Sheep population in relation to the seasonal pattern 



Efficient utilization of shrub pastures through intensive grazing during periods 

 of active growth can only be attained by fitting stock numbers to the long term rain- 

 fall pattern, which is the primary determinant of forage resources ; and by close sub- 

 division of pastures together with the provision of adequate watering places. In this 

 way, maximum production will be attained, stock losses avoided, and the pastures 

 either improved or maintained in a sound condition. If, on the other hand, the num- 

 bers of grazing animals are not so adjusted, pastures either may not be utilized 

 effectively, or may be permanently damaged in attempting to maintain high numbers 

 during a sequence of drought seasons. 



The Yudnapinna rainfall records reflect the seasonal pattern for the North- 

 west District, and the record of sheep population in this area (Fig. 3) shows that 

 stock numbers have not been well adjusted to the broader rainfall trends. 



The years 1870- 1951 may be grouped into five main periods characterized by 

 particular trends in rainfall, pasture status and livestock population. 



First period (1870- 1895). The sheep population of South Australia increased 

 from the middle years of the nineteenth century to a maximum in 1890 (Davidson, 

 1938) largely by expansion to virgin pastures, including those of the North-west 

 District. In this area numbers rose during a succession of generally favourable 

 seasons from 374,000 in 1870 to 789,000 in 1882, a sheep density which the pas- 

 tures could not permanently support under the existing conditions of subdivision and 

 water supply. In the second phase of this period, from 1882- 1895, the number of 

 sheep maintained decreased to 618,000 by 1892, and to a still lower figure in 1895 

 for which no record is available. It is certain that considerable deterioration of the 

 pastures commenced during these years. 



Second period (1895- 1905). The years of high rainfall prior to 1895 were fol- 

 lowed by a succession of dry seasons from 1895- 1905. Pastures had been gravely 

 overstocked; sheep were concentrated on the few permanent waters, and the adjust- 

 ment to drought conditions was enforced by sheep losses rather than by planned de - 

 stocking; numbers fell to 275,000 in 1905. Extensive damage to the perennial 

 shrubs occurred during this time, and their productivity in many cases was perman- 

 ently impaired. 



Third period (1905- 1924). The third period from 1905- 1924 was on the whole 

 characterized by above average rainfall, but despite this, stock numbers tended to 

 remain at a depressed level of about 250,000 sheep; it seems probable that the pre- 

 vious degeneration of the shrub pastures was a major factor. This period may be 

 divided into three phases. The first phase from 1905- 1911 was characterized by 

 favourable rainfall; over, this period the sheep population rose from 275,000 to 

 376,000, due to temporary recovery of the forage resources. In the second phase 

 from 1911 to 1915 the degraded pastures were unable to provide forage during a 

 recession of rainfall, and stock numbers decreased to 132,000 in 1915. Only a limi- 

 ted increase to 278,000 sheep occurred in the third phase of exceptionally high rain- 

 fall from 1915- 1924, during which wartime labour shortage exerted some control. It 



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