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Site Preparation (site + preparation)
Selected AbstractsSite history affects soil and plant 15N natural abundances (,15N) in forests of northern Vancouver Island, British ColumbiaFUNCTIONAL ECOLOGY, Issue 3 2000S. X. Chang Abstract 1.,About 10 years after establishment, plantations of Western Redcedar (Thuja plicata Donn ex D. Don) on northern Vancouver Island, British Columbia become nutrient deficient and chlorotic, grow slowly, and are susceptible to invasion by the ericaceous shrub Salal (Gaultheria shallon Pursh.). 2.,To test the hypothesis that ,15N can be related to site histories (site disturbance, soil N dynamics and plant development), we measured soil and foliar ,15N in the summer of 1992 in 3-year-old (nutrient-sufficient) and 10-year-old (nutrient-deficient) plantations and in old-growth stands. The foliar and soil ,15N values of the plantations and old-growth forests were different and closely reflected site histories. Salal invasion and nutrient deficiency interacted to depress the growth of Redcedar in 10-year-old plantations. 3.,Site preparation destroyed the top soil organic layers (fresh and decaying litter) and forced Salal (ecto- and ericoid mycorrhizal) into the humus layer, where it was in direct competition with Redcedar, thereby disadvantaging arbuscular mycorrhizal/non-mycorrhizal Redcedar in its nutrient acquisition during a period when N and P are severely limited. 4.,There was a large seasonal range of foliar ,15N (5·5 and 4·3, for 10-year-old Redcedar and Salal, respectively), and there was no relationship between foliar ,15N and measured rooting depth, demonstrating that rooting depths cannot be used to explain foliar ,15N variation among coexisting woody taxa. 5.,Foliar and soil ,15N declined with site age and with a presumed change from ,open' to ,closed' N cycling; the 15N-depleting effects of mycorrhizal N transformations contributed to the observed ,15N decline. [source] Baseflow and peakflow chemical responses to experimental applications of ammonium sulphate to forested watersheds in north-central West Virginia, USA,HYDROLOGICAL PROCESSES, Issue 12 2002Pamela J. Edwards Abstract Stream water was analysed to determine how induced watershed acidification changed the chemistry of peakflow and baseflow and to compare the relative timing of these changes. Two watersheds in north-central West Virginia, WS3 and WS9, were subjected to three applications of ammonium sulphate fertilizer per year to induce acidification. A third watershed, WS4, was the control. Samples were collected for 8 years from WS9 and for 9 years from WS3. Prior to analyses, concentration data were flow adjusted, and the influence of natural background changes was removed by accounting for the chemical responses measured from WS4. This yielded residual values that were evaluated using robust locally weighted regression and Mann,Kendall tests. On WS3, analyte responses during baseflow and peakflow were similar, although peakflow responses occurred soon after the first treatment whereas baseflow responses lagged 1,2 years. This lag in baseflow responses corresponded well with the mean transit time of baseflow on WS3. Anion adsorption on WS3 apparently delayed increases in SO4 leaching, but resulted in enhanced early leaching losses of Cl and NO3. Leaching of Ca and Mg was strongly tied, both by timing and stoichiometrically, to NO3 and SO4 leaching. F -factors for WS3 baseflow and peakflow indicated that the catchment was insensitive to acid neutralizing capacity reductions both before and during treatment, although NO3 played a large role in reducing the treatment period F -factor. By contrast, the addition of fertilizer to WS9 created an acid sensitive system in both baseflow and peakflow. On WS9, baseflow and peakflow responses also were similar to each other, but there was no time lag after treatment for baseflow. Changes in concentrations generally were not as great on WS9 as on WS3, and several ions showed no significant changes, particularly for peakflow. The lesser response to treatment on WS9 is attributed to the past abusive farming and site preparation before larch planting that resulted in poor soil fertility, erosion, and consequently, physical and chemical similarities between upper and lower soil layers. Even with fertilizer-induced NO3 and SO4 leaching increases, base cations were in low supplies and, therefore, unavailable to leach via charge pairing. The absence of a time lag in treatment responses for WS9 baseflow indicates that it has substantially different flow paths than WS3. The different hydrologies on these nearby watersheds illustrates the importance of understanding watershed hydrology when establishing a monitoring programme to detect ecosystem change. Published in 2002 by John Wiley & Sons, Ltd. [source] Bone regeneration in dehiscence-type defects