bluuebunny/crossref_metadata_2025 huggingface dataset:
Instructional Practices, Struggling Readers, and a University‐Based Reading Clinic
Authors: Dunston Pamela J.
Published: February 2007

The author shares insights gained through teaching middle and high school struggling readers and raises issues related to the complexity of addressing the literacy needs of adolescents for whom reading is difficult. The role of university‐based reading clinics in helping inservice teachers' think differently about struggling readers and the instructional practices they use to support adolescents' literacy learning is discussed.

The author describes five key components of a program she developed for inservice teachers who work with struggling readers in the reading clinic at her university:

Moving teachers beyond their comfort zones

Using multiple forms of text

Teaching demonstrations followed by extensive peer feedback

Self‐evaluation and reflection

Scaffolding by building on adolescents' literacy strengths rather than focusing on weaknesses

The components are designed to expand teachers' experiences with teaching struggling readers, enhance their knowledge of reading instruction, and improve instructional practices for teaching literacy.
Assessing Adolescents' Motivation to Read
Authors: Pitcher Sharon M. , Albright Lettie K. , DeLaney Carol J. , Walker Nancy T. , Seunarinesingh Krishna , Mogge Stephen , Headley Kathy N. , Ridgeway Victoria Gentry , Peck Sharon , Hunt Rebecca , Dunston Pamela J.
Published: February 2007

A team of researchers revised the Motivation to Read Profile for use with adolescents. Instruments to assess adolescents' in‐ and out‐of‐school reading motivations were administered. A survey adapted for adolescents was administered to 384 teens at eight sites throughout the United States and Trinidad, and 100 students were interviewed using a revised instrument designed to capture the real reading of adolescents today. The teens were asked questions about fiction, expository, and computer‐based reading materials; about what instruction in school motivated them to read; and in which classes was the reading material most difficult. Results revealed that student experiences with academic reading and writing did not match their interests and needs. The authors offer many recommendations for how students' preferred types of reading and instruction can be used in middle school and high school classrooms.
Effect of In Vitro Gingival Fibroblast Seeding on the In Vivo Incorporation of Acellular Dermal Matrix Allografts in Dogs
Authors: Novaes Arthur B. , Marchesan Julie Teresa , O. Macedo Guilherme , Palioto Daniela B.
Published: February 2007

Background: Acellular dermal matrix allograft (ADMA) has been used in various periodontal procedures with successful results. Because ADMA has no blood vessels or cells, slower healing and incorporation are observed compared to a subepithelial connective tissue graft. Fibroblasts accelerate the healing process by regulation of matrix deposition and synthesis of a variety of growth factors. Thus, the objective of this study was to evaluate histologically if gingival fibroblasts affect healing and incorporation of ADMA in dogs when used as a subepithelial allograft.

Methods: Gingival fibroblasts were established from explant culture from the connective tissue of keratinized gingiva collected from the maxilla of seven mongrel dogs. ADMA was seeded with gingival fibroblasts and transferred to dogs. Surgery was performed bilaterally, and the regions were divided into two groups: ADMA+F (ADMA containing fibroblasts) and ADMA (ADMA only). Biopsies were performed after 2, 4, and 8 weeks of healing.

Results: The quantity of blood vessels was significantly higher in the ADMA+F group at 2 weeks of healing (Kruskal‐Wallis; P <0.05). There was no statistical difference (P >0.05) in the number of cell layers, epithelial area, or inflammatory infiltrate between the two groups at any stage of healing.

Conclusion: The enhanced vascularization in vivo in early stages supports the important role of fibroblasts in improving graft performance and wound healing of cultured graft substitutes.
Distinctive Molecular Composition of Human Gingival Interdental Papilla
Authors: Csiszar Andrea , Wiebe Colin , Larjava Hannu , Häkkinen Lari
Published: February 2007

Background: Gingiva is composed of attached and marginal (free) gingiva and interdental papilla. Increasing esthetic demands in dentistry have created a need to restore all parts of the gingiva. However, the interdental papilla has limited regeneration potential compared to other parts of the gingiva. It also is more susceptible to gingival overgrowth, suggesting that it has distinct cellular and molecular properties from other parts of the gingiva. Very little is known about the possible differences in the molecular composition of different parts of the gingiva.

Methods: We compared the expression of a set of key molecules in interdental papilla and marginal gingiva from seven healthy subjects by immunohistochemical staining.

Results: In the interdental papilla, immunoreactivity for integrin αvβ6 and cytokeratin 19 in the oral epithelium was significantly higher than in marginal gingiva. Expression of type I procollagen, extra domain A (EDA) and extra domain B (EDB) fibronectin isoforms, tenascin‐C, transforming growth factor‐β (TGF‐β), connective tissue growth factor (CTGF), and the signaling molecule son‐of‐sevenless (SOS)‐1 also were increased in the interdental papilla. The expression of small leucine‐rich proteoglycans decorin, biglycan, fibromodulin, and lumican in the interdental papilla was partially different from the marginal gingiva.

