2024-C1 Forest Resilience and Compound Events (FoRCE) in a changing climate

Overview

Forests are critical to the realisation of UK net-zero ambitions through carbon sequestration. However, these valuable ecosystems can suffer from catastrophic forest damage and disturbances, exacerbated by the increasing impacts from compound climate events in a changing climate. This can have a significant impact on ecosystem services, such as water filtration, carbon sequestration, and wildlife habitat. As our climate changes, the increase in frequency and intensity of extreme weather events, such as droughts, storms, heat waves and their joint occurrences (IPCC 2021), threatens forests profoundly. This, in turn, leads to various forms of forest damage, from disturbance to windthrow and tree mortality, triggering both ecological and economic implications. These multiple climatic phenomena can have a compounding effect when they coincide or follow in succession. The compounded effects can amplify vulnerabilities, making trees more susceptible to hazards like windthrow. A drought may set the stage for subsequent threats, or a sequence of droughts and storms may compromise forest resilience and amplify the spread of disease. The cumulative impact of compound events often surpasses the isolated influence of individual climate events, as underscored by recent research, such as Gazol et al. (2022), which highlighted the role of combined climate events, particularly hot and dry conditions, in accentuating tree drought mortality within European forests. 

This PhD project aims to advance our understanding of forest disturbances and their association with compound extreme weather events, focusing on forest margins as biodiversity hotspots. The successful candidate will use open and proprietary Earth observation (EO) data, including airborne remote sensing and machine learning techniques, to detect and monitor forest damage. The project will explore the potential climate drivers, including both singular and interlinked extremes, that contribute to these disturbances. It will also use models such as ForestGALES and 3PG-SoNWaL to predict the risk impacts on forest function, including wind risk and climate impacts on productivity. 

This research has the potential to provide valuable insights for informed stand-level management decisions in the productive forestry sector, in light of future climate shifts. 

Figure 1: An example of a compounding physical mechanisms of hot-dry extremes and the impact on land-atmosphere interactions ​(Zhang et al., 2021)​. The evaporation is associated with land conditions and plant physiology during droughts and heat waves, potentially modulating the atmospheric boundary layer state.