On Wed, 11 Apr 2007 18:57:52 -0700, Donald Martinich <[email hidden]>
Quoted message said:In article <[email hidden]>,
Karen AKA Kajikit said:Sadly yes... some bright sparks decided that Australia didn't have
enough problems with imported plants and started an olive kick. (I say
'sadly' because we all know how well olives grow in harsh climates -
they can outcompete native plants quite easily...)
I don't know who fed you that line, but you needn't worry. Olives can
reproduce from seed but rarely beyond the original grove. I've never
seen a volunteer growing more than about 5 feet beyond the dripline and
most of those are the result of ground squirrel activity. We've got a
number of abandoned olive groves in my part of the world (California's
Sacramento Valley) and they never expand beyond the original plantings.
If olives don't go feral how come the South Australian government has
had to officially address the problem in the last few years? Just type
'feral olives' into google and up springs a forest of references to
the Australian problem. Here's just one brief abstract that summarises
it:
Résumé / Abstract
The olive (Olea europaea L.), imported into Australia and subsequently
cultivated for economic purposes, has spread into native vegetation in
several regions of southern temperate Australia. The impacts of olives
going 'feral' have only recently been quantified. It is reported that
native plant species diversity and canopy cover was 50% and 80% lower,
respectively, in a native eucalypt woodland heavily invaded with feral
olives. Consequently, feral olives are considered an environmental
weed as well as being proclaimed a Pest Plant in South Australia. The
1990s has seen a resurgence in the olive industry. In response to the
risk that new olive orchards will be foci for invasion into natural
ecosystems currently free from feral olives, risk assessment and
management guidelines were developed by the Animal and Plant Control
Commission in conjunction with an Olives Advisory Group. Local
governments and prospective growers can use the guidelines when
assessing the suitability of a proposed olive orchard. However, if
olives have escaped from orchards into native vegetation, then their
removal is paramount. Unfortunately, feral olive control is a very
costly and time consuming exercise, and requires careful planning
before doing so. In severe cases of olive infestations, the removal of
olives may lead to other problems in fragile ecosystems. It can cost
up to A$15,000 per hectare to remove a dense infestation of feral
olives, such as the one described in this paper.