Conclusions: Molecular composition of the interdental papilla is distinct from marginal gingiva. Increased expression of molecules normally induced in wound healing (αvβ6 integrin, fibronectin‐EDB and ‐EDA, tenascin‐C, type I procollagen, TGF‐β, CTGF, and SOS‐1) suggests that the cells in the interdental papilla are in an activated state and/or inherently display a specific phenotype resembling wound healing.
The Use of Porous β‐Tricalcium Phosphate Blocks With Platelet‐Rich Plasma as an Onlay Bone Graft Biomaterial
Authors: Tamura Kazuaki , Sato Shuichi , Kishida Mamoru , Asano Shoichi , Murai Masakazu , Ito Koichi
Published: February 2007

Background: An experimental study of rabbit calvaria evaluated the suitability of porous β‐tricalcium phosphate (β‐TCP) block as a biomaterial for onlay bone grafting and determined whether the addition of platelet‐rich plasma (PRP) can accelerate bone formation inside the pores of the β‐TCP block.

Methods: In eight rabbits, the calvarium was exposed, and the marrow was penetrated. The β‐TCP blocks were made of Ca3(CO4)3 (porosity, 75%; diameter, 8 mm; thickness, 5 mm). For the experimental group, the blocks were treated with PRP; for the control group, the blocks were treated with venous blood only. Each block was placed in the bone, attached with a titanium screw, and covered with a cutaneous flap. The animals were sacrificed after 3 months, and the tissue ingrowth into the blocks was euthanized.

Results: Histologic and histomorphometric measurements demonstrated that there was no inflammatory infiltration around the blocks in either group. New bone formation inside the blocks originated from the parent bone in both groups. The mineralized bone generated tended to climb along the inner walls of the block. In addition, mineralized bone formation was noted around the titanium screw. Furthermore, there was no significant difference between the experimental and control groups in the relative amounts of newly generated tissue and mineralized bone generated in the blocks.

Conclusion: Porous β‐TCP block is a promising biomaterial for clinical situations requiring bone augmentation; however, the addition of PRP did not induce significantly more new bone formation.
Three‐Dimensional Micro‐Computed Tomographic Imaging of Alveolar Bone in Experimental Bone Loss or Repair
Authors: Park Chan Ho , Abramson Zachary R. , Taba Mario , Jin Qiming , Chang Jia , Kreider Jaclynn M. , Goldstein Steven A. , Giannobile William V.
Published: February 2007

Background: Micro‐computed tomography (micro‐CT) offers significant potential for identifying mineralized structures. However, three‐dimensional (3‐D) micro‐CT of alveolar bone has not been adapted readily for quantification. Moreover, conventional methods are not highly sensitive for analyzing bone loss or bone gain following periodontal disease or reconstructive therapy. The objective of this investigation was to develop a micro‐CT methodology for quantifying tooth‐supporting alveolar bone in 3‐D following experimental preclinical situations of periodontitis or reconstructive therapy.

Methods: Experimental in vivo bone loss or regeneration situations were developed to validate the micro‐CT imaging techniques. Twenty mature Sprague‐Dawley rats were divided into two groups: bone loss (Porphyromonas gingivalis lipopolysaccharide‐mediated bone resorption) and regenerative therapy. Micro‐CT and software digitized specimens were reconstructed three‐dimensionally for linear and volumetric parameter assessment of alveolar bone (linear bone height, bone volume, bone volume fraction, bone mineral content, and bone mineral density). Intra‐ and interexaminer reproducibility and reliability were compared for methodology validation.

Results: The results demonstrated high examiner reproducibility for linear and volumetric parameters with high intraclass correlation coefficient (ICC) and coefficient of variation (CV). The ICC showed that the methodology was highly reliable and reproducible (ICC >0.99; 9‐% confidence interval, 0.937 to 1.000; CV <1.5%), suggesting that 3‐D measurements may provide better alveolar bone analysis than conventional 2‐D methods.

Conclusions: The developed methods allow for highly accurate and reproducible static measurements of tooth‐supporting alveolar bone following preclinical situations of bone destruction or regeneration. Future investigations should focus on using in vivo micro‐CT imaging for real‐time assessments of alveolar bone changes.
Tobacco as a Risk Factor for Survival of Dental Implants
Authors: Sánchez‐Pérez Arturo , Moya‐Villaescusa M.J. , Caffesse R.G.
Published: February 2007

Background: It has been shown that smoking habits represent an increased risk for impaired bone healing and implant failure. This study aimed to evaluate the implant survival rates among non‐smokers (NS) and different kinds of smokers (S).

Methods: A retrospective analysis was made over a 5‐year period of the clinical and radiographic findings corresponding to 66 consecutive patients who had received a total of 165 dental implants. Patients were divided into two groups: S, 40 patients (95 implants; 58% of the sample); and NS, 26 patients (70 implants; 42% of the sample). Also, S and NS were classified into four different categories according to daily tobacco use: NS, 26 patients and 70 implants; light smokers (LS), 23 patients and 44 implants; moderate smokers (MS), 11 patients and 25 implants; and heavy smokers (HS), six patients and 26 implants.

Results: Sixteen implants (9.7%) failed and had to be removed. Group S showed 15 failures and a success rate of 84.2%. Group NS had only one failure, giving a success rate of 98.6%. The risk of implant failure was ∼31% in those who smoked more than 20 cigarettes per day. HS showed statistical differences from NS or LS. However, they did not show any differences from MS.

