Wetenschap - 11 juli 1996

Non-native plants overrun Australian pastures

Non-native plants overrun Australian pastures

Two non-native plant species, Chinee apple (Ziziphus mauritiana) and Rubber vine (Cryptostegia grandiflora), are causing a great deal of trouble in Queensland, Northern Australia.

A long term research programme has been set up to study the effects of these plants on the natural ecosystems. Wilbert Pellikaan, a graduate in tropical animal husbandry, participated in this programme, focusing on the effects of natural canopy shade from the two plants on the quality and quantity of understorey herbage growth.

The Chinee apple competes with herbage for the available soil water. The Rubber vine canopies allow considerably less sunlight through, thus decreasing understorey herbage yield. Pellikaan presented his research results in a colloquium on Wednesday July 3 at the Department of Agronomy.

Both woody weeds were introduced to Australia at the beginning of this century. Rubber vine was imported as an ornamental plant from Madagascar. The Chinee apple was brought in by Chinese migrant miners for its edible fruits.

Approximately 20% of Australia is prone to infestation by these two woody weeds, mainly the arid and semi-arid open grasslands of Northern Australia. Since the extensive stock breeding farms can be up to 100,000 hectares in size it is virtually impossible to remove or control these shrubs. The Rubber vine is found mostly along open water courses, where it makes access to water resources difficult for both cattle and farmers. The shrubs limit accessibility and visibility which makes mustering a problem as the animals tend to hide under the shrubs.

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