Fallen-timber loads on southern Murray-Darling Basin floodplains: History, dynamics and the current state of Barmah-Millewa

Historical sources of information were examined to develop a picture of the structure of River Red Gum Eucalyptus camaldulensis forests of the southern Murray-Darling Basin prior to European settlement. We sought information on the density and distribution of fallen timber (grounded logs and limbs ≥ 10 cm diameter). None of these potential sources yielded much useable information to estimate fallen timber loads prior to European settlement. There is good evidence that the structure and demography of red gum forests has been significantly altered since the 1830s, with the former parklands of large, veteran trees > 500 yr being replaced by ranks of smaller, younger trees. Large trees are more likely to produce larger amounts of fallen timber, so that the landscape-scale changes in demographics coupled with the massive reduction of the area of floodplain forest are likely to have produced a much lower total fallen timber load across the whole Murray-Darling basin. Alterations of flooding and wildfire regimes, and the incessant demands for large amounts of firewood are likely to maintain the paucity of fallen timber compared with the early part of the 19th century. The current status of fallen timber in the Barmah-Millewa forest is also described.