Dealing with the curse of chytrid

chytrid fungi highlight briefComing to terms with amphibian chytrid fungus in Australia’s High Country

Frogs are in trouble. A third of all frog species are threatened with extinction. The usual culprits of habitat loss and climate change are at work, but another more insidious threat looms. A devastating disease called chytridiomycosis has been wiping out frogs, often from pristine habitats. The disease is caused by a fungus – amphibian chytrid fungus (pronounced kit-tyrid). The fungus disrupts the skin function of infected frogs leading to cardiac arrest (heart attack).

The numbers are sobering. Since the identification of chytrid by Australian researchers in 1998, the pathogen has been documented in over 500 amphibian species, and is now found on all continents (except Antarctica). Fortunately, the pathogen is not universally deadly with some species demonstrating high resistance (though this produces some problems of its own).

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Looking after our nomads

Bronze winged pigeon Jeremy RingmaGeographic range size and extinction risk

Geographic range size (the size of a species' distribution) is often treated as a fixed attribute of a species for the purposes of calculating extinction risk. All else being equal, species occupying smaller geographic ranges are assumed to have a higher risk of extinction. However many species move around the landscape. Sometimes their movements involve relatively predictable to-and-fro migrations (migratory species). But sometimes they involve complex irregular movements, with these species often being referred to as nomads (nomadic species).

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Perversity in the pasture

Perversity in the pastureGuarding against new pasture varieties becoming tomorrow's environmental disasters

Hundreds of the invasive plant species that now inflict major environmental and economic damage in Australia were originally developed and distributed as pasture species. What a perverse outcome. What's worse, we don't seem to have learnt from these mistakes.

Consider African lovegrass. It was used to 'improve pasture' in Australia for almost 100 years, but is now declared a weed in four Australian states and the ACT. It has been of little value in pastures, poses a substantial fire risk and threatens a range of native species.

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To thin or not to thin ...

To Thin or Not Chris JonesUnderstanding dense eucalypt stands and the pros and cons of thinning

Stands of dense woody regrowth are increasing in extent across Australia and around the world, and that raises many questions on how they should be managed. What's their value and should we leave them alone or actively thin them?

Dense woody regrowth commonly pops up on cleared land where there has been some change in land use, usually a reduction in grazing pressure. In some places, this regrowth is considered a bad outcome.

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Adapting conservation goals to global change

adapting conservation goals pretzelUntangling the pretzel logic of conservation?

Conservation goals at the start of the 21st century reflect a combination of contrasting ideas. 'Ideal nature' is something that is historically intact, but at the same time, futuristically flexible. Ideal nature is independent from humans, but also, because of the pervasiveness of human impacts, only able to reach expression, or maintain itself, through human management. It's very pretzel-like in its logic.

In a recent reflection on this conundrum, researchers Nicole Heller and Richard Hobbs attempted to make sense of these inherent tensions in an effort to understand what are appropriate goals for conservation in a time of rapid global change. Their exploration led to the development of an approach that they have called 'natural practice'.

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