Macadamias naturally occur in the subtropical rainforests of eastern Australia.
These rainforests are predicted to undergo significant change in coming decades as a result of climate variation, particularly shifting temperature and rainfall patterns.
The impact this will have on wild populations of macadamia is being studied by the Trust.
Three years ago, former Macadamia Conservation Trust project officer, Dr Michael Powell, established study plots in the rainforest habitats of four wild populations of macadamia. With the able assistance of local botanist Greg Smyrell, Dr Powell recorded the diversity and size of canopy trees within each plot. Each tree larger than 5cm diameter was measured and all seedlings were counted. The survey method follows that of the Queensland Herbarium, which uses it to determine altitudinal change in the subtropical rainforests of Lamington National Park, located on the border between Queensland and New South Wales.
In May 2017, Liz Gould from Healthy Land and Water (partner organisation working closely with the Trust), revisited the plots with Greg to take comparison measurements.
Preliminary results show differences between the four plots, both geographically and over time. For example, some rainforest plants recorded in 2014 were absent in 2017 and vice versa. Plus, there appeared to be more seedlings of some canopy trees present in 2017 than in 2014. There was little change in the number of macadamia trees found at each plot and no new seedlings.
It is likely that these changes are simply a reflection of natural fluctuation or even the result of large scale disturbance (such as storm or fire damage) many years ago, rather than climate change. Over time, however, these surveys will allow greater comparisons and identify trends in species occurrence and growth, which could potentially be due to climate change.
As the long-term monitoring project continues, the methodology will be reviewed and improved, and the Trust will also seek to link with universities and other researchers.
We thank Sunshine Coast Council, City of Gold Coast, HQ Plantations and the Stratford family for allowing access to their land to undertake surveys, and acknowledge the funding support provided by Horticulture Innovation Australia Limited with co-investment from Australian Macadamia Society and Healthy Land and Water and funds from the Australian Government
For more information on the long-term monitoring program or to find out how you can support the work of the Macadamia Conservation Trust, please contact us at wild@macadamias.org.
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