The first decade of the new millennium saw a boom in rubber prices. This led to rapid and widespread
land conversion to monoculture rubber plantations in continental SE Asia, where natural rubber
production has increased >50% since 2000. Here, we analyze the subsequent spread of rubber between
2005 and 2010 in combination with environmental data and reports on rubber plantation
performance. We show that rubber has been planted into increasingly sub-optimal environments.
Currently, 72% of plantation area is in environmentally marginal zones where reduced yields are
likely. An estimated 57% of the area is susceptible to insufficient water availability, erosion, frost, or
wind damage, all of which may make long-term rubber production unsustainable. In 2013 typhoons
destroyed plantations worth US$ >250 million in Vietnam alone, and future climate change is likely to
lead to a net exacerbation of environmental marginality for both current and predicted future rubber
plantation area. New rubber plantations are also frequently placed on lands that are important for
biodiversity conservation and ecological functions. For example, between 2005 and 2010 >2500 km2
of natural tree cover and 610 km2 of protected areas were converted to plantations. 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 and alter
landscape functions (e.g. hydrology, erosion) – ultimately compromising livelihoods, particularly
when rubber prices fall.