1,445 research outputs found
Complex System Governance Leadership
The purpose of this research was to develop a systems theory-based framework for leadership in governance of complex systems. Recognizing complexity and uncertainty as norms for the environments in which organizations exist encouraged researchers to suggest complexity theory, complex systems, and complex adaptive systems as appropriate for addressing these conditions. Complex System Governance (CSG), based in systems theory, management cybernetics, and governance, endeavors to provide for the design, execution and evolution of functions that provide control, communication, coordination, and integration at the metasystem level to support operations and continued system existence (viability). From a management cybernetics perspective, CSG leadership has a role in the design of the metasystem that provides governance functions for a complex system. Similarly, leadership assures the existence of conditions necessary for the requisite metasystem functions to be enabled, executed, and evolved sufficiently for continued system viability. In this research, CSG leadership functions were examined from a system theoretic perspective. An extensive body of leadership literature provides insight into leadership from a number of perspectives including leadership as personal traits, leadership as a set of skills, or leadership as a process or relationship. Systems theory conceptual foundations applied to CSG leadership functions are not represented in this literature thus resulting in a gap. This research contributes to addressing that gap by linking systems theory to leadership functions for CSG. The research was a journey of discovery with no pre-established hypotheses that could be tested using deductive approaches, therefore, an inductive approach supportive of exploring, understanding (gaining insight) and discovery was employed. As the purpose was to develop a systems theory-based framework for leadership in governance of complex systems, theory construction was required. As a recognized methodology to discover theory from data, Grounded Theory was chosen as the research methodology.
The framework that resulted from this research presents a novel contribution to CSG leadership that is grounded in systems theory and management cybernetics. It also provides practitioners the opportunity to develop novel approaches for facilitating anticipation, identification, and remediation of leadership issues
Optimal hurricane overwash thickness for maximizing marsh resilience to sea level rise
The interplay between storms and sea level rise, and between ecology and sediment transport governs the behavior of rapidly evolving coastal ecosystems such as marshes and barrier islands. Sediment deposition during hurricanes is thought to increase the resilience of salt marshes to sea level rise by increasing soil elevation and vegetation productivity. We use mesocosms to simulate burial of Spartina alterniflora during hurricane-induced overwash events of various thickness (0-60 cm), and find that adventitious root growth within the overwash sediment layer increases total biomass by up to 120%. In contrast to most previous work illustrating a simple positive relationship between burial depth and vegetation productivity, our work reveals an optimum burial depth (510 cm) beyond which burial leads to plant mortality. The optimum burial depth increases with flooding frequency, indicating that storm deposition ameliorates flooding stress, and that its impact on productivity will become more important under accelerated sea level rise. Our results suggest that frequent, low magnitude storm events associated with naturally migrating islands may increase the resilience of marshes to sea level rise, and in turn, slow island migration rates. Synthesis: We find that burial deeper than the optimum results in reduced growth or mortality of marsh vegetation, which suggests that future increases in overwash thickness associated with more intense storms and artificial heightening of dunes could lead to less resilient marshes
Mathematical Model of Heavy Metal Transfer and Transport in Lake Erie
This study was supported in part by the Office of Water Resources Technology, U.S. Department of Interior under project A-045-OHIO(print) vii, 141 p. : ill. ; 27 cm.Numerical integration of mathematical functions representing the concentration of mercury, chromium and nickel in Lake Erie sediments indicate that 3.3 x 10^5 kg Hg, 1.8 x 10^7 kg Cr, and 1.2 x 10^7 kg Ni have been added to the sediments through man's activities. Most of the mercury, chromium and nickel are contained in the sediments of western Lake Erie.
A mathematical model of sediment transport in Lake Erie shows that most of the heavy metals in western Lake Erie sediments probably originated from the Detroit metropolitan area and was input via the Detroit River. The sediment dispersal patterns are as follows: 1) the Detroit River
sediment spreads southeastward over most of the western basin, 2) the Maumee River sediment is held within 15 miles of the Ohio shore, and 3) the Cuyahoga River sediment travels northeastward along the south shore of the lake.
