A topical, tropical time bomb

Deforesting our lungs WWF

Based on a recent article by Laurence, Sayer and Cassman about
“Agricultural expansion and its impacts on tropical nature”

The world is currently hurtling along in an attempt to be bigger, better, faster and wealthier than ever before. However, if we carry on at the rate we’re going, we’ll have to convert an area the size of Canada into cropland by 2050.

By 2011 the world’s population exceeded 7 billion and it is expected that we will reach 11 billion by the end of this century. With this exponential growth comes the ever increasing demand for fuel and food and of course the land to produce them on.

As the price of oil skyrockets, so do food prices – driving increasing efforts to produce cheaper sources of fuel. 


Bio-fuels are made by converting organic matter produced by living organisms into convenient energy containing substances. For example, one can produce bioethanol by fermenting starch rich crops and extracting the alcohol. Bio-fuels are a potential solution to our looming energy crisis, as while coal and oil take geological time to produce, crops grow comparatively instantly and are therefore ‘renewable’.

The best place to grow crops for these bio-fuels is in the tropics. The tropics are warm and wet all year round, ideal for encouraging growth, not to mention that land is a fraction of the price compared to land in developed countries. However, the tropics are home to rain forests and are hot-spots of biodiversity. Many of the species living in these forests are endemic and endangered.

The diversity we stand to lose due to forest clearing is phenomenal, let alone the species we are yet to discover.


Tropical biodiversity: (A) tree pangolin from Gabon; (B) tree fern from north Queensland; (C) Corybas orchid from Papua New Guinea; (D) gold dove from Fiji; (E) caterpillar from Suriname.

Bio-fuel production takes a lot of space. Huge plantations take the place of natural forest leaving a monoculture of soybean, oil-palm or the like.


Deforestation for plantations: (A) industrial oil palm plantation in Sumatra, Indonesia; (B) clearing of native forest for industrial wood-pulp production in Sumatra; (C) small-scale farmers in Gabon; (D) aftermath of slash-and-burn farming in the central Amazon.

Clearing large tracts of land poses challenges to conservation as it causes fragmentation and isolation of forest patches. Forest species need migration and dispersal corridors to ensure their survival and maintain genetic diversity. Modified land is not useless to conservation, however. It provides important foraging land and stepping stones to other forest patches. The challenge to conservation is when this modified land in between healthy forest patches is overly transformed or too large. Perhaps an important study would be to determine the threshold size and quality where species stop being able to cross modified land.

The argued solution is to intensify farming practices on already modified land. Increasing the productivity of each hectare should in theory decrease the spread into surrounding hectares. To satisfy the demand for food and fuel there is a ‘yield-gap’ which needs to be filled. Laurence, Sayer and Cassman offer advanced farming technologies as the mechanism to fill this gap.

These technologies should provide better pest management, crop rotation and crop-specific fertilisers among others. Studies have also found that 10-40% of produce in developing countries is lost after harvest, during storage and transport. Improved facilities and refrigerated-transportation could decrease food wastage dramatically.

Genetically modified crops are another possible solution. Plants can be bred to produce greater proportions of protein or to be pest and drought resistant and so contribute to closing the yield-gap.

The problem here is that the poorer farmers do not have access to these improved technologies and simply taking over the landscape with big corporations and their fancy equipment will only open a Pandora’s box of  further problems. Tropical farmers also cannot afford to buy new seeds each year which is often the case with genetically modified crops which are only viable for one season.

Too much fertilizer can also cause problems though. Excess nitrogen causes eutrophication in rivers and has knock on effects to the health of surrounding ecosystems.

What is the solution then?


If I knew, I would probably be the next Wangari Maathai, but for now I can only say that perhaps it is a delicate combination of all the possible solutions that will be the answer.

Perhaps well-managed, multi-use landscapes can be compatible with conservation while still providing food and fuel for a growing world. Perhaps Eco-certification, incentives for good practice and subsidies for technology will help to get us there.

The important thing is that environmental strategies must be in line with current political, economic and social reality. There is no one size which fits all solution that we can enforce across the tropical board. The problems experienced by oil-palm farmers in Sumatra will be different to those faced by sorghum farmers in the Congo.

The main issue is still, how do we fill the yield-gap? I think we need to tackle the gap from both sides. Be less greedy to decrease demand to make the gap smaller and then be intensive instead of extensive to decrease the spread of cropland and destruction of rain forests.

We also better be investing in perfecting harnessing other forms of renewable energy. Solar power is not cheap enough yet to replace coal and oil. Once we can harness and store solar power, there will be no need for growing crops for biofuel. We also better be thinking out the box. Imagine we could irrigate the Sahara desert with desalinated sea water. That would certainly take the pressure off the tropics.

Ultimately we  need to do something NOW to prevent the topical, tropical time bomb from exploding in our faces.


Laurence, W.F., Sayer, J. and Cassman, K.G. (2014) Agricultural expansion and its impacts on tropical nature. Trends in Ecology and Evolution. 29(2):107-116.



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