bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Performance and Automatic Capture Characteristics of a 3.5‐mm2 Passive Fixation Lead during 1‐Year Follow‐Up
Authors: LOTZE ULRICH , FISCHER SVEN , HÖFS TILL , LIEBETRAU JOHANNES , FETTIN WOLFGANG , SCHEINER JÖRG , LANG ANDREAS ,   for the German IsoFlex Lead Registry Investigators
Published: July 2009

Background: Bipolar low polarization electrodes are recommended for a regular AutoCapture™ (St. Jude Medical, Inc., Sylmar, CA, USA) function in order to effectively detect the evoked response (ER) signal. The objective of this national multicenter registry was to evaluate the electrical performance and the AutoCapture™ characteristics of the bipolar ventricular pacing lead IsoFlex S, model 1636T or 1646T (St. Jude Medical), in combination with single‐ and dual‐chamber pacemakers.

Methods: Ventricular pacing and sensing thresholds, lead impedance, ER amplitude, and polarization signals were measured at discharge and routine follow‐up visits after 1, 3, 6, 9, and 12 months. AutoCapture™ activation was recommended based on the results of the ER sensitivity test.

Results: Of the 252 patients initially included, 109 (43%) have completed the follow‐up. The mean ventricular pacing threshold was 0.43 ± 0.19 V at discharge and 0.68 ± 0.32 V at 12 months postimplant. The values for the ventricular sensing threshold were between 9.51 ± 4.12 and 9.99 ± 4.09 mV at discharge and at the 12‐month follow‐up. The unipolar lead impedance decreased from 533 ± 94 to 476 ± 73 ohms during the follow‐up. The mean ER amplitude was 16.47 ± 6.70 mV at discharge and 17.42 ± 7.43 mV after 12 months, and the corresponding mean polarization signals were 0.59 ± 1.00 and 0.74 ± 1.24 mV, respectively. AutoCapture™ activation was recommended in at least 95% of the patients investigated over the 12‐month follow‐up.

Conclusion: The bipolar ventricular pacing lead IsoFlex S 1636/1646T shows a good electrical performance and is mostly compatible with the AutoCapture™ algorithm.
Is There a Role for Statins in Atrial Fibrillation?
Authors: DAWE DAVID E. , ARIYARAJAH VIGNENDRA , KHADEM ALIASGHAR
Published: July 2009

3‐Hydroxy‐3‐methyl‐glutaryl‐CoA reductase inhibitors (statins) are some of the most commonly prescribed drugs in the world. While lipid modification remains the primary function of statins, there has been increasing interest in its potential pleiotropic effects, particularly as an anti‐inflammatory agent in its role as an antiarrhythmic. Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and carries with it a significant burden in both morbidity and mortality. Treatment for AF currently involves either rate or rhythm control where both have demonstrable associated risks. Rate control necessitates anticoagulation, which can cause life‐threatening bleeding, while rhythm control has a poor side‐effect profile that may lead to greater mortality and may not completely eliminate the need for anticoagulation. Considering this pressing need for novel therapeutic interventions in AF, this long overdue systematic review explores the potential role of statins in the treatment and prevention of AF. Physicians, especially cardiologists, need to be aware of the host of currently available literature and, more importantly, need to be stimulated to generate discussion and formulate studies that will help debate the issues under the most erudite standards.
Cardioversion for Atrial Fibrillation: Treatment Options and Advances
Authors: REIFFEL JAMES A.
Published: July 2009

Atrial fibrillation (AF) is associated with significant morbidity and mortality. There are two basic approaches to managing AF: slowing the ventricular rate, while allowing the arrhythmia to continue (the rate‐control approach), and restoring and maintaining sinus rhythm (the rhythm‐control approach) with antiarrhythmic drugs (AADs) and/or ablation, electrical cardioversion (CV), if needed, or both. Strategy trials comparing rate and rhythm control have found no survival advantage of one approach over the other, but other considerations, such as symptom reduction, often necessitate pursuit of rhythm control. Electrical, or direct current, CV is a widely used and effective method for termination of nonparoxysmal AF, although its success can be affected by patient‐ and technique‐related variables. Pharmacological CV options also exist and are preferable in specific circumstances. Both pharmacological and electrical CV are associated with the risk of proarrhythmia. Many AADs are under development for both CV and maintenance of sinus rhythm. Some are atrioselective, such as vernakalant, and target ion channels in the atria, with little or no effects in the ventricle. Vernakalant, currently under Food and Drug Administration review, appears to offer a safer profile than current CV agents and is likely to expand the role of pharmacological CV. Other new AADs that provide increased efficacy or safety while maintaining normal sinus rhythm may also be better than current drugs; if so, rate‐rhythm comparisons will differ from those of previous studies. In conclusion, further trials should clarify the long‐term safety profiles of new atrioselective agents and other investigational drugs and define their role in the treatment of AF.
Catheter Ablation of Atrial Fibrillation in the Elderly
Authors: YAMADA TAKUMI , KAY G. NEAL
Published: July 2009

