[vc_row][vc_column width=”1/1″][vc_column_text]Nature and society can be overwhelming in their complexity; well-meaning or reasoned interventions can have counterintuitive outcomes that emerge from complex feed-backs inherent to system dynamics.
The construction of dynamic models of biological or socioeconomic systems is severely limited by the difficulty of measuring system variables and interaction strengths. Fortunately, although we usually cannot precisely measure the magnitude of all variables in a system or their interactions strenghts, we often have extensive qualitative information of systems obtained by general observation.
Qualitative models work without measuring system parameters and instead rely on the general shape of functions that mediate relationships between variables. In sacrificing precision, they seek to maximize generality in a causal understanding of complex systems. This means they permit the inclusion of relevant but often immeasurable details in order to capture the structural aspects and essential dynamics of the whole system.[/vc_column_text][vc_separator color=”grey”][vc_column_text]An example…
Signed digraphs of the socioeconomic system and the shallow-water reef-edge fish community of Lihir Island, Papua New Guinea.
Open circles are system variables, links ending in an arrow denote a direct positive effect from one variable to another, links ending in a filled circle denote a direct negative effect, and a link connecting a variable to itself denotes self-regulation.
Legend: Artisa.= artisanal; BC = benthic coral cropper; BG = blue-green algae; BI = benthic invertebrates; BP = benthic piscivorous fish; CO = coral; EA = epiphytic algae; econ. = economy; HC = herbivorous cropper (fish); HS = herbivorous scraper (fish); IC = benthic invertebrate consumer (fish); MA = macroalgae; PF = planktivorous fish; PH. = phytoplankton; PP = pelagic piscivorous fish; ZP = zooplankton; Com. agr. = commercial agriculture; Subs. = subsistence.
[/vc_column_text][vc_column_text][/vc_column_text][vc_column_text][/vc_column_text][vc_column_text]Source: Qualitative modelling of Gold Mine Impacts on Lihir Island’s Socioeconomic System and Reef-Edge Fish Community. (Dambacher et al., 2007)
Thanks Anne for sharing.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][/vc_column][/vc_row]