Press release: Birds and bats increase cacao crop yield in Indonesia

Nr. 210/2013 - 06.11.2013

Göttingen agricultural ecologists study economic impact of natural pest control

(pug) The presence of birds and bats on cacao plantations positively impacts cacao crop yields. This is what scientists from the University of Göttingen found in the large-scale exclosure field experiment they conducted on the Indonesian island of Sulawesi. The agricultural ecologists prevented birds and bats from obtaining access to certain cacao trees. As a result, the number of insects on the plantations increased and the affected trees produced up to 31 per cent less yield. The investigations took place over a period of 15 months on one of the largest cacao agroforestry areas in the world. The results were published in the scientific journal Ecology Letters.

Especially in tropical regions, which feature some of the world's greatest species biodiversity, natural pest control has been a previously little understood and hardly used service. The increasing demand for land use is the primary cause for the decline in these species-rich and natural habitats. "That is why we urgently need alternative approaches and improved management to be able to farm these agroforestry landscapes more effectively and sustainably," explains the Göttingen agricultural ecologist Bea Maas. "The presence of birds and bats increased yields for small farmers valued at US$ 730 per year and hectare arable land. With certainty, targeted management will let us increase this effect even further."

The scientists are therefore appealing for land utilisation measures that contribute to greater structural biodiversity in the agroforestry regions. "A better distribution and selection of shade cover trees, indispensable in cacao cultivation, would lead to an improved supply of nesting places and nutrition for birds and bats," elucidates Professor Teja Tscharntke, Head of the Agroecology Department at Göttingen University. "If natural pest control achieved by birds and bats were considered during cultivation, then this would not only benefit the small farmers, but also help in biodiversity conservation."

Original publication: Bea Maas et al. Bats and birds increase crop yield in tropical agroforestry landscapes. Ecology Letters 2013. Doi: 10.111/ele.12194.

Contact address:
Bea Maas
Georg-August-Universität Göttingen
Faculty of Agricultural Sciences
Department of Crop Sciences – Agroecology
Grisebachstrasse 6, 37077 Göttingen, Germany, phone (0551) 39-22157
E-mail: beamaas@gmx.at
website: www.uni-goettingen.de/en/74726.html