Risky rubber plantations: a lose-lose scenario

Manufacturers make more than a billion tires every year from natural rubber, much of which comes from a plant called the para-rubber tree. Rubber plantations have spread through southeast Asia, including areas rich in biodiversity. Now a new analysis suggests that this rapid growth at the expense of environmental protection may not even pay off economically. Many new plantations are located in areas ill-suited for growing rubber trees, and the sites could become even less productive with climate change.

“Overall, expansion into marginal areas creates potential for loss-loss scenarios: clearing of high-biodiversity value land for economically unsustainable plantations that are poorly adapted to local conditions,” the authors write in Global Environmental Change.

The team studied records of wild para-rubber trees to determine which climate- and landscape-related factors were important for the species’ growth. The researchers also searched reports, news stories, and scientific papers for clues to how environmental variables affect rubber tree yields and survival. Then they analyzed maps of rubber plantations in Laos, Cambodia, and parts of China, Vietnam, Thailand, and Myanmar to find out whether the sites were suitable for rubber production.

The original rubber tree species is sensitive to frost, needs more than 60 millimeters of rain per month for at least half the year, and can’t tolerate winds of more than 4 to 5 meters per second, the team reports. Plantations established from 2005 to 2010 have appeared mainly in zones that the authors call “sub-optimal” because of stresses such as increased frost, steeper terrain, and fewer rainy months. The researchers estimate that 72 percent of plantations are in these sub-optimal areas, and more than half are in risky areas where growth may not be sustainable.

While people have bred tougher versions of the rubber tree, the improvements might not be enough to make plantations sustainable, the authors say. And climate change could bring new challenges, such as more droughts and storms.

The researchers also found sobering trends when they looked at the types of land converted to rubber plantations during the study period. About 2,500 square kilometers was originally natural forest, 610 square kilometers was in protected areas, and 1,624 square kilometers encroached on conservation corridors that link habitat. Many southeast Asian countries plan to continue expanding rubber plantations into forests and high-biodiversity spots — a loss for flora, fauna, and perhaps farmers as well. Roberta Kwok | 9 July 2015

Source: Ahrends, A. et al. 2015. Current trends of rubber plantation expansions may threaten biodiversity and livelihoods. Global Environmental Change doi: 10.1016/j.gloenvcha.2015.06.002.

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