Collaborative Research Centre 990: Ecological and Socioeconomic Functions of Tropical Lowland Rainforest Transformation Systems (Sumatra, Indonesia) (Phase 3: 2020 – 2023)

Assessment of ecological and socioeconomic functions, synergies and trade-offs across different land-use systems

Transformation of tropical rainforest into monoculture production systems such as rubber or oil palm increases socioeconomic functions, but commonly entails substantial losses in biodiversity and associ-ated ecological functions and services (Hooper et al. 2005, MEA 2005, Stork et al. 2009, Cardinale et al. 2012). The resulting ecological-socioeconomic trades-offs are at odds with sustainable development of tropical regions (Cumming et al. 2014). However, the underlying mechanisms and relationships between rainforest transformation and responses among ecological and socioeconomic functions are still poorly understood. With its focus on valuation of local synergies and trade-offs among these functions, the research efforts combined in Focus 1 centre on three Hypotheses:


  1. Transformation of rainforest to monoculture production systems is associated with a strong decline in biodiversity and ecological functions, however, these monoculture production systems are socioeco-nomically more valuable than rainforests, resulting in ecological-socioeconomic trade-offs.

  2. Differences in management or ecological setting of rubber and oil palm plantations have both addi-tive and interactive effects on ecological and socioeconomic functions, resulting in non-linear relation-ships and both synergies and trade-offs among and between functions.

  3. Enrichment of oil palm plantations by planting of indigenous multi-purpose trees and reduced-input oil palm management mitigate the ecological-socioeconomic trade-offs that are associated with the transformation of tropical lowland forest to oil palm monoculture.


In Phase 1, we addressed hypothesis 1 with an interdisciplinary synthesis of ecological and socioeco-nomic functions across different land-use systems (Clough et al. 2016). This synthesis and a large num-ber of case studies clearly demonstrated that rainforest transformation to monocultures causes pro-nounced trade-offs between socioeconomic and ecological functions by reducing biodiversity and eco-system functioning at the expense of increasing socioeconomic benefits. Examples of losses in biodi-versity in ecosystem functioning include decreases of at least 45% in species diversity, density and biomass of invertebrate communities (Barnes et al. 2014) and a loss of soil carbon content in the Ah-horizon of about 70% when comparing rainforest to oil palm plantations (Guillaume et al. 2015). However, monoculture production systems have higher socioeconomic benefits, as indicated by gains in average household welfare and village wealth through oil palm expansion (Feintrenie et al. 2010, Gatto et al. 2017, Euler et al. 2017, Kubitza et al. 2018a).
In Phase 2, we have addressed hypothesis 2 and focussed on non-linear relationships between econom-ic and ecological functions across land-use transitions. In particular, we established how land-use transi-tions of smallholder farmers from rainforest and agroforestry jungle rubber to rubber and oil palm mono-culture increase their economic profits (after correcting for inputs and non-household and household labour costs), and linked these to biodiversity and ecological functions on their production sites. We found widespread non-linear biodiversity-profit trade-offs, for above- and belowground species and ecosystem multidiversity (see Fig. 1). Despite variation between ecosystem functions, profit gains also came at the expense of ecosystem multifunctionality, indicating far-reaching ecosystem deterioration. Using a genetic algorithm we identified landscape compositions that can mitigate trade-offs under opti-mal land-use allocation but also showed that intensive monocultures always lead to higher profits. These findings suggest that losses in biodiversity and ecosystem functioning can only be reduced if economic incentive structures are changed through well-designed policies (Grass et al. unpubl. data).
The low environmental complexity within monoculture production systems is arguably a main driver of their comparably low biodiversity (Stein et al. 2014). Promoting environmental heterogeneity within these systems should increase biodiversity and ecosystem functioning (Foster et al. 2011). While previous work focussed on upland locations of land-use systems (Clough et al. 2016), riparian areas close to or within land-use systems can act as refuges or corridors for biodiversity (Koh et al. 2009, Gray et al. 2015), which could mitigate socioeconomic-ecological trade-offs of agricultural production.
In-depth follow-up analyses of upland vs. riparian land-uses are planned for Phase 3 (for first results see Focus 2). In line with hypothesis 2, work within Focus 1 will furthermore focus on identifying best practic-es for improving the ecological value of oil palm plantations, drawing on the huge amount of data from different socioeconomic and ecological contexts investigated by EFForTS (oil palm estates, smallhold-ers, riparian/upland locations, fertilizer/weeding management based on the EFForTS-OPMX and the EF-ForTS-BEE B11 Hölscher/Kreft/Wollni). Moreover, the Landscape Assessment will play a major role, which, for example, includes assessments of the relative importance of local vs. landscape context for socioeconomic-ecological trade-offs and synergies of tropical land-use. Together with the quantification of the heterogeneity of ecological and socioeconomic functions in space and time (Focus 2), and how they can be scaled from local to regional scales (Focus 3), these in-depth assessments within the framework of Focus 1 can contribute to designing policies towards more sustainable land-use systems (Focus 4).