scholarly journals The relative importance of seed competition, resource competition and perturbations on community structure

2011 ◽  
Vol 8 (5) ◽  
pp. 1107-1120 ◽  
Author(s):  
K. Bohn ◽  
J. G. Dyke ◽  
R. Pavlick ◽  
B. Reineking ◽  
B. Reu ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Community Structure ◽  
Resource Competition ◽  
Regional Climate ◽  
Global Scale ◽  
Relative Importance ◽  
Plant Strategies ◽  
Primary Selection ◽  
Growth And Reproduction ◽  
Do So

Abstract. While the regional climate is the primary selection pressure for whether a plant strategy can survive, however, competitive interactions strongly affect the relative abundances of plant strategies within communities. Here, we investigate the relative importance of competition and perturbations on the development of vegetation community structure. To do so, we develop DIVE (Dynamics and Interactions of VEgetation), a simple general model that links plant strategies to their competitive dynamics, using growth and reproduction characteristics that emerge from climatic constraints. The model calculates population dynamics based on establishment, mortality, invasion and exclusion in the presence of different strengths of perturbations, seed and resource competition. The highest levels of diversity were found in simulations without competition as long as mortality is not too high. However, reasonable successional dynamics were only achieved when resource competition is considered. Under high levels of competition, intermediate levels of perturbations were required to obtain coexistence. Since succession and coexistence are observed in plant communities, we conclude that the DIVE model with competition and intermediate levels of perturbation represents an adequate way to model population dynamics. Because of the simplicity and generality of DIVE, it could be used to understand vegetation structure and functioning at the global scale and the response of vegetation to global change.

scholarly journals Linking plant ecophysiology to the dynamics of diverse communities

2010 ◽  
Vol 7 (6) ◽  
pp. 8215-8243 ◽  
Author(s):  
K. Bohn ◽  
J. G. Dyke ◽  
R. Pavlick ◽  
B. Reineking ◽  
B. Reu ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Community Dynamics ◽  
Resource Competition ◽  
Spatial Dynamics ◽  
Generic Model ◽  
Terrestrial Vegetation ◽  
Plant Strategies ◽  
Local Climate ◽  
Plant Ecophysiology ◽  
Slow Growing

Abstract. The local climate represents the primary selection pressure acting on vegetation, but competitive interactions between plant strategies determine their composition. We link growth and reproduction characteristics from different plant strategies, that emerge from climatic constraints, to their competitive abilities and calculate explicitly their spatial dynamics. DIVE (Dynamics and Interactions of VEgetation), a simple generic model is built, that calculates population dynamics in the presence of perturbations, seed and resource competition. To understand the impacts of competition and perturbations on the population dynamics, a range of sensitivity experiments are conducted. DIVE simulations feature successional dynamics from fast-growing towards slow-growing plant strategies and as such corresponds to widely observed characteristics of terrestrial vegetation. Perturbations, seed and resource competition were found to affect succession and diversity, with the community composition at steady state ranging from competitive exclusion to coexistence and total extinction. We conclude that linking ecophysiological characteristics of vegetation to competition is a valid approach to determine population dynamics. Furthermore, incorporating mechanisms of perturbations and competition may be essential in order to effectively predict the response of community dynamics to changing environmental conditions.

The Six E’s of Consumer Choice

2018 ◽  
Author(s):  
Gordon Moore ◽  
John A. Quelch ◽  
Emily Boudreau
Keyword(s):  
Consumer Choice ◽  
Relative Importance ◽  
Health And Wellness ◽  
Healthcare Decision ◽  
Do So

Whenever consumers make a choice—in healthcare or in other situations—they do so based on the benefits they anticipate. Chapter 5 focuses on the most common benefits consumers seek when making health and wellness decisions. Though they may vary in relative importance based upon the healthcare decision at hand, these six commonly sought benefits are economy, effectiveness, empathy, efficiency, empowerment, and experience. This chapter reviews each of these benefits in-depth, highlighting examples of each in today’s market. Consumers have different ways of assessing these benefits ranging from simultaneously trading off importance between them to using four shortcuts that make comparisons easier.