The incidence and prevalence of atrial fibrillation (AF) increase with age. Catheter ablation has been suggested to improve the quality of life of patients with AF. However, in order to expand the indications for AF ablation to the elderly, several important questions should be answered as to whether safety and efficacy of AF ablation in elderly patients are similar to those in younger populations, whether the AF mechanisms in elderly patients are similar to those in younger patients so that the same ablation techniques can be used in both groups, and whether anticoagulation strategies should be the same for elderly patients as for younger patients after AF ablation. Recent studies reported that the risk of complications from AF ablation did not vary with age, nor was the AF recurrence rate age‐dependent for any type of AF, suggesting that the AF mechanisms in elderly patients were similar to those in younger patients. On the other hand, the feasibility of discontinuation of anticoagulation in the elderly after successful AF ablation has not been established since it is difficult to be certain whether AF has been truly cured and since many elderly people are likely to be considered as high‐risk based on their CHADS2 score. In addition, the elderly patients who have been included in published trials of AF ablation may not represent an unselected population of individuals in this age group. Randomized trials of catheter ablation will be necessary before this procedure can be promoted for wider use in the elderly.
ICD Implantation in Noncompaction of the Left Ventricular Myocardium: A Case Report
Authors: COPPOLA GIUSEPPE , GUTTILLA DANIELA , CORRADO EGLE , FALLETTA CALOGERO , MARRONE GIANLUCA , FARULLA RICCARDO AIRÒ , CIARAMITARO GIANFRANCO , ASSENNATO PASQUALE , NOVO SALVATORE
Published: July 2009

Isolated noncompaction of the ventricular myocardium (INVM) is an uncommon cardiomyopathy characterized by the persistence of fetal myocardium with prominent trabecular meshwork and deep intertrabecular recesses, often associated with systolic dysfunction and ventricular dilatation. A 23‐year‐old man from Burkina Faso was referred to our operative unit with a diagnosis of INVM, made with echocardiogram and magnetic resonance imaging and nonsustained ventricular tachycardia. The literature reports the incidence of malignant ventricular arrhythmias in as many as 47% of the patients and sudden cardiac death in almost 50% of them and this supported our decision to perform implantable cardioverter‐defibrillators implantation.
ICD Proarrhythmia as a Consequence of an Interaction with an Algorithm to Prevent Atrial Arrhythmias
Authors: MARTÍNEZ‐SÁNCHEZ JUAN , GARCÍA‐ALBEROLA ARCADI , SÁNCHEZ‐MUÑOZ JUAN JOSÉ , PEÑAFIEL‐VERDÚ PABLO , GINER‐CARO JOSÉ ANTONIO , VALDÉS‐CHÁVARRI MARIANO
Published: July 2009

An episode of device‐related proarrhythmia is reported. Ventricular tachycardia was induced by ventricular pacing in a dual‐chamber implantable cardioverter‐defibrillator due to an inappropriate interaction of programmed device settings with the atrial preference pacing, an automatic algorithm designed to prevent atrial tachyarrhythmias.
Microstructural Investigation of Ba(Ti(1−x)Mnx)O3 Ceramics with 6H‐ and 12R‐Polytypes
Authors: Wu Yu‐Chuan , Wang Sea‐Fue , Chen Shin‐Hong
Published: July 2009

Ba(Ti1−xMnx)O3 ceramics were synthesized by a traditional solid‐state reaction. The Ba(Ti1−xMnx)O3 samples with x=0.15, 0.3, 0.4, and 0.5 of MnO, Mn2O3, and Mn3O4 were sintered at 1450°C for 2 h, then cooled to room temperature to obtain hexagonal barium titanate. The microstructures and dielectric properties of the Ba(Ti1−xMnx)O3 samples were analyzed by dielectric property measurement, X‐ray diffractometry, scanning electron microscopy, and transmission electron microscopy (TEM). The results showed that the lattice parameters decrease as the x value increases from 0.15 to 0.5, and a secondary phase, which is similar to BaFeO3 structure (JCPDS 74‐0646), was detected at x=0.5. With an increasing x, the grains developed a plate‐like morphology. For samples with MnO additive, the secondary phase, which is similar to Ba2TiO4 structure (JCPDS 38‐1481), was detected on the grain boundaries due to the excess of divalent Ba ions. For samples with Mn2O3 and Mn3O4 additives, the liquid phase and nanocrystalline Mn2O3 grains were detected due to the excess of Ti and Mn atoms. For dielectric properties, the quality factor (Q×f ) reaches the maximum value (18 344 GHz) at x=0.3 for the addition of Mn3O4. The TEM analysis was focused on the Ba(Ti0.5Mn0.5)O3 specimens in order to identify the relationship between the 6H‐ and 12R‐structures, and their formation mechanism.
Effect of Co2O3 Additive on Structure and Electrical Properties of 85(Bi1/2Na1/2)TiO3–12(Bi1/2K1/2)TiO3–3BaTiO3 Lead‐Free Piezoceramics
Authors: Hu Hanchen , Zhu Mankang , Xie Fangyan , Lei Na , Chen Jian , Hou Yudong , Yan Hui
Published: July 2009

