Reproductive Development and Seedling Establishment of Aristida ramosa R.Br. in Northern New South Wales.

Abstract

The reproductive development and seedling recruitment of Aristida rarnosa R.Br. \vas studied under field conditions at six sites on the Northern Tablelands and Northwestern Slopes of New South Wales. A. rarnosu is an undesirable species in pastures because of its low palatability and the propensity of its seeds for causing fleece contamination and mechanical injury to stock. All tillers ofA. vanlosa plants appear to be potentially reproductive and the extensive tiller branching means that each tiller has a high probability of completing the reproductive cycle. Individual plants, therefore, have a high potential for seed production. 'The majority of the seed production occurred in March averaged over all sis sites. Seedlings appeared in each one of the 20 months of observation when the results from all sites were added together, with the majority of seedlings appearing in the spring and autumn. Autumn seedlings had the greatest chance of becoming established at the lower, more western sites while spring seedlings survived best on the Tablelands. The results are discussed with respect to devising pasture management strategies aimed at reducing the abundance of A. wrnosa.

Establishment of Warm- and Cool-Season Native Perennial Grasses on the North-West Slopes of New South Wales. Ii. Establishment and Seedling Survival in the Field

“…On the north-west slopes, however, very few seedlings were observed to germinate in spring in the field, probably as a result of wide fluctuations in temperature, low mean minimum temperatures or intra and interspecific competition. Results of similar studies in this environment (Harradine and Whalley 1980) also showed that few seedlings of A. vamosa appeared in spring, though spring emergence in this species was common at higher elevations on the Northern Tablelands.…”

“…Harper (1977): in a review of available literature, found little evidence that germination was enhanced by a cover of vegetation, and in the present study seedling emergence and survival were highest for all species that germinated in the open spaces between the bases of plant tussocks. High mortality of native perennial grass seedlings may also have resulted from intraspecific competition from neighbouring mature plants of the same species whose phenologies would be synchronized with those of the seedlings (Harper 1977), as well as from competition from rapidly growing annual species (Harradine and Whalley 1980).…”

“…Harradine and Whalley (1980), from a study of seedling emergence and survival of Aristida ramosa R.Br. in the same region, found that seedling establishment in native pastures was controlled primarily by moisture availability and the degree of competition from annual species.…”

Emergence and survival of herbaceous seedlings in temperate grassy woodlands: Recruitment limitations and regeneration niche

“…The burn treatments, however, promoted the recruitment of weedy annuals into the surface‐disturbed sites. These weeds might have subsequently competed for soil moisture and reduced the emergence of perennial species (see Harradine & Whalley 1980).…”

“…Mortality of herbaceous seedlings is typically very high, but declines with age if post‐emergence disturbance events are rare (Williams 1968; Grice & Barchia 1992; Morgan 1995). Suggested causes of seedling mortality include water stress (Gilfedder & Kirkpatrick 1994; Burrows 1995; Morgan 1995), competition (Harradine & Whalley 1980; Morgan 1995; Hitchmough et al . 1996), herbivory (Morgan 1995) or combinations of these.…”