scholarly journals A Multiobjective Decision-Making Model for Risk-Based Maintenance Scheduling of Railway Earthworks

2021 ◽  
Vol 11 (3) ◽  
pp. 965
Author(s):  
Irina Stipanovic ◽  
Zaharah Allah Bukhsh ◽  
Cormac Reale ◽  
Kenneth Gavin
Keyword(s):  
Utility Theory ◽  
Structural Reliability ◽  
Structural Performance ◽  
Maintenance Planning ◽  
Relative Importance ◽  
User Cost ◽  
Multi Attribute Utility Theory ◽  
Network Maintenance ◽  
Decision Making Model ◽  
Do So

Aged earthworks constitute a major proportion of European rail infrastructures, the replacement and remediation of which poses a serious problem. Considering the scale of the networks involved, it is infeasible both in terms of track downtime and money to replace all of these assets. It is, therefore, imperative to develop a rational means of managing slope infrastructure to determine the best use of available resources and plan maintenance in order of criticality. To do so, it is necessary to not just consider the structural performance of the asset but also to consider the safety and security of its users, the socioeconomic impact of remediation/failure and the relative importance of the asset to the network. This paper addresses this by looking at maintenance planning on a network level using multi-attribute utility theory (MAUT). MAUT is a methodology that allows one to balance the priorities of different objectives in a harmonious fashion allowing for a holistic means of ranking assets and, subsequently, a rational means of investing in maintenance. In this situation, three different attributes are considered when examining the utility of different maintenance options, namely availability (the user cost), economy (the financial implications) and structural reliability (the structural performance and subsequent safety of the structure). The main impact of this paper is to showcase that network maintenance planning can be carried out proactively in a manner that is balanced against the needs of the organization.

scholarly journals Effects of Infectious Diseases on Population Dynamics of Marine Organisms in Chesapeake Bay

2021 ◽  
Author(s):  
Jerelle A. Jesse ◽  
M. Victoria Agnew ◽  
Kohma Arai ◽  
C. Taylor Armstrong ◽  
Shannon M. Hood ◽  
...  
Keyword(s):  
Climate Change ◽  
Population Dynamics ◽  
Infectious Diseases ◽  
Chesapeake Bay ◽  
Eastern Oyster ◽  
Marine Organisms ◽  
Ecosystem Dynamics ◽  
Climate Change Effects ◽  
Pathogen Dynamics ◽  
Growth And Reproduction

AbstractDiseases are important drivers of population and ecosystem dynamics. This review synthesizes the effects of infectious diseases on the population dynamics of nine species of marine organisms in the Chesapeake Bay. Diseases generally caused increases in mortality and decreases in growth and reproduction. Effects of diseases on eastern oyster (Crassostrea virginica) appear to be low in the 2000s compared to effects in the 1980s–1990s. However, the effects of disease were not well monitored for most of the diseases in marine organisms of the Chesapeake Bay, and few studies considered effects on growth and reproduction. Climate change and other anthropogenic effects are expected to alter host-pathogen dynamics, with diseases of some species expected to worsen under predicted future conditions (e.g., increased temperature). Additional study of disease prevalence, drivers of disease, and effects on population dynamics could improve fisheries management and forecasting of climate change effects on marine organisms in the Chesapeake Bay.

scholarly journals Individual-based modelling of resource competition to predict density-dependent population dynamics: a case study with white storks

