Over the past ten years or so, discussion of vegetation change in rangeland science has emphasised event- driven or episodic processes, occurring on timescales measured in decades or longer. Management recommendations arising from this literature have stressed that management must also be event-driven. This paper cautions against the uncritical acceptance of such a world view into management philosophies. We conclude that for management purposes, appropriate models of change in rangeland systems should include a balance between the effects of infrequent, unpredictable events and the effects of more continuous processes, measured in timescales of years or less. This may involve explicit recognition of multiple timescales in a hierarchical model system. We arrive at these conclusions from a number of perspectives. Firstly, a substantial proportion of total demographic change in shrub populations occurs between events. Secondly, managers are best able to devise appropriate management strategies by a process of adaptive management. This can only be successful if the adaptive cycles have a short return time. Thirdly, it is important that managers think of change as being continuous. Mental models held by managers must acknowledge the value of continuous change. This provides the best opportunity for acquiring knowledge through experience and helps prevent management inertia when faced with an event outside previous experience. Finally, management can take best advantage of a given event by 'conditioning' the resource. This can be thought of as managing within states, say by building up a seedbank, and provides the opportunity to alter the probability of a given event occurring.

The role of a monitoring system for Western Australian pastoral shrublands is examined. The authors argue that the objective of management is to maximise sustained animal productivity, and that this can only be attained if the soil is maintained in a stable state. In non-degraded rangelands this objective is synonomous with the maintenance of a pasture community with its natural balance of edible and less edible species. In degraded rangelands the objective of regaining the pristine vegetation may, in many cases, be unattainable. Nevertheless, the objective of maximum sustained productivity again appears suitable since this would ensure that, where management is able to influence the direction of change, it is towards a pasture dominated by useful, rather than non-palatable, species. Our monitoring system aims to assist management achieve these objectives. The Western Australian Rangeland Monitoring System (WARMS) has been designed to include the assessment of ecological processes but with a strong bias towards characteristics that can be interpreted in production terms. We expect that the system will primarily and most importantly, aid pastoralists in their season by season decisions on stock movements. It will also provide a tool for the land administrator, who must be able to assure the wider community that the land is being used wisely. Finally, it should assist range scientists towards a better understanding of rangeland ecosystems. The WARMS system involves a series of grazed range monitoring sites, lightly grazed reference areas and ungrazed control areas. At each monitoring site a photograph is taken and plants within a fixed area are identified and marked on an overlay. The number and size of perennial shrubs are recorded within fixed belt transects and the contribution from perennial grasses and biennial species is assessed. Soil stability is also assessed using a rating scale and a modified step point procedure.

This study was undertaken to assess whether the nutritional quality of spinifex pasture lands is improved by buming to promote the growth of grasses other than spinifex. We selected two comparable sites in the Exmouth Gulf region of Western Australia; one had been bumt in late 1979 and the other had not been burnt for many years. On these sites we sampled the five grass species present, as well as Triodia pungens (soft spinifex) and Plectrachne >chinzii (Oat eared spinifex) on 10 occasions from March 1980 to April 1982. Plant parts were analysed for nitrogen, phosphorus and sulphur content, and in vitro digestibility. None of the common grass species tested was more nutritious or more palatable than soft spinifex. It seems that little is gained from manipulating spinifex pastures through burning if the aim is to encourage alternative grass species. There is a need however for further studies into the importance of woody herbs and forbs in the nutrition of grazing animals on spinifex country and the effect of fire on these species.

The nutritive value of Astrebla elymoides, A. pectinata, Chrysopogon fallax, Iseilema vaginiflorum, Neptunia monosperma from black soil plains (BSP) pasture land; and Plectrachne pungens, Chrysopogon fallax, Sorghum plumosum, and Eriachne obtusa of curly spinifex-ribbon grass (CSRC;) pasture land, was assessed over the period October 1975 to October 1977 at the Fitzroy Pastoral Research Station, north Western Australia. Seasonal trends in crude protein, crude fibre. phosphorus. calcium and in vitro digestibility, together with some physiological parameters are described for each species. BSP pastures were found to be higher in crude protein, lower in crude fibre and more digestible than CSRG pasture species. Crude protein contents of most BSP pasture species were sufficient for maintenance of cattle during the dry season while CSRG species were below maintenance All species were deficient in phosphorus over the dry season and some species were marginal to deficient over the wet season.

Townsville stylo cv. Gordon dehulled seed and intact pods were exposed to temperatures ranging from 40� to 11 5�C for between 12 and 48 hours in the expectation that a method of reducing hardseededness could be devised. Dry heat temperatures of 75� and 95�C markedly decreased the level of hardseededness in both dehulled seed and intact pods. A temperature of 11 5�C for 12 hours was sufficient to kill all seeds and pods. Fifty per cent germination was achieved after 2.5 days for dehulled seeds and after 5 days for pods exposed to a pretreatment of 95�C. Untreated scarified dehulled seeds took only 1.5 days to achieve 50 per cent germination. It was suggested that a suitable heat pretreatment on Townsville stylo pods should result in a seed material with a soft-seed level similar to dehulled scarified seed, yet with the pods still retaining considerable immunity from 'false starts' to the wet season.