Conclusions: Within the limits of the present study, the use of tobacco involves a 15.8% risk of implant failure, with a 13.1 odds ratio. LS or MS tobacco use involves a 10.1% relative risk of implant loss, whereas the consumption of >20 cigarettes per day increases this risk to 30.8%.
Hemostatic and Anesthetic Efficacy of 4% Articaine HCl With 1:200,000 Epinephrine and 4% Articaine HCl With 1:100,000 Epinephrine When Administered Intraorally for Periodontal Surgery
Authors: Moore Paul A. , Doll Bruce , Delie Robert A. , Hersh Elliot V. , Korostoff Jonathan , Johnson Sharon , Goodson J. Max , Halem Stephen , Palys Michael , Leonel Juliana S. , Kozlowski Vitoldo A. , Peterson Carrie , Hutcheson Matthew
Published: February 2007

Background: The objective of this double‐masked, randomized, multicenter crossover study was to compare the efficacy of 4% articaine HCl with 1:100,000 epinephrine (A100) to 4% articaine HCl with 1:200,000 epinephrine (A200) for providing effective local anesthesia and hemostasis for periodontal surgery.

Methods: Anesthetic efficacy was based on patient self‐report and lack of need for reinjection during the surgical procedures. Hemostatic properties of the formulations were compared using ratings of the surgeons’ ability to visualize the surgical field and expectation for bleeding. The volume of blood collected during each surgical session also was measured and compared.

Results: Forty‐two adult subjects (26 males and 16 females, mean age 46.3 ± 9.7 years) diagnosed with moderate to severe periodontal disease requiring local anesthesia for matched bilateral periodontal surgery were enrolled and completed the study. Subjects reported satisfactory surgical anesthesia following the A100 and A200 formulations; no supplemental local anesthesia was administered. Significant differences between the A100 and A200 treatments were found for the surgeons’ ability to visualize the surgical field (rated as clear 83.3% of the time with A100 and 59.5% of the time with A200; P = 0.008), bleeding expectation (rated as equal to or better than expected 85.7% of the time with A100 and 71.4% of the time with A200; P = 0.034), and volume of blood loss (54.9 ± 36.0 ml for A100 and 70.2 ± 53.0 ml for A200; P = 0.018). Sixteen patients experienced 27 mild or moderate adverse events; the most common were postoperative pain (nine patients) and swelling (eight patients). Six adverse events may have been related to treatment. The frequency of adverse events did not vary between formulations.

Conclusions: For patients undergoing periodontal surgery, 4% articaine anesthetic formulations containing epinephrine (1:100,000 or 1:200,000) provided excellent surgical pain control. For patients who can tolerate higher amounts of epinephrine, the 4% articaine 1:100,000 epinephrine formulation had the additional therapeutic advantage of providing better visualization of the surgical field and less bleeding.
Asthma Among Homeless Children in New York City: An Update
Authors: Grant Roy , Bowen Shawn , McLean Diane E. , Berman Douglas , Redlener Karen , Redlener Irwin
Published: February 2007

Homeless children in New York City had an extremely high asthma prevalence—40%—in a cross-sectional study at 3 shelters (n=740) during 1998 to 1999. We used the same protocol to summarize subsequent data through December 2002. Asthma prevalence was 33% (n=1636); only 15% of the children previously diagnosed were taking an asthma controller medication. Emergency department use was 59%. These data were used to support a class action lawsuit that was resolved in favor of homeless children with asthma in New York City.
Early Risk Factors, Job Strain, and Atherosclerosis Among Men in Their 30s: The Cardiovascular Risk in Young Finns Study
Authors: Kivimäki Mika , Hintsanen Mirka , Keltikangas-Järvinen Liisa , Elovainio Marko , Pulkki-Råback Laura , Vahtera Jussi , Viikari Jorma S.A. , Raitakari Olli T.
Published: February 2007

We examined whether preemployment influences confounded the association between job strain and atherosclerosis. We assessed biological, familial, and socioeconomic risk factors of coronary heart disease at 12 to 18 years of age and job strain and carotid artery intima-media thickness at 33 to 39 years of age for a cohort of 358 men.

Adolescent risk factors predicted adult intima-media thickness but had little effect on the dose–response relation between greater job strain and greater intima-media thickness. Pre-employment influences did not confound the association between job strain and atherosclerosis.
Socioeconomic Differences in the Impact of HIV Infection on Workforce Participation in France in the Era of Highly Active Antiretroviral Therapy
Authors: Dray-Spira Rosemary , Gueguen Alice , Ravaud Jean-François , Lert France
Published: February 2007

Objectives. We sought to measure the difference in employment rates between HIV-seropositive and HIV-seronegative persons and to establish whether this difference varied according to the HIV-infected persons’ socioeconomic position as defined by education level.

Methods. We used data from the VESPA (VIH: Enquête Sur les Personnes Atteintes) study, a large cross-sectional survey conducted among a nationally representative sample of 2932 HIV-infected patients in France. Age-, gender-, nationality-, and education-standardized employment rates were estimated with the French general population as the reference. The differences in employment rates with the general population were computed overall and according to education level.

