bluuebunny/crossref_metadata_2025 huggingface dataset:
Association between positive patch tests to epoxy resin and fragrance mix I ingredients
Authors: Andersen Klaus Ejner , Christensen Lars Porskjær , Vølund Aage , Johansen Jeanne Duus , Paulsen Evy
Published: February 2009

Background:  Both epoxy resin (diglycidyl ether of bisphenol A) and fragrance mix I are included in the European baseline series of contact allergens. A significant association between positive reactions to epoxy resin and fragrance mix has been reported by others.

Objective:  To investigate and possibly reproduce this association with the use of TRUE® test data and supplementary tests with fragrance mix ingredients from the Department of Dermatology, Odense University Hospital.

Materials and Methods:  Six thousand one hundred and fifteen consecutive eczema patients tested from 1995 to 2007 were included, and test results from all patients tested with fragrance mix ingredients were analysed.

Results:  One hundred and forty‐five (2.4%) were positive to epoxy resin and 282 (4.6%) were positive to fragrance mix I. Nineteen were positive to both giving an odds ratio of 3.3, which is significant (95% CI 2.0–5.4). Analysis of association to individual fragrance mix ingredients showed a significant association to α‐amyl cinnamal and isoeugenol.

Conclusions:  The significant association between positive reactions to epoxy resin and fragrance mix I was reproduced. However, the clinical implications are not clarified, and even though the association may be coincidental, the fact that it can be reproduced with a different patch test system and in a different population speaks against a random result. Further studies may help to interpret the association.
A correlation found between contact allergy to stent material and restenosis of the coronary arteries
Authors: Svedman Cecilia , Ekqvist Susanne , Möller Halvor , Björk Jonas , Pripp Carl‐Magnus , Gruvberger Birgitta , Holmström Eva , Gustavsson Carl‐Gunnar , Bruze Magnus
Published: February 2009

Background:  Metallic implants, stents, are increasingly being used especially in patients with stenosis of the cardiac vessels. Ten to thirty per cent of the patients suffer from restenosis regardless of aetiology. We have shown increased frequency of contact allergy to stent metals in stented patients.

Objectives:  To we evaluate whether contact allergy to stent material is a risk factor for restenosis.

Methods:  Patients with stainless steel stents, with or without gold plating, were epicutaneously tested and answered a questionnaire. The restenosis rate was evaluated.

Results:  We found a correlation between contact allergy to gold, gold stent, and restenosis (OR 2.3, CI 1.0–5.1, P = 0.04). The risk for restenosis was threefold increased when the patient was gold allergic and stented with a gold‐plated stent. An increased degree of chest pain in gold‐allergic patients stented with gold‐plated stent was found.

Conclusions:  We found a correlation between contact allergy to gold, gold‐stent, and restenosis. It may be of importance to consider contact allergy when developing new materials for stenting.
The impact of measures for secondary individual prevention of work‐related skin diseases in health care workers: 1‐year follow‐up study
Authors: Apfelbacher Christian J. , Soder Stefanie , Diepgen Thomas L. , Weisshaar Elke
Published: February 2009

Background:  Specific instruction courses as a tool for secondary prevention of occupational skin disease (secondary individual prevention, SIP courses) affecting individuals have been introduced in Germany. Little is yet known about the outcome of occupational disease and related behavioural patterns following these courses.

Objectives:  To investigate the outcome of occupational skin disease in health care workers (HCW) 1 year after attendance of a SIP course.

Patients/methods:  Two hundred and fifty‐three HCW participated in SIP courses and were contacted by telephone 1 year after attendance. Patients were interviewed about skin lesions, medical treatment, sick leave, change of occupation, skin protection, skin care and skin cleansing, and the impact of skin disease.

Results:  The follow‐up rate was 81%. The proportion of participants reporting skin lesions decreased significantly (68% at follow‐up compared with 77% at baseline; P = 0.02). Seventy‐two per cent reported that their skin lesions had improved. Nine per cent reported having left their occupation due to their skin disease. Skin care and skin protection had improved, while the frequency of reported hand washing was reduced. Twenty‐seven per cent said their quality of life was impaired due to the skin disease, compared with 54% at baseline (P < 0.001).

Conclusions:  Outcome parameters, including behavioural parameters, indicate a positive impact of courses for SIP on skin health of HCW 1 year after attendance.
Immunomodulation by a novel, dissociated Vitamin D3 analogue
Authors: Zügel Ulrich , Steinmeyer Andreas , May Ekkehard , Lehmann Manfred , Asadullah Khusru
Published: February 2009

