Emergence and Implications of Conservation Opinion Propagation in Dynamic Coupled Socio-Ecological Systems

Human behaviour is rarely a static phenomenon. In life, individuals are presented with choices that define the trajectories they will experience days, weeks or months later. As an example consider farmer decision-making and orchard dynamics. If an avocado orchard is well taken care of, a bountiful harvest can lead to a lower price of avocados that will more easily attract grocers to stock the product. Alternatively, if the orchard is not properly cared for, avocado prices can surge (due to their low supply) and become a greater risk for grocers, causing them to seek other suppliers. If a particular 'care' routine is developed by the farmer, this can have a significant impact on the long-term trajectories of orchard dynamics. From this simple example, it is clear how dynamic human behaviour can interact with environmental system dynamics. This motivates the potential value of capturing this interaction in mathematical modelling. In this thesis, we develop two different coupled human-environment system (CHES) models that incorporate a dynamic feedback loop mechanism to link human impact and environmental system responses and vice versa. The first model is developed using a game-theoretic approach to describe dynamics of opinion spread. The model is then coupled to a previously established coral reef ecosystem model. We investigate the effects of key factors such as social learning, social norms, and exploitation rate on the trajectories predicted by the model. We discover stable regimes that are made possible by the presence of human coupling and we identify the potentially harmful role of social norms. In the second model, we utilize a similar game-theoretic approach to couple a dynamic human component to a previously established grassland model of the Southeastern Australian grasslands. The aim of this model is to determine conditions that suppress invasive exotic grasses, in the presence of human feedback that determines how strongly the local population mitigates its own pollution. Finally, we conduct a systematic review of the CHES modelling literature between May 2009 and April 2019 using the Web of Knowledge and PUBMED databases. Results reveal an increasing trend in the number of mathematical models using a CHES approach. Results also show that these models utilize a wide range of techniques of varying complexity. In general, most work focuses on agricultural systems. We postulate that application to other environmental systems is relatively unexplored and can be implemented using techniques similar to those of the models developed in this thesis, or via adaptations of other modelling techniques from different fields of research. We suggest that including dynamic human behaviour is necessary in order to improve existing environmental policies and improve the predictive power of mathematical modelling techniques in environmental systems research

The Influence Of Social Norms On The Dynamics Of Vaccinating Behaviour For Paediatric Infectious Diseases

Definitive version as published available at: Oraby, T., Thampi, V., & Bauch, C. T. (2014). The influence of social norms on the dynamics of vaccinating behaviour for paediatric infectious diseases. Proceedings of the Royal Society B: Biological Sciences, 281(1780), 20133172–20133172., http://dx.doi.org/10.1098/rspb.2013.3172Mathematical models that couple disease dynamics and vaccinating behaviour often assume that the incentive to vaccinate disappears if disease prevalence is zero. Hence, they predict that vaccine refusal should be the rule, and elimination should be difficult or impossible. In reality, countries with non-mandatory vaccination policies have usually been able to maintain elimination or very low incidence of paediatric infectious diseases for long periods of time. Here, we show that including injunctive social norms can reconcile such behaviour-incidence models to observations. Adding social norms to a coupled behaviour-incidence model enables the model to better explain pertussis vaccine uptake and disease dynamics in the UK from 1967 to 2010, in both the vaccine-scare years and the years of high vaccine coverage. The model also illustrates how a vaccine scare can perpetuate suboptimal vaccine coverage long after perceived risk has returned to baseline, pre-vaccine-scare levels. However, at other model parameter values, social norms can perpetuate depressed vaccine coverage during a vaccine scare well beyond the time when the population's baseline vaccine risk perception returns to pre-scare levels. Social norms can strongly suppress vaccine uptake despite frequent outbreaks, as observed in some small communities. Significant portions of the parameter space also exhibit bistability, meaning long-term outcomes depend on the initial conditions. Depending on the context, social norms can either support or hinder immunization goals

Socio-Ecological Dynamics Of Caribbean Coral Reef Ecosystems And Conservation Opinion Propagation

The Caribbean coral reef ecosystem has experienced a long history of deterioration due to various stressors. For instance, over-fishing of parrotfish - an important grazer of macroalgae that can prevent destructive overgrowth of macroalgae - has threatened reef ecosystems in recent decades and stimulated conservation efforts such as the formation of marine protected areas. Here we develop a mathematical model of coupled socio-ecological interactions between reef dynamics and conservation opinion dynamics to better understand how natural and human factors interact individually and in combination to determine coral reef cover. We find that the coupling opinion and reef systems generates complex dynamics that are difficult to anticipate without use of a model. For instance, instead of converging to a stable state of constant coral cover and conservationist opinion, the system can oscillate between low and high live coral cover as human opinion oscillates in a boom-bust cycle between complacency and concern. Out of various possible parameter manipulations, we also find that raising awareness of coral reef endangerment best avoids counter-productive nonlinear feedbacks and always increases and stabilizes live coral reef cover. In conclusion, an improved understanding of coupled opinion-reef dynamics under anthrogenic stressors is possible using coupled socio-ecological models, and such models should be further researched