We first identified areas that are suitable for rubber, by developing a model of global climatic suitability for the species based on its natural distribution. The areas you see in red have climates that are particularly suitable for the crop, and the areas in blue and grey are less suitable. As you can see the model suggests that mainland South East Asia does not actually have a lot of optimal rubber growing space.
Zooming into the area it is evident that the vast majority of rubber plantations, which are the black dots here, are located in potentially sub-optimal environments. As much as 90% of the plantations are located in non-traditional habitat. In many of these areas rubber seems to be performing fine at the moment and to be lucrative at current price levels, but this does not necessarily equate to long-term sustainability.
For instance, almost 4,000 km2 are located in areas where there are frequent extreme events such as prolonged frost or typhoons
We have been trawling for evidence for plantation performance in relation to these risk zones. This has never been systematically captured before and reports on rubber performance are scattered in local newspapers. The challenge has thus been go to beyond the anecdotal to systematically collated information from news sources.We found many of examples of significant plantation damage due to frost or wind over the past ten years. For example, the tree trunks snap easily at already moderate windspeeds. In the last half year alone farmers in Vietnam have lost plantations worth over 250 mio US$ due to typhoons. Restoration or recovery of such damage takes 3-7 years, which means that there are lengthy income lags. This poses a significant economic risk to small-holders if rubber constitutes their sole income source.
Furthermore, over 6,300 km2 of plantations are located above 900 m altitude or on steep slopes.
In these locations rubber production is no longer deemed economically viable, even at record price levels. Furthermore, significant land degradation may occur due to erosion and stream sedimentation and there is an increased risk of landslides. It is likely that plantations in these locations will ultimately be abandoned, and countries such as China have begun to try to re-convert the rubber plantations in these areas to forest.
Yet another 3,300 km2 of plantations are located in areas characterised by low rainfall and a long dry season.
Here rubber trees will take longer to reach maturity, yields are generally lower and the harvesting period is shorter – thus, rubber prices need to remain sufficiently high to render the plantations economically viable. Furthermore, we found evidence for high levels of tree mortality in relation to regularly occurring droughts in these areas. It has also been suggested that dry stress increases the susceptibility of rubber trees to diseases such as powdery mildew. Thus, small-holders are again exposed to a great economic risk. Another major concern is that the first evidence that is becoming available now on longer-term impacts of rubber on these areas suggests that large-scale planting of rubber drought-prone areas may result in the depletion of ground-water.
This is the situation now. In the future as the climate will get warmer the risk of frost damage will decrease, but overall marginality increases as the climate gets more seasonal. The amount of rainfall in the wet season and the frequency of heavy precipitation events are expected to increase, which in turn means that rubber at slopes will be more vulnerable to top-soil erosion and landslides. There will also be an increased risk of drought for large parts of the dry zone, and the frequency and severity of tropical storms is predicted to increase.
Economic forecasts predict that the global rubber consumption will continue to increase by 2-3% per year. At the same time the available stocks are likely to decrease relative to demand levels, which means that rubber prices are likely to remain high or even increase.Synthetic rubber does not yet match the performance of natural rubber and the production price (which is tightly coupled with the crude oil price) is high. Therefore, although the production of synthetic rubber has increased, it is currently not a viable alternative for natural rubber.
1. Risky economics of rubber
Ahrends, A., Hollingsworth, P. M., Ziegler, A., Fox, J., Chen, H., Su, Y., Xu, J.
2. Expanding rubber plantations
• Natural rubber (Hevea brasiliensis) major source of world’s rubber for
high pressure applications.
• Used in manufacture of >1 billion tyres per year.
• Rubber prices have tripled in the last decade (Chinese car industry).
rubber production globally has increased by 50% since 2000
rapid land use conversion to rubber in SE Asia (supplies 97%)
At 1 US$/kg
Source: index mundi
3. credit: Science 2009 324:1024
Nature 2009 457:246
credit: Science 2009 324:1024
Rubber plantations Xishuangbanna, China, 2010
>20,000 km2 have been converted to mono-culture rubber in mainland SE
Asia (5,000 km2 forest)
4. Environmental/social implications
• Often planted by small-holders brought wealth to impoverished areas.
• Dependence global markets of small-scale farmers. Less food security?
• Clearance of primary and secondary forest (biodiversity, carbon).
