Investigation on regime shifts in coupled socio-ecological system
Sugiarto, Hendrik Santoso
Date of Issue2017
School of Physical and Mathematical Sciences
The social and economic progress of mankind essentially relies on the services of ecosystems that come in the form of hospitable climate, clean air, fresh water, and also nutritious food. As our civilization advances, the coupling between human and ecology becomes more significant, but the enhanced coupling has so far served to deteriorate the state of the ecosystem. Although many studies have found that rational individuals cooperate to preserve their ecological resources, some fundamental questions such as how the interaction structure affects their cooperation remains unanswered. This thesis presents an integrative approach that aims to answer these questions. We use common pool resource (CPR) framework from TSL model, with complex network structure. This framework assumes resource utilization through Cobb-Douglas production function and social control by neighboring individual through ostracism mechanism. By using this model, we can study the influence of different type of social network on dynamical stability of the whole system. This analysis provides useful insights for studying socio-ecological system with different social settings. Since it based on CPR framework, the results from this model can be applied to general coupled socio-ecological system with any specific social interaction and common resource sharing. In particular, we focus our investigation on regime shifts in coupled socio-ecological system since such a critical transition typically bears catastrophic effects. We performed our studies based on theoretical modeling, with computational simulations and analytical calculations used to express the results of our model. We have shown from numerical simulations that alternate stable states and hysteresis results from the intrinsic nature of the social interaction network structure. Furthermore, we have validated these results by analytical calculations based on the approach of statistical physics and non-linear dynamics. We have used mean field theory and pair approximation to reveal the existence of multiple stable regimes in the system. We have found strong association between network structure and dynamical behavior in the system with the presence or absence of hysteresis behavior dependent on the social network degree. In this respect, our research has shown that social interaction network structure can lead to a stronger social inertia against change within the SES when average network degree increases. Under this scenario, critical transitions are delayed which brings about the effect of hysteresis. In addition, network structure also plays a role in influencing the accuracy of generic early warning signals in predicting the upcoming regime shifts. We also found strong association between hysteresis behavior and network topology such as the scale-free and modular structure. Interestingly, the existence of community structure in the social interaction network gives rise to additional stable regimes between the cooperative and the defective regime. The community structure in the social network interaction corresponds to social segregation in which the new intermediate stable regime corresponds to communities of defectors free riding on communities of cooperator. This generates disharmony between the two sets of communities. Significantly, the intermediate stable regime possesses characteristics that relate closely to those observed in the real-world data of a traditional SES: the Balinese subaks. In addition, we have also explored the effects of different social mechanisms such as the ostracism and voluntary enforcement mechanism on the emergence of social cooperation. We catalogued the social dynamical behavior due to these mechanisms in the form of a phase diagram. We compare the dynamical similarity and dissimilarity between them and found the interesting phase of bi-stability and disequilibrium dynamical behavior, in addition to the cooperation phase, the defection phase, and mixture of cooperation and defection phase, in specific parameter region. In summary, by providing a more generic investigation on the complex network of social interactions and new forms of social mechanisms, this thesis has brought progress to the study of SES regime shift as well as the early warning prediction of its possible occurrence.
DRNTU::Science::Mathematics::Applied mathematics::Complex systems