Abstract:  The biologically active metabolite of vitamin D3, 1α,25‐dihydroxyvitamin D3, has potent immunomodulatory activity; however, its clinical use is limited because of its hypercalcaemic activity in anti‐inflammatory active doses. Here, we present ZK203278, a novel, structurally different vitamin D3 analogue with profound immunomodulatory activities. It potently inhibits lymphocyte proliferation in the mixed lymphocyte reaction, and release of cytokines that are central in inflammation, such as TNFα and IL‐12 in the low nanomolar range. Similarly, expression of cell‐surface molecules involved in cell adhesion and antigen presentation, e.g. to T cells, is down‐regulated on human monocytes by low nanomolar concentrations of ZK203278. Potent anti‐inflammatory activity has been demonstrated also in vivo in rodent disease models. ZK203278 inhibited allergic contact dermatitis in rodents after oral administration in doses approximately two orders of magnitude below the hypercalcaemic threshold dose. Moreover, ZK203278 significantly prolonged skin allograft survival in rats in well‐tolerated doses. Altogether ZK203278, in contrast to 1α,25‐dihydroxyvitamin D3, exerts considerable immunomodulatory activity at non‐hypercalcaemic dosages and may have therapeutic potential for immune disorders or transplant rejection.
Cervical necrotizing fasciitis and myositis in a western lowland gorilla (Gorilla gorilla gorilla)
Authors: Allender M.C. , McCain S.L. , Ramsay E.C. , Schumacher J. , Ilha M.R.S.
Published: February 2009

A 39‐yr‐old wild‐caught, female western lowland gorilla (Gorilla gorilla gorilla) died during an immobilization to assess swelling and apparent pain of the cervical region. Necropsy revealed a fistulous tract containing plant material in the oropharynx, above the soft palate, communicating with a left‐sided cervical necrotizing fasciitis and myositis. Alpha‐hemolytic Streptococcus and Prevotella sp. were isolated from the cervical lesion. This is a report of cervical necrotizing fasciitis in a western lowland gorilla.
The use of calcium hydroxide and mineral trioxide aggregate on apexification of a replanted tooth: a case report
Authors: Jacobovitz Marcos , De Pontes Lima Regina Karla
Published: February 2009

Abstract –  Aim:  To report the outcome of the endodontic treatment of a reimplanted central maxillary incisor with open apex after 8 years and 7 months of follow‐up.

Summary:  This case report presents the treatment of a right central maxillary incisor of an 8‐year old white male patient with history of traumatic avulsion and immediate replantation. The endodontic therapy consisted of periodical changes of calcium hydroxide dressing and a definitive root canal filling with mineral trioxide aggregate (MTA). The treatment was successful without pathologies up to 7 years of follow‐up. After the institution of orthodontic treatment a localized and late root resorption was noticed at the last radiographic examination (8 years and 7 months postoperative follow‐up). Moreover, the use of MTA promoted a mild crown grey discoloration.
Long‐term results of early condylar fracture correction: case report
Authors: Farronato Giampietro , Grillo Maria Elena , Giannini Lucia , Farronato Davide , Maspero Cinzia
Published: February 2009

Abstract –  Condylar fractures in childhood occur frequently, often with minimal pain and discomfort and therefore the diagnosis is not made at the time of injury. Management may be surgical or non‐surgical. Non‐surgical therapy in children is the method of choice if the condyle can translate normally. In fact, there is an excellent chance of regeneration and continued normal development after fracture in growing patients. The purpose of this article is to describe the long‐term clinical and radiological evaluation of a conservatively treated unilateral condylar fracture, a result of trauma, in a 6‐year‐old patient. In addition, she presented a congenitally missing lower incisor ipsilateral to the fracture and a class II malocclusion. She was treated with functional jaw orthopedics using a splint and an activator and subsequent orthodontic treatment with fixed appliances [J Orofac Orthop5 (2002) 429]. The remodeling process of the condylar head and neck is clearly observed in the panoramic radiographs of the 12‐year follow‐up records presented.
Double ‘pink tooth’ associated with extensive internal root resorption after orthodontic treatment: a case report
Authors: Silveira Frank F , Nunes Eduardo , Soares Janir A , Ferreira Cynthia L , Rotstein Ilan
Published: February 2009

Abstract –  Advanced internal resorption affecting the crown of teeth may result in the appearance of a ‘pink tooth’, which, when located in the root canal, can perforate the external root surface. Therapeutically, this condition represents a clinical challenge and normally requires a combined endodontic and surgical focus. Presented herein are cases of double ‘pink tooth’ which appeared at different times after orthodontic treatment. In the most severe case, upon radiographic examination and computed tomography, the maxillary right central incisor presented an internal resorption, extending from the pulp chamber to the root middle third. After pulp removal, the debridement of the defect was performed using a 2.5% sodium hypochlorite solution, a #80 Kerr file, and an ultrasonic tip ST‐17, aided by a surgical microscope. During the cleaning process, various sites of periodontal communication were identified. Upon controlling the hemorrhaging, the root canal was completely filled with White mineral trioxide aggregate. Within the 3‐month follow‐up treatment, a pink spot appeared on the maxillary left central incisor, which received conventional root canal therapy. Clinically and radiographically, over 18 months of follow up, both cases responded favorably to the proposed treatments. Therefore, it is important to monitor the patient due to the fact that pulp and periodontal sequelae can develop at varied moments after orthodontic treatment. Furthermore, with the current technology and biomaterials, it is possible to resolve cases with extensive internal perforating resorption through endodontic treatment.
Reversing spontaneous succession to protect high‐value vegetation: Assessment of two Scottish mires using rapid survey techniques
Authors: Large Andrew R.G.
Published: February 2009