In this paper, Co2O3‐added‐85(Bi1/2Na1/2)TiO3–12(Bi1/2K1/2)TiO3–3BaTiO3 (BNKB) lead‐free piezoceramics were fabricated by the conventional solid oxide routine. By the use of X‐ray photonic spectra, X‐ray diffraction, and scanning electronic microscope, the valence state of Co cations, lattice distortion, and microstructures were investigated. It is revealed that the Co2O3 addition affects the concentration of Co3+ cations and changes the tetragonality c/a of the perovskite lattice. The variation in tetragonality and microstructure, combined with the acceptor doping behavior of Co2O3, play a determinant role in the depolarization temperature Td, mechanical quality factor Qm, and other electrical properties of the ceramics. The Td is elevated to 157°C for 0.5 mol% Co2O3 addition; and the Qm reaches a maximum of 626 at 1.5 mol% Co2O3 addition, which is in the highest flight compared with other BNKB ceramics reported until now.
Properties of Liquid‐Phase Deposited Silica Films for Low‐k Dielectric Applications
Authors: Wang Liwei , Yu Shijun , Cho Junghyun
Published: July 2009

Both the electrical and mechanical properties of silica thin films deposited by liquid phase deposition (LPD) have been evaluated in this study. Silica thin films have been prepared on glass surface by immersing it in a supersaturated Hexafluorosilicic acid (H2SiF6)‐based solution at a low temperature of 50°C. The as‐deposited LPD silica films exhibit a low dielectric constant (k) that varies from 1.7 to 2.7 depending on the film morphology and fluorine content of the film. Young's modulus of these films was measured in the range of 18.9–24.5 GPa by a nanoindentation technique. The combination of extremely low k and fairly high modulus made this low‐temperature‐processed LPD silica films a very promising candidate for an interlayer dielectric film for the next‐generation semiconductor devices.
Transference Numbers for In‐Plane Carrier Conduction in Thin Film Nanostructured Gadolinia‐Doped Ceria Under Varying Oxygen Partial Pressure
Authors: Podpirka Adrian , Ramanathan Shriram
Published: July 2009

We demonstrate a modified Hebb–Wagner approach to quantitatively estimate transference numbers for carrier conduction in thin film oxide conductors using blocking electrodes in an in‐plane geometry. We report ionic transference numbers, ti, for gadolinia‐doped ceria (GDC) thin films, a model mixed ion–electron conductor, at 973K and oxygen partial pressure ranging from 0.21 atm down to approximately 10−22 atm. Our results indicate that GDC reaches the electrolytic regime (ti=0.5) at an oxygen partial pressure of 5 × 10−19 atm at 973K. This approach may be useful for understanding carrier transport mechanisms in low‐dimensional oxide heterostructures with specific relevance to nanostructured energy materials.
Impact of grazing regime on a Mongolian forest steppe
Authors: Van Staalduinen Marja A. , During Heinjo , Werger Marinus J.A.
Published: July 2009

Question: What is the impact of grazing regime on plant species abundance, plant growth form, plant productivity and plant nutrient concentrations in a forest steppe?

Location: Hustai National Park in the forest steppe region of Mongolia.

Methods: On the Stipa steppe we applied three different grazing regimes by using; (1) one type of exclosure which excluded grazing by large mammalian herbivores, mainly takh (Przewalski horse), (2) another type of exclosure that excluded both large and small (Siberian marmots) mammalian herbivores, and (3) control plots which were freely grazed. We measured species frequencies, tiller densities, plant biomass and nitrogen concentrations of the vegetation.

Results: Exclusion from grazing by takh and marmots significantly increased plant standing crop, but marmot grazing and full grazing did not show significant differences. Protection from grazing decreased forage quality, shown by a lower N‐concentration of the standing crop. However, this was solely the result of the lower live‐dead ratio of the vegetation. The frequency of the rhizomatous Leymus chinensis decreased under reduced grazing, as did the frequency of the total of rhizomatous species. The frequency of Stipa krylovii increased under reduced grazing, as did its basal areas, tiller density and tussock height.

Conclusion: Reduced grazing leads to a lower abundance of rhizomatous species and an increase in tussock species.
Dynamics of species‐rich upland hay meadows over 15 years and their relation with agricultural management practices
Authors: Critchley C.N.R. , Fowbert J.A. , Wright B.
Published: July 2009

Questions: Has the species‐rich vegetation of upland hay meadows been maintained under low intensity management imposed by an agri‐environment scheme? Is the target plant community re‐establishing where it has been modified previously by intensive agricultural practices? What combinations of management practices and soil properties are associated with changes towards or away from the target community?

Location: The Pennines, northern England, UK.

Methods: A survey of 116 hay meadows in 1987 was repeated in 2002 by recording plant species in permanent quadrats. Changes in community variables (species richness, Ellenberg values, upland hay meadow community coefficients) were analysed in species‐rich, modified species‐rich and degraded grassland types. Redundancy Analysis and Generalised Linear Models were used to show the relationship between management practices and soil properties and change in species composition and community variables.

Results: Few sites contained the species‐rich grassland type, and here forb richness declined. In the modified species‐rich type, total and grass species richness increased but Ellenberg N‐values also increased. Total and grass species richness increased in the degraded type and the community coefficient increased. Management was weakly related to change in species composition but showed clear relationships with the community variables. Re‐establishment of the target species‐rich community was more likely with late cutting, in the absence of cattle or prolonged spring grazing, and at lower soil nutrient status.

