Ebony Potts is an Honours student at James Cook University in Queensland. In 2020 was she awarded the Sir Joseph Banks Medal for excellence in Botany.

Project Summary: Relative shoot-level flammability of native and invasive tropical forest life-form species: A quantitative assessment.

Anthropogenic climate change and land-use change are triggering unprecedented ecosystem alterations and biodiversity declines world-wide. Among those are changes in wildfire events, which are increasing in severity, frequency, and duration. The magnitude of these increases can be identified from the Australian 2019-2020 megafires that burned >8 million hectares of bushland and impacting >50% of the population ranges of over 800 native species of vascular plants. The total area that burned in these megafires were recorded as an entire order of magnitude larger than any other global wildfire witnessed in this past decade, and were caused by extensive and prolonged droughts leading up to the fires and increased average temperatures. Surprising to many, tropical forests were among these areas impacted by fire, largely as a result of agricultural or logging practices, changes in microclimates along fragmented forest edges, and prolonged seasonal droughts.

In response to increased severity of wildfire, studies into the flammability of vegetation is emerging as a helpful descriptor of the flammable traits of species and their roles in fuelling or quelling wildfires. Vegetation flammability is generally determined by four components, including (1) ignitability: time it takes for the plant to ignite, (2) sustainability: total duration plant burns following ignition, (3) consumability: proportion of plant burnt, and (4) combustibility: how rapidly and intensely the plant burns. These components allow us to understand how vegetation across biomes may be influenced by fire and what scale or fire (surface or canopy) they are likely to fuel. Flammability studies are used widely for a number of conservation purposes, such as the selection of less-flammable species in urban areas and species for green breaks in fire management controls. Moreover, they are used to explore phylogenetic fire signalling traits of plants and how specific plant traits may interact in whole communities.

Where this flammability research has an apparent gap, however, is within tropical closed forest ecosystems, largely due to these systems historically being regarded as ‘pyrophobic’ and being one of the least flammable biomes in the world. Yet in recent years, wildfires have been recorded increasing in tropical forests in Australia, south-east Asia and Brazil, with >760,000 ha of forest in the Amazon burning in 2020 alone. In addition, a large amount of flammability studies to date have focused heavily on measuring only single components of plants, such as leaves, failing to account for whole-individual traits and how they influence overall flammability.

Ebony Potts’ research intends to fill both of these gaps by conducting flammability studies on tropical forest species of various life forms (trees, vines, epiphytes, pioneer shrubs). She will include common invasive species across various life forms that are found within and along the edges of the closed canopy tropical rainforest ecosystems, which are primarily driven by anthropogenic disturbances. The primary aims of this research are to quantify and compare the shoot-level flammability in tropical forest plants in order to understand how certain species traits may influence fire incursions in this ecosystem. The purpose of measuring across the functional groups (life forms) is due to the highly complex structure of closed canopy tropical forests and is aimed to provide inferences of flammability at both vertical and horizontal levels.

This research will be the first of its kind and will add to plant flammability research by providing a highly standardised quantitative assessment of rainforest plants and invasive species and how they may fuel or suppress fires.