Abstract. Despite existing management agreements, significant change has occurred on Carnwath Moss and Coladoir Bog, two mire complexes in central and western Scotland. Spontaneous succession has accelerated, resulting in extensive degradation of the mire vegetation on both sites and, in particular, widespread expansion of Calluna vulgaris‐ and Molinia caerulea‐dominated vegetation types. Vegetation surveys across strong gradients of change were conducted with the aim of quantifying the extent of early (desirable) and late (undesirable) successional vegetation on both sites. For each site multivariate analyses of the vegetation data were carried out using TWINSPAN, which clearly differentiated higher quality and degraded surfaces. In management terms percentage Sphagnum cover can act as a useful proxy measure of water level and shrub layer height can also serve as a useful indicator of the degree of degradation. A broad‐based, five class condition continuum was developed for the Carnwath Moss site. While such an assessment scheme is a somewhat arbitrary means of allocating mesotope areas to specific condition classes, it is rapid to apply and simple enough to be applied by a range of users. A drawback is that the methodology is data‐light in temporal terms and is not a long‐term substitute for properly‐funded monitoring programmes for important sites. For both mires, recommendations are made for management with the main emphasis being on maintaining water tables at appropriate levels to maximise the floristic diversity of active mires.
Soil seed bank and driftline composition along a successional gradient on a temperate salt marsh
Authors: Wolters Mineke , Bakker Jan P.
Published: February 2009

Abstract. This study focuses on the relationship between vegetation succession and soil seed bank composition on the Schiermonnikoog (The Netherlands) salt marsh over 100 yr. The importance of driftline material in seed dispersal and the relationship with succession is also investigated. The results indicate that the majority of species have a transient or short‐term seed persistent bank. Seeds of most species are able to float over the salt marsh and become concentrated in the driftline higher up the marsh. After plants have established a seed bank forms, which disappears when vegetation is replaced by later‐successional species. Exceptions are Spergularia mar‐itima, which is still present in the seed bank of late successional stages, and Juncus gerardi and Glaux maritima, which appear in the seed bank of early successional stages, but are absent in the vegetation. Based on the results of this study constraints and possibilities for salt‐marsh restoration by de‐embankment are discussed.
Vegetation change in an ombrotrophic mire in northern England after excluding sheep
Authors: Smith R.S. , Charman D. , Rushton S.P. , Sanderson R.A. , Simkin J.M. , Shiel R.S.
Published: February 2009

Abstract. The role of sheep grazing on vegetation change in upland mires removed from livestock farming and surrounded by conifer plantation was investigated with a grazing trial at Butterburn Flow in northern England. Paired grazed and ungrazed plots from central and peripheral locations were compared over 14 yr. Vegetation data from 34 mires in Kielder Forest provided an ordination framework within which vegetation trends were investigated. A gradient from dry moorland/hummock to wet mire/hollow vegetation dominated this framework and may reflect hydrological variability and structural vegetation differences between the mires.

Some species were significantly affected by change in grazing intensity and there were differences between the edge and the centre of the mire. Overall vegetation change depended upon the grazing management and the position of the plots such that the removal of sheep grazing decreased the cover of species typical of wet ombrotrophic conditions, but only at the periphery of the mire. The vegetation in one plot became very similar to that of mires elsewhere in Kielder Forest where sheep were removed several decades ago.

Cessation of grazing on upland mires is likely to lead to slow structural and species change in vegetation at the mire edge with a long‐term loss of ombrotrophic species. The nature conservation significance of these changes will depend upon whether or not management objectives target natural conditions or wish to maximize ombrotrophic vegetation. The context of external factors such as climate and pollution may, however, be more important in determining site condition on the wettest mires.
Initial response of understorey vegetation to fire severity and salvage‐logging in the southern boreal forest of Québec
Authors: Purdon Mark , Biais Suzanne , Bergeron Yves
Published: February 2009

Abstract. In this study we compared the effects of fire on understorey vegetation in the Québec southern boreal forest with effects of salvage‐logging (clear‐cutting after fire). All 61 400‐m2 sampling sites were controlled for overstorey composition (Deciduous, Mixed and Coniferous) and disturbance type, which consisted of three fire impact severity (FIS) classes (Light, Moderate and Extreme) and two harvesting techniques (Stem‐only and Whole‐tree Harvesting). Percent‐cover data of vegetation and post‐disturbance environmental characteristics were recorded in the field during the first two years after fire as well as soil texture. Ordination of fire alone demonstrated that, on Coniferous sites, fire initiates a succession whereby the understorey Coniferous sites approaches that of Deciduous‐Mixed sites, due to the release of the understorey from Sphagnum spp. dominance, this pattern being a function of FIS. On Deciduous‐Mixed stands, increased FIS resulted in a transition from herb to shrub dominance. Ordination of all five disturbance types showed that the impact of salvage‐logging on understorey composition was within the range of fire, but marginalized to the extreme end of the FIS spectrum. Variance partitioning demonstrated that overstorey and soil texture were the most important explanatory variables of fire alone, while disturbance type explained the largest independent fraction of understorey variation when salvage‐logging was introduced. Salvage‐logging also results in significant reductions in understorey abundance, richness and diversity, while indicator species analysis suggests that it favours mesoxerophytic to xeric species. Results are interpreted in light of shade‐tolerance dynamics, forest floor disturbance and soil moisture regimes. Implications for sustainable forest management are discussed.
Experimental trampling and vegetation recovery in some forest and heathland communities
Authors: Roovers P. , Verheyen K. , Hermy M. , Gulinck H.
Published: February 2009