Results. Compared with that of the general population, the overall employment rate was 25% lower (95% confidence interval [CI]=16%, 32%) among HIV-infected patients diagnosed before 1994 and 9% lower (95% CI = 5%, 16%) among HIV-infected patients diagnosed from 1994 onward. The difference in employment rates with the general population was significantly higher among patients with a low education level. The employment rate of highly educated HIV-infected patients diagnosed from 1994 onward did not differ from that of the general population.

Conclusions. HIV infection was associated with decreased workforce participation among those with a low education level but not among highly educated individuals.
Promoting Sun Safety Among US Postal Service Letter Carriers: Impact of a 2-Year Intervention
Authors: Mayer Joni A. , Slymen Donald J. , Clapp Elizabeth J. , Pichon Latrice C. , Eckhardt Laura , Eichenfield Lawrence F. , Elder John P. , Sallis James F. , Weinstock Martin A. , Achter April , Balderrama Cynthia , Galindo Gabriel R. , Oh Sam S.
Published: February 2007

Objectives. We examined whether US Postal Service letter carriers who received a sun safety intervention would wear wide-brim hats and sunscreen significantly more often than those who did not receive the intervention.

Methods. We used a 2-group randomized design with 2662 evaluation cohort participants from 70 US postal stations. Evaluations were conducted at baseline, 3 months, 1 year, and 2 years. Questionnaire items assessed occupational use of sun-screen and wide-brim hats. The 2-year sun safety intervention included the provision of wide-brim hats, accessible sunscreen, reminders, and 6 educational sessions.

Results. At the 3-month follow-up evaluations, the odds ratio (OR) for regular sun-screen use was 2.8 times higher among the intervention group than among the control group (95% confidence interval [CI]=2.2, 3.5); at the 2-year follow-up evaluations, the rate was still significantly higher (OR=2.0; 95% CI=1.6, 2.6). Intervention group participants also had significantly higher rates of hat use, with the differences remaining consistent across all follow-ups (OR=2.9; 95% CI=2.3, 3.6).

Conclusions. The intervention should be disseminated to postal stations nationwide and possibly to other occupational groups that work outdoors.
Work, Obesity, and Occupational Safety and Health
Authors: Schulte Paul A. , Wagner Gregory R. , Ostry Aleck , Blanciforti Laura A. , Cutlip Robert G. , Krajnak Kristine M. , Luster Michael , Munson Albert E. , O’Callaghan James P. , Parks Christine G. , Simeonova Petia P. , Miller Diane B.
Published: February 2007

There is increasing evidence that obesity and overweight may be related, in part, to adverse work conditions. In particular, the risk of obesity may increase in high-demand, low-control work environments, and for those who work long hours. In addition, obesity may modify the risk for vibration-induced injury and certain occupational musculoskeletal disorders.

We hypothesized that obesity may also be a co–risk factor for the development of occupational asthma and cardiovascular disease that and it may modify the worker’s response to occupational stress, immune response to chemical exposures, and risk of disease from occupational neurotoxins. We developed 5 conceptual models of the interrelationship of work, obesity, and occupational safety and health and highlighted the ethical, legal, and social issues related to fuller consideration of obesity’s role in occupational health and safety.
The Allegheny Initiative for Mental Health Integration for the Homeless: Integrating Heterogeneous Health Services for Homeless Persons
Authors: Gordon Adam J. , Montlack Melissa L. , Freyder Paul , Johnson Diane , Bui Thuy , Williams Jennifer
Published: February 2007

The Allegheny Initiative for Mental Health Integration for the Homeless (AIM-HIGH) was a 3-year urban initiative in Pennsylvania that sought to enhance integration and coordination of medical and behavioral services for homeless persons through system-, provider-, and client-level interventions.

On a system level, AIM-HIGH established partnerships between several key medical and behavioral health agencies. On a provider level, AIM-HIGH conducted 5 county-wide conferences regarding homeless integration, attended by 637 attendees from 72 agencies. On a client level, 5 colocated medical and behavioral health care clinics provided care to 1986 homeless patients in 4084 encounters, generating 1917 referrals for care.

For a modest investment, AIM-HIGH demonstrated that integration of medical and behavioral health services for homeless persons can occur in a large urban environment.
Raphael's PortraitLeo X with Cardinals Giulio de' Medici and Luigi de' Rossi: A Religious Interpretation
Authors: Minnich Nelson H.
Published: February 2007

A recent cleaning of the painting, scientific examinations of it, the publication of new letters related to it, and studies of the prophetic culture in which it was produced all call for a reevaluation of the traditional interpretations of Raphael's portraitLeo X with Cardinals Giulio de' Medici and Luigi de' Rossi. After a close analysis of the major iconographic details in the painting, the strengths and weaknesses of the various secular and religious interpretations of the painting are reviewed. That the painting is primarily religious in theme with prophetic and devotional overtones is argued as the most reasonable interpretation, given the iconographic details and context.
Tropes of Revelation in Raphael'sTransfiguration*
Authors: Cranston Jodi
Published: February 2007