Oikos ◽  
2014 ◽  
Vol 124 (3) ◽  
pp. 319-330 ◽  
Author(s):  
Damaris Zurell ◽  
Ute Eggers ◽  
Michael Kaatz ◽  
Shay Rotics ◽  
Nir Sapir ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Resource Competition ◽  
Density Dependent ◽  
White Storks

scholarly journals Pharmaceuticals from natural products: current trends

2002 ◽  
Vol 74 (1) ◽  
pp. 145-150 ◽  
Author(s):  
PETER R. SEIDL
Keyword(s):  
Nineteenth Century ◽  
Natural Products ◽  
Biological Diversity ◽  
Pharmaceutical Companies ◽  
Relative Importance ◽  
Discovery Process ◽  
Current Trends ◽  
Principal Source ◽  
Do So

The use of products extracted from plants for medicinal purposes can be traced to the beginnings of civilization and up until the end of the nineteenth century natural products were the principal source of medicines. Since then their relative importance has oscillated according to the strategies of large pharmaceutical companies. Now that these strategies are changing, there are new opportunities for countries like Brazil, in which a large proportion of the world's biodiversity is located. There are, however, new circumstances that must be taken into consideration: material must be collected by groups which are formally authorized to do so and under the conditions of the Convention of Biological Diversity, the discovery process is being successively outsourced to smaller specialized firms and there is a growing integration with producers of cosmetics and phytomedicines.

scholarly journals Masters of Wine on Twitter: presence, activity, impact and community structure

2021 ◽  
Vol 10 (1) ◽  
pp. 73-88
Author(s):  
Enrique Orduña-Malea ◽  
Cristina I. Font-Julian ◽  
José Antonio Ontalba-Ruipérez ◽  
Raúl Compés-López
Keyword(s):  
Social Media ◽  
International Trade ◽  
Community Structure ◽  
Descriptive Statistics ◽  
Wine Industry ◽  
The Internet ◽  
The World ◽  
Credible Information ◽  
Do So ◽  
The Way

Globalisation, the Internet and social media have changed the kind of actors with influence in the wine industry and the way these actors create signals to communicate credible information about experience and trust attributes. Among the most prestigious experts in the world of wine are the Masters of Wine (MW). Although initially devoted to international trade, they have spread their activities and their opinion is more and more appreciated by producers and consumers. The main objective of this article is to determine this community of experts’ behaviour on Twitter. In order to do so, four factors (presence, activity, impact and community) have been considered. All Twitter profiles belonging to users awarded with the MW qualification were identified and analysed. In addition, a set of 35,653 tweets published by the MWs were retrieved and analysed through descriptive statistics. The results show MWs on Twitter as high attractors (number of followers), moderate publishers (original contents published), moderate influencers (number of likes and retweets), and low interactors (number of friends and mentions to other users). These findings reveal that the MW community is not using Twitter to gain or reinforce their reputation as an accredited expert in the wine industry, giving more influential space on Twitter to consumers and amateurs.

Life history and environmental influences on population dynamics in sockeye salmon

2014 ◽  
Vol 71 (8) ◽  
pp. 1198-1208 ◽  
Author(s):  
Douglas C. Braun ◽  
John D. Reynolds
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Population Growth ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Sockeye Salmon ◽  
Life History Traits ◽  
Relative Importance ◽  
Population Growth Rates ◽  
Habitat Variables

Understanding linkages among life history traits, the environment, and population dynamics is a central goal in ecology. We compared 15 populations of sockeye salmon (Oncorhynchus nerka) to test general hypotheses for the relative importance of life history traits and environmental conditions in explaining variation in population dynamics. We used life history traits and habitat variables as covariates in mixed-effect Ricker models to evaluate the support for correlates of maximum population growth rates, density dependence, and variability in dynamics among populations. We found dramatic differences in the dynamics of populations that spawn in a small geographical area. These differences among populations were related to variation in habitats but not life history traits. Populations that spawned in deep water had higher and less variable population growth rates, and populations inhabiting streams with larger gravels experienced stronger negative density dependence. These results demonstrate, in these populations, the relative importance of environmental conditions and life histories in explaining population dynamics, which is rarely possible for multiple populations of the same species. Furthermore, they suggest that local habitat variables are important for the assessment of population status, especially when multiple populations with different dynamics are managed as aggregates.

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