ScienceDirect - Ecological Modelling : A standard protocol for describing individual-based and agent-based models

ScienceDirect - Ecological Modelling : A standard protocol for describing individual-based and agent-based models

"Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation models, which can make them difficult to understand and to duplicate. This paper presents a proposed standard protocol, ODD, for describing IBMs and ABMs, developed and tested by 28 modellers who cover a wide range of fields within ecology. This protocol consists of three blocks (Overview, Design concepts, and Details), which are subdivided into seven elements: Purpose, State variables and scales, Process overview and scheduling, Design concepts, Initialization, Input, and Submodels. We explain which aspects of a model should be described in each element, and we present an example to illustrate the protocol in use. In addition, 19 examples are available in an Online Appendix. We consider ODD as a first step for establishing a more detailed common format of the description of IBMs and ABMs.

Ulysse: a qualitative tool for eliciting mental models of complex systems - Desthieux - 2010 - System Dynamics Review - Wiley Online Library

Ulysse: a qualitative tool for eliciting mental models of complex systems - Desthieux - 2010 - System Dynamics Review - Wiley Online Library

Stakeholders involved in the definition of managerial problems perceive and internalize the complexity of these problems as mental models. These models are not always made explicit, which can lead to misunderstandings and conflicts. This article presents Ulysse, a tool that enables stakeholders to progressively elicit their mental models as causal loop models. Ulysse uses web technologies that store information in a database and interactively display the modeling results. It is based on matrix calculation that facilitates statistical operations and provides better understanding of the model structure. Analysis and comparison of individual models reveal the most important variables and relationships among them as a basis for identifying key issues, divergent and convergent opinions between stakeholders. Ulysse has been tested in the context of regional economic development in Atlantic Canada. The tool was designed to support managers, during interviews, in building qualitative models of indicators

ScienceDirect - Encyclopedia of Ecology : Systems Ecology

 

Systems ecology is the study of the structure and behavior of complex ecological systems using a holistic, or systems, approach. This article provides a brief overview of the general characteristics of complex ecological systems and the general steps of the systems approach. Ecological systems are thermodynamically open, hierarchical, self-organized, and self-regulating. They are complex because they are composed of many interacting components whose interactions are characterized by time lags, thresholds, feedbacks, and indirect effects. The systems approach is characterized by the conceptualization, quantification, evaluation, and application of a model representing the ecological system of interest. This approach, including systems analysis and simulation, is necessary because the cause–effect relationships within complex ecological systems can only be identified by examining the system as a single, functionally integrated entity.

ScienceDirect - Encyclopedia of Ecology : Systems Ecology

ScienceDirect - Encyclopedia of Ecology : Herbivore-Predator Cycles1

 

Terrestrial herbivores often exhibit complex or cyclic population dynamics. Approximately 30% of surveyed animal species and populations undergo population cycles, with a latitudinal gradient in cycle strength found in many mammal populations. In addition to their regularity, these cycles are often synchronous over large geographic areas. The proximate and ultimate causes of these cycles have been examined in many separate systems using both time-series analyses and large-scale manipulative experiments. Time-series analyses can point to the process order of systems, with lower orders suggesting little or no time lags and higher orders suggesting significant (3 years or longer) lags between drivers and population reactions. Manipulative experiments have generally been unable to stop the cycles entirely, but can delay or lessen some of the population crashes in mammals such as voles and hares. The drivers of the cycles vary among populations, but a major trend is that of trophic interactions between either predators and herbivores or between parasites and herbivores. It is only through a mixture of mathematical analysis and experimental manipulation that we can accurately explain how cycles begin, end, and persist over several cycles.

ScienceDirect - Encyclopedia of Ecology : Herbivore-Predator Cycles1

ScienceDirect - Ecological Modelling : Multi-agent simulations and ecosystem management: a review

 

This paper proposes a review of the development and use of multi-agent simulations (MAS) for ecosystem management. The use of this methodology and the associated tools accompanies the shifts in various paradigms on the study of ecological complexity. Behavior and interactions are now key issues for understanding and modeling ecosystem organization, and models are used in a constructivist way. MAS are introduced conceptually and are compared with individual-based modeling approaches. Various architectures of agents are presented, the role of the environment is emphasized and some computer tools are presented. A discussion follows on the use of MAS for ecosystem management. The strength of MAS has been discussed for social sciences and for spatial issues such as land-use change.

ScienceDirect - Ecological Modelling : Multi-agent simulations and ecosystem management: a review

ESA Online Journals - Responses to alternative rainfall regimes and antipoaching in a migratory system

 

Migratory ungulates may be particularly vulnerable to the challenges imposed by growing human populations and climate change. These species depend on vast areas to sustain their migratory behavior, and in many cases come into frequent contact with human populations outside protected areas. They may also act as spatial coupling agents allowing feedbacks between ecological systems and local economies, particularly in the agropastoral subsistence economies found in the African savanna biome. We used HUMENTS, a spatially realistic socioecological model of the Greater Serengeti Ecosystem in East Africa, to explore the potential impacts of changing climate and poaching on the migratory wildebeest (Connochaetes taurinus) population, the fire regime, and habitat structure in the ecosystem, as well as changes in the size and economic activities of the human population outside the protected area.

ESA Online Journals - Responses to alternative rainfall regimes and antipoaching in a migratory system

SpringerLink - Environment, Development and Sustainability, Online First™

The Arctic is a region of the world experiencing extremely rapid climatic and social change. Indigenous communities have faced similar challenges for millennia and have historically demonstrated remarkable resilience to socioecological perturbations. In contemporary contexts, however, it appears that the pace and extent of change is overwhelming the adaptive capacities of many indigenous communities. Scholars recently completed a survey of living conditions spanning the circumpolar Arctic to quantitatively document the impacts of social and ecological stress across regions. The database they created is called the Survey of Living Conditions in the Arctic or SLiCA. This article explores the utility of using this dataset to compare livelihood systems across three sub-regions of Alaska and four sub-regions within the Chukotka Autonomous Okrug of the Russian Federation. The results point out that livelihood systems in Chukotka have a substantially lower level of sustainability than in Northwest Alaska due to the high prevalence of vulnerable households

SpringerLink - Environment, Development and Sustainability, Online First™