Our biodiversity ‘hotspot’

Western Kangaroo Island has been identified as the most botanically unique area in South Australia.

Conservation biologists have published a landmark analysis of plant diversity across South Australia, with western Kangaroo Island one of six areas identified for exceptionally high plant diversity.

Published in the journal PLOS ONE, the Adelaide University research, in partnership with the Environment, Water and Natural Resources Department and Terrestrial Ecosystem Research Network, highlighted South Australia’s biodiversity 'hotspots' and their key threats.

“We also looked at the extent to which the vegetation of each site was likely to change under future climates. We concluded that all of the state's ecosystems are expected to be impacted,” said lead author Dr Greg Guerin.

“About 4500 plant species have been recorded in South Australia and some 10 percent of the native species are found nowhere else.

“I actually think we have an moral obligation to do something about biodiversity decline but there are also more practical reasons. Native ecosystems provide services like carbon storage and providing habitat for crop pollinators.

“Native plant diversity has previously been linked to increased diversity of pollinators in adjacent crops, for example. Then there are aesthetic aspects and tourism.” 

The report said that the western side of Kangaroo Island had the most significant plant biodiversity in South Australia, but the local region was rated by Adelaide University researchers as less vulnerable than the other hotspots, due to higher reservation levels and lower incidences of weed species.

“There are fifty species found nowhere else (the highest proportion of any region in the state) and high overall diversity by any metric. Examples of these endemic species are the Kangaroo Island Logania and the Kangaroo Island Mallee Ash,” Dr Geurin said. 

“Because Kangaroo Island is physically isolated and has areas with low soil fertility that have been less developed for agriculture, the island's ecosystems are more intact than those adjacent on the mainland, with larger areas of native vegetation remaining.

“There are also fewer weed species occurring within these remnant woodlands, possibly due to lower disturbance and lack of opportunity for weed seeds to spread from the mainland.

“Some of the biodiversity value of KI related to historical process – the island once exchanged species with the Eyre, Yorke and Fleurieu Peninsulas, increasing its diversity. There are even records of species otherwise only known from Western Australia!”