Is Burning a Standing Population of Invasive Legumes a Viable Control Method? Effects of a Wildfire on anAcacia mearnsiiPopulation

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rapid for most seeds (4)1% seeds germinable after 2 years; S. Campbell, Queensland Department of Natural Resources, unpublished report 1996) some seeds remain viable for up to 7 years (Bolton et al, 1987).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).…”

“…As shown by 100% kill of seeds in dung, a large part of the seed bank, found in cow dung (Harvey, 1981;Carter, 1994;Radford et al, 2001) or wild herbivore dung in Africa (Coe & Coe, 1987;Miller, 1994; may be killed during a single fire. Stimulation of seed germination and the resultant depletion of seed banks can potentially be exploited by managers (Pieterse & Cairns, 1988;Sabiiti & Wein, 1988;Pieterse & Boucher, 1997). Manipulation of germination events allows managers to effectively plan follow up treatments of seedlings and increases the probability that seedlings will emerge during unfavourable conditions.…”

“…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). Increased stem density was observed for A. nilotica in one African study following burning (Pratt & Knight, 1971), however, no information was given on the susceptibility of different sized plants or on the seed bank.…”

“…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).…”

“…and woody thicket formation and also for the maintenance of open savannas in many parts of Africa (Trollope, 1980). 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).…”