Rainforest transformation into agricultural lands: current and future challenges

• INT42 • Biodiversity and connectivity in fragmented rainforest landscapes > J. Jane HILL
Content : Many tropical rainforests have been converted to agriculture to feed a growing human population and support local livelihoods. In SE Asia, tropical forests support many iconic animal and plant species which have been impacted by the conversion of forest to oil palm, and concerns for biodiversity in these fragmented forest landscapes have led the Roundtable on Sustainable Oil Palm (RSPO) to develop sustainability standards for oil palm cultivation. For example, RSPO members are required to conserve patches of forest with High Conservation Values and High Carbon Stocks. I am a member of the SEnSOR project (www.sensorproject.net) which is testing the environmental impacts of RSPO certification, and I will discuss how the size, placement and quality of forest patches affects species richness (e.g. forest patches >200ha core area support 60-70% of forest species) and carbon stocks. In addition, local species richness of forest patches is affected by the amount of forest in the wider landscape, which also affects connectivity. These findings raise research challenges about how to conserve and restore biodiversity in oil palm landscapes, as well as wider issues about the transformation of rainforest landscapes and trade-offs between crop yield, management, biodiversity and ecosystem functioning. • INT43 • Implementing a large-scale assessment of biodiversity and ecological functions in human-modified tropical landscapes > F. Fabian BRAMBACH
Content : Fabian Brambach1, Co-authors (preliminary, in alphabetical order): Ashehad Ali1, Damayanti Buchori2, Carina Carneiro de Melo Moura1, Kevin Darras1, Jochen Drescher1, Stefan Erasmi1, Sebastian Fiedler1, Ingo Grass1, Dirk Hölscher1, Alexander Knohl1, Martyna Kotowska1, Valentyna Krasehvska1, Holger Kreft1, Anton Potapov1, Michael Schlund1, Kibrom T. Sibhatu1, Christian Stiegler1, Sri Sudarmiyati Tjitrosoedirdjo2, Aien Tjoa3, Teja Tscharnke1, Arne Wenzel1, Kerstin Wiegand1, Catrin Westphal1
1 Georg-August-University of Göttingen, Göttingen, Germany
2 Bogor Agricultural University (IPB), Bogor, Indonesia
3 Jambi University, Jambi, Sumatra, Indonesia

Tropical land-use change, the conversion of rain forest into agricultural production systems, is causing major socioeconomic changes, often leading to improved livelihoods for multiple local stakeholders. At the same time, this change leads to profound and mostly negative effects on biodiversity and ecological functions, putting the long-term sustainability of human-modified tropical landscapes in question. To design sustainable landscapes, a detailed understanding of the effects of land-use change on biodiversity, ecological functions, and human livelihoods is necessary. While these effects have been comparatively well-explored for single taxa and functions at local scales, integrated patterns at the landscape-scale are still largely unknown. The Landscape Assessment of CRC990 EFForTS, a long-term Indonesian-German research collaboration, aims to fill this knowledge gap by combining plot-based rapid assessment of multiple taxa and functions with remote sensing and socioeconomic surveys across different land-uses in the province of Jambi, Sumatra, Indonesia. The talk covers the rationale for conducting this landscape-scale study, gives an overview of the employed methods, discusses challenges in the implementation of the fieldwork during the Covid-19 pandemic, identifies valuable lessons learned during the process and presents preliminary results. • INT44 • Win-win opportunities combining high yields with high multi-taxa biodiversity in tropical agroforestry > A. Annemarie WURZ
Content : Annemarie Wurz1,2, Teja Tscharntke1,3, Dominic Andreas Martin4,5, Kristina Osen6, Anjaharinony A. N. A. Rakotomalala1,7 , Estelle Raveloaritiana1,8, Fanilo Andrianisaina9, Saskia Dröge4,10, Thio Rosin Fulgence4,11,12, Marie Rolande Soazafy6,12,13, Rouvah Andriafanomezantsoa11, Aristide Andrianarimisa11, Fenohaja Soavita Babarezoto14, Jan Barkmann15, Hendrik Hänke15, Dirk Hölscher6,3, Holger Kreft4,3, Bakolimalala Rakouth8, Nathaly R. Guerrero-Ramírez4, Hery Lisy Tiana Ranarijaona13, Romual Randriamanantena12, Fanomezana Mihaja Ratsoavina11, Lala Harivelo Raveloson7 and Ingo Grass16
1 Agroecology, University of Göttingen, Grisebachstr. 6, 37077 Göttingen, Germany
2 Conservation Ecology, Department of Biology, Philipps-University Marburg, Marburg, Germany
3 Centre for Biodiversity and Sustainable Land Use (CBL), University of Göttingen, Büsgenweg 1, 37077 Göttingen, Germany
4 Biodiversity, Macroecology and Biogeography, University of Göttingen, Büsgenweg 1, 37077 Göttingen, Germany
5 Department of Geography, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
6 Tropical Silviculture and Forest Ecology, University of Göttingen, Büsgenweg 1, 37077 Göttingen, Germany
7 Entomology Department, Faculty of Science University of Antananarivo, PO Box 906, Antananarivo 101, Madagascar
8 Plant Biology and Ecology Department, University of Antananarivo, Antananarivo, Madagascar
9 Department of Tropical Agriculture and Sustainable Development, Higher School of Agronomic Sciences, University of Antananarivo, Madagascar
10 Division of Forest, Nature and Landscape, KU Leuven, Leuven, Belgium
11 Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Madagascar
12 Natural and Environmental Sciences, Regional University Centre of the SAVA Region (CURSA), Antalaha, Madagascar
13 Doctoral School of Natural Ecosystems (EDEN), University of Mahajanga, Mahajanga, Madagascar
14 Diversity Turn in Land Use Science, coordination office, Sambava, Madagascar
15 Department of Agricultural Economics and Rural Development, Research Unit Environmental- and Resource Economics, University of Göttingen, Germany
16 Ecology of Tropical Agricultural Systems, University of Hohenheim, Garbenstrasse 13, 70599 Stuttgart, Germany

