Hollow-Bearing Tree Ecology in Eucalypt Forests

Hollow-bearing trees represent a foundational element of eucalypt forest ecosystems, providing critical nesting, roosting and refuge sites for a wide array of vertebrate and invertebrate fauna. These hollows form over decadal to centennial timeframes through processes of heartwood decay, fire‐induced injury and mechanical damage. Their abundance and size distribution are governed by tree species, age structure, stand dynamics and local disturbance regimes. In mature eucalypt stands, large old trees accumulate multiple hollows of varying dimensions, supporting specialist and generalist cavity users alike. Conversely, landscapes subject to repeated wildfire or intensive logging often exhibit sharp declines in hollow density, with recruitment of new hollows lagging behind removal of older trees. Climatic factors such as rainfall seasonality and temperature extremes further modulate decay rates and hollow formation, while interactions among fire frequency, severity and post-fire regeneration shape the spatial mosaic of suitable cavities. Conservation and management strategies emphasise retention of hollow-bearing trees at harvest, installation of artificial hollows or nest boxes, and landscape-scale planning to ensure connectivity of key habitat elements. As keystone structures, tree hollows underpin biodiversity, drive faunal community structure and serve as indicators of long-term ecosystem integrity in eucalypt forests worldwide.

Research from Nature Portfolio

High-resolution terrestrial LiDAR imaging has recently been applied to three-dimensional mapping of log-pile microhabitats, quantifying entry dimensions, internal volume and surrounding vegetation structure associated with cavity use by an endangered reptile. This work demonstrates the potential for non-invasive remote sensing to characterise hollow features and assess habitat suitability at fine spatial scales. By capturing sub-centimetre detail on cavity morphology and microclimate conditions, such approaches can be translated to hollow-bearing tree surveys, enabling more precise monitoring of cavity availability, structural decay stages and post-disturbance hollow dynamics in eucalypt forests.

Hollow-Bearing Tree Ecology in Eucalypt Forests publication trend

The graph below shows the total number of articles in hollow-bearing tree ecology in eucalypt forests across all publications each year (not limited to Nature Index journals).

Technical terms

Hollow-bearing tree: A tree that contains internal cavities formed naturally through decay, fire injury or mechanical damage, providing habitat for fauna.

Cavity formation: The suite of biological and physical processes (e.g. fungal decay, bark loss, wound closure) by which tree hollows develop over time.

Eucalypt forest: A woodland or forest ecosystem dominated by Eucalyptus species, characteristic of Australian temperate and subtropical regions.

Fire regime: The pattern of wildfire occurrence, including frequency, intensity and seasonality, that shapes forest structure and hollow dynamics.

Stand structure: The spatial and size composition of trees within a forest, encompassing age classes, species mix and canopy layering.

Microhabitat: A localized set of environmental conditions and physical features within a larger habitat, critical for species with specialised requirements.

References

1. Interacting Factors Driving a Major Loss of Large Trees with Cavities in a Forest Ecosystem. PLOS ONE (2012).
2. Revealing microhabitat requirements of an endangered specialist lizard with LiDAR. Scientific Reports (2022).
3. Seasonality of Climate Drives the Number of Tree Hollows in Eastern Australia: Implications of a Changing Climate. International Journal of Ecology (2015).
4. Forest Conservation Policy Implementation Gaps: Consequences for the Management of Hollow-bearing Trees in Australia. Conservation and Society (2014).
5. Wildfire and Climate Impacts Tree Hollow Density in a Temperate Australian Forest. Forests (2023).
6. Tree hollow decline in new forest reserves with a long history of logging. Austral Ecology (2024).