| 1. |
- An, Li, et al.
(författare)
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Challenges, tasks, and opportunities in modeling agent-based complex systems
- 2021
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 457
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Forskningsöversikt (refereegranskat)abstract
- Humanity is facing many grand challenges at unprecedented rates, nearly everywhere, and at all levels. Yet virtually all these challenges can be traced back to the decision and behavior of autonomous agents that constitute the complex systems under such challenges. Agent-based modeling has been developed and employed to address such challenges for a few decades with great achievements and caveats. This article reviews the advances of ABM in social, ecological, and socio-ecological systems, compare ABM with other traditional, equation-based models, provide guidelines for ABM novice, modelers, and reviewers, and point out the challenges and impending tasks that need to be addressed for the ABM community. We further point out great opportunities arising from new forms of data, data science and artificial intelligence, showing that agent behavioral rules can be derived through data mining and machine learning. Towards the end, we call for a new science of Agent-based Complex Systems (ACS) that can pave an effective way to tackle the grand challenges.
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| 2. |
- An, Li, et al.
(författare)
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Corrigendum to “Challenges, tasks, and opportunities in modeling agent-based complex systems”, Ecological Modeling, 2021, 457 : 109,685, page 1–15 (Ecological Modelling (2021) 457, (S030438002100243X), (10.1016/j.ecolmodel.2021.109685))
- 2022
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 471
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Tidskriftsartikel (refereegranskat)abstract
- DOI of original article: 10.1016/j.ecolmodel.2021.109685. The authors regret that the following references are missing from the original article's online supplementary information: Box, P., 2001. Kenge GIS-CA class template for Swarm. Nat. Resour. Environ. Issues 8, 31–35. Minar, A., Burkhart, R., Langton, C.G., Manor, A., 1996. The Swarm simulation system: A toolkit for building multi-agent simulations (SFI Working paper No. 96- 06–042). Santa Fe Institute, Santa Fe, NM. Wilensky, U., Rand, W., 2015. An introduction to agent-based modeling: modeling natural, social, and engineered complex systems with NetLogo. MIT Press, Cambridge, MA. The authors would like to apologize for any inconvenience caused.
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| 3. |
- Banitz, Thomas, et al.
(författare)
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Model-derived causal explanations are inherently constrained by hidden assumptions and context : The example of Baltic cod dynamics
- 2022
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Ingår i: Environmental Modelling & Software. - : Elsevier BV. - 1364-8152 .- 1873-6726. ; 156
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Tidskriftsartikel (refereegranskat)abstract
- Models are widely used for investigating cause-effect relationships in complex systems. However, often different models yield diverging causal claims about specific phenomena. Therefore, critical reflection is needed on causal insights derived from modeling. As an example, we here compare ecological models dealing with the dynamics and collapse of cod in the Baltic Sea. The models addressed different specific questions, but also vary widely in system conceptualization and complexity. With each model, certain ecological factors and mechanisms were analyzed in detail, while others were included but remained unchanged, or were excluded. Model-based causal analyses of the same system are thus inherently constrained by diverse implicit assumptions about possible determinants of causation. In developing recommendations for human action, awareness is needed of this strong context dependence of causal claims, which is often not entirely clear. Model comparisons can be supplemented by integrating findings from multiple models and confronting models with multiple observed patterns.
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| 4. |
- Banitz, Thomas, et al.
(författare)
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Visualization of causation in social-ecological systems
- 2022
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Ingår i: Ecology & Society. - : Resilience Alliance, Inc.. - 1708-3087. ; 27:1
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Tidskriftsartikel (refereegranskat)abstract
- In social-ecological systems (SES), where social and ecological processes are intertwined, phenomena are usually complex and involve multiple interdependent causes. Figuring out causal relationships is thus challenging but needed to better understand and then affect or manage such systems. One important and widely used tool to identify and communicate causal relationships is visualization. Here, we present several common visualization types: diagrams of objects and arrows, X-Y plots, and X-Y-Z plots, and discuss them in view of the particular challenges of visualizing causation in complex systems such as SES. We use a simple demonstration model to create and compare exemplary visualizations and add more elaborate examples from the literature. This highlights implicit strengths and limitations of widely used visualization types and facilitates adequate choices when visualizing causation in SES. Thereupon, we recommend further suitable ways to account for complex causation, such as figures with multiple panels, or merging different visualization types in one figure. This provides caveats against oversimplifications. Yet, any single figure can rarely capture all relevant causal relationships in an SES. We therefore need to focus on specific questions, phenomena, or subsystems, and often also on specific causes and effects that shall be visualized. Our recommendations allow for selecting and combining visualizations such that they complement each other, support comprehensive understanding, and do justice to the existing complexity in SES. This lets visualizations realize their potential and play an important role in identifying and communicating causation.
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| 5. |
- Basurto, Xavier, et al.