Abstract. Over the past decades outdoor recreation has become progressively more important and as a result human‐induced potential damage has increased. In this study, short‐term effects – a 2‐yr period – of human trampling on some common forest and heath communities in Central Belgium were studied experimentally. Vulnerability to disturbance was compared among plant communities in terms of resistance, resilience and tolerance, which are based on cover measurements. The herb layer of the examined mesophilous forest communities appeared to be more sensitive than the heath and dry forest community, which were dominated by more resistant graminoid (Molinia caerulea, Deschampsiaflexuosa) and dwarf‐shrub species (Vaccinium myrtillus, Calluna vulgaris, Erica tetralix). The analysis showed that site structure and vegetation were already affected by low intensities of trampling, while vegetation recovery during the first year after trampling was limited in most plant communities. Recovery during the second year in vegetation cover as well as height was most pronounced in mesophilous forest communities. Occasional trampling clearly can lead to increased visual evidence of previous use and continued recreational disturbance. Therefore management plans should discourage hiking activity off paths and restrict recreation activities to the least vulnerable communities.
A new forest cover map of continental southeast Asia derived from SPOT‐VEGETATION satellite imagery
Authors: Stibig H.‐J. , Achard F. , Fritz S.
Published: February 2009

Question: Can recent satellite imagery of coarse spatial resolution support forest cover assessment and mapping at the regional level?

Location: Continental southeast Asia.

Methods: Forest cover mapping was based on digital classification of SPOT4‐VEGETATION satellite images of 1 km spatial resolution from the dry seasons 1998/1999 and 1999/2000. Following a geographical stratification, the spectral clusters were visually assigned to land cover classes. The forest classes were validated by an independent set of maps, derived from interpretation of satellite imagery of high spatial resolution (Landsat TM, 30 m). Forest area estimates from the regional forest cover map were compared to the forest figures of the FAO database.

Results: The regional forest cover map displays 12 forest and land cover classes. The mapping of the region's deciduous and fragmented forest cover remained challenging. A high correlation was found between forest area estimates obtained from this map and from the Landsat TM derived maps. The regional and sub‐regional forest area estimates were close to those reported by FAO.

Conclusion: SPOT4‐VEGETATION satellite imagery can be used for mapping consistently and uniformly the extent and distribution of the broad forest cover types at the regional scale. The new map can be considered as an update and improvement on existing regional forest cover maps.
A new practical tool for deriving a functional signature for herbaceous vegetation
Authors: Hunt R. , Hodgson J.G. , Thompson K. , Bungener P. , Dunnett NP. , Askew AP.
Published: February 2009

Hypothesis: For any one time and place a ‘functional signature’ can be derived for a sample of herbaceous vegetation in a way that concisely represents the balance between the different clusters of functional attributes that are present among component species.

Methods: We developed a spreadsheet‐based tool for calculating functional signatures within the context of the C‐S‐R system of plant functional types. We used the tool to calculate and compare signatures for specimen British vegetation samples which differed in management regime and location in time.

Conclusion: The integrative power of the ‘C‐S‐R signature’ is useful in comparative studies involving widely differing samples. Movements in the signature can be used to indicate degree of resistance, resilience, eutrophication and dereliction. Systems of plant functional types other than C‐S‐R might also be approached in this way.

Availability: The tool can be downloaded free of charge from the first author's web pages or from the journal's electronic archive.
Landscape, soil and meteorological influences on canopy dynamics of northern flooding Pampa grasslands, Argentina
Authors: Posse Gabriela , Oesterheld Martín , Bella Di , Marcelo Carlos
Published: February 2009

Question:How do meteorological variations at seasonal, interannual scales differentially affect the canopy dynamics of four contrasting landscape units within a region?

Location:Flooding Pampa, Buenos Aires, Argentina. 5000 km2. Central point: 35°15′S, 57°45′W.

Methods:We used a 19‐year series of the normalized difference vegetation index (NDVI) derived from NOAA‐AVHRR PAL (Pathfinder AVHRR Land) images and meteorological data provided by a nearby weather station. The NDVI was used as surrogate of canopy photosynthetic status. The relationship between annually integrated NDVI and meteorological conditions was explored by stepwise multiple regressions for each defined unit. PC A was performed to compare units and growing seasons on a multivariate basis.

