Understanding the effects of ecosystem changes on the circular bioeconomy through system dynamics modelling and life cycle approaches
Main Presenter: Charlene Vance
Seagrass meadows, while recognized as essential ecosystem service providers, are degrading worldwide. This has a profound impact on the environment but also on socioeconomic systems which hope to utilize beach-cast seagrass (wrack) as a bioresource. Despite being a key tool for assessing sustainability, life cycle assessment (LCA) studies rarely consider the impacts of ecosystem degradation on resource availability. To better understand such impacts, systems thinking is a relevant tool. This study proposes utilizing System Dynamics (SD) modelling to understand how ecosystem changes feedback on a circular bioeconomy, integrating with LCA and life cycle costing (LCC) to understand the complexities of waste management and ecosystem restoration. The research considers a case study of seagrass wrack management in an Italian coastal municipality, where a reduction in wrack has been observed for the past 16 years. Three scenarios are determined: a baseline scenario (degrading seagrass meadow and landfilling of wrack), valorization scenario (degrading seagrass meadow and valorization of wrack through anaerobic digestion), and valorization scenario including seagrass meadow restoration (recovery of seagrass meadow and valorization of wrack through anaerobic digestion). An SD model is first created to model the seagrass meadow area, deposition of seagrass wrack onto the beach, collection during summer months (tourist season), and decomposition and return of seagrass wrack to the ecosystem during winter months. The SD is then expanded to quantify the ecosystem services provided by the seagrass meadow and allocate costs associated with its degradation. The LCA and LCC are then performed, accounting for the environmental and economic impacts of seagrass wrack valorization compared to landfilling. Finally, an extended LCC is performed, combining the results of the SD model, LCA, and LCC to demonstrate the cost of seagrass meadow degradation and value of restoration on both the ecosystem services provided by the meadow and the valorization of the produced wrack. The final results show that if the ecosystem services provided by the seagrass meadow are properly valued, restoration efforts can be worth their high costs, and can improve the economic sustainability of valorization for the AD operator.