Simulating eco-hydrological feedbacks and resilience of blanket bogs in the context of climate change

Resumen

Blanket bogs, a type of peatland, are a globally rare yet significant ecosystem which stores large quantities of carbon, supports biodiversity, and regulates local hydrology. Their carbon sequestration is a result of persistently shallow water tables, cool climates, and low nutrient availability, shifting the balance between plant productivity and plant litter decay into the positive. The accumulation of peat carbon is mediated by a complex combination of interconnected ecological, hydrological, mechanical, and climatological processes and feedbacks. Many of these processes act to stabilise carbon accumulation and protect the existing carbon stock from disturbance, referred to as peatland resilience. Peatland models that simulate the governing processes of peatland function have been used to investigate their development through time and response to change. However, there has been limited application of peatland development models
for simulating historical carbon accumulation of blanket bogs and as climate impact assessment tools.
This thesis focused on using a peatland development model, DigiBog, to simulate
blanket bogs of the Flow Country and their resilience to climate change. First,
DigiBog was tested across a well-constrained parameter space to explore the effects of climate, decay, saturated hydraulic conductivity (𝐾𝑠𝑎𝑡 ), and landscape morphology. This revealed the importance of parameterising the relationship between 𝐾𝑠𝑎𝑡 and decay as a primary control on the spatial distribution of peat accumulation. DigiBog was then used to simulate the peat accumulation along two transects of peat from the Flow Country (Munsary and Dalchork), which highlighted challenges in modelling complex topography and the need to better represent bulk water movement through processes such as macropore and overland flow. The skilful simulation of the carbon accumulation at Munsary was then used as a baseline to be projected into the future using an ensemble forecasting approach. The driving climate projections followed three Shared Socio-economic Pathways (SSPs), SSP1-2.6, SSP2-4.5, and SSP5-8.5, outlined by the Intergovernmental Panel on Climate Change (IPCC). The simulations predict that Munsary is likely to switch from a small net sink to a small net source of carbon to the atmosphere. The magnitude of change in the net carbon balance suggests
that near-natural peatlands will be mostly resilient to climate change. However, this is unlikely to be the case for degraded bogs, which have had their natural resilience mechanisms disrupted by anthropogenic disturbance.

Fecha de lectura	13 nov 0202
Idioma original	English
Institución de lectura	University of the Highlands and Islands
Patrocinadores	Leverhulme Trust
Supervisor	Roxane Andersen (Supervisor) & Andrew Duncan (Supervisor)