Attempts to model the transfer and transport of mercury within the ecosystem resulted in partial success. Very little transfer results between the sediments and other phases within the system. In contrast the exchange of mercury between the benthic organisms and other trophic and abiotic levels is very rapid.Abstract -- Key Words -- Project Personnel -- Introduction -- Mercury, Chromium and Nickel in Lake Erie Sediments -- Sediment Transport Model -- Model of Mercury Transfer and Transport in Lake Erie - Appendice
Impacts of terrain attributes on economics and the environment: costs of reducing potential nitrogen pollution in wheat production
The economic cost of achieving desired environmental outcomes from uniform and variable rate fertilizer application technologies depends both on market forces and agronomic properties. Using spatial econometric methods, we analyze the impact of nitrogen fertilizer supply by terrain attribute on the yield and protein content of hard red spring wheat grown in EasternWashington as well as the impact on residual nitrogen.We find significant association with all three. The economic impact of nitrogen restrictions depends critically on both prices and level of the restriction. Uniform application of nitrogen was found to economically outperform variable rate application, but variable rate application provided positive environmental benefits due to less residual nitrogen
Massive Upland to Wetland Conversion Compensated for Historical Marsh Loss in Chesapeake Bay, USA
Sea level rise leads to coastal transgression, and the survival of ecosystems depends on their ability to migrate inland faster than they erode and submerge. We compared marsh extent between nineteenth-century maps and modern aerial photographs across the Chesapeake Bay, the largest estuary in North America, and found that Chesapeake marshes have maintained their spatial extent despite relative sea level rise rates that are among the fastest in the world. In the mapped region (i.e., 25% of modern Chesapeake Bay marshland),94 km2of marsh was lost primarily to shoreline erosion,whereas 101 km2of marsh was created by upland drowning.Simple projections over the entire Chesapeake region suggestthat approximately 100,000 acres (400 km2) of uplands have converted to wetlands and that about a third of all present-day marsh was created by drowning of upland ecosystems since the late nineteenth century. Marsh migration rates were weakly correlated with topographic slope and the amount of development of adjacent uplands, suggesting that additional processes may also be important. Nevertheless, our results emphasize that the location of coastal ecosystems changes rapidly on century timescales and that sea level rise does not necessarily lead to overall habitat loss
Experimental Tree Mortality Does Not Induce Marsh Transgression in a Chesapeake Bay Low-Lying Coastal Forest
Transgression into adjacent uplands is an important global response of coastal wetlands to accelerated rates of sea level rise. “Ghost forests” mark a signature characteristic of marsh transgression on the landscape, as changes in tidal inundation and salinity cause bordering upland tree mortality, increase light availability, and the emergence of tidal marsh species due to reduced competition. To investigate these mechanisms of the marsh migration process, we conducted a field experiment to simulate a natural disturbance event (e.g., storm-induced flooding) by inducing the death of established trees (coastal loblolly pine, Pinus taeda) at the marsh-upland forest ecotone. After this simulated disturbance in 2014, we monitored changes in vegetation along an elevation gradient in control and treatment areas to determine if disturbance can lead to an ecosystem shift from forested upland to wetland vegetation. Light availability initially increased in the disturbed area, leading to an increase in biodiversity of vegetation with early successional grass and shrub species. However, over the course of this 5-year experiment, there was no increase in inundation in the disturbed areas relative to the control and pine trees recolonized becoming the dominant plant cover in the disturbed study areas. Thus, in the 5 years since the disturbance, there has been no overall shift in species composition toward more hydrophytic vegetation that would be indicative of marsh transgression with the removal of trees. These findings suggest that disturbance is necessary but not sufficient alone for transgression to occur. Unless hydrological characteristics suppress tree re-growth within a period of several years following disturbance, the regenerating trees will shade and outcompete any migrating wetland vegetation species. Our results suggest that complex interactions between disturbance, biotic resistance, and slope help determine the potential for marsh transgression
The Electronic Controls Used in a Search For Fractional Charges in Mercury Drops