Results:Mean seasonal NDVI curve was similarly shaped among landscapes. However, the absolute values differed widely. There was high interannual variation so that the mean seasonal pattern was seldom observed in any particular year. Annually integrated NDVI of all landscapes was negatively associated with summer temperature and positively with previous year precipitation. It was also directly related with current year winter precipitation in two landscapes and with summer precipitation in the others. NDVI response to September and March precipitation accounted for some of the differences in interannual variation among landscapes.

Conclusions:Our results revealed a strong intra‐regional variation of canopy dynamics, closely linked to landscape (vegetation‐soil) and water availability (mainly in summer and during the previous year). These links may be used to predict forage production rates for livestock.
Disturbance of suburban Fagus forests by recreational activities: Effects on soil characteristics, above‐ground vegetation and seed bank
Authors: Amrein Dominik , Rusterholz Hans‐Peter , Baur Bruno
Published: February 2009

Questions: How does recreational disturbance (human trampling) affect soil characteristics, the performance of the understorey vegetation, and the density and species composition of the soil seed bank in Fagus sylvatica forests?

Location: Suburban forests near Basel, northwestern Switzerland.

Methods: We compared various soil characteristics and the performance of the understorey vegetation in six beech forest areas frequently disturbed by recreational activities with those in six undisturbed control areas, in spring 2003. In the same forest areas, the soil seed bank was investigated using the seedling emergence method. Samples were obtained from soil cores in January 2003.

Results: We found substantial changes in soil compaction, above‐ground vegetation and in the soil seed bank due to recreational activities. In frequently visited areas, soil compaction was enhanced which caused a decrease in cover, height and species richness of both herb and shrub layers. Compared with control areas, the number of trampling‐tolerant species of the seed bank was significantly higher in disturbed areas, and total species richness tended to be higher in disturbed than in control areas. Furthermore, the similarity in species composition between the above‐ground vegetation and seed bank was significant lower in disturbed than in control areas.

Conclusions: The intensive use of suburban forests for recreational activities, mainly picnicking, affects the vegetation of natural beech forests. Our study indicates that a restoration of degraded forest areas from the soil seed bank would result in a substantial change of the vegetation composition.
Conservation of genetic diversity in old‐growth forest communities of the southeastern United States
Authors: Hamrick J.L. , Godt Mary Jo W. , Gonzales Eva
Published: February 2009

Question: How do studies of the distribution of genetic diversity of species with different life forms contribute to the development of conservation strategies?

Location: Old‐growth forests of the southeastern United States.

Methods: Reviews of the plant allozyme literature are used to identify differences in genetic diversity and structure among species with different life forms, distributions and breeding systems. The general results are illustrated by case studies of four plant species characteristic of two widespread old‐growth forest communities of the southeastern United States: the Pinus palustris – Aristida stricta (Longleaf pine – wiregrass) savanna of the Coastal Plain and the Quercus – Carya – Pinus (Oak‐hickory‐pine) forest of the Piedmont. Genetic variation patterns of single‐gene and quantitative traits are also reviewed.

Results: Dominant forest trees, represented by Pinus palustris(longleaf pine) and Quercus rubra (Northern red oak), maintain most of their genetic diversity within their populations whereas a higher proportion of the genetic diversity of herbaceous understorey species such as Sarracenia leucophylla and Trillium reliquum is distributed among their populations. The herbaceous species also tend to have more population‐to‐population variation in genetic diversity. Higher genetic differentiation among populations is seen for quantitative traits than for allozyme traits, indicating that interpopulation variation in quantitative traits is influenced by natural selection.

Conclusion: Developing effective conservation strategies for one or a few species may not prove adequate for species with other combinations of traits. Given suitable empirical studies, it should be possible to design efficient conservation programs that maintain natural levels of genetic diversity within species of conservation interest.
Comparison of three devices for estimating fire temperatures in ecological studies
Authors: Wally Alaä L. , Menges Eric S. , Weekley Carl W.
Published: February 2009

Questions:Are calorimeters and pyrometers accurate and reliable for describing fire parameters in large‐scale ecological projects, and can data from them predict data derived from thermocouples? Do mechanical pre‐treatments in Florida scrub areas alter fire properties?

Location:Lake Wales Ridge, Florida, USA.

Methods:We deployed thermocouples attached to digital dataloggers, copper and lacquer paint pyrometers and aluminium can calorimeters filled with water in four areas of undisturbed Florida scrub and sandhill vegetation and in adjoining areas pre‐treated with logging, subcanopy felling or mowing. Individual dataloggers were positioned in areas spanning a range of vegetation structure; three calorimeters and three pyrometers were placed with each thermocouple. We also deployed individual calorimeter‐pyrometer pairs. Sites were burned, after which we compared methods for characterizing fire, particularly the ability of pyrometers and calorimeters to predict values derived from thermocouples.

