WEED ECOLOGY
Results Summary
A review of the research carried out to date, illustrates
that the impact of bitou bush on coastal ecosystems is widespread,
affecting both flora and fauna. Alterations in nutrient cycling
and increased decomposition rates are accompanied by changes
to plant community structure and composition, with the flow-on
effects of these changes influencing invertebrate and bird assemblages.
The establishment of bitou seedlings may be the key phase for
successful invasion by this species. We have shown that bitou
bush outcompetes native species through both resource and interference
(i.e. allelopathic effects) competition mechanisms. In addition,
established individuals can produce high numbers of seed that
remain viable within the soil seed bank and are readily able
to take advantage of future opportunities for germination.
The control of bitou bush is often limited to removal of the
species by aerial spraying, hand spraying or hand removal. We
have found that these techniques alone can reduce the availability
of bitou bush seed but do not allow for the restoration of all
native species found within uninvaded coastal communities.
We suggest that seedlings should be specifically targeted in
weed management strategies and stress the importance of long
term management plans to ensure coastal communities are not in
danger of invasion by secondary weeds following bitou removal.
Fire may be used to encourage native seed germination and to
potentially remove volatile allelopathic chemicals in the soil.
This method is currently used to encourage germination of bitou
seed stored within the soil seed bank. The resultant seedlings
are then destroyed and the potential for re-establishment of
bitou bush from the seed bank is reduced. Finally, management
strategies should also include replanting schemes to increase
species richness of all plant structural groups and to build
ecosystem resilience.
Additional reading
French K, Ens E, Gosper CR, Lindsay E, Mason T, Owers B and
Sullivan N (2008) Management implications of recent research
into the
effect of bitou bush invasion. Plant Protection Quarterly
23,24-28
|
