Nutrient-Enhanced Decomposition Of Plant Biomass In A Freshwater Wetland

We studied soil decomposition in a Panicum hemitomon (Schultes)-dominated freshwater marsh located in southeastern Louisiana that was unambiguously changed by secondarily-treated municipal wastewater effluent. We used four approaches to evaluate how belowground biomass decomposition rates vary under different nutrient regimes in this marsh. The results of laboratory experiments demonstrated how nutrient enrichment enhanced the loss of soil or plant organic matter by 50%, and increased gas production. An experiment demonstrated that nitrogen, not phosphorus, limited decomposition. Cellulose decomposition at the field site was higher in the flowfield of the introduced secondarily treated sewage water, and the quality of the substrate (% N or % P) was directly related to the decomposition rates. We therefore rejected the null hypothesis that nutrient enrichment had no effect on the decomposition rates of these organic soils. In response to nutrient enrichment, plants respond through biomechanical or structural adaptations that alter the labile characteristics of plant tissue. These adaptations eventually change litter type and quality (where the marsh survives) as the % N content of plant tissue rises and is followed by even higher decomposition rates of the litter produced, creating a positive feedback loop. Marsh fragmentation will increase as a result. The assumptions and conditions underlying the use of unconstrained wastewater flow within natural wetlands, rather than controlled treatment within the confines of constructed wetlands, are revealed in the loss of previously sequestered carbon, habitat, public use, and other societal benefits. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.orgflicenses/by-nc-nd/4.0/)

Technology Use as Consumption: A Longitudinal Study of Smart Phones

This paper investigates technology adoption and continued use as consumption behavior instead of through the traditional innovation/diffusion/acceptance frameworks. Building on consumer research we introduce the Theory of Consumption Values (TCV) to IS research in order to understand the underlying values and motives of technology usage. Data was collected through interviews, focus groups, and surveys from smart phone users during a six month period. We have adopted a narrative approach to analyze our empirical data and present the data as a dialogue between two smart phones. The story presented in the dialogue shows how different consumption values, including functional, epistemic, emotional, social, and conditional values, drive technology use and how they evolve over time. In the beginning, epistemic, emotional, social values drove the use. Later, functional value became the key driver

Technology Use: Time-In or Time-Out

This paper investigates evolving technology use by applying the distinction of time-in and time-out usage. This distinction describes how uses of technology within the life-world (i.e. the ordinary, the un-reflected) can be punctuated by time-out use when a user takes out time to consciously use or reflect on a medium. Data was collected through a longitudinal field study involving focus groups, interviews, and surveys from smart phone users during a six-month period. We have adopted a theoretically informed grounded approach to analyze our empirical data and present rich data. The results show how technology use evolves over time and provides theoretical explanation as to why usage changes with time. The time-in/out distinction shows how the value of an “extraordinary device” changes over time, thus accomplishing sensitivity to the artifact by examining the flow of activities. By repurposing the time-in/out distinction from its origin in media- and communications theory, this paper marks a pragmatic move that allows the distinction to be applied to more deeply understand the adoption and appropriation of technology products

Implementation of Web-based Information Systems in Distributed Organizations: A Change Management Approach

This article presents results elicited from studies conducted in relation to implementing a web-based information system throughout a large distributed organization. We demonstrate the kind of expectations and conditions for change that management face in relation to open-ended, configurable, and context specific web-based information systems like Lotus QuickPlace. Our synthesis from the empirical findings is related to two recent models, the improvisational change management model suggested by Orlikowski and Hofman (1997), and Gallivan’s (2001) model for organizational adoption and assimilation. In line with comparable approaches from the knowledge management area (Dixon 2000; Markus 2001), we relate to, refine, and operationalize the models from an overall organizational view by identifying and characterizing four different and general implementation contexts

Soil Shear Strength Losses In Two Fresh Marshes With Variable Increases In N And P Loading

We measured soil shear strength (SSS) from 2009 to 2018 in two hydrologically distinct freshwater marshes dominated by Panicum hemitomon after nitrogen (N) and phosphorous (P) were applied to the surface in spring. The SSS averaged over 100-cm depth in the floating and anchored marshes declined up to 30% throughout the profiles and with no apparent differences in the effects of the low, medium, and high N + P dosing. Plots with only N or P additions exhibited significant changes in SSS at individual depths below 40 cm for the anchored marsh, but not the floating marsh. The average SSS for the anchored marsh over the entire 100 cm profile declined when N and P were added separately or together. At the floating marsh, however, the SSS decreased when N and P were added in combination, or P alone, but not for the N addition. Increasing nutrient availability to these freshwater marsh soils makes them weaker, and perhaps lost if eroded or uplifted by buoyant forces during storms. These results are consistent with results from multi-year experiments demonstrating higher decomposition rates, greenhouse gas emissions, and carbon losses in wetlands following increased nutrient availability