Conclusion: The species‐rich community was not maintained but some reversion occurred in degraded grassland. Inorganic fertiliser application and intensive spring grazing should be avoided and cutting delayed until late July.
Using satellite imagery to assess plant species richness: The role of multispectral systems
Authors: Rocchini D. , Ricotta C. , Chiarucci A.
Published: July 2009

Question: The use of variations in the spectral responses of remotely sensed images was recently proposed as an indicator of plant species richness (Spectral Variation Hypothesis, SVH). In this paper we addressed the issue of the potential use of multispectral sensors by testing the hypothesis that only some of the bands recorded in a remotely sensed image contain information related to the variation in species richness.

Location: Montepulciano Lake, central Italy.

Methods: We assessed how data compression techniques, such as Principal Component Analysis (PCA), influence the relationship between spectral heterogeneity and species richness and evaluated which spectral interval is the most adequate for predicting species richness by means of linear regression analysis.

Results: The original multispectral data set and the first two non‐standardized principal components can both be used as predictors of plant species richness (R2∼ 0.48; p < 0.001), confirming that PCA is an effective tool for compressing multi‐spectral data without loss of information. Using single spectral bands, the near infrared band explained 41% of variance in species richness (p < 0.01), while the visible wavelengths had much lower prediction powers.

Conclusions: The potential of satellite data for estimating species richness is likely to be due to the near infrared bands, rather than to the visible bands, which share highly redundant information. Since optimal band selection for image processing is a crucial task and it will assume increasing importance with the growing availability of hyperspectral data, in this paper we suggest a ‘near infrared way’for assessing species richness directly from remotely sensed data.
Long‐term effects of nitrogen deposition on vegetation in a deciduous forest near Munich, Germany
Authors: Bernhardt‐Römermann M. , Kudernatsch T. , Pfadenhauer J. , Kirchner M. , Jakobi G. , Fischer A.
Published: July 2009

Question: What are the main reasons for changes in the spatial distribution of vegetation types during the last four decades?

Location: Isolated small deciduous forest; surrounded by farmland in the northeast of Munich (Germany).

Methods: Based on sequential vegetation mapping from the last four decades the spatial development of the vegetation was analysed. Additionally, environmental parameters (soil parameters, PAR, N‐deposition) have been analysed to describe the different vegetation types.

Results: By linking the vegetation types to environmental parameters, it was possible to identify N‐deposition as the most important factor for the changes. In the 1960s to 1980s the replacement of vegetation types adapted to N‐poor conditions by N‐rich vegetation was very fast. A vegetation type containing species signifying soil impoverishment vanished totally, another vegetation type indicating nutrient poor conditions decreased dramatically. However, since 1985 up to now the decrease of N‐poor vegetation types has slowed, but is still ongoing. As a reason for the decreased rate of replacement, we stressed changes in the vertical structure: From 1961 to 1985 both N‐deposition as well as changes in vertical vegetation structure seem to be important. Since 1985 up to now only minor changes in vertical structure could be found; changes are mainly due to N‐availability.

Conclusion: In this paper, the limitations of different methods to detect vegetation changes are discussed. We focus on the potentials of historical vegetation data and vegetation maps. It is shown that valuable information on N‐induced vegetation changes can be retrieved from historical vegetation data.
Using long‐term monitoring of fen hydrology and vegetation to underpin wetland restoration strategies
Authors: Large A.R.G. , Mayes W.M. , Newson M.D. , Parkin G.
Published: July 2009

Question: How can long‐term monitoring of hydrological and ecological parameters support management strategies aimed towards wetland restoration and re‐creation in a complex hydrological system?

Location: Newham Bog National Nature Reserve, Northumberland, UK, a site with a long history of active management, and recorded as drought‐sensitive over the last 100 years.

Methods: Water level readings are correlated with longer‐term hydrological databases, and these data related to vegetation data collected intermittently over a 12 year period. Two analyses are undertaken: (1) a composite DCA analysis of 1993 and 2002 survey data to assess plant community transitions within the wetland and over time, and (2) analysis of recent vegetation data to explore wider vegetation gradients. This allows (3) communities to be classified using NVC classes and (4) integrated with revised Ellenberg F‐values.

Results: Drought impact and subsequent hydrological recovery over a 22‐year period are quantified. Vegetation data display strong moisture and successional gradients. Analysis shows a shift from grassland communities toward mire communities across much of the site.

Conclusion: The site is regionally unique in that it has a detailed long‐term monitoring record. Hydrological data and vegetation survey have allowed the impact of the most recent ‘groundwater’drought (1989–1997) to be quantified. This information on system resilience, combined with eco‐hydrological analyses of plant community‐water regime/quality relationships, provide a basis for recommendations concerning conservation and restoration.
A multi‐site assessment of the effectiveness ofPteridium aquilinumcontrol in Great Britain
Authors: Cox E.S. , Marrs R.H. , Pakeman R.J. , Le Duc M.G.
Published: July 2009

Questions:The objectives of this study were to assess the effect ofPteridium aquilinum(bracken) control treatments, at the national scale, and the impact of restoration practices, at the local scale, onP. aquilinumperformance.

Hypotheses:1. Geographical location (locally between and within sites) affects the control ofP. aquilinumthrough time. 2. Are theP. aquilinumcontrol treatments successful at all sites, and if so which ones? 3. The treatments applied at the individual site level to restore vegetation influences the performance ofP. aquilinumthrough time.

