HOLLINGS FIGURE-8 MODEL - A TECHNICAL REEVALUATION IN RELATION TO CLIMATE-CHANGE AND BIODIVERSITY

Holling proposed a four-phase conceptual model of ecosystem dynamics t hat includes exploitation, conservation, and destructive and renewal c omponents to explain the failure of many natural resource management s chemes. The model is drawn as a sideways figure-eight i.e. oo. There a re two dimensions in this model, connectivity (abscissa) and the amoun t of capital stored in the system (ordinate). This conceptual model ha s been suggested as a guide to thinking about the impact of climate ch ange on biodiversity, but the two dimensions are insufficient and the alignment of the figure-eight model is problematic when compared with actual data. Kay has adjusted the dimensions of the figure-eight model and renamed the abscissa as exergy stored and the ordinate as exergy consumed. We realign the original figure-eight model, labeling the abs cissa as carbon stored and the ordinate as nutrients, such that the re lative values of both axes are in qualitative agreement with data from four different studies. This new alignment is then shown to fit relat ively well with Holling's original labels. This revision of the figure -eight model brings Holling's model into agreement with observations a nd provides insight into the linkages between biodiversity and climate change.