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CHRISTCHURCH - Some native forests, which have few or no natural defences against browsing mammals and have been devastated by possums, are fighting back.
Farmers trying to control possums have noticed that certain trees are "possum magnets," while other trees of the same species are left alone.
Studies published recently by Landcare Research show this is also happening on a forest scale.
A South Westland study has shown that possums in a forest site they have occupied for 30 years or more are smaller and breed less often, probably because they feed on less palatable species than possums in a recently colonised site.
The clear trend was for both possums and the forest to deteriorate as palatable plants were browsed out.
But other information on the variable palatability of native plants to possums has shown a different trend.
Fuchsia, rata and mistletoe are often regarded as indicators of possum activity, but in a few places some or all of these species are left alone.
Rata are sometimes browsed to the point of death while nearby trees of the same species remain almost untouched.
Feeding trials have confirmed that the same species from different sites can vary significantly in their possum palatability.
If botanists can find exactly what it is that either attracts or deters possums, browse-resistant plants could be propagated.
- NZPA
Plants get back at browsing possums
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