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MISCELLANEOUS PUBLICATION 1271, U.S. DEPARTMENT OF AGRICULTURE 



cent {28). Sheep populations in the rangelands 

 have never fully recovered. 



In New South Wales 



Grazing by sheep began between 1850-60 in the 

 Western Division, which covers most of the arid 

 and semiarid pastoral areas of N.S.W. The sheep 

 population rose from 6.5 million in 1879 to 15.4 

 million in 1891. The rainfall during this period 

 was very favorable and well above the long-term 

 average, particularly in the northern part of the 

 Division. From the midnineties, the rainfall in 

 the Western Division began to fall, and an ex- 

 tended drought period began. The period ended 

 with a severe drought, 1901-02, by which time 

 the sheep population had fallen to 4 million. Dur- 

 ing this latter period the reserve of perennial 

 plants was greatly depleted, and soil erosion 

 became a serious problem. 



Since 1902, stock numbers recovered slowly 

 to 6 to 7 million and remained around this num- 

 ber until the late 1950's. During the late 1950's 

 and early 1960's, stock numbers rose to 9 million. 

 A severe drought, 1965-67, led to a fall in sheep 

 numbers to 6 million. 



The increase in numbers during the late 1950's 

 and early 1960's was a result of good seasons, a 

 major reduction in the rabbit population and high 

 wool prices, which led to considerable invest- 

 ment in additional watering points and fencing. 



The drought in the midsixties, and consequent 

 reduction in stock, indicate that the Division is 

 still very susceptible to drought when stock num- 

 bers increase. However, at the close of the drought 

 in 1967, most areas were in fairly good condi- 

 tion, although several areas which had carried 

 very high stock numbers became seriously wind- 

 swept, indicating that a repeat of the 1902 sit- 

 uation could occur again with unwise use. 



During the period from 1900 to 1971, develop- 

 ment, by way of additional fencing and provision 

 of water, has increased so that the area available 

 for grazing has increased markedly. Probably 80 

 percent of the pastures in New South Wales are 

 now within 3 miles of water. Early droughts, as 

 measured by livestock condition, appeared to be 

 more frequent but were due to the paucity of 

 water supplies. These droughts were water 

 droughts and led to severe concentration of stock 



around the watering points. Droughts of the 

 present day tend to be feed droughts. 



Experience was similar in Central Australia 

 {6, 22), Western Australia {1, 23, 29), and South 

 Australia {2Jf). 



Effect Of Grazing On The Landscape 



All of the rangeland types described by Perry 

 {23) have been significantly affected by grazing. 

 Newman and Condon {20) described the effect 

 on each of the six major rangeland types. The 

 six major types are: 



Grassland 



Grassland, composed of mitchell grasses {As- 

 trebla spp. on grey -brown cracking clays). 



Shrublands 



Shrublands, composed of saltbushes and blus- 

 bushes {Atriplex spp.. Kochia spp., Chenop od- 

 ium spp.) on a range of soil types. 



The shrub lands are frequently associated with 

 texture contrast soils, which are susceptible to 

 serious degradation. 



Low Woodlands 



Low woodlands represent a wide range of 

 vegetation associations depending upon the soils 

 and climate. 



The most important tree species in the range- 

 land type is the mulga {Acacia aneura F. Muell.), 

 which occurs on red earths, red loamy soils, 

 sandy soils, and texture contrast soils. Much of 

 the deterioration in the mulga lands is attributed 

 to the loss *of palatable understory species {29) 

 and their replacement by unpalatable species. 



Some other woodland communities, such as 

 cypress pine-box ( Callitris collumellaris F. Muell. 

 and Eucalyptus popuhieum F. Muell.). are af- 

 fected by invasion of inedible scrub, and produc- 

 tion has been seriously affected {18). 



Flood Plains And Alluvial Fans 



The soils and vegetation vary within this range- 

 land type which includes the well watered out- 

 wash plains adjacent to mountain ranges, the 

 flood-out plains alongside ephemeral streams 

 (both of which have coarse textured alluviums), 

 and the broad plains of fine textured alluviums 



