Ecological restoration with biodiversity enrichment in oil palm plantations

Delphine Clara Zemp, Faculty of Forest Sciences and Forest Ecology, University of Göttingen, Göttingen, Germany, Delphine Clara Zemp, Institute of Biology - Faculty of Science, University of Neuchâtel, Neuchâtel, Switzerland, Nathaly Guerrero-Ramirez and Fabian Brambach, Biodiversity, Macroecology and Biogeography, University of Göttingen, Göttingen, Germany, Ingo Grass, Ecology of Tropical Agricultural Systems, University of Hohenheim, Hohenheim, Germany, Isabelle U. W. Arimond, Functional Agrobiodiversity, University of Göttingen, Göttingen, Germany, Johannes Ballauff and Andrea Polle, Forest Botany and Tree Physiology, University of Göttingen, Göttingen, Germany, Hermann Behling, Albrecht-von-Haller Institute of Plant Sciences, University of Göttingen, Göttingen, Germany, Dirk Berkelmann, Department of Genomic and Applied Microbiology, University of Göttingen, Göttingen, Germany, Siria Biagioni, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, Göttingen, Germany, Dylan James Craven, Centre for Ecosystem Modeling and Monitoring, Universidad Mayor, Chile, Rolf Daniel, Genomic and Applied Microbiology, University Goettingen, Goettingen, Germany, Kevin Darras, Crop Sciences, University of Göttingen, Göttingen, Germany, Florian Ellsäßer, Johanna Kückes, Hendrik Lorenz, Alexander Röll and Dirk Hölscher, Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany, Rico Fardiansah, University of Jambi, Jambi, Indonesia, Nina Hennings, Biogeochmistry of Agroecosystems, University of Göttingen, Göttingen, Germany, Bambang Irawan, Faculty of Forestry, University of Jambi, Jambi, Germany, Watit Khokthong, Environmental Science Research Center, Chiang Mai University, Chiang Mai, Thailand, Alena Krause, Valentyna Krashevska, Anton Potapov and Di Ajeng Prameswari, J.F. Blumenbach Institute of Zoology and Anthropology, University of Göttingen, Göttingen, Germany, Kevin Li and Lena Sachsenmaier, University of Göttingen, Göttingen, Germany, Mark Maraun, J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Goettingen, Goettingen, Germany, Miryam Sarah Merk, Chairs of Statistics and Econometrics, University of Göttingen, Göttingen, Germany, Anton Potapov, Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russian Federation, Herni Dwinta Pebrianti, Faculty of Forestry, University of Jambi, Jambi, Indonesia, Stefan Scheu, JFB-Institute for Zoology and Anthropology, Georg-August University, Goettingen, Germany, Dominik Schneider, Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, University of Göttingen, Göttingen, Germany, Fitta Setiajiati and Leti Sundawati, Department of Forest Management, IPB University, Bogor, Indonesia, Christina Ani Setyaningsih, Department of Palynology and Climate Dynamics, University of Göttingen, Göttingen, Germany, Teja Tscharntke, Agroecology, University of Göttingen, Göttingen, Germany, Meike Wollni, Environmental and Resource Economics, University of Göttingen, Göttingen, Germany, Holger Kreft, Biodiversity, Macroecology & Biogeography, Georg-August University, Goettingen, Germany

Background/Question/Methods
Widespread expansion of monocultural oil palm plantations have led to dramatic losses of biodiversity and ecosystem functioning in the lowland tropics. Establishing islands of native trees may alleviate negative ecological impacts, but scientific evidence of the potential positive effects and trade-offs of tree diversity enrichment is still lacking. Here, we assess restoration success in a biodiversity enrichment experiment where 52 tree islands of systematically varying sizes and levels of tree diversity were established in an oil palm plantation. We measured biodiversity of 15 taxonomic groups from soil microbes to birds, and 19 ecosystem functions representing a range of services.
Results/Conclusions
Compared to conventionally managed controls, the tree islands hosted a higher species diversity of trees, birds and soil fauna, and a lower diversity of pathotrophic fungi and seed rain. Planted tree diversity and island size affected multi-diversity and ecosystem functions directly and indirectly, mediated by changes in vegetation structure. Tree diversity enhanced structural complexity and density, which increased productivity, nutrient cycling, pollination and multi-diversity. Through increased tree dominance, larger tree islands hosted more abundant and species-rich communities of several groups. Trade-offs with oil palm yield existed locally but were minimized at the tree island scale, when considering positive effect on the yield on the surrounding oil palm plantation. We provided the first empirical evidence of ecological restoration in oil palm plantations, and showed that in some configurations biodiversity and ecosystem functioning can be enhanced without losing yield.