at chemically modified (SLActive®) and conventional SLA titanium implants: a pilot study in dogsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2007Frank Schwarz Abstract Objectives: The aim of the present study was to evaluate bone regeneration in dehiscence-type defects at titanium implants with chemically modified (mod) and conventional sand-blasted/acid-etched (SLA) surfaces. Material and Methods: Standardized buccal dehiscence defects (height: 3 mm, width: 3 mm) were surgically created following implant site preparation in both the upper and lower jaws of four beagle dogs. modSLA and SLA implants were inserted bilaterally according to a split-mouth design. The animals were sacrificed after 2 and 12 weeks (n=2 animals each). Dissected blocks were processed for histomorphometrical analysis: defect length, new bone height (NBH), percent linear fill (PLF), percent of bone-to-implant contact (BIC-D) and area of new bone fill (BF). Results: Wound healing at SLA implants was predominantly characterized by the formation of a dense connective tissue at 2 and 12 weeks, without significant increases in mean NBH, PLF, BIC-D or BF values. In contrast, modSLA implants exhibited a complete defect fill at 12 weeks following implant placement. In particular, histomorphometrical analysis revealed the following mean values at 12 weeks: NBH (3.2±0.3 mm), PLF (98%), BIC-D (82%) and BF (2.3±0.4 mm2). Conclusion: Within the limits of the present study, it was concluded that modSLA titanium surfaces may promote bone regeneration in acute-type buccal dehiscence defects at submerged implants. [source] SEDIMENT TRAPPING WITHIN FORESTRY STREAMSIDE MANAGEMENT ZONES: GEORGIA PIEDMONT, USA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2004Jason M. Ward ABSTRACT: The effectiveness of streamside management zones (SMZs) was assessed for reducing sediment transport from concentrated overland flow draining two Georgia Piedmont clearcuts that had undergone mechanical and chemical site preparation and planting. Silt fences were used to trap sediment transport from zero-order ephemeral swales at the edge of and within SMZs. Four control swales and nine treatment swales were studied. A double mass curve approach was used to graphically compare sediment accumulation rates at the edge of SMZs to accumulation rates within the SMZs at a distance consistent with current recommendations for SMZ width in Georgia. SMZ efficiencies for trapping sediment transported by concentrated flow ranged from 71 to 99 percent. No statistical model was found to explain how SMZ efficiencies varied with SMZ and contributing area characteristics. Measured sediment accumulations at the SMZ boundary were compared to Revised Universal Soil Loss Equation (RUSLE) predictions of up- slope erosion, and a delivery ratio of 0.25 was calculated. SMZs had a quantifiable and substantial ameliorating effect on sediment transport from concentrated overland flow on the clearcut study sites. [source] Optimizing Hardwood Reforestation in Old Fields: The Effects of Treeshelters and Environmental Factors on Tree Seedling Growth and PhysiologyRESTORATION ECOLOGY, Issue 2 2008Etienne Laliberté Abstract Strong competition for water is largely recognized as the main factor explaining the resistance of herbaceous old fields to tree invasion. Therefore, site preparation as well as chemical and mechanical vegetation control are recommended when establishing hardwood tree plantations on such sites, but those methods are sometimes socially or ecologically inappropriate. The main objective of this study was to analyze whether treeshelters could improve early tree growth in herbaceous old fields, when mulching alone is used to partially control herbaceous competition. Our results indicate that treeshelters can facilitate tree growth in those conditions but that this was not caused by an improvement of tree water relations. Rather, it appeared to be related to an optimization of light levels inside the shelter, where light intensity was low enough to lead to a photosynthetic system less costly to maintain due to a greater specific leaf area but high enough to have no adverse effects on photosynthetic rates. Although treeshelters increased tree growth when surrounding herbaceous vegetation was low (either height or standing biomass), allowing high light levels, they reduced growth when surrounding vegetation was high and blocked a substantial quantity of light. Therefore, environmental factors such as light availability need to be considered to optimize the success of hardwood plantations when treeshelters are used in recently abandoned agricultural fields. [source] Increasing the Effectiveness of Reed canary grass (Phalaris arundinacea L.) Control in Wet Meadow RestorationsRESTORATION ECOLOGY, Issue 3 2006Carrie Reinhardt Adams Abstract Restoration practices are often based on trial and error or anecdotal