Computer simulation shows adding trees to coffee growing land can increase yields

Apr 08, 2014 by Bob Yirka weblog
Coffee Plantation near Sakleshpur. Credit: Wikipedia

( —A computer simulation created and run by a pair of researchers at Humboldt State University, in California shows that coffee growers in Jamaica could improve coffee harvests if they planted trees in some of their cropland. The two, Steven Railsback and Matthew Johnson have published a paper describing their simulation and results in Proceedings of the National Academy of Sciences.

Whether to dedicate land specifically to a single crop (land sparing) versus mixing one crop with others (land sharing) has been a problem farmers (and researchers) have been working on for thousands of years. In this new effort, the researchers at Humboldt looked specifically at the way coffee plants are grown to see if they could figure out a way to improve yields. Most coffee growers tend to dedicate land to coffee plants—experience over the years has shown it to be the most productive. But there is a known problem—the coffee berry borer—a beetle that bores into a coffee berry to lay its eggs, stealing profits from farmers. Railsback and Johnson noted that a certain kind of bird, a warbler, is a predator of the beetles that eat . But, because they have nowhere to roost in land dedicated to coffee growing, they don't offer farmers much help. They wondered what would happen if farmers planted just enough trees among the coffee plants to provide roosting places for the birds—would that cause a decrease in berry borers and thus an increase in harvests? To find out, instead of trekking to Jamaica to talk farmers into giving it a try, the two created a computer model that simulates various bird, beetle and coffee tree environments. Interestingly, they found that if they set the parameters just right, the loss in production due to less land devoted to coffee plants and tree shade, could be more than made up for by less losses due to the berry borer.

The key, the two suggest, lies in the right mix of ingredients—their simulation showed that an increase in production could only be achieved using sun , versus shade , for example. Farmers would also have to plant just the right number of trees, to create small groves, for example, instead of forests.

The next step now will be to see if the findings by the team can be confirmed in a real world setting, i.e. field studies. If they prove successful, that might be enough to cause some to give it a try.

Explore further: Citizen science effort encouraged to track new coffee pest

More information: Effects of land use on bird populations and pest control services on coffee farms, Steven F. Railsback, PNAS, DOI: 10.1073/pnas.1320957111

Global increases in both agriculture and biodiversity awareness raise a key question: Should cropland and biodiversity habitat be separated, or integrated in mixed land uses? Ecosystem services by wildlife make this question more complex. For example, birds benefit agriculture by preying on pest insects, but other habitat is needed to maintain the birds. Resulting land use questions include what areas and arrangements of habitat support sufficient birds to control pests, whether this pest control offsets the reduced cropland, and the comparative benefits of "land sharing" (i.e., mixed cropland and habitat) vs. "land sparing" (i.e., separate areas of intensive agriculture and habitat). Such questions are difficult to answer using field studies alone, so we use a simulation model of Jamaican coffee farms, where songbirds suppress the coffee berry borer (CBB). Simulated birds select habitat and prey in five habitat types: intact forest, trees (including forest fragments), shade coffee, sun coffee, and unsuitable habitat. The trees habitat type appears to be especially important, providing efficient foraging and roosting sites near coffee plots. Small areas of trees (but not forest alone) could support a sufficient number of birds to suppress CBB in sun coffee; the degree to which trees are dispersed within coffee had little effect. In simulations without trees, shade coffee supported sufficient birds to offset its lower yield. High areas of both trees and shade coffee reduced pest control because CBB was less often profitable prey. Because of the pest control service provided by birds, land sharing was predicted to be more beneficial than land sparing in this system.

add to favorites email to friend print save as pdf

Related Stories

Gene found to have jumped from gut bacteria to beetle

Feb 28, 2012

( -- Genes jumping between bacteria are rather common which in part explains their ability to rapidly develop immunity to antibacterial agents. What’s not so common are examples of genes jumping ...

No magic bullet for coffee rust eradication

Jan 22, 2014

Spraying fungicide to kill coffee rust disease, which has ravaged Latin American plantations since late 2012, is an approach that is "doomed to failure," according to University of Michigan ecologists.

How climate-friendly is your cup of coffee?

Jul 03, 2013

Coffee drinkers are encouraged to buy environmentally-friendly coffee, whether it be certified, organic or shade coffee (grown under the shade of trees that are important habitat for birds), but how effective are these ways ...

Recommended for you

China bans ivory carving imports for one year

4 hours ago

Beijing has imposed a one-year ban on the import of ivory carvings, amid international criticism that rapidly-growing Chinese demand could push wild African elephants to extinction within a generation.

Forest tree seeds stored in the Svalbard seed vault

21 hours ago

A new method for the conservation of the genetic diversity of forest trees will see its launch on 26 February 2015, as forest tree seeds are for the first time stored in the Svalbard Global Seed Vault on the Spitsbergen Island, ...

Baby sea turtles starved of oxygen by beach microbes

22 hours ago

On a small stretch of beach at Ostional in Costa Rica, hundreds of thousands of sea turtles nest simultaneously in events known as arribadas. Because there are so many eggs in the sand, nesting females freque ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.