At San Francisco State University, we have developed an Automatic Millikan Device (AMI)) for measuring the charge on small drops of Mercury. The device uses a standard atomic physics laboratory Millikan chamber, a piezoelectric driven ink-jet glass dropper, and a laser-photomultiplier system for tracking the motion of the drop. This paper describes the electronic control and error detection system used with the AMO. Signals from this system are sent to a microprocessor which controls the experiment. To this date (Dec 7, 1981), we have measured 175 micrograms of Hg and found no fractional charges in 1.05 x 1020 nucleons
Spatio-Temporal Migration Patterns of Pacific Salmon Smolts in Rivers and Coastal Marine Waters
BACKGROUND: Migrations allow animals to find food resources, rearing habitats, or mates, but often impose considerable predation risk. Several behavioural strategies may reduce this risk, including faster travel speed and taking routes with shorter total distance. Descriptions of the natural range of variation in migration strategies among individuals and populations is necessary before the ecological consequences of such variation can be established. METHODOLOGY/PRINCIPAL FINDINGS: Movements of tagged juvenile coho, steelhead, sockeye, and Chinook salmon were quantified using a large-scale acoustic tracking array in southern British Columbia, Canada. Smolts from 13 watersheds (49 watershed/species/year combinations) were tagged between 2004-2008 and combined into a mixed-effects model analysis of travel speed. During the downstream migration, steelhead were slower on average than other species, possibly related to freshwater residualization. During the migration through the Strait of Georgia, coho were slower than steelhead and sockeye, likely related to some degree of inshore summer residency. Hatchery-reared smolts were slower than wild smolts during the downstream migration, but after ocean entry, average speeds were similar. In small rivers, downstream travel speed increased with body length, but in the larger Fraser River and during the coastal migration, average speed was independent of body length. Smolts leaving rivers located towards the northern end of the Strait of Georgia ecosystem migrated strictly northwards after ocean entry, but those from rivers towards the southern end displayed split-route migration patterns within populations, with some moving southward. CONCLUSIONS/SIGNIFICANCE: Our results reveal a tremendous diversity of behavioural migration strategies used by juvenile salmon, across species, rearing histories, and habitats, as well as within individual populations. During the downstream migration, factors that had strong effects on travel speeds included species, wild or hatchery-rearing history, watershed size and, in smaller rivers, body length. During the coastal migration, travel speeds were only strongly affected by species differences
Interactions between barrier islands and backbarrier marshes affect island system response to sea level rise: Insights from a coupled model
Interactions between backbarrier marshes and barrier islands will likely play an important role in determining how low-lying coastal systems respond to sea level rise and changes in storminess in the future. To assess the role of couplings between marshes and barrier islands under changing conditions, we develop and apply a coupled barrier island-marsh model (GEOMBEST+) to assess the impact of overwash deposition on backbarrier marsh morphology and of marsh morphology on rates of island migration. Our model results suggest that backbarrier marsh width is in a constant state of change until either the backbarrier basin becomes completely filled or backbarrier marsh deposits have completely eroded away. Results also suggest that overwash deposition is an important source of sediment, which allows existing narrow marshes to be maintained in a long-lasting alternate state (similar to 500m wide in the Virginia Barrier Islands) within a range of conditions under which they would otherwise disappear. The existence of a narrow marsh state is supported by observations of backbarrier marshes along the eastern shore of Virginia. Additional results suggest that marshes reduce accommodation in the backbarrier bay, which, in turn, decreases island migration rate. As climate change results in sea level rise, and the increased potential for intense hurricanes resulting in overwash, it is likely that these couplings will become increasingly important in determining future system behavior
A Model for Assessing the Visual Resources of River Basins as an Aid to Making Landuse Planning Decisions
The visual quality of a river basin and its associated properties can be identified, evaluated and integrated into the landscape planning process. The model developed provides a quantitative methodology for determining visual quality on the basis of available Geographic Information System factors. These factors are utilized to develop the preference attributes, COLOR, FORM, TEXTURE and LINE, which are associated with the assessment of visual quality. The preference attributes are then combined through a decision making process into a continuum of DISTINCTIVE, GOOD, AVERAGE and MINIMAL visual quality and is expressed digitally in map format. By providing visual quality information in a digital format it can be treated as a discrete component of the planning process similar to physical, cultural and economic attributes
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