information because data from controlled experiments are not available. In wet meadow restorations of the upper Midwest United States, Reed canary grass (Phalaris arundinacea L.) is controlled with spring burning and spring glyphosate herbicide applications, but the relative effectiveness of either treatment with respect to P. arundinacea growth and life history has not been assessed. We designed a multiyear field experiment to evaluate effects of burning and herbicide application timings on P. arundinacea populations. Burning did not reduce P. arundinacea biomass but reduced the P. arundinacea seed bank, potentially limiting recolonization of P. arundinacea. Glyphosate applications in late August and late September were more effective than in mid-May (due to enhanced glyphosate translocation to rhizomes), such that two mid-May applications reduced P. arundinacea biomass to a level equivalent to that achieved by one late-season application. Phalaris. arundinacea recolonized rapidly from the seed bank and, in plots that received suboptimally timed (mid-May) herbicide, from rhizomes. Establishment of native species was very low, likely due to competition with recolonizing P. arundinacea. Unplanted species (from the seed bank and refugial populations) accounted for the majority of non- P. arundinacea biomass. Recolonization of other species was strongly limited by a threshold level of P. arundinacea biomass. Adequate site preparation (over multiple growing seasons) and aftercare (selective removal of P. arundinacea) will be the key to facilitating subsequent wet meadow vegetation establishment. This research provides an example of the importance of experimental evidence as the basis to improve the efficiency of restoration practices. [source] Surgical advantages with ITI TE® implants placement in conjunction with split crest techniqueCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 200518-month results of an ongoing prospective study Abstract: Implant rehabilitation of the edentulous maxilla may be somewhat problematic because of anatomic situations involving insufficient bone thickness. One approach in this situation is localized ridge augmentation with the split crest technique. This surgical approach allows the external cortical plate of the maxilla to be moved in a labial direction to gain an increase in width to introduce implants of appropriate diameter. This ongoing prospective study evaluated: (i) the surgical advantages that the new ITI TE® implants have showed compared with the ITI standard solid-screw implants when placed in conjunction with the split crest technique and (ii) the implant success rate associated with 42 ITI TE® implants and 40 ITI standard solid-screw implants placed in 40 patients in conjunction with the split crest technique. ITI TE® implants have shown direct and indirect advantages in reducing the risk of fracture of the labial cortical plate during all the three fundamental surgical steps of this technique: (a) the ridge expansion with osteotomes; (b) implant site preparation with drills and (c) implant insertion. The overall success rates of ITI TE® implants and standard screw implants were 100% and 95%, respectively. Based on the preliminary results of the present study, it can be concluded that ITI TE® implants inserted in conjunction with split crest technique seem to be a promising surgical procedure to treat selected anatomic situations involving insufficient maxillary bone thickness. Résumé La réhabilitation implantaire du maxillaire édenté peut être problèmatique à cause des situations anatomiques comportant une insuffisance de l'épaisseur osseuse. Une approche de cette situation est d'effectuer un épaississement du rebord localisé avec la technique du rebord osseux fendu. Cette approche chirurgicale permet au plateau cortical externe du maxillaire d'être déplacé en une direction linguale pour augmenter la largeur afin de pouvoir ensuite placer des implants d'un diamètre approprié. Cette étude prospective encore en cours a évalué 1) les avantages chirurgicaux des nouveaux implants ITI TE comparés aux implants ITI en vis solide ITI standard lorsqu'ils étaient placés en association avec cette technique de rebord osseux fendu et 2) le taux de succès implantaire associé avec 42 implants ITI TE et 40 implants vis solides ITI standard placés chez 40 patients en association avec cette technique de rebord osseux fendu. Les implants ITI TE ont montré des avantages directs et indirects en réduisant le risque de fracture de la corticale linguale durant les trois étapes chirurgicales fondamentales de cette technique : a) l'expansion du rebord alvéolaire avec les ostétomes, b) la préparation des sites implantaires avec les forets et c) l'insertion implantaire. Les taux de succès généraux des implants ITI TE et des implants vis standards étaient respectivement de 100 % et 95%. Basé sur le résultat