A Contemporary Approach to a Classic Model: Exploring the Influence of Local Interactions and Disturbance on Mangrove Forest Dynamics with a Spatially-Explicit Version of FORMAN

The mangrove forest gap dynamic model, FORMAN, was the first individual-based model (IBM) to simulate the long-term successional dynamics of three Caribbean mangrove species, Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle. Assumptions under the spatially implicit approach of gap dynamic models limit their application to small-scale simulations. An expanded, spatially-explicit version of FORMAN was developed to allow for simulations of larger spatial grids, through the inclusion of localized soil conditions and neighborhood-based light resource competition. This expanded model was used to investigate the influence of localized interactions and disturbances of varying size on forest dynamics. A data-model comparison using field data from the Shark River Estuary in the Florida Coastal Everglades (FCE) tested the model’s ability to predict spatial relationships (inter-tree distances) based on tree size and species. The structure and function of the simulated mangrove forests were sensitive to complex interactions between localized soil and light competition based on neighboring trees. Under spatially varying soil conditions, neighborhood-based light competition limited tree growth (especially that of A. germinans and L. racemosa) in favorable soil zones, while allowing for sapling establishment in less optimal habitats. Forest recovery rates following disturbance were sensitive to both soil stress and disturbance size. L. racemosa experienced the greatest increase in annual productivity following disturbance, and exhibited a positive relationship between post-disturbance structure (biomass and basal area) and disturbance size. There was good agreement between the model and field data for frequencies of inter-tree distances and for the distribution of inter-tree distances when examined by size-class and by each species within sizes classes. However, there were no consistent differences or trends in inter-tree distance probability distributions observed across size-classes or for species within size-classes. The expanded FORMAN model, while still limited to the km2 scale in scope, is a very first step in increasing its spatial capability beyond the gap scale. This expansion potential is important in the context of climate change, as IBMs have been suggested as potentially useful tools in identifying and minimizing inaccuracies resulting from current methods of scaling biomass and productivity estimates from site to continental scales

A comparative study of imagery in quarto one and quarto two of william shakespeare\u27s hamlet

The purpose of this paper is to compare the imagery of the first quarto of Hamlet with the imagery of the second quarto and the first folio. This paper examines verbal and visual imager, including a comparison of dramatic images based on physical appearance of characters, settings, stage effects, and time sequence

The Grizzly, October 10, 1995

Diversity Committee Report • The Stolen Credit Card Conundrum • The Juice is Loose • Greek Service Requirements • Green Bringing Awareness to Campus • More Rules Change Pledging • Statement on Hazing • Circus Trial = Circus Ending • Debate: U.C. Sculptures • The Myth of Unity and Diversity • More Than a Protest? • Homosexuality: Not a Good Alternative • Intelligently Expressing Your Opinion? • Gossip, Responsibility, and Education • Failing Ourselves, Failing Others • Shackled by the Life Chain • The Not-so-Traditional Tradition: Is There Really a Fall Day? • No ID, No Cover Charge • Alumna Spotlight: Mary Harris • Trumpeter Mike Mossman to Lead Jazz Quintet at Ursinus • Sophomores To Focus On Campus Pride • Dr. Juan Espadas Receives Award • Team Loses to Widener and F&M • Ursinus Finishes Eighth at Susquehanna Fall Classic • Big Plays Doom Football Team • Streak Continues • Team Splits Conference Gameshttps://digitalcommons.ursinus.edu/grizzlynews/1365/thumbnail.jp

Stability of precast prestressed concrete bridge girders considering imperfections and thermal effects

The spans of precast prestressed concrete bridge girders have become longer to provide more economical and safer transportation structures. As the spans have increased, so has the depth of the girders which in turn have increased the slenderness of the girders. Slenderness in a beam or girder would increase the likelihood that a stability failure would occur. Stability failures could pose a danger to construction personnel due to the sudden nature in which a stability failure would occur. Furthermore, stability failures of prestressed concrete girders during construction would cause a detrimental economic impact due to the costs associated with the failure of the girder, the ensuing construction delays, damage to construction equipment and potential closures to highways over which the bridge was being constructed. An experimental and analytical study was performed to determine the stability behavior of prestressed concrete beams. Two stability phenomenons were investigated: (1) lateral-torsional buckling and (2) global stability. An emphasis was placed on the effects of initial imperfections on the stability behavior; the effect elastomeric bearing pads and support rotational stiffness was investigated. The experimental study involved testing six rectangular prestressed concrete beams for lateral-torsional buckling, a PCI BT-54 for thermal deformations and the same PCI BT-54 for global stability. The 32-ft. long rectangular beams were 4-in. wide and 40-in. deep. The PCI BT-54 had a 100-ft. long span. A material and geometric nonlinear, incremental load analysis was performed on the six rectangular beams. The nonlinear analyses matched the experimental load versus lateral displacement and load versus rotation behavior, and the analysis predicted the experimental maximum load within an error of 2%. The nonlinear analysis was extrapolated to several different initial imperfection conditions to parametrically study the effect of initial lateral displacement and initial rotation on the inelastic lateral-torsional buckling load. A simplified expression for lateral-torsional stability of beams with initial imperfections was developed. The data from the parametric study were used to develop reduction parameters for both initial sweep and initial rotation. The rollover stability behavior of the PCI BT-54 was investigated experimentally, and it was found that support end rotations and the elastomeric bearing pads had an adverse effect on the global stability. The nonlinear analysis was employed with the addition of a bearing pad model. It was found that the behavior was sensitive to the bearing pad stiffness properties and the assumption of uniform bearing. From the research, it was apparent that rollover stability was the controlling stability phenomenon for precast prestressed concrete bridge girders, not lateral-torsional buckling.Ph.D.Committee Chair: Dr. Lawrence F. Kahn; Committee Member: Dr. Abdul-Hamid Zureick; Committee Member: Dr. Donald W. White; Committee Member: Dr. Kenneth M. Will; Committee Member: Dr. T. Russell Gentr

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Wholesale price list of melon seeds : no seeds by mail /

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