A lack of data is precluding a holistic assessment of the resilience of Australia's forests to climate change. Research integrating the use of research infrastructure with a more traditional field inventory is addressing this with respect to Melaleuca forests, which cover more than six million hectares—about the area of Tasmania.
A patch of Melaleuca forest adjacent to TERN’s permanent monitoring station at its Cumberland Plain SuperSite in western Sydney
Storing around 5% of the total carbon of all Australian native forests, little has been known about how melaleucas sequester carbon under different growing conditions and increasing climate-driven stresses.
A timely new collaborative study fills this knowledge gap by assessing the dynamics of melaleuca and eucalypt ecosystems in western Sydney’s critically endangered Cumberland Plain woodland, a dwindling refuge for melaleuca trees in this peri-urban region.
Dr Anne Griebel of Western Sydney University’s Hawkesbury Institute for the Environment led the investigations, which employed an innovative approach using a suite of research infrastructure, including from TERN.
A vertical transect through the Cumberland Plain woodland (top row) and associated 3D point clouds (middle row) outlining the approximate source areas of fluxes for the eucalypt-dominated stand (left) and for the melaleuca-dominated stand (right) generated from airborne LiDAR. The point clouds are coloured according to canopy height: red colour indicates eucalypt trees emerging through the melaleuca-dominated stratum (green shade) while blue shades indicate a low vegetation height. Photographs (bottom row) demonstrate the extensive shrub layer in the eucalypt stand in contrast to the sparse understory vegetation in the melaleuca stand.
By combining inventory and airborne LiDAR data, Anne and her team were able to fully characterise forest dynamics and attribute carbon and water exchanged to specific species. This work provides a vital first assessment of the instantaneous carbon and energy cycling for a melaleuca stand in Australia, which could then be compared to a nearby eucalypt-dominated stand that has received much more attention in recent years.
Not only do these findings have implications for on-going national carbon accounting, they also highlight the potential for increased vulnerability of melaleucas to projected hotter and drier future climates.
Importantly, Anne notes that that distribution of melaleuca trees and their natural habitats in the Sydney Basin are increasingly threatened by land-use-change and associated habitat fragmentation, which in addition to projected changes in climate adds further pressure on local ecosystems.
Micro-meteorological data collected by the eddy covariance flux tower at TERN’s Cumberland Plain SuperSite (above) with a mobile observatory (below)set up in a pure melaleuca patch adjacent to TERN’s permanent monitoring station
Published in TERN newsletter October 2019