What The HEC | Biodiversity Loss in the Adelaide Hills

This article discusses biodiversity loss, the function of major extinction events in the earth’s evolution, and how these events relate to the Adelaide Hills region.

Introduction

Our planet is currently going through a mass extinction event, something that has only occurred 5 other times in life’s history. But what is a mass extinction? And how does it differ from the natural continuous extinction of species? This piece will uncover the mysteries of mass extinction, discussing examples closer to home with some species found in your own backyard that are affected by the current 6th mass extinction.

What is a Mass Extinction?

A mass extinction is a period where greater than 75% of species numbers go extinct in under 2.5 million years (1). During the earth’s history, species have continuously gone extinct as the result of climatic change, predation, geographical change, or other significant shifts. This is the driving force for evolution and speciation and, therefore essential to life on Earth. Scientists can compare species diversity in the past based on fossil records, to current species diversity, and look at extinction rates through time. This gives them an estimation of a species lifetime within a kingdom, for example, for any bird it is estimated that 1 species will die out every 400 years. For mammals, this number is 1 every 200 years, however in the past 400 years we have lost at least 89 mammal species. Some scientists even predict that we lose 1 species every 20 minutes (2), many of which are undiscovered insect species. Due to this accelerated extinction rate, many scientists attribute the current mass extinction to human activity, making this event known as the anthropogenic extinction. The main factors that contribute to the 6th extinction are habitat fragmentation, the introduction of invasive species, human population growth and urbanisation, human attributes such as pollution, and overexploitation of natural resources (1).   

Biodiversity Loss in the Adelaide Hills and Mount Lofty Region

Living in the Adelaide Hills and Mount Lofty ranges, we are blessed with a startlingly large variety of flora and fauna right at our doorstep. Research has determined species richness in the Mount Lofty region to be among the highest in the state (1). Infact our region has been identified as one of 12 national biodiversity “hotspots”. However, with habitat loss, introduction of pest species and climatic changes, this diversity is at risk.

Some of the most commonly found species include Xanthorrhoea semiplana (Yacca trees), Gonocarpus tetragynus (Common Raspwort), and Acacia pychantha (Golden Wattle).  A majority of the species found in the Mount Lofty region are native, around 75%. Some of the more common weeds include Blackberry, Boneseed, and Gorse, rapidly increasing in density since their introduction.

Not only is plant diversity at risk, but also mammalian diversity. Since European colonisation in the Mount Lofty ranges (1836), the total number of mammalian species has dropped from 31 to 22. These 8 extinct species consist of seven marsupials, and one eutherian (placental). To better understand those species still existing in the region, the three most at-risk species are identified as the Southern Brown Bandicoot, the Platypus (existence currently unconfirmed in the region), and the Koala (2).

Protection Interventions

To protect these species, much work is currently being done in the region. Landcare and other volunteer groups all work towards the preservation of our native species and protecting the biodiversity we have in our beautiful Hills region. Everyone can make a difference to best help the environment, from joining a volunteer group, planting local natives in your backyard, keeping your feline friends contained or minimizing and managing your waste to reduce your carbon footprint. Through all of our combined efforts, we can lead the way to a more sustainable future, where humans can coexist with nature’s biodiversity.

References

  1. Begum, T. (2021). What is mass extinction and are we facing a sixth one? [online] Natural History Museum. Available at: https://www.nhm.ac.uk/discover/what-is-mass-extinction-and-are-we-facing-a-sixth-one.html#:~:text=A%20mass%20extinction%20event%20is.
  2. Anderson, K. (2018). What is Background Extinction Rate and How is it Calculated? [online] Population Education. Available at: https://populationeducation.org/what-is-background-extinction-rate-how-is-it-calculated/.
  3. Guerin, G. R., Biffin, E., Baruch, Z., & Lowe, A. J. (2016). Identifying centres of plant biodiversity in South Australia. PLOS ONE, 11(1), e0144779. https://doi.org/10.1371/journal.pone.0144779.
  4. Pievani, T. (2013). The sixth mass extinction: Anthropocene and the human impact on biodiversity. Rendiconti Lincei, 25(1), 85–93. https://doi.org/10.1007/s12210-013-0258-9.

Biodiversity Loss in the Adelaide Hills

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