Sydney — A curious breed of rifle-toting hunter is coming to Australia. His target: trees.
The tree hunters tromp about Australia aiming their special weapons at this country's fast-growing eucalyptus, acacia, and casuarina trees, shooting down branches.
Their motive: to get tree seeds that can be planted in their home countries to supply new sources of fuel quickly.
Zimbabwean and Brazilian scientists are regular tree hunters in Australia. Dozens of other countries trust Australia's scientists to choose trees for them. Seeds have been sent to more than 150 nations.
It is an example of quiet international cooperation in tackling some of the world's most serious challenges. The United Nations Food and Agriculture Organization predicts that, by the year 2000, the availability of fuel for cooking may be a more serious problem in parts of the world than finding enough food to eat.
Depletion of indigenous forests in countries such as Thailand and the creeping advance of the desert in Africa's Sahel region are just two situations in which Australian seeds are being used experimentally.
The key to Australia's ability to provide other nations with several billion tree seeds each year is the seed section of the Commonwealth Scientific and Industrial Research Organization's Divison of Forest Research in Canberra, the Australian capital.
Dr. John Turnbull, a research scientist with the Division of Forest Research, describes his unit as a ''major supplier'' that sends ''many millions'' of seeds out each year. According to Stephen Midgley, an experimental officer with the unit, sending seeds abroad isn't as simple as it sounds.
''Take eucalyptus, for example,'' he explains. ''There are numerous sorts of eucalyptus - and researchers have to try growing a selection of these in the country that wants them to determine which will thrive best. Initially, we got seeds from a part of Australia that is most similar to the place where trees are to be grown. But it's not quite that simple: Often there are surprises and trees from particular seeds will thrive in unexpected places.''
Midgley and other forest research personnel comb the vast Australian outback for seeds that might suit a particular locale: ''We sometimes get calls from people who know what we're looking for. They'll say there are plenty of seeds in a certain spot and we race off to retrieve them.
''Mostly we just break off branches and take them back to Canberra but, if the seeds are in high treetops, we use rifles to shoot down some branches.''
Back in the laboratory the gum-nuts, in the case of eucalyptus, or seedpods of other trees, are placed on sheets of calico cloth. When the gum-nut or pod opens, the seeds fall onto the cloth and can be collected. Some seeds are so small they resemble dust. Others are pea-sized, or larger.
''Australian trees are uniquely popular,'' Midgely says, ''because they are fast-growing, need minimal tending skills, and thrive in poor soil. What's more, when you chop down eucalyptus, new trees grow from the stumps, so you don't have to replant.
''The Brazilians have refined eucalyptus-growing to the point where it takes only seven years to bring trees to the point where they can be harvested.''
Midgley says Australian trees are planted primarily to provide fuel: wood to burn for cooking. But there is optimism that acacias - also known as wattles - may help hold back the Sahara's advance in Africa.
Casuarinas, highly effective as windbreaks, have been planted along canals in Egypt to prevent sand blocking the channels. A 1,550-mile belt of casuarinas shelters crops and provides fuel along the Chinese coast. Large plantations of the same tree are growing in Argentina.
Acacias boost reforestation programs in nations as far apart, geographically, as Guyana and Malaysia. And because of huge forests, eucalyptus are now more common in Brazil than in Australia. They are commonplace, too, in Spain, Portugal, India, and South Africa.
Eucalyptus are no rarity in North America, either. And Midgely notes he has planted them in Laos, Thailand, Vietnam, and Nepal. ''They even adapt to the Scandinavian climate,'' he says.
''Whatever the basic reason for wanting a particular Australian tree,'' he observes, ''they're all excellent for firewood as well. Availability of these Australian trees as a source of fuel may, in the future, be the only way to save something of the indigenous forests of Burma and Thailand, for instance.''
Zimbabwe wants to develop eucalyptus growth in its areas of least lush vegetation. And Brazilian scientists, despite their advanced knowledge of eucalyptus, visit Australia regularly in a quest for even better specimens from remote locales. They aim to cut growing time still further as demand for wood to burn increases.