PLANT MORPHOGENESIS FOR SCIENTIFIC MANAGEMENT OF RANGE RESOURCES 



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Figure 1. — Shrubland pasture distribution in Australia. Modified from Moore and others (21) and Perry (24). 



an increase in unpalatable species, though their 

 total expression was often tempered by drought. 

 Where cover was completely destroyed, serious 

 soil erosion took place. Complementary to this 

 regression, additional stresses were placed upon 

 the vegetation through the provision of watering 

 points and fences, which restricted stock to spe- 

 cific areas. The explosion of the European wild 

 rabbit into the rangelands of Eastern Australia 

 in 1890 aggravated this situation, because they 

 entirely removed the herbaceous vegetation which 

 provided some protection for the remaining 

 woody perennials. Through burrowing and ring- 

 barking, rabbits contributed to the death of those 

 plants which survived the effects of domestic live- 

 stock. Crocker and Skewes (6) described a num- 

 ber of paths by which specific pasture types de- 

 generated from perennial woody shrubs to annual 

 species in South Australia. Hall and others (9) 

 described a dramatic sequence in vegetation de- 

 cline in the natural shrubland pastures of north- 



east South Australia. However, it is not clear 

 whether these changes in species composition are 

 the direct result of increased competition from 

 undesirable species in the pasture, if they are due 

 simply to reduced vigor, or to adverse changes 

 in the total pasture environment induced by over- 

 use by grazing animals. 



In this setting of decline in condition of the 

 shrub range, a number of studies have been under- 

 taken which have aimed at determining the spe- 

 cific worth of particular pastures and their com- 

 ponents; at investigating special aspects in the 

 life cycles of pasture species; and at achieving 

 an understanding of the interrelationships in 

 grazed and ungrazed pastures. These are here 

 described under the broad headings of halophytic 

 (A triplex and Kochia) pastures and of Acacia, 

 particularly A. aneura, pastures. Very few, if any, 

 of the investigations have developed to include 

 the whole scope of the life history of pasture 

 species and the impact of grazing upon the in- 



