Support from Dr Marianne Horak, Honorary Fellow, ANIC (Lepidoptera), CSIRO Ecosystem Sciences. Canberra - calling for a moratorium on prescribed burning for the Cape Liptrap Coastal Park until meaningful studies on leaf litter accumulation and break-down have been done. To whom it may concern Whilst responsible for Lepidoptera (moths and butterflies) at the Australian National Insect Collection at CSIRO Ecosystem Sciences (formerly CSIRO Entomology) I have during the last 10 years repeatedly suggested that it would be crucial to do research into the effects of the widespread control burning on mallee moths (Oecophoridae), whose larvae are the major agent of eucalypt leaf litter break-down. Hence I’m delighted that such a study is now being considered at the Cape Liptrap Coastal Park, finally providing a scientific underpinning for decisions on fire management as far as leaf litter break-down by mallee moths is concerned, and I would like to give my full support to this endeavour. Obviously, a moratorium on currently planned burning is a precondition for any such study to be possible. Unlike in northern hemisphere temperate forests and in tropical rain forests the leaf litter in the Australian myrtaceous forests is to a large extent broken down by the small caterpillars of the mallee moth family (Oecophoridae), which live in the various leaf litter layers and also feed on loose dead leaves still on twigs or on the ground. This group of moths, usually numbering a few hundred species in any fauna, has radiated to the tune of 5000 species in Australia after managing to colonise living and then dead myrtaceous leaves, both nutritionally challenging substrates. About 25% of all Australian Lepidoptera species are mallee moths, which clearly demonstrates their ecological importance. While we know from a lifetime of collecting experience that recently or, worse, frequently burned forests have very low numbers and diversity of mallee moths, we have only few observations of actual caterpillar numbers in the leaf litter. However, what we have suggests that the larvae can reach very high densities: Plowmann 1979: 438 Lepidoptera larvae per m2 of leaf litter in wet sclerophyll forest; I F B Common pers. comm.: 54-252 Lepidoptera larvae in casual leaf litter samples (ca. 130 g dry weight) at Depot Beach, NSW. There can be no doubt that such numbers mean a huge reduction of leaf litter as anybody can infer who observes the relatively sparse layer of eucalypt leaf litter in a mature and undisturbed forest, compared to the build up of leaves in eucalypt forests recently burned or in eucalypt plantations overseas. As a certain humidity is required for larval feeding the oecophorid caterpillars are mostly active in winter, which also happens to be the time of control burning, inflicting the largest possible damage on the oecophorid population. This means that the post burning leaf fall will not be broken down until the area is recolonised by moths from unburnt areas. Whilst it is becoming acknowledged that frequent burning encourages exactly those plants such as introduced grasses that will make fire even more of a hazard, the quiet work of leaf litter break-down by oecophorid moths (and of wood by termites and beetles) has still not gained the necessary attention. I emphatically add my voice to the call for a moratorium on prescribed burning for the Cape Liptrap Coastal Park until meaningful studies on leaf litter accumulation and break-down have been done. Together with my colleague Ted Edwards I’m very willing to advise and help set up research into mallee moth populations with regard to fire management. As far as mallee moths are concerned, there is a comprehensive revision of the Australian Oecophoridae available and we now have the molecular tools to make such research possible. With best wishes, Dr Marianne Horak Honorary Fellow ANIC (Lepidoptera) CSIRO Ecosystem Sciences Canberra, ACT 2601 AUSTRALIA
Posted on: Thu, 06 Mar 2014 01:52:26 +0000
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