The Population Dynamics of the WeedAcacia longifolia(Fabacae) in the Absence and Presence of Fire

Abstract

The population dynamics studies of Acacia longifolia (Andr.) Willd. differed greatly in the absence or presence of fire. In the absence of fire few seedlings established under the living parent plant even though a large quantity of seeds is incorporated into the seed bank annually. Fire caused the destruction of the parent trees but resulted in the establishment of a dense, even-aged stand of seedlings. However, this treatment depleted the seed bank of this weed by 90%. The implications of these findings for integrated control are discussed.

Impact of prescribed burning on Acacia nilotica seed banks and seedlings in the Astrebla grasslands of northern Australia

“…This may be important in areas with very large seed banks, such as riparian zones, because although seed decay is relatively rapid for most seeds (4)1% seeds germinable after 2 years; S. Campbell, Queensland Department of Natural Resources, unpublished report 1996) some seeds remain viable for up to 7 years (Bolton et al, 1987). Mass germination and emergence as a single cohort, and the resulting depletion of seed banks has been observed for other invasive Acacia species in Africa, including A. mearnsii, A. longifolia and A. sieberiana (Pieterse & Cairns, 1988;Sabiiti & Wein, 1988;Pieterse & Boucher, 1997). In addition, many Australian indigenous Acacia seeds have increased germination after being subjected to the effects of fire (Bell, 1999;Auld, 1996).…”

“…However, the effects of fire on Acacia species generally (Pratt & Knight, 1971;Pieterse & Boucher, 1997) and A. nilotica in particular (Burrows et al, 1990), are unclear and sometimes contradictory. Fire is often reported to reduce tree canopy cover (Pratt & Knight, 1971;Trollope, 1980) and to deplete seed banks in some species (Pieterse & Cairns, 1988;Holmes, 1988;Pieterse & Boucher, 1997). But fire is also associated with increasing stem density in some situations (Pratt & Knight, 1971) due to both coppicing and promotion of seedling germination (Pieterse & Boucher, 1997).…”

Impacts of invasive Australian acacias: implications for management and restoration

“…Even after 'apparent success' in control of the trees, seeds of most Acacia species can lie dormant in the soil for decades (Milton & Hall, 1981;Pieterse & Cairns, 1988) and can hamper restoration following subsequent disturbance events such as fire. In this case, followup action and biological control can play key roles in the Box 3 Case study: Acacia dealbata invasions in Chilean woodlands and forests -driven by disturbance and competition Acacia dealbata was introduced to Chile for ornamental purposes, and invasions currently extend from Los Lagos in the south to Valparaiso in the north.…”

Melinis repens Seed Bank Longevity in Miami-Dade County

“…There is a strong link between seed production and seed bank accumulation (Pieterse and Cairns 1988). Species that produce more seeds tend to build up in the seed bank and persist for a longer period of time than species that have lessabundant seeds (Pieterse and Cairns 1988).…”

“…Species that produce more seeds tend to build up in the seed bank and persist for a longer period of time than species that have lessabundant seeds (Pieterse and Cairns 1988). After dispersal, seeds are removed from the seed bank either through germination, natural death that results from aging, decay (Marchante et al 2010) or predation (Hulme 1998).…”