(författare)
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Governing the commons beyond harvesting : An empirical illustration from fishing
- 2020
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:4
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Tidskriftsartikel (refereegranskat)abstract
- Harvesting has received most theoretical, empirical, and policy attention towards understanding common-pool resource dilemmas. Yet, pre-harvesting and post-harvesting activities influence harvesting outcomes as well. Broadening the analytical focus beyond harvesting is needed to imagine new ways of theorizing and governing the commons. Fishing-which is synonymous with harvesting-is a case in point. We contribute to a beyond-harvesting research agenda by incorporating concepts from common-pool resources theory that have not received enough attention in the literature. We compare two ubiquitous self-organizing strategies (i.e., fishing cooperatives and patron-client relationships) fishers use to access means of production and analyze their effects on the distribution of benefits resulting from harvesting. We use rarely available longitudinal data of monetary loans to fishers in Mexican small-scale fisheries and find that cooperatives can deliver broader distribution of benefits than patron-client relationships. Our study highlights the importance of historically and contextually situating analyses linking the effects of pre-harvesting processes on harvesting outcomes, and the benefits of broadening the scope of inquiry beyond a narrow policy attention on harvesting to move towards a fuller understanding of commons dilemmas.
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| 6. |
- González García-Mon, Blanca, 1993-
(författare)
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Harvesting from land and sea : Social relationships, trade networks, and spatial connectivity in changing social-ecological systems
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the era of global change, the connectivity of aquatic and terrestrial food production systems across spatial scales is increasing. At the same time, diverse actors that participate in food systems, from production to consumption, face the need to adapt their daily activities to an increasingly changing context. This thesis aims to better understand actors’ responses to social or environmental changes in food systems that are characterized by their cross-scale dynamics and social-ecological interactions. The four papers that constitute this thesis address this overarching aim by investigating two processes that are important in responding to changes and creating spatial connectivity between geographical locations: trade (Papers I-III), and spatial diversification or actor’s geographical mobility (Paper IV). The papers analyze fisheries and agricultural systems in Mexico and South Africa, using interview-based data collection and analysis, network analysis, agent-based modeling, and combinations of these methods. Papers I-III specifically examine how trade networks, which are embedded in social relationships and networks that operate across spatial scales, can influence the responses of food system actors to multiple types of changes. Paper I shows that trade relationships across fisheries and agricultural systems are generally embedded in stable business relationships characterized by reciprocity. Paper II finds that different trade network structures in a multi-species Mexican fishery can buffer changes in fish availability and create cascading effects between different species and geographical regions. Paper III describes four types of social networks consisting of relationships within and across scales that enable responding to multiple types of changes in a South African agricultural trade network. Paper IV identifies potential factors, such as environmental changes, that could influence changes in fisheries actors’ spatial diversification observed in Mexico. The thesis contributes to social-ecological systems research with theoretical insights regarding the embeddedness of trade networks in multidimensional social relationships within and across scales, where diverse types of social relationships and networks can influence fishing and farming practices. In addition, it highlights that spatial and temporal heterogeneity can have a key role in responses to changes based on spatial connectivity. Finally, the mixed-method methodology applied in this thesis enables simultaneously analyzing networks and processes in social-ecological systems, while illustrating the challenges and opportunities of method integration.
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| 7. |
- González-Mon, Blanca, 1993-, et al.
(författare)
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Fish provision in a changing environment : The buffering effect of regional trade networks
- 2021
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:12
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Tidskriftsartikel (refereegranskat)abstract
- Local and regional trade networks in small-scale fisheries are important for food security and livelihoods across the world. Such networks consist of both economic flows and social relationships, which connect different production regions to different types of fish demand. The structure of such trade networks, and the actions that take place within them (e.g., people fishing, buying, selling), can influence the capacity of small-scale fisheries to provide sufficient fish in a changing social and ecological context. In this study, we aim to understand the importance of networks between different types of traders that access spatially-distinct fish stocks for the availability and variability of fish provision. We deployed a mixed-methods approach, combining agent-based modelling, network analysis and qualitative data from a small-scale fishery in Baja California Sur, Mexico. The empirical data allowed us to investigate the trade processes that occur within trade networks; and the generation of distinct, empirically-informed network structures. Formalized in an agent-based model, these network structures enable analysis of how different trade networks affect the dynamics of fish provision and the exploitation level of fish stocks. Model results reveal how trade strategies based on social relationships and species diversification can lead to spillover effects between fish species and fishing regions. We found that the proportion of different trader types and their spatial connectivity have the potential to increase fish provision. However, they can also increase overexploitation depending on the specific connectivity patterns and trader types. Moreover, increasing connectivity generally leads to positive outcomes for some individual traders, but this does not necessarily imply better outcomes at the system level. Overall, our model provides an empirically-grounded, stylized representation of a fisheries trading system, and reveals important trade-offs that should be considered when evaluating the potential effect of future changes in regional trade networks.
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| 8. |
- González-Mon, Blanca, 1993-, et al.
