The probability of wildfires, or prescribed fires, occurring in mallee rangelands, is strongly dependent on availability of adequate grass fuel loads. Grass fuels comprise two major elements, a perennial component dominated by the hummock species Triodia scariosa (porcupine grass) and an ephemeral component dominated by the annual/biemial tussock species Stipa nitida (speargrass). Population dynamics and abundance of both fuel elements are, in turn, strongly influenced by rainfall regime, particularly during the seedling recruitment phase. This paper records data on the spatial distributions of different fuels, plant architecture and post-fire seedling recruitment and survivorship of T. scariosa, obtained during field studies on contrasting mallee sites in western New South Wales. In addition, rainfall data extending over c. 100 years were used in a water balance study at one mallee site (Pooncarie); while similar rainfall data were analysed for three mallee sites (Pooncarie, Ivanhoe and Mount Hope) using a filter technique to examine quasi- periodicities of rainfall and potential correlations with known wildfire seasons in the past. Precipitation records from the Meteorological Districts of western New South Wales, and from various towns in the area, were analysed as well. All data sets exhibited strong coherence and the resulting filter curves resembled each other closely, with peaks reflecting 'above-average rainfall' and troughs 'below-average rainfall or drought'- the latter often being associated with El NiiiolSouthern Oscillation events. The management implications of these phenomena, particularly as they relate to major drought events, are discussed in the context of vegetation manipulation based on prescribed fire.

Semi-arid woodlands are an important part of the Australian landscape and they have been the focus for scientific research by CSIRO since the 1960s. This book reviews that research and sets it in a historical perspective. It examines the development of pastoral science, with particular reference to the farming frontier in western New South Wales, as well as research conducted by CSIRO over the past thirty years aimed at helping manage increasing shrub densities while improving productivity. The author discusses past, current and future research directions and looks at how management perceptions and approaches continue to change as understanding of ecological processes and new strategies evolve.

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).

This article describes the effects of the 1974175 wildfires on the mallee vegetation in the Western Division of New South Wales using two properties as case studies. The management implications arising from these experiences are described in some detail, particularly the potential for some form of management based on periodic prescribed burning to promote herbage productivity and also to reduce any future wildfire hazard. The need for appropriate research to be undertaken in this field is also discussed.

The Great Artesian Basin (GAB) underlies a vast, mainly arid, region where most of the indigenous biota are not dependent upon surface water. In contrast, an important minority is dependent on refuges such as mound springs and their associated wetlands. In some parts of the GAB, such as western New South Wales, many springs have either ceased to flow, or are now barely detectable, because the proliferation of artesian waterbores has reduced groundwater pressures. Because of the rarity of species endemic to mound springs, and the damage they have suffered since pastoral settlement, emphasis should be directed towards conservation and possible rejuvenation of these ecosystems. Provision of artificial sources of water allows more widespread grazing by livestock, larger native and feral herbivores, thereby posing threats to native plants and animals that do not use the water. Because of the proliferation of artificial waters and the grazing they allow, terrestrial grazing-sensitive species now appear to be confined to tiny patches in the landscape. Some nature reserves within the GAB retain numerous artificial sources of water. Most of these should be closed over time to reduce negative impacts on grazing-sensitive plants and animals, especially where these species are inadequately protected elsewhere. In those regions where the ratio of artificial to natural waters is still low, consideration should be given to balancing provision of water for livestock with conservation of biological diversity, by maintaining a patchwork of areas remote from water. In regions where the density of artificial waters is high, conservation of biodiversity on freehold and leasehold lands might be enhanced with a mix of approaches accommodating the needs of the biota and the aspirations of landholders, tailored according to land type and condition. Key words: Great Artesian Basin, biological diversity, mound springs, refuges, rare biota, grazing impact, conservation management, groundwater.