Factors contributing to changes in the condition of saltbush communities (Airiplcs ~wicaria) in the Riverine Plain and
Barrier Range regions of New South Wales were measured under a variety of seasonal situations. Groups of eight plots, rcpresenting
a range of past grazing intensity, were established at each location and measurements were made of species biomass,
canopy cover and frequency, forage availability and soil fertility.
In both regions, high graz,ing intensity was characterized by the elimination of the saltbush (A. ~~esicaria) and an increase
in other species, such as Astwbla (mitchell grass), Sclc3rokarrza spp. (copperburrs), annual Airiplrx spp. and a wide range of
ephenleral species. These changes were best characterized by canopy cover measurements which gave a quantitative assessruent
of the vegetation changes (in contrast to frequency) and gave values that were less seasonally variable than biomass. Up to 83
species were recorded, but these were aggrcpated into approximately 9 groups to simplify the collection and analysis of data,
without loss of information.
On the Barrier Range site, the A. ~csic'aria was replaced by palatable specics, so that thcre was little loss of overall forage
production. Similarly, there was little cvidence of loss of soil fertility, as rneasured by various measures of soil nitrogen, available
phosphorus and oraanic carbon. There was no erosion on these sites, although this may occur on other saltbush communities
that grow on texture contrast soils.
On the basis of these results? four separate indices of condition are proposed for saltbush cotnniunities. These arc based
on the n~easurement in the growing season of the canopy cover of major perennial and biennial species or specics groups. They
are (i) the relative cover of A. 11rsicariu (the major observable change in thcse communities), (ii) the relative total cover of
desirable forage species (an index of forase productivity), (iii) pcrccntage similarity (an index of conmunity change for conservation
purposes), and (iv) the relative area of eroded soil surface.
Full-text publications from the Australian Rangelands Society (ARS) Biennial Conference Proceedings (1997-), Rangeland Journal (ARS/CSIRO; 1976-), plus videos and other resources about the rangelands of Australia.