Results:Pyrometers best predicted peak 1‐minute mean temperatures and were least successful at estimating maximums. Calorimeters were associated with the number of minutes maximum temperatures exceeded 60 ßC, but were damaged at high residence times and inconsistent at low temperatures. Both pyrometers and calorimeters detected site and treatment differences in fire intensities. These analyses and logistic considerations give pyrometers an edge over calorimeters in situations where dataloggers are impractical. Mechanical pre‐treatments to fire altered fire parameters. Mowing reduced fire temperatures but had different effects on areas burned; this was related to the length of time elapsed between mowing and burning. Subcanopy felling increased both fire coverage and temperatures.

Conclusion:Pyrometers outperformed calorimeters as a cheap method for describing relative temperature regimes that are a function of both temperature and residence time. Pyrometers were able to demonstrate how mechanical treatments applied prior to prescribed burning altered fire parameters. Pyrometers are a useful tool for investigating biological responses to fire at multiple scales and in heterogeneous vegetation.
The effects of groundwater discharge, mowing and eutrophication on fen vegetation evaluated over half a century
Authors: van Belle Jasper , Barendregt Aat , Schot Paul P. , Wassen Martin J.
Published: February 2009

Questions: Were continued groundwater discharge and mowing regimes sufficient for vegetation preservation from 1944 to 1993? Which has a stronger effect on vegetation development; groundwater discharge or mowing? What is the role of surface water eutrophication as driver of vegetation change?Location: Het Hol, The Netherlands (ca. 92 ha, 52°13′N, 5°05′E).

Methods: Hydrology was simulated for the late 1940s, early 1960s and 1987. Vegetation maps (1944, 1960, 1975 and 1993) were compared for biotope cover. Vegetation recordings in 1944 and 1987 were compared. Surface water quality was compared between 1950 and 1987. Which sites were mown was reconstructed from an interview. Effects of periodic mowing and groundwater discharge on vegetation development were tested for correlation.

Results: Biotope diversity reduced significantly through decrease of semi‐aquatic and tall‐herb biotopes, and expansion of forest. The quagfen terrestrialization sere nearly disappeared from 1987 recordings, while the reed sere did well concerning abundance and species richness. Several typical (rich) fen species disappeared from recordings, while new species were mostly field margin species. Periodic mowing and discharge combined are correlated with increasing species numbers. The P‐concentration in surface water increased while N‐concentration decreased.

Conclusions: Preservation of the reed sere was successful, whereas preservation of the quagfen sere was not. Periodic mowing and discharge stimulate species richness, discharge more so than periodic mowing. But slight eutrophication likely induced a shift from P‐limitation to N‐limitation, which stimulated the reed sere at the expense of the quagfen sere.
Comparison of nitrogen and phosphorus fluxes in some European fens and floodplains
Authors: Wassen Martin J. , Olde Venterink Harry
Published: February 2009

Question: How do nitrogen and phosphorus budgets and balances differ between eutrophic fens and floodplains in western Europe and fens and floodplains in Poland, where we expect less eutrophication to occur?

Location: Wetlands along the rivers Dommel (The Netherlands), Zwarte Beek (Belgium) and Biebrza (NE Poland).

Methods: Assessment of external input and output fluxes as well as net N‐mineralization rates. Annual N‐ and P‐balances were estimated by the sum of all external input and output fluxes: atmospheric deposition, input of dissolved matter by flooding, input of sediment by flooding, input by groundwater, output by leaching, output by hay‐making and for N also input by N2‐fixation. For N we also estimated net annual N‐availability for plant growth, i.e. the N‐budget, which includes net mineralization in soil.

Results: The studied wetland sites had a negative balance, which means that nutrients are depleted but only if mown annually, except for the Dutch/Belgian fens which had an equilibrium N‐balance and the Polish fen which had an equilibrium P‐balance. For the N‐budget it appeared that atmospheric deposition added significantly to the budget of Dutch/Belgian fens and N‐mineralization added significantly to fen and floodplain budgets, except for the Polish fens. Mineralization dominates the N‐budget of the western European floodplains. Hay‐making is the most important output pathway, particularly if practised annually. It seems to diminish N‐enrichment in the Dutch fens and floodplains.

Conclusions: We conclude that western European fens and floodplains as well as Polish floodplains have a significant positive N‐budget indicating that there is a surplus of N for plant growth. In the Polish fens this is less due to low atmospheric deposition and lower N‐mineralization rates. The latter is associated with less drying out of the studied Polish ecosystems in summer. Our approach, although an approximate quantification, is helpful for assessing priorities focused on nutrient management.
Scaling hierarchy of factors controlling riparian vegetation patterns of the Fynbos Biome at the Western Cape, South Africa
Authors: Sieben E.J.J. , Mucina L. , Boucher C.
Published: February 2009

Question: How can vegetation gradients be described in riparian zones located in a species‐rich mountain range and how do these gradients explain the variation found in the vegetation?

Location: Hottentots Holland Mountains, Western Cape, South Africa.