• Rubber pulls water from sub-soils in dry season groundwater reserves.
• Heavy use of fertilisers and pesticides water contamination.
Xishuangbanna, China 2013
Laos 2009 (Mongabay)
5. Rapid and large-scale land conversion to rubber all over mainland SE Asia in
areas previously regarded as unsuitable for rubber consequences?
No systematically collated evidence whether rubber can tolerate marginal
environments (long-term) or whether there is a concern.
1. Quantify extent to which plantations have moved in marginal areas.
2. Tease out the different types of risks and establish whether there is
evidence for poor plantation performance in relation to these risks.
Provide region-wide overview and much needed information to guide
management and policy.
Xishuangbanna, China (Google Earth Jan 2013)
6. Global bioclimatic model of suitability for rubber
(based on the natural distribution of H. brasiliensis)
7. Spread into non-traditionally suitable habitats
space is becoming scarce.
90% of plantations are now
located in non-traditional
In many of these areas
currently performing fine
Environmental suitability equate to longnecessarily
8. 63% of plantations now situated in risk zones
>3,800 km2 in
9. Recent examples of storm and frost damages
• Loss of plantations worth US$250 Mio in Vietnam due to typhoons Wutip
and Nari (Sep-Oct 2013); additional loss due to Haiyan (Nov 2013).
• Cold weather kills 95% plantations in 4 Provinces in Vietnam in 2010.
• Freezing hazard in China causes major damage to plantations in 2008.
• A typhoon causes devastating plantation loss in Hainan, China in 2005.
10. 63% of plantations now situated in risk zones
>3,800 km2 in
>6,300 km2 at
>900 m altitude or
on slopes >24⁰
11. Risks at high altitudes and steep slopes
• Plantations >900 m and/or slopes >24⁰ not deemed economically viable1.
• Soil compaction, erosion, stream sedimentation, risk of landslides
(e.g. hazardous landslide southern Thailand 1988)2.
small-scale farmers may be left with degraded land.
Rubber plantation on slope
Natural forest on slope
(1) Yi et al. 2014. Ecol. Indicators 36: 788-797
(2) Li et al. 2012Environmental Management 50: 837-848
12. 63% of plantations now situated in risk zones
>3,800 km2 in
>6,300 km2 at
>900 m altitude or
on slopes >24⁰
>3,300 km2 in dry
13. Risks in dry zones
• Reduced yield, and no yield during the dry season (up to 5-6 months).
• Loss of US$26 Mio plantations in Xishuangbanna, China in drought 2010.
• Mortality of trees up to 50% in dry provinces in NE Thailand.
• 24% reduction in yield in Hainan, China during drought in 2005.
• Plantations may deplete ground water.
Rubber in dry season, Phitsanulok, Thailand
Yunnan, China 2010
14. Net exacerbation of marginality with future
39 models (CMIP Phase 5) across RCPs 2.6, 4.5, 6.0, 8.5 for 2050
• Temperature increase in 100% of rubber area (decreased frost risk).
• Generally seasonality will increase.
Increased rainfall wet season in 96-100% of area erosion/landslides
Increased risk of drought for 43-77% plantations in dry zone
• The number and severity of typhoons may increase.
Landslide SW China (www.news.cn)
Yunnan, China 2010
Typhoon Haiyan (Karen Nyberg, ISS)
15. Global consumption expected to increase
Regional rubber consumption
• Consumption increase 2-3% yr-1.
• Available stocks likely to
decrease relative to demand.
Rubber prices likely to remain
Natural vs. synthetic rubber
• Synthetic rubber does not
• Production price high (coupled
with Crude Oil price).
No immediate alternatives.
The Rubber Economist Ltd. Quarterly Report (2013)
1. Increasing demand for rubber will continue to lead to land conversion.
2. Conversion to cash-crops is the main driver of forest loss in SE Asia.
Plantations increasingly in areas with potential environmental risks.
3. Possibility for worst-case “loss-loss” scenarios: conversion of highbiodiversity value land to mono-culture plantations which yield shortterm returns before becoming degraded and abandoned.
4. Study highlights urgent need for systematic monitoring of plantation
losses. Policy interventions and agro-forestry practices (intercropping)
may be necessary to avoid loss-loss scenarios, and to reduce exposure
of small-holders to economic risks.