(författare)
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Spatial diversification as a mechanism to adapt to environmental changes in small-scale fisheries
- 2021
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Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011 .- 1873-6416. ; 116, s. 246-257
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Tidskriftsartikel (refereegranskat)abstract
- Small-scale fisheries’ actors increasingly face new challenges, including climate driven shifts in marine resource distribution and productivity. Diversification of target species and fishing locations is a key mechanism to adapt to such changes and maintain fisheries livelihoods. Here we explore environmental and institutional factors mediating how patterns of spatial diversification (i.e., utilization of alternative fishing grounds) and target species diversification change over time. Using small-scale fisheries in Baja California Sur (Mexico) as a case study, we adopt a social-ecological network approach to conduct a spatially explicit analysis of fisheries landings data (2008–2016). This approach quantifies relative patterns of diversification, and when combined with a qualitative analysis of existing literature, enables us to illuminate institutional and environmental factors that may influence diversification strategies. Our results indicate that interannual changes in spatial diversification are correlated with regional oceanographic change, while illustrating the heterogeneity and dynamism of diversification strategies. Rather than acting in isolation, we hypothesize that environmental drivers likely operate in combination with existing fisheries regulations and local socioeconomic context to mediate spatial diversification. We argue that small-scale fisheries policies need to better account such linkages as we move towards an increasingly variable environment. Overall, our results highlight spatial diversification as a dynamic process and constitute an important step towards understanding and managing the complex mechanisms through which environmental changes affect small-scale fisheries.
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| 9. |
- Hertz, Tilman, et al.
(författare)
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Eliciting the plurality of causal reasoning in social-ecological systems research
- 2024
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Ingår i: Ecology and Society. - : Resilience Alliance. - 1708-3087. ; 29:1
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Tidskriftsartikel (refereegranskat)abstract
- Understanding causation in social-ecological systems (SES) is indispensable for promoting sustainable outcomes. However, the study of such causal relations is challenging because they are often complex and intertwined, and their analysis involves diverse disciplines. Although there is agreement that no single research approach (RA) can comprehensively explain SES phenomena, there is a lack of ability to deal with this diversity. Underlying this diversity and the challenge of dealing with it are different causal reasonings that are rarely explicit. Awareness of hidden assumptions is essential for understanding how the causal reasoning of an RA is constituted, and for promoting the integration, translation, or juxtaposition of different RAs. We identify the following elements as particularly relevant for understanding causal reasoning: methods, frameworks and theories, accounts of causation, analytical focus, and causal notions. We begin with the idea that one of these elements typically figures as an entry point to an RA. This entry point is particularly important because it generates a path dependence that orients causal reasoning. In a subsequent step, when an approach is applied, causal reasoning concretizes as a result of a particular constellation of the remaining elements. We come to these insights by studying the application of four different RAs to the same social-ecological case (the collapse of Baltic cod stocks in the 1980s). On the basis of our findings we developed a guide for the analysis of causal reasoning by raising awareness of the assumptions, key elements, and the relations between these key elements for a given RA. The guide can be used to elicit the causal reasoning of RAs, facilitate interdisciplinary collaboration, and support disclosure of ethical/political dimensions that underlie management/governance interventions that are formulated on the basis of causal findings of research studies.
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| 10. |
- Hussain, Alia A., et al.
(författare)
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Increased lipid and lipoprotein concentrations in anorexia nervosa : A systematic review and meta-analysis
- 2019
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Ingår i: International Journal of Eating Disorders. - : John Wiley & Sons. - 0276-3478 .- 1098-108X. ; 52:6, s. 611-629
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Forskningsöversikt (refereegranskat)abstract
- Objective: Alterations in blood lipid concentrations in anorexia nervosa (AN) have been reported; however, the extent, mechanism, and normalization with weight restoration remain unknown. We conducted a systematic review and a meta-analysis to evaluate changes in lipid concentrations in acutely-ill AN patients compared with healthy controls (HC) and to examine the effect of partial weight restoration.Method: A systematic literature review and meta-analysis (PROSPERO: CRD42017078014) were conducted for original peer-reviewed articles.Results: Forty-eight studies were eligible for review; 33 for meta-analyses calculating mean differences (MD). Total cholesterol (MD = 22.7 mg/dL, 95% CI = 12.5, 33.0), high-density lipoprotein (HDL; MD = 3.4 mg/dL, CI = 0.3, 7.0), low-density lipoprotein (LDL; MD = 12.2 mg/dL, CI = 4.4, 20.1), triglycerides (TG; MD = 8.1 mg/dL, CI = 1.7, 14.5), and apolipoprotein B (Apo B; MD = 11.8 mg/dL, CI = 2.3, 21.2) were significantly higher in acutely-ill AN than HC. Partially weight-restored AN patients had higher total cholesterol (MD = 14.8 mg/dL, CI = 2.1, 27.5) and LDL (MD = 16.1 mg/dL, CI = 2.3, 30.0). Pre- versus post-weight restoration differences in lipid concentrations did not differ significantly.Discussion: We report aggregate evidence for elevated lipid concentrations in acutely-ill AN patients compared with HC, some of which persist after partial weight restoration. This could signal an underlying adaptation or dysregulation not fully reversed by weight restoration. Although concentrations differed between AN and HC, most lipid concentrations remained within the reference range and meta-analyses were limited by the number of available studies.
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