Our
rainforests are sick
 |
 |
| |
Dieback caused by the phytophthora root rot fungus affects
a wide variety of ecosystems, such as the banksia woodland
shown here. Photo: John Hicks |
|
Phytophthora root rot, a form of ‘dieback’,
is a disease that affects many native plants and ecosystems,
important crops and horticultural plants in Australia and throughout
the world. Its global spread has been the consequence of trade
and human migration in Australia, the disease infects an especially
large range of mainly woody perennial plant species and is also
a major threat to some rare and endangered species, including
our guardian of the rainforest – the cassowary.
CSIRO monitor a series of twenty long-term
research plots across the Wet Tropics. One of these was established
near Wallaman Falls on the Seaview Range in 1975, ahead of
any logging activity. At
establishment there were signs of Phytophthora in the
area, and by 1977 it had moved into the research plot. Monitoring
of the progress and impact of the infection continued for the
next 12 years. That the disease was present before road-building,
logging operations and other human disturbance suggests that
another vector introduced the disease to the area.
Extensive pig activity in the area and movement of the infection
area uphill out of a gully (infections typically spread downhill
as spores are spread in water) support previous suggestions that
pigs are implicated in the spread of Phytophthora (e.g.
in Brown 1999*). Phytophthora is not only a serious
concern in natural forest habitats, but can cause extensive damage
and loss in avocado plantations and to other agricultural crops.
* Brown, B. 1999. Occurrence
and impact of Phytophthora
cinnamomi and other Phytophthora species in rainforests
of the Wet Tropics World Heritage Area, and of the Mackay region,
Queensland. Pp. 41-76 in Gadek, P.A. (ed.) Patch Deaths
in Tropical Queensland Rainforests: Association and Impact
of Phytophthora cinnamomi and other Soil Borne Organisms. CRC
Tropical Rainforest Ecology & Management, Cairns
To read more about Phytophthora download the following
factsheet:
 http://www.environment.gov.au/biodiversity/invasive/publications/p-root-rot/pubs/p-root-rot.pdf
Thanks to Dr Daniel J. Metcalfe, Tropical Plant Ecologist,
Tropical Forest Research Centre, Atherton, for this information |