The development of thecontrappostopose in Renaissance art depends, as is well known, on ancient discussions of the rhetorical figure of antithesis. Such philological associations, however, have drawn attention to the pose as a motif of style, notable only for its gracefulness of form. This essay considers how the turning pose in Raphael's work, rather than merely referring to the rhetorical figure of antithesis, evokes the thematic and structural significance of the trope. The discussion focuses on the turning female in hisTransfigurationas a figuration of the antithetical event of revelation, where the unknown becomes known.
Inventing Information Systems: The Systems Men and the Computer, 1950–1968
Authors: Haigh Thomas
Published: February 2007

During the 1960s, many academics, consultants, computer vendors, and journalists promoted the “totally integrated management information system” (MIS) as the destiny of corporate computing and of management itself. This concept evolved out of the frustrated hopes of 1950s corporate “systems men” (represented by the Systems and Procedures Association) to establish themselves as powerful “generalist” staff experts in administrative techniques. By redefining the computer as a managerial “information system,” rather than a simple technical extension of punch-card “data processing,” the systems men sought to establish jurisdiction over corporate computing and to replace accountants as the primary agents of managerial control. The apparently unlimited power of the computer supported a new conception of information, defined as the exclusive domain of the systems men (assisted by operations research specialists and computer technicians). While MIS proved impossible to construct during the 1960s, both its dream of all-encompassing automated information systems and the resulting association of information with the computer endured into the twenty-first century.
Robert Noyce and Fairchild Semiconductor, 1957–1968
Authors: Berlin Leslie R.
Published: February 2007

Robert Noyce's career at Fairchild Semiconductor sheds light on several developments that were central to the growth of Silicon Valley and the semiconductor industry: entrepreneurship, technical leadership, and the management of growth in a high-technology company. Noyce served as Fairchild Semiconductors first head of R&D and as its general manager for the six years of the company's most dramatic growth. His technical orientation, personal interest in new technologies, and hands-off management style helped establish a culture at the firm that welcomed innovations in research, process technology, manufacturing, and marketing. As Fairchild Semiconductor grew into a multidivisional mass producer, Noyce's entrepreneurial leadership proved inadequate. Communication breakdowns between divisions, coupled with a series of poor decisions by the parent company, further contributed to the decline of Fairchild Semiconductor.
Effects of litter accumulation on riparian vegetation: Importance of particle size
Authors: Xiong Shaojun , Nilsson Christer , Johansson Mats E.
Published: February 2007

Abstract. The floristic effects of river‐borne litter that accumulates in riparian zones may vary in space and time depending on variations in mass and particle size of the deposited litter. To analyse the effects of litter mass and size we applied differentsized litter (natural uncut pieces and powder) to riparian vegetation at different quantities. Vegetation responses were analysed after one season at the community level (total biomass or richness for all species) and species traits (biomass or richness for groups of species). At the community level uncut litter, but not powder, reduced species richness and both uncut and ground litter reduced above‐ground biomass. At the species trait level uncut litter had a stronger effect than powder on species richness and biomass. The only positive effect of litter addition was that powder increased graminoid species richness. The topsoil conditions indicated that the major impact of deposited, river‐borne litter was that it acted as a physical barrier directly preventing established plants from penetrating the litter layer and reducing light and soil temperature.
Responses of exotic plant species to fires in Pinus ponderosa forests in northern Arizona
Authors: Crawford Julie A. , Wahren C.‐H.A. , Kyle S. , Moir W.H.
Published: February 2007

Abstract. Changes in disturbance due to fire regime in southwestern Pinus ponderosa forests over the last century have led to dense forests that are threatened by widespread fire. It has been shown in other studies that a pulse of native, early‐seral opportunistic species typically follow such disturbance events. With the growing importance of exotic plants in local flora, however, these exotics often fill this opportunistic role in recovery. We report the effects of fire severity on exotic plant species following three widespread fires of 1996 in northern Arizona P. ponderosa forests. Species richness and abundance of all vascular plant species, including exotics, were higher in burned than nearby unburned areas. Exotic species were far more important, in terms of cover, where fire severity was highest. Species present after wildfires include those of the pre‐disturbed forest and new species that could not be predicted from above‐ground flora of nearby unburned forests.
Factors determining the modes of tree death in three Bornean rain forests
Authors: Gale Neil , Hall Pamela
Published: February 2007

Abstract. Mode of tree death in relation to topography was examined in three lowland rain forests; Belalong and Andalau, in Brunei Darussalam and Danum, in Sabah, East Malaysia. In total, 1543 dead trees ≥20 cm diameter at breast height (DBH) were enumerated in an area of 36 ha. In Belalong, 31% of the dead trees had died standing, 26% had snapped, 21% had uprooted, 19% had either died‐standing or snapped and 3% remained undetermined (n = 436). In Andalau, 46% had died standing, 11% had snapped, 14% had uprooted, 26% had either died standing or snapped and 3% remained undetermined (n = 591). In Danum, 37% had died standing, 22% had snapped, 14% had uprooted, 24% had either died‐standing or snapped and 3% remained undetermined (n = 516). Slope position, e.g. whether the tree was located in a valley, mid‐slope, upper slope or ridge, was related to mode of death in all three sites. Elevation and tree diameter were related in two of the sites, and drainage, soil depth and soil shear strength were related in one of the sites. Generally the proportion of standing deaths increased moving from the valleys up to the ridge tops while uprooting proportions had the converse relationship. Slope position had little effect on the proportions of snapped trees.