Location:Four geographically distinct acid grassland and heathland sites infested withP. aquilinumacross Great Britain.

Methods:Six main‐plot, bracken control treatments were applied to all sites with site‐specific vegetation restoration treatments. Response variables (P. aquilinumcover, frond length and density) were monitored twice yearly, in June and August between 1993 and 2003.

Results:Between‐ and within‐site spatial variation was found, although impact is perhaps less than suggested from shorter‐term data. Despite local variation all sites responded similarly to bracken control treatments; asulam treatment resulted in a rapid reduction in frond performance followed by a continued recovery taking approximately ten years to return to untreated values. Cutting treatments tended to have a slower impact at the start but an increasing one over time, especially cutting twice per year. Restoration treatments had a limited impact; the only significant effect in August was grass seeding on frond length at Sourhope. In June only, the plots where sheep were fenced out showed a significant reduction inP. aquilinumcover at Peak.

Conclusions:Long‐term control ofPteridium aquilinumat all sites and on all measures was best achieved using a continuous cutting treatment, preferably twice per year.
Effects of topsoil removal, seed transfer with plant material and moderate grazing on restoration of riparian fen grasslands
Authors: Rasran L. , Vogt K. , Jensen K.
Published: July 2009

Question: How do moderate grazing, topsoil removal and hay transfer affect species diversity and abundance on a eutrophic fen grassland site?

Location: Northern Germany.

Method: A three‐factorial field experiment with the factors grazing, topsoil removal and hay transfer of diaspore‐rich material was established in 2001. Soil nutrients and seed bank were analysed at the beginning of the experiment, species composition and vegetation development was monitored for four years (2002–2005).

Results: Topsoil removal had a significant effect on the abundance of different plant species groups: resident vegetation of agricultural grasslands was suppressed, while clonal reed species were facilitated in recolonising the area. The establishment of regionally rare and endangered species of nutrient‐poor fens and wet meadows introduced with hay was achieved mainly on plots with topsoil removal, with the exception of Rhinan‐thus angustifolius, which also established on plots with intact topsoil. Effects of grazing after four years of experiments were of minor influence on species composition.

Conclusion: The establishment of target plant species of nutrient‐poor fens is most successful when both an adequate number of viable diaspores and suitable sites for germination and establishment are available. In our experiment this was achieved by the combination of topsoil removal and hay transfer. We recommend this combination, together with continuous management (grazing/cutting), for further restoration in fen grasslands.
The spatial relationship between post‐crop remaining trees and the establishment of saplings inPinus sylvestrisstands in Spain
Authors: Montes F. , Cañellas I.
Published: July 2009

Question:What is the spatial relationship between remaining trees and the establishment and development of recruited saplings?

Location:ThePinus sylvestrisforestPinar de Valsaín, in the Sistema mountain range (central Spain).

Methods:Three 0.5 ha plots have been analysed. The saplings were located in a 2 m x 2 m grid, characterizing their spatial pattern through a nested ANO VA. The spatial pattern of stems was analysed using theL(d)function. To analyse the spatial relationship between stems belonging to different cohorts, the intertypeLrs(d)function was used. Finally a new functionKrx(d)is presented as a method to analyse the relationship between the spatial distribution of stems and the sapling density (a sampled continuous variable).

Results:The mother trees show cluster pattern at scales of ca. 12 m ‐ 22 m, leading to a spatial pattern at 14 m–16 m for the saplings during the regeneration period. At the beginning of the shelter phase, saplings less than 1.30 m in height show spatial repulsion from the old crop at distances above 10 m, whereas taller saplings show repulsion at shorter distances, due to the suppression of sapling development near the mother trees. At the end of the regeneration period, saplings < 1.30 m appear under the last remaining mother tree canopies.

Conclusions:In the stands analysed, located at the southern limit ofPinus sylvestrisdistribution, this species behaves as half‐shade tolerant. This study shows that theKrx(d)function might be widely applied to analyse the relationship between patterns that occur at different scales or between a point pattern and a continuous variable, being a useful tool for analysing some forest processes.
Optimal management of the rare Gladiolus imbricatus in Estonian coastal meadows indicated by its population structure
Authors: Moora Mari , Kose Marika , Jõgar Ülle
Published: July 2009

Questions: What is the best grassland management regime for the threatened plant species Gladiolus imbricatus; is the stage structure of local populations a feasible indicator of the effect of changed management.

Location: Coastal meadow system in southwestern Estonia. Methods: The effect of five management regimes was studied in a long‐term (three‐year) field experiment: (1) mowing in late July, (2) grazing by cattle, (3) grazing by sheep, (4) sheep grazing during the first year and mowing during subsequent years, (5) no management (control).

Results: The population density increased significantly in response to the mowing treatment and to the mowing after sheep grazing treatment. The proportion of grazed plant individuals was higher in the sheep‐grazed than in the cattle‐grazed treatment. Generative and vegetative adult individuals of G. imbricatus were significantly more damaged by cattle herbivory than juveniles. All management regimes shifted the population structure towards a dynamic state where juvenile stages dominate, while the not managed control retained a regressive population structure.

