System Dynamics Research Research Articles

A Review of Fine Root Dynamics in Populus Plantations

Production of native and hybridized varieties of Populus has received considerable interest in temperate regions as an alternative to agricultural crops and an additional wood source, while acting as a potential carbon (C) sink to offset emissions of fossil fuel-based greenhouse gases. Research of root system dynamics in Populus species is expanding, however, our understanding of the nature and role of fine roots (FR) is incomplete. The study objective, therefore, was to review the literature regarding FR production, mortality and longevity in Populus, and evaluate the magnitude and significance of the FR fraction to C sequestration. FRs, conventionally defined as less than 2 mm in diameter and responsible for water and nutrient uptake, are an essential component of the tree. Populus FRs are relatively short-lived, with reported lifespans ranging from 30 to 300 days, depending on root diameter, tree species and age, and soil environmental factors. Standing FR biomass fluctuates throughout the growing season. Fine root production generally peaks in mid-summer, and ranges between 1.0 and 5.0 mg ha−1 yr−1, while FR mortality has less seasonal amplitude. Production and mortality dynamics in Populus are highly plastic in response to soil environmental conditions, and although opposing conclusions have been proposed, research suggests soil moisture and nitrogen to be most important. Results from the literature indicate annual FR turnover to the soil C pool may be small (0.2–1.6 mg C ha−1 yr−1), but substantial in maintaining or enhancing C levels in natural and managed stands of Populus.

Managing relationships, networks, and complexity in innovation, diffusion, and adoption processes

PurposeSeeks to introduce a JBIM special issue of articles that moves the innovation‐diffusion‐adoption (IDA) literature beyond identifying key success factors to thick descriptions of the dynamics of human interactions and the enactment of decisions‐events‐outcomes using multiple rounds of informant‐researcher interpretations.Design/methodology/approachAdopts the view that informants' views as to what is happening, why it is happening, and the consequences of what is happening often go through a series of revisions depending on when the informant data are collected.FindingsIndividuals successful in guiding IDA processes exhibit great adaptability in going around and through road‐blocks that they encounter over the months and years from innovation to market success. Informants in second and third interviews provide critical information on process nuances that go unreported in single‐meeting interviews.Research limitations/implicationsSpecific case studies are absent of how executives might use such process data to revise their sense‐making and improve decisions based on insights that become available only through such explicit retrospection. The implication is that this special issue is a stepping‐stone from cross‐sectional survey research to system dynamics research with hands‐on participation by executives.Practical implicationsNow one should get real, describe, understand, and play inside IDA processes in real‐time with executives and researchers working together via multiple meetings using system dynamics research tools.Originality/valueFor IDA research this special issue calls for embracing a revolution ending the dominance of closed‐end self‐completed survey data to using multiple‐rounds of face‐to‐face interviews and direct observations with informant revisions of findings.

Mental models concepts revisited: some clarifications and a reply to Lane

This article revisits a conceptual definition of “mental models of dynamic systems” proposed for use in system dynamics research by Doyle and Ford and commented on by Lane. Lane's proposed amendments to the definition are discussed in turn, with particular attention to the history and appropriate use of the term “cognitive map.” A revised definition informed by Lane's commentary is offered. Copyright © 1999 John Wiley & Sons, Ltd.

Mental models concepts for system dynamics research

Although “mental models” are of central importance to system dynamics research and practice, the field has yet to develop an unambiguous and agreed upon definition of them. To begin to address this problem, existing definitions and descriptions of mental models in system dynamics and several literatures related to cognitive science were reviewed and compared. Available definitions were found to be overly brief, general, and vague, and different authors were found to markedly disagree on the basic characteristics of mental models. Based on this review, we concluded that in order to reduce the amount of confusion in the literature, the mental models concept should be “unbundled” and the term “mental models” should be used more narrowly. To initiate a dialogue through which the system dynamics community might achieve a shared understanding of mental models, we propose a new definition of “mental models of dynamic systems” accompanied by an extended annotation that explains the definitional choices made and suggests terms for other cognitive structures left undefined by narrowing the mental model concept. Suggestions for future research that could improve the field's ability to further define mental models are discussed. © 1998 John Wiley & Sons, Ltd.

Improving dynamic decision making in complex systems through ecological interface design: A research overview

Research on dynamic decision making in complex systems has paid little attention to the impact of interface design on human performance. Ecological interface design (EID) is a theoretical framework for designing computer interfaces for complex human-machine systems that addresses this issue. This article provides an overview of a research program on EID conducted in the author's laboratory. A detailed example showing how the principles of EID can be applied to design an interface for a simplified but representative thermal-hydraulic process-control simulation is presented. Also, the results from laboratory research, lessons learned from an industrial prototype, and the details of technology transfer to industry are reviewed. Collectively, the findings from this research program demonstrate that dynamic decision-making performance in complex systems can be significantly improved through appropriate interface design. This conclusion has significant implications for system dynamics research.

Benchmarking the system dynamics community

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.A.

Computer‐based case studies and learning laboratory projects

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.A.

Synthetic data experiments using system dynamics models: A survey of results and a research agenda

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.A.

The world hunger problem: Do we really understand it?

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Department of Mathematics and Computer Science, Wheaton College, Norton, MA 02766, U.S.A.

Dominant structure

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies.

Generic structures

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Department of Mathematics and Computer Science, Wheaton College, Norton, MA 02766, U.S.A.

The Development of System Dynamics as a Methodology for System Description and Qualitative Analysis

This paper is based on the results of experience within the System Dynamics Research Group at Bradford Management Centre of teaching methods of system description. A routine procedure for general system description has been developed which facilitates problem recognition, understanding and qualitative analysis.The approach, which is centred on a taxonomy of system dynamics modules, is described in detail and demonstrated through a practical ecological example.

System Dynamics in Perspective

The purpose of this paper is to highlight and enhance recent developments in system dynamics by presenting the subject as currently perceived by the System Dynamics Research Group at Bradford Management Centre. Emphasis is placed on the role of System Dynamics in system description, problem identification and qualitative analysis. It is concluded that the subject satisfies many of the requirements of a general methodology, as currently sought within the systjem field, as well as being a sophisticated dynamic modelling technique.

Systems Dynamics Applications to Industrial and Other Systems

This paper describes the results of ideas derived from the work of the System Dynamics Research Group at the University of Bradford. The basic underlying ideas of System Dynamics are outlined and examples of their application to a number of practical problems given. The major results obtained and the lines of research suggested by these studies are discussed.

System Dynamics Research Group at Bradford University

System Dynamics Research Group at Bradford University

System Dynamics Research Group at Bradford University

System Dynamics Research Group at Bradford University