The three modes of death create different types of gaps. The findings substantiate that different topographies have different proportions of these gap types. The predominant gap type may have consequences for local and regional differences in forest structure and composition.
Spatial and temporal variability during primary succession on tropical coastal sand dunes
Authors: Martínez M. Luisa , Vázquez Gabriela , Sánchez Colón Salvador
Published: February 2007

Abstract. We studied primary succession on mobile tropical coastal sand dunes over an 8‐yr period. Every six months, we monitored changes in species composition and sand movement in permanent quadrats located on the windward slopes, the arms and the crests. Our results indicate that sand movement decreased over time but was significantly higher on the slopes and crests than on the arms. In all cases, there were seasonal fluctuations in sand movement which increased during the period with strong northerly winds and decreased during the rainy season. Sand movement was significantly correlated with species distribution. Plant cover and species richness increased at all three locations. Diversity increased on the slope, decreased on the arms and remained unchanged on the crest. However, the equitability values indicated the dominance of a few species, especially at the end of the study period. Temporal trends and species turnover rates differed among locations. Species turnover occurred first on the arms (1994), then on the crests (1998) and lastly on the slopes (at the end of the study period). In all cases the tall grass, Schizachyrium scoparium var. littoralis, became dominant over the endemic legume, Chamaecrista chamaecristoides var. chamaecristoides. Similar to temperate dunes, primary succession on tropical sand dunes was spatially and temporally heterogeneous.
Vertical structure of wet grasslands under grazed and non‐grazed conditions in Tierra del Fuego
Authors: Díaz Barradas M.C. , García Novo F. , Collantes M. , Zunzunegui M.
Published: February 2007

Abstract. We studied the vertical structure of wet grazed grasslands in Tierra del Fuego (southern Argentina). A point quadrat method was developed using a fine needle graduated in cm. The vertical and horizontal frequency of species and organs was quantified in samples collected from non‐grazed and grazed plots in the field. There was vertical stratification in both types of samples, but only in the first eight cm above the ground in grazed samples, with a dominance of Caltha sagittata. In non‐grazed samples graminoids grew taller than forbs and their inflorescences were an important element of the canopy structure. In both treatments, vertical species diversity was maximum in the lower part of the canopy, although diversity was significantly higher in grazed pots. In grazed samples, Caltha sagittata was the dominant species in 46% of samples and its leaves occupied 35% of the upper canopy. In the non‐grazed samples, Hordeum pubiflorum and Festuca magellanica were dominant in 63% of the samples, with H. pubiflorum leaves occupying 55% of the upper canopy. Comparing species by pairs, significant differences in vertical position were maintained in non‐grazed versus grazed pots. It is concluded that vertical stratification occurs even in the shortest communities. In this community, forb species grew close to the ground in the grazed areas, while forbs grew in the gaps and grasses above them in the non‐grazed areas. The main differences were in the relative dominance of forb and grass species and the presence of inflorescences.
Alpine and subalpine snow patch vegetation on the Bogong High Plains, SE Australia
Authors: Wahren C.‐H. , Williams R.J. , Papst W.A.
Published: February 2007

Abstract. Snow patch vegetation in Australia is rare, being restricted to the relatively small area of alpine and subalpine country in the highlands of southeastern Australia. Snow patch vegetation occurs on steeper, sheltered southeastern slopes, where snow persists until well into the growing season (December/January). We surveyed the vegetation of 33 snow patch sites in the alpine and subalpine tracts of the Bogong High Plains, within the Alpine National Park, in Victoria. The vegetation was dominated by herbs and graminoids, with few shrubs and mosses. Major structural assemblages identified included closed herb‐fields dominated by Celmisia spp, and grasslands dominated by Poa fawcettiae or Poa costiniana. These assemblages occurred on mineral soils. Open herb‐fields dominated by Caltha introloba and several sedge species occurred on rocky and stony substrata. Vegetation‐environment relationships were explored by ordination and vector fitting. There was significant variation in the floristic composition of snow patch vegetation as a function of duration of snow cover, altitude, slope and site rockiness. Alpine sites were floristically distinct from subalpine sites, with a greater cover of Celmisia spp. and a lesser cover of low shrubs in the former. There was floristic variation within some snow patches as a function of slope position (upper, middle or lower slope) but this was not consistent across sites. The current condition of snow patch vegetation on the Bogong High Plains is degraded, with bare ground exceeding 20% cover at most sites. Snow patch vegetation is utilized preferentially by domestic cattle, which graze parts of the Bogong High Plains in summer. Such grazing is a potential threat to this rare vegetation type.
The effect of plant litter on ecosystem properties in a Mediterranean semi‐arid shrubland
Authors: Boeken Bertrand , Orenstein Daniel
Published: February 2007

Abstract. We studied the distribution of litter in a shrubland of the Negev with a semi‐arid Mediterranean climate of less than 200 mm of rainfall per year. Our focus was on the effects of litter on properties of landscape patches relevant to ecosystem processes (water runoff and soil erosion), annual plant community responses (seedling density, biomass production and species richness), and animal activity (soil disturbance by termites). Three 60‐m transects, extending across a pair of opposing north‐ and south‐facing slopes and their drainage channel, showed that litter accumulates not only under shrubs, but to a lesser extent also on the crusted inter‐shrub open areas.

