Research: in the field : Water reduces diversity

10 May 1997

CSIRO ecologists have gathered the first hard
evidence that grazing is degrading arid and semi-arid Australia. A research
group from the Division of Wildlife and Ecology, funded by environment
Australia, has shown that bores, dams and troughs lower the biodiversity of
native plants, animals and birds in the surrounding land. The group found that
the decline in diversity was greater closer to water and that this was related
to intensity of grazing, mainly by sheep and cattle, but also by kangaroos. “The
effect is not unique to the arid environment,” says researcher Steve
Morton. “It crops up again and again, in all landscapes.” The researchers
chose 48 artificial water sources across five states, from the far west of Western
Australia to southwestern Queensland. They then measured biodiversity of plants,
birds, reptiles, small mammals, and certain groups of insects at six points
along a line out from the source to a point remote from water. It was
particularly difficult to find points more than 10 km from water, the maximum
distance cattle will move. The results were consistent across the whole
geographical area. Between 15 per cent and 38 per cent of the species declined
in abundance the nearer they were to water. Nearly all these species were native
to Australia. The research group has recommended that artificial water sources in
nature reserves be closed off, and even some of those on pastoral lands. But
Morton admits this will be difficult. “It is unrealistic to expect grazing to
stop. For anything to happen, the community as a whole must be interested in
seeing biodiversity preserved.”