Conclusions: Population stage structure was a useful indicator of different management conditions, even in the case where population density did not differ. As indicated by population stage structure, the best management regime for G. imbricatus was either mowing in late July only, or alternation of grazing and mowing in different years.
Improving predictive mapping in Swiss mire ecosystems through re‐calibration of indicator values
Authors: Feldmeyer‐Christe Elizabeth , Ecker Klaus , Küchler Meinrad , Graf Ulrich , Waser Lars
Published: July 2009

Question: How may Landolt indicator values be re‐calibrated to improve the performance of predictive models?

Location: Mires Gross Moos Schwändital (1250 m a.s.l.) in the Prealps, Burgmoos (465 m. a.s.l.) on the Central Plateau and La Burtignière (1000 m a.s.l.) in the Jura, Switzerland.

Methods: Habitat distribution models based on high resolution remotely sensed data and vegetation field data are applied to monitor 130 mires. Instead of plant species or communities we used mean indicator values of vegetation records as response variables. To improve the differential power of indicator values for wetland habitat conditions, we calibrated these values using field data. Different methods were tested with our predictive models in three mires to see which calibration method is best in enhancing model performance. To assess the effect of the uneven distribution of vegetation records along environmental gradients, calibrations based on random and evenly distributed samples were compared. As a test of the predictive power of the models we used r2 between ground truth and model prediction.

This approach is illustrated through an application with nutrient indicator values in the mire La Burtignière. Results: Model performances were not the same for the three mires. The predictive power was better for the nutrient values, soil reaction and humus values than for light and moisture values. 2000 records were sufficient as basis for re‐calibration. Models based on original Landolt indicator values were overall the weakest compared with re‐calibrated values. By comparing the predictive power of Models based on randomly or evenly selected records were about equally predictive.

Conclusions: 1. Ahabitat‐specific re‐calibration of the Landolt indicator values enhances the predictive mapping of the Swiss mire ecosystems. 2. The re‐calibration based on weighted averaging gives a better performance than the one based on Gaussian logistic regression. 3. The uneven distribution of indicator values due to the over‐representation of mire habitats does not hamper model performance. 4. 2000 vegetation records are a sufficient basis for an optimal re‐calibration of the vegetation types. An illustration of the method is given by using the soil fertility pattern of the mire La Burtignière.
Monitoring succession from space: A case study from the North Carolina Piedmont
Authors: McDonald Robert I. , Halpin Patrick N. , Urban Dean L.
Published: July 2009

Question: Is the successional transition from pine to hardwood, which has been inferred from chronosequence plots in previous studies, validated through a time line of satellite imagery?

Location: Durham, North Carolina, USA.

Methods: We examined successional trends in a time‐series of winter‐summer pairs of Thematic Mapper imagery from 1986 to 2000. We calculated the normalized difference of vegetation index (NDVI) for winter and summer, as well as the difference between summer and winter NDVI (i.e., summer increment NDVI). A set of approximately 50 forest stands of known age and phenology were used to interpret patterns in winter and summer increment NDVI over successional time, and a continuum was found to exist between pine‐dominance and hardwood‐dominance. We fitted a series of linear regressions that modeled the change in winter and summer increment NDVI as a function of initial winter and summer increment NDVI, and additional explanatory variables.

Results: All regressions were highly significant (P < 0.0001, R2= ca. 0.3). Predicted dynamics are in accord with successional theory, with pixels moving from evergreen dominance to deciduous dominance along a line of fairly constant summer NDVI. A large disturbance event that occurred over the course of this study, Hurricane Fran, appeared to slow rates of succession in the short term (1–3 years), but increase the rate of conversion to hardwoods over longer time spans.

Conclusions: We conclude that temporal sequences of remote sensing images provide an excellent opportunity for broad‐scale monitoring of successional processes, and that continuous metrics of that change are essential to accurate monitoring.
Improving knowledge of urban vegetation by applying GIS technology to existing databases
Authors: Altobelli A. , Bressan E. , Feoli E. , Ganis P. , Martini F.
Published: July 2009

Question: Can we improve the knowledge of urban vegetation using data from ongoing floristic and management projects with a data mining approach? We have two questions: 1. How strong is the relationship between land cover pattern and the species composition of vegetation? 2. What is the relationship between land cover pattern and species richness?

Location: Trieste, northeastern Italy.

Methods: Using land cover maps and GIS we characterized the cells of a floristic project grid by percentage cover of land cover types. We applied Canonical Correlation Analysis to test the correlation between floristic composition of the cells and land cover. We classified the cells by clustering methods, based on land cover description. With these clusters, we analysed the variation of species composition of urban vegetation along a gradient of urban density. We used Jaccard's similarity index to compare floristic composition of the clusters with the floristic composition of the homogeneous cells with respect to the land cover types. To answer question 2, we calculated land cover heterogeneity with the Shannon index and correlated the number of species in clusters with land cover heterogeneity and urban density.

Results: Each land cover type contributes to species richness and species composition of the clusters. Species richness decreases significantly and linearly as urban density increases and land cover heterogeneity decreases in the clusters.