We used 35 experimental units (‘cells’, 0.5m × 1 m), each containing a crust and a shrub patch. Because runoff flows from crusted patches and is intercepted by shrub patches, the latter were in the lower third of the cells. Leaf litter was added in single and double amounts providing ca. 0.5 and 1.0 cm litter depth, to either, both, or none of the patches. Litter addition significantly decreased the amount of runoff, regardless of the location and amount of litter applied. Litter on the crust increased species number and seedling density of species with low abundance. Adding a double litter layer increased annual plant biomass production, while a single amount had no effect. Litter addition to the shrub patch affected neither biomass nor species richness. Litter addition to both patches at both quantities caused a large increase in termite activity. Termites caused disturbance by disrupting the crust, which may contribute to the reduction in runoff amounts.

In the open, flat crust patches, annual plant communities are limited in their productivity and species richness, as there are few structures stopping the outflow of water, soil and seeds. Litter adds such structures, but affects the plant communities only when added to litter‐free crust. Litter accumulation and its patchy distribution have large impacts on landscape patch properties affecting resource distribution, plant productivity and diversity, and animal activity. Therefore, understanding litter distribution in relation to the patchy structure of the landscape of semi‐arid shrubland should be viewed as an important component of shrubland management.
Effects of browsing and grazing on cyclic succession in nutrient‐limited ecosystems
Authors: Bokdam Jan
Published: February 2007

Abstract. This paper deals with browsing and grazing as forces driving cyclic succession. Between 1989 and 1994 reciprocal transitions between the dwarf shrub Calluna vulgaris and the grass Deschampsia flexuosa were monitored in permanent plots in a cattle grazed grass‐rich Dutch heathland on podsolic soils in which tree encroachment was prevented. Heather beetles killed Calluna in four of the nine plots during 1991/1992. The monitoring revealed reciprocal transitions and cycles between Calluna and Deschampsia on a subplot scale. Beetles and cattle had additional and complementary effects on the two competing species. Defoliation by beetles and trampling by cattle‐killed Calluna and favoured grass invasion. Grazing and gap creation by cattle in Deschampsia favoured the establishment and recovery of Calluna. Analysis of the causal mechanisms suggests that indirect, resource‐mediated herbivory effects may be as important for the replacement processes as direct effects of defoliation and trampling. Herbivory created differential light and nutrient levels in Calluna and Deschampsia gaps. Grazing and browsing improved the resource‐capturing abilities of Calluna and its resistance to herbivory and abiotic disturbances. The emerged Calluna‐Deschampsia cycle and its driving forces are summarized in a conceptual triangular resource‐mediated successional grazing cycle (RSGC) model, a limit cycle involving herbivore‐plant‐plant resource interactions. It offers a deterministic equilibrium model as alternative for stochastic transitions between the meta‐stable states with dominance of Calluna and Deschampsia respectively. The validity range of the RSGC model and its management implications are briefly discussed.
Spatial pattern of downed logs and wood‐decaying fungi in an old‐growth Picea abies forest
Authors: Edman Mattias , Jonsson Bengt Gunnar
Published: February 2007

Abstract. Since many wood‐living forest species are influenced by the dynamics of coarse woody debris (CWD), information about the spatial pattern of CWD under natural conditions is essential to understand species distributions. In this study we examined the spatial pattern of downed logs and wood‐decaying fungi in an old‐growth boreal Picea abies forest in northwestern Sweden that is governed by gap‐phase dynamics. The spatial pattern of wood‐decaying fungi was studied to draw conclusions about species dispersal abilities. A total of 684 logs with a diameter > 10 cm were mapped and analysed with Ripley's K‐function. The distribution of all logs taken together displayed a significant aggregated pattern up to 45 m. The different decay stages also deviated from random expectations. Fairly fresh logs and logs in the middle decay stage were clumped up to about 25 and 35 m respectively, and late decayed logs aggregated up to 95 m. Logs with diameters from 10–29 cm were aggregated up to 25 m, whereas logs ≥30 cm diameter were randomly distributed. The result suggests that gap‐dynamics do have an impact on the spatial pattern of the CWD, creating fine‐scale clumping. The random distribution of large logs may result from the slightly regular spacing of large living trees. The spatial patterns of 16 species (n > 20) of wood‐decaying fungi were analysed with Ripley's K‐function. Three patterns were aggregated, for Gloeophyllum sepiarium, Coniophora olivacea and Vesiculomyces citrinus. These results indicate that the distribution of most species at the stand level is generally not influenced by dispersal limitations.
Responses of riparian plants to accumulation of silt and plant litter: the importance of plant traits
Authors: Xiong Shaojun , Nilsson Christer , Johansson Mats E. , Jansson Roland
Published: February 2007

