Many catastrophic transitions in ecosystems occur due to the interplay of both natural causes and human activities/interventions, as for example in the case of species extinctions or desertification. From a modelling and nonlinear dynamical point of view, ecosystems which undergo catastrophic transitions are often characterized by bistability which emanates from a turning point. Thus, the systematic modeling, analysis and forecasting of the complex behavior of ecosystems in response to their ongoing changes constitutes one of the major challenges of nowadays. In particular, more and more important is becoming the prediction of the effect of human interactions on ecosystems as political decisions that may be driven by social dynamics. Over the last few years, simple mathematical models in the form of ordinary and/or partial differential equations have been proposed to approximate in a qualitatively manner the observed complex phenomena. While, the vast majority of the studies dictate the importance of the notion of bifurcations for the better understanding of the mechanisms that pertain to the regime shifts, most of them use simple temporal simulations as a tool of choice for the system analysis. In this work, using the arsenal of numerical bifurcation theory, we analyze the impact of human interaction on an ecological model which represents the dynamics of a forest-grassland mosaic ecosystem. By constructing the bifurcation diagrams in the two dimensional parameter space with respect to the impact of human influence and natural causes, we were able to map the regions where different dynamics is observed and to detect codimension-2 bifurcations which mark the passage from a catastrophic shift to transitions characterized by smooth changes.
FROM GRADUAL CHANGES TO CATASTROPHIC SHIFTS IN ECOSYSTEMS WITH HUMAN INTERACTION
Lucia Russo
2018
Abstract
Many catastrophic transitions in ecosystems occur due to the interplay of both natural causes and human activities/interventions, as for example in the case of species extinctions or desertification. From a modelling and nonlinear dynamical point of view, ecosystems which undergo catastrophic transitions are often characterized by bistability which emanates from a turning point. Thus, the systematic modeling, analysis and forecasting of the complex behavior of ecosystems in response to their ongoing changes constitutes one of the major challenges of nowadays. In particular, more and more important is becoming the prediction of the effect of human interactions on ecosystems as political decisions that may be driven by social dynamics. Over the last few years, simple mathematical models in the form of ordinary and/or partial differential equations have been proposed to approximate in a qualitatively manner the observed complex phenomena. While, the vast majority of the studies dictate the importance of the notion of bifurcations for the better understanding of the mechanisms that pertain to the regime shifts, most of them use simple temporal simulations as a tool of choice for the system analysis. In this work, using the arsenal of numerical bifurcation theory, we analyze the impact of human interaction on an ecological model which represents the dynamics of a forest-grassland mosaic ecosystem. By constructing the bifurcation diagrams in the two dimensional parameter space with respect to the impact of human influence and natural causes, we were able to map the regions where different dynamics is observed and to detect codimension-2 bifurcations which mark the passage from a catastrophic shift to transitions characterized by smooth changes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
