Clearly the most important, but least advertised koala research undertaken in recent times, is the thesis, avaiable on the UOW website, titled ‘Conservation of Forest Habitats: Examining tree species preferences and habitat quality of a low-density koala population, South East NSW.’ (Heather Gow-Carey, 2012).
For the first time, the work categorized tree species preferences, and habitat requirements, based on the data from 72 of the 657 RGB-SAT plots where koala pellets were found, between 2007 and 2011. The species preference outcome provides for three primary tree species, (E. longifolia, E.cypellocarpa, E.tricarpa), three secondary species (E. bosistoana, E.mulleriana, E. globodia) and two supplementary species (A. floribunda, E. sieberi).
Despite the data limitations, due largely to poorly conceived survey method changes, spatial auto correlation found there was a 1% chance that ‘clustering’ of koala evidence is random. Using the aforementioned data, a spatial layer was generated defining highly suitable, suitable, marginal, not suitable, and potential habitat.
From this layer a fragmentation analysis was undertaken, although this was restricted to the main roads, and didn’t include logging history or die-back.
Consequently, the assessment found there is sufficient habitat for the current number of koalas, although ” . . . threats from logging, land clearing, drought and bushfire could jeopardise the stability of the population, and ” . . As there is a large extent of habitat where there has been no evidence of koalas recorded it is apparent that there are other factors influencing the distribution of the population.”
These other factors include logging, and the majority of roading, but the most important is soils. On the soil issue the thesis indicates ” . . . An investigation of the underlying substrate across the study area revealed that 98.6% of active survey points were on ‘Bega Coastal Foothills’ (Figure 4.2) From this finding, it was concluded that soils would not provide additional value as an explanatory variable for the overall quality of habitat and the habitat usage choices that koalas were making. No further analysis using this soils layer was undertaken.”
The term “Bega coastal foothills’ comes from the document ‘Descriptions for NSW (Mitchell) Landscapes’ (2002) and the methodology indicates soil landscapes were ‘set aside’ and combinations of dominant geologies were employed, apparently on the basis that rock type equates to soil fertility. The map above provides soil landscapes, although they are from different map sheets, and are yet to be tagged for consistency. The large red dots are koala records from the original RGB-SAT data and the small pink ones dated from 2007, are from the official OE&H data-base. Both of these data sources are different.
The questions are, why are those organising the koala recovery projects yet to undertaken the work required to define the area properly, and why isn’t there a consistent koala records data-base? Heather Gow-Carey’s thesis ” . . identifies the need for a localised analysis of the South Coast koala habitat across multiple tenures to assess the area in its entirety in order to facilitate an informed decision-making process.”
Looks like if the NSW government won’t do it, some -one else will have to.