Fire history and environmental drivers influence vegetation structure derived from space-borne LiDAR

Researchers and collaborators: PhD Candidate Kathryn Fuller, Prof Matthias Boer, M, Dr Rachel Nolan, Prof Mike Aspinwall (international)

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Summary: Fuel structure, broadly defined as the physical structure of flammable vegetation material, plays a major role in determining fire behaviour. The allocation of fuels to understory, midstory and overstory determines the extent to which fuel loads in these strata influence fire spread rates and, ultimately, the ecological consequences resulting from fire. Fuels in these different strata are consumed at different rates depending on the severity of a fire and, once consumed, take time to accumulate. This process is described by fuel accumulation curves, which are used to model fire behaviour. However, quantitative information on fuel structure across south-eastern Australia is limited, a region impacted by an unprecedented extent and severity of fires in recent years. Ground-based assessments cannot account for large areas due to logistical constraints, and no wall-to-wall airborne Light Detection and Ranging (LiDAR) dataset current exists for this region. The newly released Global Ecosystem Dynamics Investigation (GEDI) LiDAR data product provides nearly global coverage of forest structural metrics, including measures of vegetation in 5 m vertical increments. We modeled these novel forest structural metrics to identify the role of environmental drivers and fire history in determining forest structure, shedding light on fuel accumulation dynamics at different strata within forest stands. We then used these models to predict forest structural metrics, creating unprecedented wall-to-wall maps of forest structure for south-eastern Australia. The models and maps created in this study will be used to examine the influence of forest structure on fire behaviour in future research.