préléminaire de cette étude, il peut être conclu que les implants ITI TE insérés en association avec la technique du rebord osseux fendu semble être un processus chirurgical prometteur pour traiter des situations anatomiques sélectionnées qui comportent une épaisseur osseuse insuffisante du maxillaire. Zusammenfassung Die Rekonstruktion einer zahnlosen Situation im Oberkiefer ist dann etwas problematischer, wenn anatomisch ungünstige Gegebenheiten wie zum Beispiel eine ungenügende vertikale Breite des Alveolarknochens besteht. Eine mögliche Vorgehensweise in dieser Situation ist die lokale Knochenaugmentation mittels Spaltung und Spreizung der Knochenkortikalis. Diese chirurgische Methode erlaubt uns, die äussere Kortikalis des Oberkiefers in labialer Richtung abzuspreizen und somit ein genügend breites Knochenbett zu erhalten, um Implantate mit dem geeigneten Durchmesser setzen zu können. Diese noch weiterverfolgte Langzeitstudie untersuchte: (i) die chirurgischen Vorteile, die uns das neue ITI TE-Implantat verglichen mit der Vollschraube des ITI-Standardimplantates in Verbindung mit der Kortikalisspreiztechnik bringt und (ii) die Implantaterfolgsrate von 42 ITI TE-Implantaten und 40 Vollschrauben der ITI-Standartimplantate, die man bei 40 Patienten in Verbindung mit der Kortikalisspreiztechnik gesetzt hat. Die ITI TE-Implantate zeigten direkte und indirekte Vorteile bei der Verminderung des Frakturrisikos in der labialen Kortikalisplatte während den drei grundlegenden Schritten dieser Technik: (a) Spreizung des Knochenkamms mit Osteotomen; (b) Vorbohren des Implantatbettes und (c) Eindrehen der Implantate. Die Erfolgsrate lag bei den ITI TE-Implantaten bei 100% und bei den Standartschraubenimplantaten bei 95%. Basierend auf diesen ersten Resultaten der Studie kann man schliessen, dass es sich bei ITI TE-Implantate, die in Verbindung mit der Kortikalisspreiztechnik eingesetzt worden waren, um eine vielversprechende chirugische Technik handelt, um ausgewählte anatomische Situationen, wie zu Beispiel eine ungenügende vertikale Breite des Alveolarknochens im Oberkiefer, zu behandeln. Resumen La rehabilitación con implantes del maxilar edéntulo puede ser un tanto problemática debido a situaciones anatómicas que comprenden situaciones de grosor óseo insuficiente. Un enfoque en esta situación, es el aumento localizado de la cresta con la técnica de cresta dividida. Este enfoque quirúrgico permite mover la placa cortical externa del maxilar en dirección labial para ganar un aumento en anchura para introducir implantes del diámetro apropiado. Este estudio prospectivo continuado evaluó: i) los avances quirúrgicos que los nuevos implantes ITI TE han mostrado en comparación con los implantes macizos roscados ITI estándar al colocarse en combinación con la técnica de cresta dividida y ii) el índice de éxito del implante asociado con 42 implantes ITI TE y 40 implantes macizos roscados estándar colocados en 40 pacientes en combinación con la técnica de cresta dividida. Los implantes ITI TE han mostrado ventajas directas e indirectas en reducir el riesgo de fractura de la placa cortical labial durante los tres pasos quirúrgicos fundamentales de esta técnica: a) expansión de la cresta con osteotomos; b) preparación del lecho implantario con fresas y c) inserción del implante. El índice total de éxito de los implantes ITI TE y de los implantes estándar roscados fue del 100% y del 95% respectivamente. Basado en los resultados preliminares del presente estudio, se puede concluir que los implantes ITI TE insertados en combinación con la técnica de cresta dividida parece ser un procedimiento quirúrgico prometedor para tratar situaciones anatómicas determinadas que conllevan un grosor óseo maxilar insuficiente. [source] Temporoparietal fascial free flap for correction of first web space atrophyMICROSURGERY, Issue 1 2010Arthi Kruavit M.D. Fourteen temporoparietal fascial free flaps were used for correction of first web space atrophy from ulnar nerve palsy in 13 patients. Ten sustained ulnar nerve injuries and three suffered from leprosy. The procedures were performed under general anesthesia except one leprosy patient with bilateral ulnar nerve palsy in which local anesthesia and brachial block were employed to harvest bilateral free flaps and recipient site preparations, respectively. The follow-up time varied from 4 to 64 months. The postoperative results were satisfactory and there was no resorption of the free flaps. The consistency of the augmented first web space was soft and compressible like natural feel. The size of the flap was more than enough for augmentation of first web space and donor site morbidity was minimal and accepted by all patients. We conclude that temporoparietal fascial free flap is an ideal autogenous tissue for correction of first web space atrophy. © 2009 Wiley-Liss, Inc. Microsurgery 2010. [source] | ||||||||||||||||