The Belowground Intersection Of Nutrients And Buoyancy In A Freshwater Marsh

! An oligotrophic coastal freshwater marsh converted to open water within months after receiving partially-treated sewage water in fall 2006. Rafts of the upper 60 cm of marsh soil were found throughout the area within two years, as parts of the 1100 year-old marsh were re-distributed in the open water. We examined the marsh soils from 2009 to 2012 to determine some of the cause-and-effect consequences of their decomposition to the formation of these floating mats. There was a lack of herbivory damage in April 2009 where the outer boundary of the soil profile was weakened at 50-60 cm depth, and eventually converted to open water. A 2012 storm event flooded the area by 1.5 m, resulting in new marsh mat \u27pop-ups\u27 whose bottom underside was coincidental with the layer of maximum decline in soil strength in the sewage treated area. We conclude that the addition of partially-treated sewage weakened the soil structure during this high water event and others to allow for the vertical separation of the marsh as the buoyancy forces exceeded the marsh\u27s anchor strength, thereby exposing the softer older peats to decomposition, and smothering marsh underneath the mat\u27s new location. A chronic effect of eutrophication on these marshes was, therefore, revealed in a dramatic flooding event. A bottom up (nutrient addition), not top-down stress (herbivory) contributed to wetland loss in the area, and is a potentially significant chronic stressor for other eutrophied marshes with significant aboveground flooding

The Scandinavian School Revisited: A Case Study on New Roles in the ISD Process

In the knowledge economy collaboration between practitioners and academic researchers becomes increasingly important. Practice as well as theory development becomes an important part of the curriculum for both practitioners and researchers. For the collaboration to succeed new roles arise. This study focuses on the roles in the information systems development process, and demonstrates how theoretical knowledge of academic researchers can be integrated in the information systems development process in a new and more refined way through different roles. This study, based on case study methodology, focuses on particularly the roles of the academic researchers within the field of Human Resource management. The objective of the information systems project is to develop a web portal for the purpose of collecting data on human resource practices and processes. The end-users of the portal are both practitioners and academic researchers. The study suggests that the researchers act as mediators through the fulfillment of the roles, which are naturally born out of the Scandinavian approach and the traditional software engineering approach to system development

The annual, temporal and spatial pattern of Setaria tundra outbreaks in Finnish reindeer : a mechanistic transmission model approach

BackgroundIn northern Finland (Lapland), reindeer are reared as semi-domesticated animals. The region has a short summer season of 2-3 months, yet reindeer are infected with the mosquito-borne filarioid parasite Setaria tundra. The infection causes peritonitis and perihepatitis, which cause significant economic losses due to reduced body weight of infected animals. The objective of this study was to: (i) describe the spatial and temporal pattern of outbreaks in three different areas across Finnish Lapland; and (ii) construct a temperature-driven mechanistic transmission model to quantify the potential role of temperature on intensity of S. tundra transmission in reindeer.MethodsWe developed a temperature-driven transmission model able to predict the number of S. tundra potentially transmitted from an infectious reindeer. We applied the model to the years 2004-2015, and compared the predictions to the proportion of reindeer whose livers were condemned due to S. tundra infection at the time of slaughter.ResultsThe mean proportion of liver condemnation increased in reindeer slaughtered in late autumn/winter compared to earlier dates. The outbreaks were geographically clustered each year but there were no fixed foci where outbreaks occurred. Larger outbreaks were recorded in the southern regions of reindeer-herding areas compared to the central or northern parts of Lapland. Our model showed that temperatures never allowed for transmission of more than a single generation of S. tundra each season. In southern (Kuusamo) and central (Sodankyla) Lapland, our model predicted an increasing trend from 1979 to 2015 for both the duration of the effective transmission period of S. tundra (P <0.001) and for the potential number of L3 S. tundra larvae being transmitted from an infectious reindeer (P <0.001).ConclusionsThe effective transmission period for S. tundra in reindeer is very short in Lapland, but it increased over the period studied. Only one generation of S. tundra can be transmitted in one season among reindeer in Lapland. Increasing temperatures may facilitate a range expansion and increasing duration of effective transmission period for S. tundra.Peer reviewe

Epidemiology of Malaria in an Area Prepared for Clinical Trials in Korogwe, North-eastern Tanzania.

Site preparation is a pre-requesite in conducting malaria vaccines trials. This study was conducted in 12 villages to determine malariometric indices and associated risk factors, during long and short rainy seasons, in an area with varying malaria transmission intensities in Korogwe district, Tanzania. Four villages had passive case detection (PCD) of fever system using village health workers. Four malariometric cross-sectional surveys were conducted between November 2005 and May 2007 among individuals aged 0-19 years, living in lowland urban, lowland rural and highland strata. A total of 10,766 blood samples were collected for malaria parasite diagnosis and anaemia estimation. Blood smears were stained with Giemsa while haemoglobin level was measured by HaemoCue. Socio-economic data were collected between Jan-Apr 2006. Adjusting for the effect of age, the risk of Plasmodium falciparum parasitaemia was significantly lower in both lowland urban, (OR = 0.26; 95%CI: 0.23-0.29, p < 0.001) and highlands, (OR = 0.21; 95%CI: 0.17-0.25, p < 0.001) compared to lowland rural. Individuals aged 6-9 years in the lowland rural and 4-19 years in both lowland urban and highlands had the highest parasite prevalence, whilst children below five years in all strata had the highest parasite density. Prevalence of splenomegaly and gametocyte were also lower in both lowland urban and highlands than in lowland rural. Anaemia (Hb <11 g/dl) prevalence was lowest in the lowland urban. Availability of PCD and higher socio-economic status (SES) were associated with reduced malaria and anaemia prevalence. Higher SES and use of bed nets in the lowland urban could be the important factors for low malaria infections in this stratum. Results obtained here were used together with those from PCD and DSS in selecting a village for Phase 1b MSP3 vaccine trial, which was conducted in the study area in year 2008