Resolving ecological-economic trade-offs between biodiversity and yields is a key challenge when addressing the biodiversity crisis in tropical agricultural landscapes. Here, we focused on the relation between seven different taxa (trees, herbaceous plants, birds, amphibians, reptiles, butterflies, and ants) and yields in vanilla agroforests in Madagascar. Agroforests established in forests supported overall 23% fewer species and 47% fewer endemic species than old-growth forests, and 14% fewer endemic species than forest fragments. In contrast, agroforests established on fallows had overall 12% more species and 38% more endemic species than fallows. While yields increased with vanilla vine density and length, non-yield related variables largely determined biodiversity. Nonetheless, trade-offs existed between yields and butterflies as well as reptiles. Vanilla yields were generally unrelated to richness of trees, herbaceous plants, birds, amphibians, reptiles, and ants, opening up possibilities for conservation outside of protected areas and restoring degraded land to benefit farmers and biodiversity alike. • INT45 • Mechanical weeding promotes ecosystem multifunctionality and profitability more than herbicide weed control in a large-scale oil palm plantation > N-A. Najeeb Al-Amin IDDRIS
Content : Najeeb Al-Amin Iddris, Greta Formaglio, Carola Paul, Volker von Groß, Guantao Chen, Andres Angulo-Rubiano, Dirk Berkelmann, Fabian Brambach, Kevin Darras, Valentyna Krashevska, Anton Potapov, Arne Wenzel, Bambang Irawan, Muhammad Damris, Rolf Daniel, Ingo Grass, Holger Kreft, Stefan Scheu, Teja Tscharntke, Aiyen Tjoa, Edzo Veldkamp, Marife D. Corre

Industrial oil palm plantations are very productive but strongly depend on high fertilizer and herbicide applications, causing negative environmental impacts. Presently, there is a dearth of knowledge on how different oil palm management affects ecological and economic productivity. Here, we experimentally test whether alternatives to current nutrient and weed management practices can reduce the negative impacts on ecosystem functions and biodiversity while maintaining current high production levels. We compare conventional vs. reduced (i.e., equal to harvest export) fertilization rates and herbicide vs. mechanical (i.e., brush cutter) weeding, using a full factorial field experiment. Our study was conducted in a large-scale, state-owned oil palm plantation located in Jambi, Indonesia. After four years, ecosystem multifunctionality was higher in mechanical than herbicide weeding, due to the positive effect of mechanical weeding on litter decomposition, soil fertility, pollination potential and water filtration. Biodiversity was also enhanced by mechanical weeding, driven by increased understory vegetation diversity. Reduced fertilization and mechanical weeding also increased profit by 12% and relative gross margin by 11% than the conventional management due to reduction in material cost while attaining comparable yields. We provide strong experimental evidence that mechanical weeding with reduced compensatory fertilization in mature oil palm plantation is a sustainable management practice for increasing profit and enhancing biodiversity and ecosystem multifunctionality. • INT46 • Restoring multiple facets of biodiversity in oil-palm plantations > G. Gustavo PATERNO
Content : Gustavo Brant Paterno, Fabian Brambach, Nathaly Guerrero Ramírez, Delphine Clara Zemp, Aiza Fernanda Cantillo; Nicolò Camarretta, Carina C. M. Moura, Johannes Ballauff; Andrea Polle; Leti Sundawati, Bambang Irawan, Meike Wollni, Dirk Hölscher, Holger Kreft.

