A SCOTTISH expert has warned of an impending worldwide rubber shortage driven by insatiable demand for the finite resource and the lack of an adequate man-made substitute.

A team including lead researcher Antje Ahrends from the Royal Botanic Garden Edinburgh and the World Agroforestry Centre has unveiled milestone research amid warnings that more than half of the main source of the critical plant is set to die out because of poor farming methods.

The research, partly funded by the Scottish Government, found that the expansion of rubber outside its comfort zone is equally bad for people as for nature and a "loss-loss" scenario.

Ms Arhends said: "We estimate that 57 per cent of plantations in continental south east Asia may not be sustainable.

"There is widespread evidence for plantation failures, with severe economic impacts."

Hevea brasiliensis, the para-rubber tree, is the major source of natural rubber for the global annual production of more than a billion car, truck and aircraft tyres.

However, the scientists are calling for better rubber management methods and policy in China, Vietnam, Thailand and Laos, among others.

They say increasing amounts of environmentally valuable and protected land are being cleared for rubber plantations that are economically unsustainable, and more widespread monitoring is vital to design policy that protects livelihoods and environments.

The research was published in Global Environmental Change and constitutes a joint effort by scientists at the World Agroforestry Centre (ICRAF) East and Central Asia office, the Chinese Academy of Sciences, the Royal Botanic Garden Edinburgh, the University of Singapore and the East-West Center.

Although global natural rubber prices have fluctuated strongly in the last 15 years, they are likely to continue rising as synthetic alternatives are no match for natural latex.

This financial incentive, as well as the expansion of oil palm, an even more lucrative rival, has caused rubber plantations to expand beyond their tropical comfort zone in Indonesia and into the margins of continental south-east Asia.

This has brought wealth to some, but not all, say the researchers. As marginal lands are often too dry, too slanted, too high, too wet, too cold, too windy, rubber plantations require increasing amounts of input in the form of fertiliser, pesticides, and labour in order to maintain yield levels – and even then may not be profitable.

The research also suggests that climate change will render 70 per cent of current and another 55 per cent of future plantation areas environmentally poorly suited for rubber.

Smallholder farmers’ livelihoods face additional threat from price fluctuations, loss of food security, and the narrowing of income sources.

The environment also suffers. The surge in rubber demand saw valuable and even protected lands being converted into rubber plantations, drastically reducing carbon stocks, soil productivity, water availability, and biodiversity. This is particularly tragic given the high chance of failure, it is claimed.

Ms Ahrends said: "There is clear potential for loss-loss scenarios when forest is being cleared for rubber plantations that are not economically sustainable, and that have negative impacts on soils and water balance."

The team argues that carefully formulated payment for ecosystem services programmes, and a certification scheme for “environmentally friendly rubber” have potential to reduce the environmental impact of rubber expansion while ensuring the supply.

Meine Van Noordwijk, chief science advisor at the World Agroforestry Centre, which has its global headquarters in Nairobi, Kenya, said: “Oil palm has received much more global attention than rubber, but in fact environmental and social impacts are comparable and the dynamics of the two are related.

"It may be time for a roundtable on sustainable rubber where the private sector, public parties and scientists can try to bridge the various interests and agree on standards."

This research into rubber in the Mekong region is funded by the German Federal Ministry for Economic Cooperation and Development (BMZ) and the German Corporation for International Cooperation (GIZ) under a grant to ICRAF, as well as by the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS).