scholarly journals Effects of prolonged shading stress on growth and survival of seagrass Posidonia australis in Jervis Bay, New South Wales, Australia

1995 ◽  
Vol 127 ◽  
pp. 279-289 ◽  
Author(s):  
J Fitzpatrick ◽  
H Kirkman
1968 ◽  
Vol 8 (33) ◽  
pp. 470 ◽  
Author(s):  
MH Campbell

The effects of herbicide, inoculation, and nitrogen on establishment, growth and survival of Trifolium pratense, T. repens, T. subterraneum, Lolium perenne, Dactylis glomerata, and Phalaris tuberosa were recorded at Rockley, New South Wales. Seed was surface sown on unploughed land dominated by tussock grass (Nassella trichotoma). All clovers established on unploughed land but only T. subterraneum survived successfully two years after sowing. Establishment of L. perenne and D. glomerata was three to four times as high as P. tuberosa, but two years later there were more P. tuberosa plants than either L. perenne or D. glomerata. Herbicide treatment increased establishment and growth of all grasses and was essential for their survival ; it was not essential for establishment or nodulation of the three clovers nor for regeneration of T. mbterranew, but did have beneficial effects. Nitrogen decreased the establishment of D. glomeratb but increased growth of all grasses and survival of L. perenne and D. glomerata; it depressed the establishment, nodulation, and growth of clovers. Three-step inoculation gave successful nodulation and proved essential for growth of all clovers and regeneration of subterranean clover.


1996 ◽  
Vol 18 (1) ◽  
pp. 80 ◽  
Author(s):  
CA Booth ◽  
F Sanchez-Bayo ◽  
GW King

Growth and survival of hopbush (Dodonaea attenuata), turpentine (Eremophila sturtii) and punty bushes (Cassia eremophila and C. artemisioides) were studied in relation to the effects of grazing and shrub density, at four sites in the Bourke-Wanaaring region of western New South Wales during 1979 to 1982. Hopbush shrubs grew faster than turpentine and punty bushes. Small hopbush grew better on open areas, while mature shrubs grew better in dense stands. Turpentine showed better performance in open areas, and punty bush growth was unaffected by shrub population density. All these species showed a high survival rate, particularly in height classes greater than 25 cm, and they kept growing even during drought periods. The effects of grazing on survival were inconclusive. Hopbush and turpentine root development was rapid, attaining depths of over 1.1 m in wet soils, 14 weeks after germination. Mature plants in the field, both hopbush and turpentine, were observed to have extensive lateral root networks at either 22 cm or 30-70 cm soil depth respectively, as well as a tap root system. The characteristics of both species help explain the competitive advantage of these shrubs over herbaceous species, and their survival capability in times of drought. Competition of hopbush with the perennial grass woollybutt (Eragrostis eriopoda) and annual herbage was also examined. In spring, survival of hopbush seedlings was favoured within woollybutt tussocks, this situation being reversed in autumn. Woollybutt biomass was negatively affected by the proximity of hopbush shrubs. Annual herbage seemed not to have any effect on hopbush survival, although shrub seedlings grew better under conditions of moderate herbage cover. Microtopography affected the establishment of both grasses and shrubs, with depressions favouring the growth of grasses at the expense of shrubs during periods of adequate moisture, and the growth of shrubs during drier times. The findings suggest that the woody weed problem is unlikely to wax and wane and that turpentine may be particularly difficult to control. Maintenance of high levels of pasture cover from perennial grasses and annuals may slow down recruitment and growth in open areas with scattered parent shrubs, where control will be less costly, and may contain future spread.


1997 ◽  
Vol 37 (1) ◽  
pp. 19 ◽  
Author(s):  
M. Freer ◽  
J. R. Donnelly ◽  
A. Axelsen ◽  
L. F. Myers ◽  
J. L Davidson ◽  
...  

Summary. In 2 field experiments on the southern highlands of New South Wales, the short-lived perennial grass secale (Secale montanum Guss. cv. Black Mountain) was grazed by Merino wether weaners at stocking rates of 10–17 animals/ha to test the suggestion that persistence might be enhanced by occasional deferment of grazing to encourage seedling germination. In the first of these experiments (experiment 1), designed to compare secale and phalaris, when accompanied by white and subterranean clovers, growth and survival of both grasses was poor, despite the application of >600 kg/ha superphosphate and the experiment was abandoned after 2 years. A subsequent pot trial (experiment 2) with secale grown in soil from the experimental site, where the fertiliser had been applied, showed a large growth response to additional phosphorus. Because inadequate soil fertility may have been the cause of poor grass persistence in experiment 1, a second field experiment (experiment 3) was established on the same site to compare secale, perennial ryegrass and cocksfoot, each accompanied by white and subterranean clovers and with the application of a further 850 kg/ha superphosphate over 3 years. Initial growth of all the grasses was good and animal production on the secale and ryegrass plots was high (up to 100 kg/ha greasy wool and 300 kg/ha liveweight gain). Secale failed to survive more than 3 years, despite deferment of grazing and it may be that persistence depends more on the reliability of autumn rainfall. However, mean weight gain from the clovers and volunteer grasses on the secale plots in the fourth year was as high as from the ryegrass plots and double that from the cocksfoot plots, which became increasingly cocksfoot-dominant. While the results indicate a need for more work on the fertiliser requirements of perennial grasses on these soils, they also raise questions about whether these grasses benefit animal production sufficiently to justify the cost of establishing them.


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