Conclusions: A data mining approach can combine different existing projects to improve knowledge of the urban vegetation system. The methods we have applied offer tools to answer the specific questions mentioned above.
Facilitation and interference underlying the association between the woody invaders Pyracantha angustifolia and Ligustrum lucidum
Authors: Tecco P.A. , Díaz S. , Gurvich D.E. , Perez‐Harguindeguy N. , Cabido M. , Bertone G.A.
Published: July 2009

Questions: 1. Is there any post‐dispersal positive effect of the exotic shrub Pyracantha angustifolia on the success of Ligustrum lucidum seedlings, as compared to the effect of the native Condalia montana or the open herbaceous patches between shrubs? 2. Is the possible facilitation by Pyracantha and/or Condalia related to differential emergence, growth, or survival of Ligustrum seedlings under their canopies?

Location: Córdoba, central Argentina.

Methods: We designed three treatments, in which ten mature individuals of Pyracantha, ten of the dominant native shrub Condalia montana, and ten patches without shrub cover were involved. In each treatment we planted seeds and saplings of Ligustrum collected from nearby natural populations. Seedlings emerging from the planted seeds were harvested after one year to measure growth. Survival of the transplanted saplings was recorded every two month during a year. Half of the planted seeds and transplanted saplings were cage‐protected from rodents.

Results:
Ligustrum seedling emergence did not differ among treatments while growth was significantly higher in the absence of shrub cover. Sapling survival was significantly higher under the canopy of Pyracantha, intermediate under Condalia, and lowest in the absence of shrub cover. Caging did not affect growth but enhanced seedling emergence and sapling survival.

Conclusion: The differential sapling survival in the shrub canopy treatments is consistent with natural sapling distribution. Pyracantha and, less so, Condalia, has a nurse‐plant effect on Ligustrum. This results from contrasting effects of the shrubs on different stages of the life cycle of Ligustrum: no effect on seedling emergence, negative on seedling growth, and positive on sapling survival. This suggests that efforts to control the expansion of Ligustrum over the landscape should tackle Pyracantha as well.
Regional species pools of hay meadows: A case study
Authors: Losvik Mary H.
Published: July 2009

Questions: Is it possible to render the species pool concept operational for cultural landscape management and restoration?

Location: Hordaland and Sogn & Fjordane counties, western Norway.

Methods: An initial regional species list, based on information on the distribution of species and habitats in the Norwegian flora, was filtered using information on target communities and species lists from 95 sites in the region. Owing to the importance of both mowing and grazing Ellenberg indicator values were not used in the identification process.

Results: The final regional species pool consisted of 227 species, of which 194 were extracted from the flora, while 33 agricultural landscape species were added from the actual pool or from a list of species in additional hay meadows. Some of the 33 species were regular inhabitants of hay meadows, others were rare in the region. The regional species pool list includes information on each species on demands when hydrology, nutrients and base saturation in the soil is concerned, and whether or not they are characteristic for either of the boreal or boreo‐nemoral vegetation zones.

Conclusions: Specialist knowledge was an advantage when adding cultural landscape species other than meadow species of the flora; 77 species were documented only by the flora, interesting from the point of view of restoration as this part of the pool would not have been found by just adding species lists. The diversity of the now isolated hay meadow sites in the region may be kept up by replacing the lost natural invasion by an artificial one, using local seed mixtures and transplants.
Prescribed fires in Artemisia tridentata ssp. vaseyana steppe have minor and transient effects on vegetation cover and composition
Authors: Seefeldt Steven S. , Germino Matthew , DiCristina Katherine
Published: July 2009

Question: What is the impact of prescribed fires on the cover and composition of vegetation in Artemisia tridentata ssp. vaseyana steppe?

Location: United States Department of Agriculture, Agricultural Research Service, United States Sheep Experiment Station, eastern Idaho (44°14′44′’ N, 112°12′47′’ W).

Methods: Multiple prescribed fires were lit in 2002 and 2003 in an Artemisia tridentata ssp. vaseyana (mountain big sagebrush) steppe ecosystem that was relatively free of exotic plants. Measurements of cover components and plant species frequencies were taken pre‐ and for 2 to 3 years post‐fire.

Results: Cover of forbs and grasses returned to pre‐fire levels after two years. Shrub cover declined from 36 to 6% in the first year post‐fire. Fire reduced the frequencies of three species, A. tridentata ssp. vaseyana, Festuca idahoensis, and Cordylanthus ramosus, of rangeland plants. Frequencies of four plant species, Hesperostipa comata, Polygonum douglasii, Chenopodium fremontii and Chenopodium leptophyllum increased, but only P. douglasii increased for more than a year.

Conclusion: This study demonstrates that in an Artemisia tridentata ssp. vaseyana steppe ecosystem without significant non‐native species or anthropogenic disturbances vegetative cover and species composition of the herbaceous community are only minimally altered by fire. The herbaceous component returned to pre‐fire conditions within three years of a fire.
Biodiversity of semi‐arid Mediterranean grasslands: Impact of grazing and afforestation
Authors: Alrababah M.A. , Alhamad M.A. , Suwaileh A. , Al‐Gharaibeh M.
Published: July 2009

Question: What is the impact of grazing and/or afforestation on grassland diversity, species composition and cover parameters?

Location: Semi‐arid Mediterranean grasslands of Jordan.

