Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification

doi:10.1073/pnas.0608409104

Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification

^aDepartment of Agroecology, Georg-August-Universität Göttingen, Waldweg 26, 37073 Göttingen, Germany;
^dAlbrecht von Haller Institute of Plant Sciences, Georg-August-Universität Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany;
^eDepartment of Agricultural Economics, Georg-August-Universität Göttingen, Platz der Göttinger Sieben 5, D-37073 Göttingen, Germany;
^gFaculty of Agriculture, Department of Plant Protection, Bogor Agricultural University, Jalan Padjajaran, 16144 Bogor, Indonesia;
^hInstitute of Geography, Georg-August-Universität Göttingen, Goldschmidtstrasse 5, 37077 Göttingen, Germany;
ⁱFaculty of Biology, Bogor Agricultural University, Jalan Padjajaran, 16144 Bogor, Indonesia;
^jLICOS Centre for Institutions and Economic Performance, Faculty of Economics and Applied Economics, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium;
^kInstitute of Zoology and Anthropology, Georg-August-Universität Göttingen, Berliner Strasse 28, 37073 Göttingen, Germany;
^lFaculty of Agriculture, Tadulako University, Palu 94118, Indonesia; and
^mInstitute of Rural Development, Georg-August-Universität Göttingen, Waldweg 26, 37073 Göttingen, Germany

Edited by Monica G. Turner, University of Wisconsin, Madison, WI, and approved January 17, 2007 (received for review September 23, 2006)

Abstract

Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. Here, we evaluate opposing land use strategies in cacao agroforestry in Sulawesi, Indonesia, by using data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Expansion of cacao cultivation by 230% in the last two decades was triggered not only by economic market mechanisms, but also by rarely considered cultural factors. Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by ≈75% and species richness of forest-using species by ≈60%. In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income. However, unshaded systems further increased income by ≈40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk. We conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends.

Footnotes

^cTo whom correspondence may be addressed. E-mail: ingolf.steffan{at}uni-bayreuth.de, mkessle2{at}gwdg.de, or jbarkma{at}gwdg.de
Author contributions: I.S.-D., M. Kessler, J.B., D.B., S.E., H.F., G.G., S.R.G., E.G., D.H., M. Kappas, C.L., R.M., S.M.-K., M.S., S.S., M.Z., and T.T. designed research; M.M.B., S.E., H.F., K.G., M.H., P.H., S.K., M.M., J.M., R.P., S.G.S., A.S., S.S.T., S.T., A.T., R.W., and L.W. performed research; I.S.-D., M. Kessler, J.B., S.E., H.F., K.G., M.H., D.H., P.H., S.K., M.M., S.M.-K., S.S., S.G.S., A.T., and R.W. analyzed data; and I.S.-D., M. Kessler, and J.B. wrote the paper.
↵ ^bPresent address: Department of Animal Ecology I, Population Ecology, University of Bayreuth, 95440 Bayreuth, Germany.
↵ ^fPresent address: Natural History Museum Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany.
↵ ⁿPresent address: Institute of Agricultural Economics and Social Sciences in the Tropics and Subtropics, University of Hohenheim, 70593 Stuttgart, Germany.
The authors declare no conflict of interest.
This article is a PNAS direct submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0608409104/DC1.