Improving the management of coastal wetland systems by modelling vegetation growth

Coastal wetland systems, such as saltmarshes and mangroves, are known for a wide range of ecosystem services worldwide, including habitat provision and flood mitigation. Over the last few decades, the high soil carbon sequestration capacity per area of these systems, which is three to four times higher than that of some other ecosystems, has been recognised as a means for mitigating the effects of greenhouse gases and climate change. As a result, numerous coastal wetland conservation and rehabilitation initiatives have been established across various regions worldwide. Located in coastal areas, however, these systems can become vulnerable to the effects of sea-level rise and management practices that impact the conditions of the vegetation and their capacity for soil carbon accumulation.

Predictive eco-geomorphic tools, integrating feedbacks between flow, sediments and plants, have been the focus of recent research. These predictive tools range from simplified empirical relationships that allow calculation of soil carbon accumulation under specific conditions, to numerical-physically-based models that simulate the complex processes driving vegetation dynamics and carbon accumulation. Such models link hydrodynamic modelling with sediment transport and vegetation establishment modules, which allow for the exploration of several scenarios. However, uncertainty remains on the capacity of vegetation to continue accumulating carbon over time. In most models, this uncertainty hinges on the representation of plant biomass within the eco-geomorphic calculation framework which results in direct inputs of organic carbon in soils.

This project aims to develop new and innovative plant growth modelling techniques based on current eco-hydrological approaches for individual plant growth that can be upscaled to improve vegetation representation in models. Following the development of these techniques, they will be integrated within well-established eco-geomorphic calculation frameworks to simulate coastal wetland dynamics under climate change and management strategies. The project will focus on the Australian and Indian context

however, the intended methodology will provide general approaches so that the modelling tools developed can be adapted in other regions. To achieve the objectives of this project, the candidate will conduct field investigations and data collection on saltmarsh and mangrove sites to establish vegetation structural parameters and hydrological conditions. This information will be used to develop modelling tools for plant growth, establishing computational libraries with different plant growth models capable of calculating mangrove and saltmarsh biomass as well as soil carbon sequestration. The intended output of the project is a set of practical calculation approaches that can be used to improve predictions of carbon sequestration rates, thus allowing for the evaluation of wetland conservation and rehabilitation initiatives and assessing the uncertainty for achieving soil carbon accumulation targets.