A lot of coffee is grown on and around Kilimanjaro, which towers almost 20,000 feet in the air.
The most traditional form of cultivation can be found in the gardens of the Chagga people. In some areas, coffee trees and other crop plants still grow in the shade of banana trees but most coffee is grown on plantations, which still feature a large number of shade trees.
However, Africans reliant on coffee for income have gradually replaced legacy coffee varietals, which prefer shade, with others that are more resistant to fungi and can also grow in the sun.
Yet the coffee may not be better overall, says Professor Ingolf Steffan-Dewenter, a tropical ecologist at the University of Würzburg's Biocenter, because without shade trees, the animal species that pollinate the coffee and eat pests may leave, leading to lesser yield. Bees, birds and bats make a huge contribution to the high yields produced by coffee farmers around Mount Kilimanjaro, according to a new paper.
The aim was to find out whether and how intensified farming can affect the ecosystem. Working with the Biodiversity and Climate Research Centre and the Institute of Experimental Ecology at the University of Ulm, the team conducted experiments in twelve areas on the slopes of Mount Kilimanjaro in Tanzania, located in all three cultivation systems (Chagga gardens, shade plantations and sun plantations).
They used finely woven nets to prevent animals’ access to the coffee flowers or even to entire coffee trees. Then they examined how the presence or absence of the “animal service providers” affects the quantity and quality of the harvest.
If birds and bats are prevented by a net from feeding on pests on coffee trees, this owers the yield. © A. Classen
They found that where birds and bats had access to the plants, there was almost a ten percent higher fruit set. “We believe that this is due to the fact that the animals eliminate pests that would otherwise feed on the coffee plants” says co-author Julia Schmack (BiK-F, Frankfurt). Reduced leaf damage is supposed to reduce the number of coffee cherries falling from the tree while ripening.
The pollination experiments showed that where bees and other insects, which should be redundant since Coffea arabica is self-pollinating, were evident, the cherries were about seven percent heavier, which contributes to a higher coffee quality.
“So, the effects of pollination and pest control complement each other perfectly; both are important for higher yields,” says Steffan-Dewenter: “Birds and bats provide more cherries; bees and other pollinators ensure better quality.”
Same effect with all cultivation systems
To the surprise of the researchers, intensified farming seems to have no negative effect: the impact of the animal provided services on the harvest was equally good in all three cultivation systems, even in the unshaded plantations.
“We put this down to the mosaic landscape structure on Mount Kilimanjaro with its gardens, forests and grasslands,” says doctoral student, Alice Classen.
Given that much of the landscape is divided into small parcels, pollinators, birds and bats still could find a suitable habitat with nesting places, and from there spread into the plantations.
“However, it is likely that these seemingly stable ecosystem services rest on shaky foundations in the sun plantations,” believe the authors, due to the fact that they registered merely one type of visitor, honey bees, to the blossoms. On the coffee blossoms in the Chagga gardens, however, they additionally recorded wild bees, hoverflies and butterflies.
So if honey bee numbers were to decrease, as they might in climatically unfavorable years, this could reduce the harvest in the sun plantations.
Citation: Classen, A, Peters, MK, Ferger, SW, Helbig-Bonitz, M, , Maassen, G, Schleuning, M, Kalko, EKV, Böhning-Gaese, K&I Steffan-Dewenter (2014): Complementary ecosystem services provided by pest predators and pollinators increase quantity and quality of coffee yields.” Proceedings of the Royal Society B, 10.1098/rspb.2013.3148
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Researchers Created A Laser Bullet To See What It Would Look Like - And Here It Is
- Will Holding Thermal Printer Paper Really Send Your BPA Levels Soaring?
- The Quote Of The Week - Shocked And Disappointed
- As The Weather Changes, So Do Beliefs About Climate Change
- Limiting Global Warming To 2°C: The Philosophy And The Science
- ECFA Workshop: Planning For The High Luminosity LHC
- Great Earthquakes Doubled In The Most Recent 10 Year Period - What That Means
- "I have no time for you. Either learn how to have a decent, mature conversation without resorting..."
- "The past 12 months—October 2013–September 2014—was the warmest 12-month period among all..."
- "Do you really think science20 readers are all so stupid that they are going to fall for Climate..."
- "'Mememine' is a well known astro-turfer for the denial industry. He spams the same identical gish..."
- "I have heard (from someone who worked there) of a laboratory in a country far, far away where they..."
- National Wildlife Refuge System bans on GMOs and neonics lack transparency, scientific rationale
- Want better sperm? Eat more pesticides
- Beyond universal donors, some people are programed with no blood type at all
- Anti-conventional ag movement spurs Big Ag to look to organic pesticides
- Can people really inherit memories?
- An end to fat shaming? The 50 year DNA mystery of metabolic dysfunction may soon be solved
- New policymaking tool for shift to renewable energy
- Teens whose parents exert more psychological control have trouble with closeness, independence
- Two days later: Adolescents' conflicts with family spill over to school, vice versa
- Children in high-quality early childhood education are buffered from changes in family income
- 'Breath test' shows promise for diagnosing fungal pneumonia