Why do we rarely think about the ecological impact of tropical fruit?
By Dora Clouttick
Whilst many of us may be aware of the social inequalities associated with the international fruit trade, as well as the complex issue of food miles, we may not have thought much about the effect that the tropical fruit trade can have on the planet’s soils.
In a fruit producing plant, nutrients are taken from the soil and combined with sugars produced by the plant and stored in the fruit. This is why fruit is so sought after not only for its taste but also for its nutrition. Those sugars too are partially composed of carbon, taken from the air in the form of CO2, and stored in the fruit.
However the story doesn’t end there as the carbon and many of the nutrients from the fruit are passed on to whomever or whatever has consumed it, be it bird, beast or biped. These elements eventually return to the soil either relatively quickly through the bodily functioning of these varied fruit feasters, or in time with the decomposition of the bodies of those same feasters in death.
This is one of the many ingenious ways that soils are replenished thanks to the clever plants pulling carbon from the atmosphere and creating lush juicy carbon stores that we call fruit. Likewise the nutrients needed to create these coveted treats are returned to the soil, ready for the plants to take them up again, so that the feasts may continue.
So what happens when that fruit is packed up and shipped to another continent? How does the soil regenerate when its nutrients are displaced to far-flung shores? And what about the carbon? And aren’t we forgetting something here? Us clever humans have invented chemical fertilizers. Never mind the lost nutrients, we can make them in a lab! Hurrah, problem solved. Or is it?
For a start chemical fertilizers contribute to climate change, not by emitting CO2, although at production it makes its own healthy contribution to those levels, but through a much less talked about cousin of CO2: nitrous oxide orN2O. This compound is 300 times better at warming our atmosphere than CO2, according to the US Environmental Protection Agency. Here in the UK agriculture is responsible for 84% of all N2O emissions as reported by DEFRA, and those emissions come from fertilizer application.
However, as if that wasn’t bad enough, our succulent, sacchariferous imported tropical fruit does not grow in the UK, it grows in the tropics. Alarmingly, according to research published in 2012 by Edzo Veldkamp a soil scientist from Wageningen Agricultural University, fertilizer application in the tropics actually results in higher levels of N20 production than temperate climates like here in the UK. So we are taking away the nutrients from these ecosystems and then ‘replacing’ them with a substitute that is speeding up climate change and its consequent dangers to us. So not quite so easily solved then?
And what about that carbon? Soil scientists and farmers alike agree that carbon is the most important and largest component of terra firma. According to the Nature Education Knowledge Project, a useful little website, plant converted carbon that is then returned to the soil through decomposition is one of the essential parts of soil carbon ‘contributing greatly to its proper functioning on which human societies depend’.
They also point out that agricultural practices over the past 150 years have depleted soil carbon stocks and advocate that changes in the agricultural management of land could actually pull some of that pesky carbon back out of the atmosphere and go some way to help cool us all down. Bonus!
But how can we return the carbon displaced through international trade? Should we literally be shipping our shit? Or is the amount moved inconsequential? If so will it remain so as our populations increase raising the demand for tropical fruit?
Looking at intercontinental trade in tropical fruit from an ecological perspective means certain resources, in this case carbon and plant nutrients, are being moved from one ecosystem to another and not being replenished. This displacement may be negligible in the grand scheme of things, it may not, but it is another example of how our current lifestyles stress ecosystems rather than support them.
International trade itself is not the problem as ecosystems themselves trade resources intercontinentally through global nutrient cycles. But cycle is the operative word here; in a balanced ecosystem nutrients are returned to sustain the next turn. Our current international trade in fruit seems to be a one-way dump with the flow of resources out of one ecosystem and into another. If we continue like this we are likely to become so top heavy that we might fall over!
For more reports on the issues surrounding fruit production pre-order today the major forthcoming book the Ecologist Guide To Food
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One Response to “Why do we rarely think about the ecological impact of tropical fruit?”
Great article Dora and some interesting points in there. While tropical countries export a lot of their fruit they still import other food and produce from other regions as well so it seems there is a nutrient exchange within the food countries import and export. I am not sure if there is anything unique that tropical fruit take from the soil that other plants don’t so maybe the issue isn’t as much where the nutrients are going but more what we are doing with our waste.
I think we have a separation between our food system and septic systems when really it should be a more connected loop. There is a lot of great plant nutrition in our body waste that we aren’t feeding back into the loop. Phosphorus comes to mind as a main component to life that we let go to waste even when it costs so much to mine and seems to be running out. Hopefully we can work to close the loop and minimize our impact.