Abstract. A 2‐yr field experiment was used to determine the response of riparian plants to accumulation of litter or silt in a river flood‐plain meadow in northern Sweden. Such disturbances occur regularly in free‐flowing rivers but are likely to change as a result of global changes in land use or climate. We anticipated that plants with different traits would differ in their response to litter and silt accumulation. We quantified plant response as relative change in above‐ground biomass, and regressed it on either litter mass or silt depth, and on plant traits such as lateral spread, plant height, relative growth rate, seed mass and seed persistence in soil. The relative changes in riparian plant biomass following litter or silt accumulation were negatively related to litter mass and silt depth, and positively related to most examined plant traits such as seed mass, seed persistence and lateral spread. The vegetation recovery in the second season was largely determined by plant traits; litter or silt accumulation had no significant effect. Litter accumulation selected for large‐seeded species, but silt accumulation selected for species with strong ability of lateral spread. Seed persistence was a useful variable in predicting species recovery from both litter and silt accumulation. Plant height was negatively related to plant recovery, but relative growth rate was not significantly related to relative change in plant biomass after silt or litter accumulation. Our results imply that plant traits are important variables to consider for predicting the responses of riparian vegetation to deposition of organic and inorganic matter.
Do commonly used indices of β‐diversity measure species turnover?
Authors: Vellend Mark
Published: February 2007

Abstract. Indices of β‐diversity are of two major types, (1) those that measure among‐plot variability in species composition independently of the position of individual plots on spatial or environmental gradients, and (2) those that measure the extent of change in species composition along predefined gradients, i.e. species turnover. Failure to recognize this distinction can lead to the inappropriate use of some β‐diversity indices to measure species turnover.

Several commonly‐used indices of β‐diversity are based on Whittaker's βW (βW = γ/α, where γ is the number of species in an entire study area and α is the number of species per plot within the study area). It is demonstrated that these indices do not take into account the distribution of species on spatial or environmental gradients, and should therefore not be used to measure species turnover. The terms ‘β‐diversity’ and ‘species turnover’ should not be used interchangeably. Species turnover can be measured using matrices of compositional similarity and physical or environmental distances among pairs of study plots. The use of indices of β‐diversity and similarity‐distance curves is demonstrated using simulated data sets.
Floristic composition across a climatic gradient in a neotropical lowland forest
Authors: Pyke Christopher R. , Condit Richard , Aguilar Salomón , Lao Suzanne
Published: February 2007

Abstract. This study deals with the floristic composition of lowland tropical forest in the watershed of the Panama Canal. The floristic composition of large trees in 54 forest plots was analysed with respect to environmental factors, including precipitation, geologic parent material, stand age, topography, and soils. The plots contain 824 species of trees with a diameter at breast height ≥10 cm and represent a regional flora with exceptional β‐diversity. Plot data indicate that the Panamanian forest is strongly spatially structured at the landscape scale with floristic similarity decreasing rapidly as a function of inter‐plot geographic distance, especially for distances <5 km. The ordinations and patterns of endemism across the study area indicate broad floristic associations well correlated with Holdridge life zones. The results indicate the positive aspects of life zone classification at regional scales, while simultaneously highlighting its inadequacy for finer scales of analysis and resource management. Multivariate gradient analysis techniques (Non‐metric Multidimensional Distance Scaling and Detrended Correspondence Analysis) show clear patterns of floristic variability correlated with regional precipitation trends, surficial geology, and local soil attributes. Geologic and edaphic conditions, such as acidic soils or excessively drained limestone substrates, appear to override the effects of precipitation and modify forest composition. We conclude that the Panamanian forest shows clear patterns of spatial organization along environmental gradients, predominantly precipitation. The rapid decline in floristic similarity with distance between stands also suggests a role for dispersal limitation and stochastic events.
Lithic Source Use and Paleoarchaic Foraging Territories in the Great Basin
Authors: Jones George T. , Beck Charlotte , Jones Eric E. , Hughes Richard E.
Published: February 2007

Paleoarchaic (11.5–8.0 ka) occupants of the Great Basin encountered numerous lithic sources as they moved across foraging territories. Source provenance and lithic technologic analyses applied to the tools manufactured from these source materials elucidate several aspects of mobility, including the geographic scale of material conveyance and extent and possible routes of population movement. This research indicates that central Great Basin groups traversed large subsistence territories, extending more than 400 km from north to south, with mobility tactics probably keyed to the distribution of resource-rich wetlands. Changes in source representation parallel warming and drying trends, suggesting that Paleoarchaic foraging ranges shifted as wetlands diminished after about 9.5–8.5 ka.
Postmarital Residence Practices in the Windover Population: Sex-Based Dental Variation as an Indicator of Patrilocality
Authors: Tomczak Paula D. , Powell Joseph F.
Published: February 2007

This study examines postmarital residence patterns at the Windover site, an Early Archaic occupation located in east-central Florida. Residence patterns are assessed using a population genetics model based on isolation by distance and migration matrix methods. Variation in nonmetric dental traits is examined among a group of 40 adult males and 43 adult females. The sex with the higher within-group variance is considered the more mobile sex, thereby providing a possible reflection of residential patterns. Results indicate that females are almost twice as variable as males, thus suggesting patrilocality. However, this result is not statistically significant at the .05 probability level. Additional lines of evidence are assessed in conjunction with dental data. Specifically, ethnographic data indicate that subsistence and sexual division of labor are important factors related to social organization, including residence. Although these lines of evidence can be used to support the dental data and patrilocality, they are not conclusive. Future studies of activity patterns, disease, mortuary remains, and material culture may help to clarify the issue of postmarital residence patterns at Windover.