Floristic patterns along an east-west gradient in grassy box woodlands of central New South Wales

Temperate grassy box woodlands are the predominant native vegetation of the 'wheat-sheep' belt of south- eastern Australia. In New South Wales, a number of different eucalypt species form the overstorey of these woodlands, with changes in dominance from Eucalyptus melliodora (Yellow Box) and Eucalyptus albens (White Box) in the east to Eucalyptus microcarpa (Grey Box) and Eucalyptus populnea (Poplar Box) in the west. Most grassy Box woodlands have now been cleared or modified for agriculture, and their conservation is dependent on adequate knowledge of the distribution, ecology and management needs of remaining woodlands. In this study we describe the understorey flora of high quality remnants of grassy Box woodlands along an east-west gradient in central New South Wales, comparing sites with a history of minimal livestock grazing (cemeteries) with sites with a history of intermittent livestock grazing (travelling stock reserves). With some important exceptions relating to Eucalyptus melliodora, dominant overstorey eucalypts were good indicators of understorey changes along the east-west gradient. A particular disjunction, involving changes in the dominant grasses from Themeda australis and Poa sieberiana to Austrostipa scabra, Austrodanthonia and Enteropogon species, distinguishes 'eastern' (Eucalyptus melliodora, Eucalyptus albens) from 'western' (Eucalyptus microcarpa, Eucalyptus populnea) Box woodlands, and has significant implications for understorey management. Notable changes in subsidiary species included changes in the main genera of shrubs and daisies, and a number of trends at the family level. Families such as Dilleniaceae, Haloragaceae, Epacridaceae and Ranunculaceae were more frequent or diverse in eastern Box woodlands, and gave way to species of the families Malvaceae, Chenopodiaceae, Myoporaceae, Amaranthaceae and Brassicaceae in the west. Intermittent grazing influenced understorey composition in all box woodlands sampled,although influences in western Box woodlands were less pronounced. Effects of grazing included a decline in shrub abundance and loss of a range of native perennials across all woodlands, changes to the dominant grasses and a considerable increase in exotic annuals in the east, and a decline in native grass diversity and increase in native annuals in the west.