Ancient Species Australian Eucalyptus in Rapid Decline Following Severe Drought, Climate Change

After several periods of extreme drought caused by climate change, an ancient species of Australian eucalyptus trees are in rapid decline.

Ancient Species of Australian Eucalyptus Trees

Red stringybark trees, which have existed in the Clare Valley for 40,000 years but are now in danger of going extinct due to climate change, have experienced a catastrophic decline that has been observed by South Australian scientists.

The South Australian species Eucalyptus macrorhyncha isolated population in the Spring Gully Conservation Park has experienced "staggering losses" as a result of two severe droughts brought on by climate change since 2000.

Associate Professor Gunnar Keppel and Udo Sarnow, Environmental biologists of the University of South Australia have conducted numerous surveys during the Big Dry from 2017 to 2019 and the Millennium Drought from 2000 to 2009 that have revealed tree and biomass losses of more than 40%.

Within two years of the first report of their dieback in 2007, over 400 trees were observed over a period of 15 years.

The red stringybark ecosystem may be replaced by more open woodland, according to scientists, who estimate that about 250 metric tons of biomass per hectare have vanished. Keppel claims that in areas that have undergone complete dieback, the only trees left are drooping she-oaks.

According to genetic evidence, the Clare Valley's red stringybark trees have been separated from their nearest relatives in Victoria's Grampians National Park for about 40,000 years. These trees have been standing earlier than the Ice Age when Australia was considerably drier and colder.

Climate Change and Severe Drought

According to Keppel, the Clare Valley offered a refuge that helped the red stringybark survive during this dry period. However, compared to the last glacial period, the current climate change is different. Compared to the earlier times, which were cold but much drier, this time it is associated with considerably hotter temperatures.

To track the progression of the eucalyptus dieback in the Clare Valley, the team used trees labeled by the Department of Environment and Water.

Sites with less water and those on flatter terrain suffered the most during the Millennium Drought, while during the Big Dry, sites under the most heat stress were most vulnerable.

Also Read: Spread of Drought-Resistant Trees on Grasslands a Big Problem, Here's Why 

Dieback, Rapid Decline

In the Clare Valley, intensive agriculture and viticulture have made the dieback problem worse, possibly increasing stress levels and preventing transition to places that might help the species survive.

Dieback, according to the Australian Capital Territory, is the gradual decline in a tree's health that can occasionally result in death.

According to Sarnow, mortality was significantly lower on slopes that faced south and east, where there was less sun exposure and consequently less stress from heat and drought. There was also evidence of some regeneration in these places. The population should be able to survive in areas with milder microclimates.

Sanrow continues by saying that the distinctive component of Australian biodiversity can be preserved by controlling the population throughout Spring Gully Conservation Park and safeguarding these microclimates, PhysOrg reports.

The research by Keppel, Sanrow, and several colleagues was published in the journal Science of the Total Environment.

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