Large-scale oil plantations cause dramatic losses in biodiversity, evolutionary history, and structural complexity of tropical rainforest regions. However, plantations also improve the livelihoods and well-being of farmers and local communities. Here, we ask if the creation of tree islands within a large-scale oil-palm monoculture plantation can promote the restoration of multiple facets of plant diversity. Specifically, we ask (1) if enriching oil-palm plantations with native trees promotes the recovery of taxonomic and phylogenetic diversity through natural regeneration and (2) what are the main internal and external drivers of natural regeneration in the tree islands (enriched oil-palm agroforestry systems)? To answer these questions, a tree diversity experiment (EFForTS-BEE) was established in Sumatra, Indonesia. Tree islands within a large oil-palm plantation were established with varying sizes (25 m2, 100m2, 400m2, 1600m2) and richness of planted trees (0: natural regeneration only, 1, 2, 3, 6). Additionally, four control plots (i.e management as usual) were established within the oil-palm plantation. After eight years, 4386 tree individuals (height > 1.5) established through natural regeneration in the tree islands, including 62 tree species from 31 plant families. Enriching oil-palm plantations promoted the restoration of multiple facets of biodiversity where larger and more diverse tree islands increased the phylogenetic and taxonomic diversity of the regenerating tree community. These results were consistent regardless of the weight given to rare species (Hill number q exponent). The increase in tree diversity further contributed to a tree island's higher vegetation structural complexity and Leaf Area Index (LAI). We also found evidence that soil nutrient availability and propagule limitation might be important constraints to natural regeneration in oil-palm plantations. In conclusion, establishing large and diverse tree islands within mono-specific oil palm plantations can promote the restoration of multiple facets of biodiversity through natural regeneration. • INT47 • Investigating management options for more sustainable oil palm: the BEFTA Programme > E. Edgar TURNER
Content : The Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme, based in Riau, Indonesia, is a large-scale collaborative project between the oil palm industry and several universities. BEFTA is investigating ways of managing established oil palm to support higher levels of biodiversity and associated ecosystem processes within the oil palm system without impacting yield. The project has set-up several large-scale experiments to achieve this, including one altering the management of understory vegetation through varying herbicide applications, and another trialling different options for restoring forest around river catchments in mature oil palm at the time of replanting. In this talk we will introduce some of the key outcomes from these two main projects, highlighting management implications from the work, and fruitful areas for future research to inform the development of more-sustainable oil palm cultivation. • INT48 • Is sustainable management and conservation of tropical forest possible? > P. Plinio SIST
Content : For more than five decades, sustainable management has been considered as a potential tool for the conservation of large area of tropical natural forests while producing timber and others goods. Tropical production forests cover about 400 million ha in the word and selective logging is the most widespread management system implemented. However, the monitoring of tropical rainforest dynamics for several decades within permanent plots suggests that the rules of selective logging in tropical rainforests (cutting intensity and duration of rotations) currently set by most forestry legislation cannot ensure a sustainable timber yield on a long term basis. The present conditions, which are supposed to promote sustainable management, are largely questioned by science. This presentation aims to first clarify what we call sustainable timber production and second to present a synthesis of what we know about short and long term impact of selective logging in the tropics. Finally, it questions the very principles of tropical silviculture still in force today as well as the place of natural tropical production forests in a context of climate change. Restoration programs are an opportunity to think about a planned forestry transition adapted to this paradigm shift, which is as necessary as it is vital for the future of tropical rainforests. • INT49 • Ecological and Socioeconomic Functions of Tropical Lowland Rainforest Transformation Systems (Sumatra, Indonesia) > S. Stefan SCHEU
Content : Stefan Scheu, Jochen Drescher, Valentyna Krashevska, Melanie Pollierer, Anton Potapov
JFB Institute of Zoology and Anthropology, University of Göttingen, Göttingen, Germany.

Starting in 2012 an integrated project has been launched by a consortium of researchers from the University of Göttingen in Germany, and the IPB University Bogor, the University of Jambi and the TADULAKO University Palu in Indonesia investigating in an integrative way ecological and socioeconomic functions of tropical lowland rainforest transformation systems in Sumatra, Indonesia (CRC990/EFForTS). Experimental plots have been set up in a replicated design investigating transformation processes associated with the conversion of rainforest into jungle rubber agroforest, rubber and oil palm monoculture plantations. The talk will give an overview on the establishment, activities and achievements of the project. It will then focus on the structure and functioning of the above- and belowground food web highlighting changes associated with changes in land use from rainforest into monoculture plantation systems of rubber and oil palm. Aboveground arthropod communities have been investigated in a comprehensive way by canopy fogging. Soil animal communities and microflora have been investigated by a combination of heat extraction and DNA metagenomics. Combined with stable isotope and compound specific stable isotope analysis of amino acids the studies allowed realistic reconstructions of the structure and functioning of food webs and their changes with the conversion of rainforest into agricultural production systems.