We recently spent a weekend out bush on a cattle property north of Dalby. While setting up camp next to a farm dam, a bird call I couldn’t quite place my finger on was coming from a nearby stand of vegetation.
Upon investigation, to our surprise, not one, but four painted honeyeaters had established breeding territories in a thin strip of Brigalow regrowth, some 20 meters wide by 300 meters long. Over the next two days we were in the constant company of these beautiful little birds as they sang and displayed in an attempt to attract a mate. On the entire 500 hectare block, just this single patch of otherwise unremarkable vegetation hosted this federally listed species. Being less than a hectare in size, the property owner would be well within their legal rights to clear this patch of regrowth without any need for government approval. Such is the nature of current clearing legislation in Australia and our attitude towards the importance of small vegetation patches.
All across the country this story is emulated in remaining stands of paddock trees, roadside easements and fence line vegetation. In increasingly fragmented landscapes the importance of small patches of vegetation for conservation is apparently disregarded.
Instead, efforts largely focus on keeping remaining large patches intact. More than 80% of native vegetation has been lost worldwide. In Australia, clearing of remnant in 2013-14 of 95,000 hectares has nearly quadrupled since 2009-2010. Without radical changes in clearing legislation unsustainable clearing at current rates are likely to continue.
Our research shows that in addition to declines in the extent of almost every vegetated ecosystem in Australia, most are becoming increasingly fragmented. Startlingly, one in five Australian vegetation communities have more than half of their remaining extent in patches smaller than 10 km2.
Worse, many vegetation communities are exposed to the double jeopardy of high loss and high fragmentation, such as Brigalow and Mulga communities in central Queensland.
Brigalow forests and woodlands previously covered almost 100,000km2 of inland Queensland –an area greater than that of Tasmania. They contain the only remaining populations of a number of unique species (below), including the endemic Brigalow Scaly-foot and Golden-tailed Gecko.
This is just one of several systems affected by the double jeopardy of both high loss (87%) and high fragmentation, with 2/3 of its remaining extent in patches smaller than 50 square kilometres.
The full list of systems threatened by double jeopardy, or comprised purely of small patches can be found in the supplement (download here).
Arbitrary patch size thresholds for native vegetation clearing are dangerous now restricted to small patches. Clearing thresholds must be scaled to reflect the fact that some ecosystems are more dominated by small patches than others. Measures of ecosystem vulnerability that only consider the extent of vegetation loss and not the size of remaining patches are likely to be ineffective for impact assessment, conservation planning and preventing ecosystem loss.
The long-term consequence of policy inaction is the slow, inevitable decline of remaining vegetation communities, and further loss of the species dependent on them: a death by a thousand cuts.
Megan Barnes and Jeremy Ringma
Check out the paper here:
Tulloch, A. I. T., Barnes, M. D., Ringma, J., Fuller, R. A. & Watson, J. E. M. Understanding the importance of small patches of habitat for conservation. Journal of Applied Ecology doi:10.1111/1365-2664.12547 (2015)
The method is unique and simple and can be used to estimate the importance of particular pieces of land for any system. To repeat it for yours, the code is also available as a supplement.