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MISCELLANEOUS PUBLICATION 1271, U.S. DEPARTMENT OF AGRICULTURE 



ternal pressures in the pasture-animal ecosystem, 

 where the animal has an immediate effect upon 

 an admittedly mobile equilibrium in the arid 

 pasture. 



Halophytic Pastures 



An understanding of the factors affecting ger- 

 mination and early seedling survival is prerequi- 

 site for the definition of management plans. Bur- 

 bidge (2) defined the optimal germination cri- 

 teria for Atrip! ex vesicaria Benth. and a number 

 of Kochia species. She noted that as A. vesicaria 

 germinated most readily at 15° C, and is signifi- 

 cantly depressed at other temperatures, germina- 

 tion can only be expected with autumn rains, 

 when in the interests of seedling survival, grazing 

 should be restricted. However, Trumble (27) and 

 Woodroffe (35) reported the survival and estab- 

 lishment of Kochia sedifolia F. Muell. seedlings 

 at grazing rates as high as 0.5 sheep per hectare. 

 Kochia species were shown by Burbidge to be 

 more tolerant of hot conditions and to have a 

 wider germination range. She also referred to 



the effect of salt as a germination inhibitor in 

 the bracteoles of A. vesicaria, which she presumed 

 prevented germination with light falls of rain. 

 However, Jones (12) working with A. nummu- 

 laria Lindl., could obtain no increases in field 

 germination after soaking seed and bracteoles in 

 water to leach out salt. Trumble (27) found that 

 A. vesicaria was adapted to a winter rainfall 

 germination and summer growth pattern. He 

 considered that this characteristic determined 

 the species distribution. 



Burbidge (2) showed that the germination of 

 A. vesicaria was substantially decreased at depths 

 greater than 1.25 cm. Winkworth (34) reported 

 rapid drying out of some desert soils to more 

 than 2.5 cm. within 24 hours which is of particu- 

 lar relevance here. It would suggest that pro- 

 longed and continuous rainfall is necessary for 

 the germination and establishment of Atriplex 

 spp., a condition found inf requently in Australian 

 rangeland. It is suggested that management of 

 degraded halophytic pastures will center upon 

 the efficient use of excess rainfall years. 



Figure 2. — Acacia ancuraAov? shrub-short grass-forb pasture in Western Australia. A. aneura in center and right rear, 



Kochia and Solatium spp. beneath the tall layer. 



