litter in native populations facilitates seed germination and recruitment of B. miersii, particularly during dry years. We suggest that the reduction of leaf litter due to extraction for gardens and horticultural activities might preclude regeneration of this endangered species.