Methods: Three gradients (geographic, longitudinal, lateral) were defined to describe the complex vegetation patterns found here. The gradients are related as follows: (1) the geographic gradient: related to the climatic and topographical changes across the entire mountain range; (2) the longitudinal gradient related to the changes along the different river reaches; (3) the lateral gradient related to the processes along the profile of the riverbed. These three gradients operated on three different hierarchical levels. Partial Canonical Correspondence Analysis (pCCA) was used to determine the amount of variation that is explained on each of the hierarchical levels.

Results: The geographical gradient explained the highest fraction (more than 50%) of the total variation explained. This can be ascribed to the high species turnover across landscapes in the Fynbos Biome; this is most likely an outcome that is specific for this region. The second most important gradient was the lateral gradient, which reflects stream power and inundation frequencies of the river. This gradient is represented by ca. 48% of the explained variation and this gradient explains the major disturbances occurring in a riverine ecosystem. The longitudinal gradient was the least important of the gradients and shows overlap with the geographical gradient.

Conclusions: In the species‐rich environment of the Fynbos Biome geographical factors do not only account for variation in zonal vegetation but also for variation within azonal vegetation, like riparian corridors.
Positive density dependence in seedlings of the neotropical tree species Garcinia macrophylla and Xylopia micans
Authors: Anderson Jill T.
Published: February 2009

Question: The Janzen‐Connell hypothesis predicts that herbivores and pathogens prevent seedlings from establishing in dense patches near adult conspecifics. Although many studies have investigated the Janzen‐Connell hypothesis, the environmental context – local or regional – in which juveniles establish is often overlooked. The objectives of this study were: (1) to evaluate Janzen‐Connell effects in contrasting environments, and (2) to incorporate microsite variation into the study of this hypothesis.

Location: Pacaya‐Samiria Reserve, Peru.

Methods: I assessed seedling performance of two tree species, Garcinia macrophylla and Xylopia micans, during one growing season. In an observational study, mortality and growth rates were regressed against distance to the nearest adult conspecific, conspecific seedling density, heterospecific plant density, and several abiotic variables in upland and floodplain forests. Field and shadehouse experiments were used to isolate distance‐ and density‐dependent effects.

Results: Contrary to predictions, seedling survivorship increased in the presence of conspecific seedlings (Garcinia) and heterospecific understory plants (Garcinia and Xylopia) in the observational study. Survivorship in the field experiment, however, was unaffected by conspecific seedling density or adult proximity. In the shadehouse, Garcinia growth rates were highest in floodplain soils collected near adult conspecifics, but mortality was unrelated to the soil's habitat or proximity to an adult.

Conclusions: The positive density dependence found in this study could have been produced by: (1) environmental factors that increase both density and survivorship, or (2) interspecific facilitation, if heterospecifics reduce herbivore or pathogen pressure on the focal species. Such interactions could help explain species coexistence in tropical forests.
Effects of water regime and habitat continuity on the plant species composition of floodplain forests
Authors: Glaeser Judith , Wulf Monika
Published: February 2009

Questions: 1. How big is the difference in the herbaceous layer composition between flooded and unflooded stands? 2. Are there species or species groups which have an affinity to ancient vs. recent forests in stands with different water regimes? 3. Are patterns of life history traits different between flooded and unflooded stands as well as between ancient and recent forests in stands with a different water regime?

Location: Floodplain forests in the Middle Elbe region and district of Leipzig, Central Germany.

Location: The herbaceous layer was studied in randomly selected quadrats of 9 m2 in 2000 and 2001. Six ancient (nplot=59) and six adjacent recent forests (nplot=108) were investigated in flooded stands as well as three ancient (nplot=41) and three recent forests (nplot=70) in stands that have not been flooded for 50 years. The association of single species, species groups and life history traits were statistically tested for flooded vs. unflooded stands and for ancient vs. recent forests.

Results: Interruption of flooding caused a complete species turnover in the herbaceous layer composition. Whereas in the still flooded stands typical alluvial species prevail, species composition in stands without flooding for 50 years showed a closed relation to the Stellario‐Carpinetum. Six herbaceous species in the flooded and five in the unflooded stands showed a preference for ancient forests. Only one species in the flooded and six herbaceous species in the unflooded stands are significantly associated with recent forests. Life history traits differ between flooded and unflooded stands but are similar in ancient and recently flooded stands, while unflooded ancient forests have more geophytes and myrmecochorous species than recent forests.

Conclusions: The specificity of species composition in floodplain forests can only be maintained by regular flooding. Interruption of inundations lead to differences in the patterns of species composition and life history traits between ancient and recent forests.
Wage Flexibility and Labour Market Institutions: A Meta‐Analysis
Authors: Clar Miquel , Dreger Christian , Ramos Raúl
Published: February 2009

Evidence during the nineties about the response of real wages to shocks highlights that this response is substantially lower in European countries than in the United States and that there are important differences among European countries. Which are the reasons that explain these different reactions? In this paper, we apply meta‐analytical techniques in order to provide a quantitative summary of the available evidence regarding the influence of labour market institutions on real wage flexibility. We find that the design of the study affects the obtained results, and that in more deregulated labour markets with a lower presence of trade unions, this response is particularly larger.
Contrasting community responses to fertilization and the role of the competitive ability of dominant species
Authors: Liancourt P. , Viard‐Crétat F. , Michalet R.
Published: February 2009

Question: Do contrasting biotic contexts in nutrient‐poor grasslands affect the predictability of invasion by exploitative species following fertilization?

