A programme investigating rain forest dynamics has won new funding. Wendy Barnaby reports

A new paradigm in tropical ecology research is emerging from work in Southeast Asia, and is so successful it has just won new funding.

Against the traditional view of rain forests existing in a broadly stable state, results from the South-East Asia Rainforest Research Programme (SEARRP) suggest that they are continually reacting to extreme climatic events.

This new way of looking at tropical rain forests could lead to better management techniques that could help logged forests recover more quickly.

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SEARRP was set up in the early 1980s out of concern for the future of tropical forests. Based in Sabah, East Malaysia, it involves 60 British and Malaysian scientists in research projects, mostly in Malaysia and Indonesia.

Its core funding, Pounds 100,000 a year, has come from the Royal Society in five-year allocations. The current one runs out at the end of 1999. The Royal Society has just decided to fund five more years.

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There seems little doubt that RS funding brings in more money: the core grant makes up about one-seventh of the total budget, with the balance being paid mainly by the Malaysian government and UK research councils.

"This is the longest-running and biggest of the Royal Society's overseas projects," said Cambridge's Timothy Clutton-Brock, chairman of the SEARRP committee.

"It runs the research station (in Sabah) which is the basis for pulling in other research projects.

The programme's extension comes just as it is overturning received wisdom about the dynamics of tropical forests. Instead of seeing the diversity of rain forest plant and animal species as the result of competition in an unchanging environment, SEARRP is drawing attention to the fact that forests suffer occasional disturbances from fire, drought, cyclones or floods.

Their mix of species will change in reaction to these extreme events. David Newbery (now of the Geobotanical Institute at the University of Berne) is particularly interested in how the forest at Danum, in Sabah, has reacted to a severe drought between 120 and 150 years ago.

He has been able to collect data on this because of SEARRP's continuity, which is allowing detailed investigation of the way forests grow and behave over time. In 1985-86, Professor Newbery enumerated all 18,000 trees in two four-hectare plots of untouched forest at Danum.

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Ten years later he re-examined them all to see how they had fared. His results showed that the middle-sized trees - which make up 90 per cent of those in the forest - were more tolerant of dryness than the bigger trees in the canopy (the overstorey).

Professor Newbery suggests that these medium trees, which form the forest's understorey, may be a far more valuable part of the dynamics of the forest system than has so far been realised.

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At the moment, the understorey is thought not to contribute to the health of logged forests, and it is thinned out to allow the bigger trees more resources. But in Sabah the natural regeneration of logged forests has been very poor.

"Could it be," asks Professor Newbery, "that the understorey effectively nurses the canopy sapling stand in drought years?" Far from being valueless, it may protect the trees, which will in future grow to be the overstorey, thus helping to stabilise the forest after drought.

Drought is not the only event SEARRP researchers point to as affecting the forest's dynamics. Floods move enormous amounts of sediment in rivers.

One storm at Danum in 1996 moved more sediment along the Segama River in two days than in any of the previous ten years. And in Central Kalimantan, studies of lowland peat have shown that the huge amount of peat burned in the 1997-98 fires released around 1,000 million tonnes of carbon: more than the 980 million tonnes released annually from power stations and vehicles in Western Europe. Taking such extreme events into account, say the scientists, would lead to a more nuanced understanding of forest dynamics and to better management practices in logged forests.

These are under the spotlight as both Malaysia and Indonesia have signed up to Target 2000. This is a scheme sponsored by a United Nations body, the International Tropical Timber Organisation (ITTO), to safeguard the future of the forests and boost the export of tropical timber products from Africa, Asia and Latin America.

Twenty-two exporting countries in these regions have undertaken to have sustainable management in place in their forests by the year 2000, in return for which their produce will be certified by the ITTO for export to environmentally conscious importers.

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Research into climate change suggests that the frequency of extreme droughts and rainstorms will increase. In the face of such forecasts, SEARRP scientists think their understanding of tropical forests could make a real contribution to underpinning sustainable management.