The latest satellite (SLATS) data on Queensland clearing is now available and it provides an interesting insight into how data can be presented in a way that is quite remote from the truth on the ground. The report, Landcover Change in Queensland 2004-2005 can be seen at www.nrw.qld.gov.au/slats
The annual average area cleared in the period was 351,000ha of which 172,000ha (49%) was remnant vegetation with the remaining 179,000ha (51%) being non-remnant woody regrowth. When this was broken down into Carnahan vegetation classes some 193,000ha (55%) was of a type that would not be included within the meaning of forest under the National Forest Inventory. That is, it was “Tussocky or Tufted Grasses” and other vegetation types that have less than 10% foliage cover and are less than 2 metres tall. This presentation still does not allow us to determine what proportion of the 158,000ha (44.7%) cleared remnant vegetation was actually non-forest vegetation types that may actually benefit from tree removal to restore the grassland/shrub ecosystems.
The report has fine tuned a previous practice of breaking the data into relevant grid squares with a colour code to indicate the area of land cleared in each square. Previous reports have used 30′ X 30′ (Lat/Long) grid cells that covered an area of approximately 280,000 hectares with codes indicating cleared area from <100ha to >5000ha for each cell. This produced a map with numerous lurid dark tones but which told us very little, other than the fact that somewhere within a square measuring 53km by 53km was somewhere between 0.01km2 and 50km2 of clearing.
This has now been broken up into 7’30” X 7’30” (Lat/Long) grid cells that cover approximately 17,500 hectares but these still retain the same colour codes for the same cleared area categories and produce a map with lots of little coloured squares that give the appearance of widespread clearing activity. These can be seen at Figure 8 P18 of the current report.
But the most interesting aspect of this presentation is what it does not tell us about the clearing. The graphic below is an enlargement of a 700,000 hectare scene to the west of Charleville which is recorded as one of the hotbeds of clearing in 2004-2005.
The lower presentation is an enlargement of the SLATS Report while the upper presentation indicates the information that is readily available and could be incorporated into the presentation if the political masters were willing to provide a budget for the truth.
Each of the grid squares has been broken up into 700 smaller squares of 25 hectares each (25 across and 28 down) so we are able to show the actual area of pasture, remnant, and woody regrowth in each grid cell. This then enables one to show each years clearing activity in the respective proportions of regrowth and remnant clearing. More importantly, it allows the viewer to gain an understanding of the relevance of that clearing in relation to the local landscape. Obviously, a large amount of clearing in a cell with a low level of remnant (eg. at E2 below) is of more concern than a cleared fence line in a cell with 75% woody remnant vegetation cover.
When the actual clearing is presented in direct spatial proportion to the area of the grid cell and the area of woody vegetation, we get a much more honest appreciation of what is taking place.
Of the approximately 3,450 grid cells indicating clearing activity in the report, more than 3,300 of them were in the two least cleared categories, showing cleared areas from 0 <100ha and 100 <500ha in each cell. The remaining 147 cells were easier to count and, after allocating a modal value in each class, we were able to determine that approximately half of all clearing, some 175,000ha, was cleared from these few cells. After allowing for a modal value of 300ha in the second lowest category and a roughly estimated proportion of 9% (or 300) of the 3300 remaining cells being in the second lowest category this indicated that another 90,000ha of clearing took place in the second lowest category. And this left only about 86,000ha of clearing taking place on the remaining 3000 cells at an average area of only 28 hectares per cell.
When that 28ha of clearing is proportionately represented on our improved data presentation below it would occupy just one of the 700 small squares in the cell. And when viewed in proper proportion it then becomes clear that the overwhelming majority of the scenes where some clearing has taken place, that clearing is of extremely marginal ecological impact. Indeed, it is at a level that would be barely detectable with the naked eye.
But it is in the allocation of this clearing (or current absence of it) between remnant and non-remnant at the grid cell level that provides the real “smoking gun” of systematic institutional deception. This is because a 28ha clearing event on an inland property is more than likely to be either fodder harvesting for stock or clearing for a fence line etc. And we know that mulga pulling for stockfeed is done on a long term rotational basis of 15 to 25 years. And that interval is more than sufficient for past regrowth to return to remnant status, being more than 70% of “normal” height. This provides grounds for informed speculation as to what proportion of remnant clearing, the assumed worst impact, is actually concentrated in small events of minimal consequence while the major events are primarily of non-remnant woody weeds.
We won’t actually know for sure unless we demand that this information, that is already at hand, be presented in a manner that properly informs the community. Anything less is serious misrepresentation by omission.
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.