An article by Dr John Wamsley OAM
Every hectare on earth evolved as a unique community of living organisms, each dependent on the community and with the community dependent on each organism. A community is made up of sub-communities and collections of communities make larger communities. Each one is unique, like fingerprints. Sometimes this is called the ‘web of life’.
We have somewhere between 3 million and 100 million species of living organisms living within these communities. About 3 million are described and named while the rest are neither described nor named. The collection of all these communities, the organisms within them and the links between the different organisms, all together give us this amazing thing we call biodiversity (biological diversity).
We do not have a measure of biodiversity as such, but we can measure Biodiversity Loss. As the links binding these organisms together are broken, some species lose their place and reduce in numbers. When this occurs, for a species, across many communities, the number of this species decreases dramatically. It loses the niche it evolved to fill, and we class it as threatened with extinction.
We define biodiversity loss, for a class of organisms, as the percentage of species, within the class, threatened with extinction. Whereas we may not know the total number of species threatened with extinction within a class, we can get a fair estimate of the percentage threatened simply by taking a sample and looking at the percentage of the class that is threatened with extinction, as we do with polling to guess who is going to win an election.
Under Australia’s Environment Protection and Biodiversity Conservation Act, a list is published, and kept up to date, of Australia’s species which have been classed as Threatened with Extinction. This gives us a complete list of Australian land vertebrates that were threatened with extinction each year from JDDD to JDJK. Table C gives the number of species threatened with extinction during JDDD-JDCK.