Relict Surface-Soil Features in Semi-Arid Mulga (Acacia Aneura) Woodlands.

Abstract

The physical dimensions and locations of two forms of circular surface-soil features, believed to be constructed by animals now locally extinct, are described for a 200 ha site and its environs in a semi- arid mulga (Acacia mura) woodland in north-western New South Wales. The most common were 48 circular (c. 10 m diameter) features, some with well-defined central depressions carrying vigorous grass tussocks. Soil chemical analysis indicated the relatively high fertility of these central depressions. Surface pebbles were analysed for comparison with similar lithological data in the literature. The evidence suggests that the malleefowl (Leipoa ocerlata) is the most likely agent responsible for building these features. While only four of the larger features (c. 30 m diameter) were located in the study site, they were particularly conspicuous on higher ridges in adjoining paddocks because of the abundance of highly reflective, calcrete fragments visible on the surface of subcircular mounds. It is postulated that they were constructed by the bumowing bettong (Bettongia lesueur).