Location: French Alps.

Methods: We examined community responses after 2 years of nutrient addition for two nutrient‐poor European calcareous grasslands, a mesoxeric community dominated by the short bunchgrass Bromus erectus and a mesic community dominated by the tall rhizomatous grass Brachypodium rupestre. We also performed reciprocal transplantations of these two dominant slow‐growing species and Arrhenatherum elatius, a tall fast‐growing grass that dominates nutrient‐rich communities and is likely to invade nutrient‐poor communities after fertilization. Transplants were grown with or without neighbors, in order to measure their individual responses (without neighbors) and competition intensity (by comparing performances with and without neighbors using the Relative Neighbor Effect index – RNE) during one growing season in all three communities.

Results: In the Bromus community, fertilization induced a strong increase in fast‐growing grasses (including A. elatius). Competition intensity was low for the three transplanted grasses, but strongly increased with resource addition, to reach values observed in the Arrhenatherum community. In the Brachypodium community, no change in competition intensity with fertilization was detected, because of the high mortality of the two “non‐resident” species, irrespective of the presence of neighbors.

Conclusions: Community responses to nutrient improvement are context‐dependent and vary as a function of the biotic environment. Soil processes are proposed as the main drivers of community resistance to the invasion of fast‐growing species in the mesic, nutrient‐poor grassland dominated by the large conservative competitor B. rupestre.
A California grasslands alkali specialist, Hemizonia pungens ssp. pungens, prefers non‐alkali soil
Authors: Veblen Kari E. , Young Truman P.
Published: February 2009

Question: Edaphically severe habitats commonly support edaphic endemics, specialized plant species that do not occur elsewhere. The endemism of native plant species in edaphically specialized habitats suggests either (a) that these native endemic species are uniquely specialized to survive and grow better under the conditions prevalent in these harsh areas, or (b) that these areas represent refuges from competition with other (often exotic) species.

Location: Central Valley, California, USA.

Methods: We surveyed the vegetation distribution in alkali sinks and carried out a reciprocal transplant greenhouse experiment crossed with a competition treatment to examine the interplay between interspecific competition and edaphic factors in determining relative performance of an alkali endemic forb (Hemizonia pungens ssp. pungens) and its exotic grass competitor (Lolium multiflorum).

Results: Lolium consistently performed better in non‐alkali soil. In contrast, Hemizonia, in the absence of competition, performed significantly better on the non‐alkali soils, but in competition with Lolium, performed equally well on alkali and non‐alkali soils.

Conclusions: These results suggest that Hemizonia does not inherently prefer harsh alkali soil, but is better able to tolerate alkali soil and may be excluded from more moderate soils by competition. Therefore, edaphic and biotic effects may interact to determine the spatial distribution of this edaphic endemic. Our data suggest a mechanism by which competition between native and exotic species on impoverished soils leads to dominance of native species and creation of refugia for native species where exotic species are unable to thrive.
Relative climatic, edaphic and management controls of plant functional trait signatures
Authors: Pakeman Robin J. , Lepš Jan , Kleyer Michael , Lavorel Sandra , Garnier Eric ,   the VISTA consortium
Published: February 2009

Objective: To identify the relative roles of climatic, edaphic and management factors in controlling the weighted mean traits of vegetation.

Location: Eleven sites in Europe and one in Israel undergoing transitions in land use.

Material and Methods: Standardised methods were used to collect information on species traits and attributes from plots covering a range of land uses at each site. This was combined with abundance data to create a plot × trait matrix. Variance partitioning was used to identify the relative roles of climate, soil and management on the weighted and unweighted mean traits of the vegetation in the full data set, and the data set divided into vegetative traits (including life‐form, clonality, defence and a range of leaf traits) and traits linked to regeneration via seeds (including seed mass, dispersal and pollination mechanism).

Results: Variance partitioning of the full data set showed that climate (18.7%), explained more variance in the weighted mean traits of the vegetation than climate and soil together (9.2), soil (6.9) and management (6.1). There was a similar distribution of variance explained for both vegetative and regeneration via seed traits, although more variance was explained for the latter. This restricted set of climatic, edaphic and management variables could explain 45‐50% of the variance in the weighted mean traits of the vegetation between plots. There were only small differences between analyses of the weighted and unweighted data.

Conclusions: Despite large variations in climate and soils between sites, there was still a separate and recognisable impact of management on the mean weighted traits of the vegetation. There was also a degree of shared variation between the three groups of factors, indicating that the response of plant traits to one group of factors may not be predictable because they may be modulated by their response to other groups.