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The Walpole-Nornalup National Park contains large areas of oldgrowth Karri, Jarrah,
and Tingle forest. The forests of the Walpole-Nornalup area are estimated to have a high
proportion (approx. 75%, Van Heurck, Burbidge and Wheeler 2000) of arthropod species with
Gondwanan affinities, the majority of which are new or undescribed species. Also contained within
these forests are a number of threatened and short-range endemic species. Short-range endemics make
up the majority of species in the following invertebrate groups: Gastropoda (snails), Oligochaeta
(earthworms), Onychophora (velvet worms), Araneae (trapdoor and other spiders), Diplopoda (millipedes),
Phreatoicidea (slaters) and Decapods (freshwater crayfish) (Harvey 2002). Little is known of the ability
of these short-range endemic species and their litter communities to survive both wild and managed fires.
No long-term systematic survey of the fire impact on the species composition of the litter invertebrate
communities of these forests has been carried out to date.
Recent worldwide estimates of the number of species of living organisms
(Stork, 1999) are of the order of 12.5 million species (invertebrates, vertebrates
and plants), of which 11 million are arthropod species. The inventory of
arthropod species is therefore critical to the State's requirement to conserve
the biodiversity of regions such as the oldgrowth forests. Recent advances
in bio-survey methods allow the simultaneous study of fire impacts on the
majority of species of an entire ecosystem component such as the forest
floor litter community. The advantage is that a rapid inventory of species
of a wide range of arthropod groups in the litter community of each site
is achieved. In addition, fire impacts on any short-range endemic species
at each site can be determined, while also comparing the post-fire species
composition between sites with a wide range of fire regimes. This allows
extrapolation to other similar oldgrowth forest ecosystems containing similar
short range endemic species, as well as predicting the impact of fire regimes
and post-fire ages on the richness and species composition of entire litter
arthropod communities in these nearby forests.
Following the March 2001 wildfire in the Nuyts Wilderness, a large group of local volunteers from the
Walpole Community and Walpole Nornalup National Parks Association (WNNPA) have been trapping and
inventorying the litter arthropod species of these forest sites, as well as long unburnt sites nearby.
Paul Van Heurck from the Science Division, Department of Parks and Wildlife was asked to
advise on the technical methods to carry out this survey. This survey is establishing a comprehensive
collection of undescribed local arthropod species and allowing the fire tolerances of these species to
be determined. The outcome should be adaptive fire management of these oldgrowth areas to conserve the
full range of arthropod biodiversity. The extension of this study over a three year period will allow
documentation of the early post-wildfire species succession.
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