Methods: Vegetation, litter, bare soil and rock cover were compared among four management types – free grazing and protected from grazing with three levels of tree cover. Species composition, plant cover, species richness and evenness were used to evaluate differences in vegetation among management types. Species composition differences among management types were also investigated.

Results: Semi‐arid Mediterranean grasslands harbour appreciable levels of plant biodiversity. Grazing did not affect plant diversity, indicating the high resilience against and adaptation to grazing; however,grazing affected species composition and cover parameters. Afforestation seems to protect soil through higher litter cover but its impact on plant biodiversity was negative and markedly affected species composition.

Conclusions: Neither protection from grazing or massive afforestation alone are sufficient for conserving biodiversity in this system. A management model is suggested where the landscape should be maintained as a mosaic of four management types: complete protection from grazing, grazing rotation, planting sparse trees in eroded areas and revegetating degraded areas using native, herbaceous and grazing tolerant species.
Vegetation response after restoring the connectivity between a river channel and its floodplain
Authors: Vercoutere B. , Honnay O. , Hermy M.
Published: July 2009

Questions: How is restored inundation affecting the ground‐water composition in a floodplain? To what extent has the floodplain plant community composition changed? What are the effects of flooding frequency and intensity and water quality on the floodplain vegetation changes?

Location: Demer river, Flanders, Belgium.

Methods: 75 10 m x 10 m plots were surveyed in 1997 and in 2003. Vegetation changes were quantified using a Detrended Correspondence Analysis on the combined 1997–2003 data‐set. Groundwater quality in the floodplain was analysed on macro‐ions. Inundation intensity and frequency were related to vegetation changes.

Results: The inundation water was rich in nutrients, although only for NH4 and ortho‐PO4, and a significant increase was recorded in the groundwater. Plant species characteristic of very nutrient‐rich herb vegetation disappeared or decreased while the cover and species richness of species from wet, moderately productive habitats increased. Very few new species colonized the floodplain.

Conclusion: Nutrient‐rich flooding water does not necessarily result in increased abundance of species from nutrient‐rich habitats, very likely because N becomes less available by deni‐trification and is transformed into biomass by tall herbs. Either micro‐site limitation or dispersal limitation could explain the colonization problems of new species. The data do not allow distinction between these two mechanisms.
Ground layer heterogeneity and hardwood regeneration in mixed oak forest
Authors: Rinkes Zachary L. , McCarthy Brian C.
Published: July 2009

Question: What are the effects of small‐scale litter disturbances (simulating large vertebrate scratching and foraging), on Quercus alba, Q. velutina, Fagus grandifolia, and Acer rubrum seedling recruitment?

Location: Southeastern Ohio, USA.

Methods: Two mixed oak forests containing four experimental management units (burned, thinned, thinned & burned, and un‐manipulated control) were utilized in this study. Silvicutural treatments were applied in the spring of 2001. A small scale disturbance experiment was initiated in the spring of 2002 (Trial 1) and was replicated again in the spring of 2003 (Trial 2). Experimental hardware cloth exclosures, each containing a control (ambient litter) and experimentally scratched (litter removed to bare soil) compartment, were erected in each management unit (N= 8 exclosures per unit).

Results:
Acer rubrum, a species that occupies a wide germination niche, produced the most numerous seedlings. Nut‐producing species established more readily in compartments with ambient leaf litter, while A. rubrum was unresponsive to scratching treatment. Units burned (surface leaf litter removed at a broad scale) had the lowest rate of seedling recruitment in Trial 1.

Conclusions: These data suggest that an adequate cover of leaf litter is needed to promote optimal recruitment. Control units had the greatest rate of seedling recruitment in Trial 2. The development of a dense understory layer (promoting excessive shading) between Trial 1 and Trial 2 may have affected the recruitment rate in the thinned and thinned & burned units.
Assessing species density and abundance of tropical trees from remotely sensed data and geostatistics
Authors: Hernández‐Stefanoni J. Luis , Dupuy Juan Manuel , Castillo‐Santiago M. Angel
Published: July 2009

Question: What relationships exist between remotely sensed measurements and field observations of species density and abundance of tree species? Can these relationships and spatial interpolation approaches be used to improve the accuracy of prediction of species density and abundance of tree species?

Location: Quintana Roo, Yucatan peninsula, Mexico.

Methods: Spatial prediction of species density and abundance of species for three functional groups was performed using regression kriging, which considers the linear relationship between dependent and explanatory variables, as well as the spatial dependence of the observations. These relationships were explored using regression analysis with species density and abundance of species of three functional groups as dependent variables, and reflectance values of spectral bands, computed NDVI (normalized difference vegetation index), standard deviation of NDVI and texture measurements of Landsat 7 Thematic Mapper (TM) imagery as explanatory variables. Akaike information criterion was employed to select a set of candidate models and calculate model‐averaged parameters. Variogram analysis was used to analyze the spatial structure of the residuals of the linear regressions.

Results: Species density of trees was related to reflectance values of TM4, NDVI and spatial heterogeneity of land cover types, while the abundance of species in functional groups showed different patterns of association with remotely sensed data. Models that accounted for spatial autocorrelation improved the accuracy of estimates in all cases.

Conclusions: Our approach can substantially increase the accuracy of the spatial estimates of species richness and abundance of tropical tree species and can help guide and evaluate tropical forest management and conservation.