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  • Publication
    Accès libre
    Transformation scenarios towards multifunctional landscapes: A multi-criteria land-use allocation model applied to Jambi Province, Indonesia
    (2024)
    Volker von Groß
    ;
    Kibrom T. Sibhatu
    ;
    Alexander Knohl
    ;
    Matin Qaim
    ;
    Edzo Veldkamp
    ;
    Dirk Hölscher
    ;
    Zemp, Clara 
    ;
    Marife D. Corre
    ;
    Ingo Grass
    ;
    Sebastian Fiedler
    ;
    Christian Stiegler
    ;
    Bambang Irawan
    ;
    Leti Sundawati
    ;
    Kai Husmann
    ;
    Carola Paul
    In tropical regions, shifting from forests and traditional agroforestry to intensive plantations generates conflicts between human welfare (farmers' demands and societal needs) and environmental protection. Achieving sustainability in this transformation will inevitably involve trade-offs between multiple ecological and socioeconomic functions. To address these trade-offs, our study used a new methodological approach allowing the identification of transformation scenarios, including theoretical landscape compositions that satisfy multiple ecological functions (i.e., structural complexity, microclimatic conditions, organic carbon in plant biomass, soil organic carbon and nutrient leaching losses), and farmers needs (i.e., labor and input requirements, total income to land, and return to land and labor) while accounting for the uncertain provision of these functions and having an actual potential for adoption by farmers. We combined a robust, multi-objective optimization approach with an iterative search algorithm allowing the identification of ecological and socioeconomic functions that best explain current land-use decisions. The model then optimized the theoretical land-use composition that satisfied multiple ecological and socioeconomic functions. Between these ends, we simulated transformation scenarios reflecting the transition from current land-use composition towards a normative multifunctional optimum. These transformation scenarios involve increasing the number of optimized socioeconomic or ecological functions, leading to higher functional richness (i.e., number of functions). We applied this method to smallholder farms in the Jambi Province, Indonesia, where traditional rubber agroforestry, rubber plantations, and oil palm plantations are the main land-use systems. Given the currently practiced land-use systems, our study revealed short-term returns to land as the principal factor in explaining current land-use decisions. Fostering an alternative composition that satisfies additional socioeconomic functions would require minor changes ("low-hanging fruits"). However, satisfying even a single ecological indicator (e.g., reduction of nutrient leaching losses) would demand substantial changes in the current land-use composition ("moonshot"). This would inevitably lead to a profit decline, underscoring the need for incentives if the societal goal is to establish multifunctional agricultural landscapes. With many oil palm plantations nearing the end of their production cycles in the Jambi province, there is a unique window of opportunity to transform agricultural landscapes.
  • Publication
    Accès libre
    Microclimate and land surface temperature in a biodiversity enriched oil palm plantation
    (2021)
    Laura Somenguem Donfack
    ;
    Alexander Röll
    ;
    Florian Ellsäßer
    ;
    Martin Ehbrecht
    ;
    Bambang Irawan
    ;
    Dirk Hölscher
    ;
    Alexander Knohl
    ;
    Holger Kreft
    ;
    Eduard J. Siahaan
    ;
    Leti Sundawati
    ;
    Christian Stiegler
    ;
    Zemp, Clara 
    Agroforestry options such as mixed-species tree planting and natural regeneration in oil palm plantations may alleviate negative effects of forest loss on biodiversity and ecosystem functioning. The effects of agroforestry on microclimate and land surface temperatures (LST) remain largely unknown despite their central role in controlling abiotic and biotic factors and in buffering climate at a larger scale. We assessed spatial and temporal microclimate and LST variability in a biodiversity enrichment experiment, in which tree islands have been planted in an oil palm plantation in Sumatra (Indonesia). Four years after establishment of the experiment, we measured microclimate and LST using mini microclimate sensors and drone-recorded thermal images. We examined experimental effects of tree species richness (0, 1, 2, 3 or 6), plot size (25 m2, 100 m2, 400 m2, 1600 m2) and stand structural complexity on microclimate and LST. Diurnal patterns showed ambient air temperature peaks and relative humidity (RH) minima at 3 pm, whereas diurnal soil temperatures peaked around 6 pm. The lowest LST were observed from oil palm canopy leaves and the highest from bare soils and understorey vegetation (including trees). Spatial and temporal ranges of ambient air temperature were smaller than LST ranges, and average ambient air temperature and LST were positively correlated. Tree species diversity had no overall significant effect neither on microclimate nor LST, but humidity was higher in planted tree islands compared to natural regeneration only. Smaller plots were characterized by higher mean air, soil and LST, compared to larger plots. Structurally complex plots were associated with low mean and maximum values of ambient air temperature, soil temperature and LST and high mean and minimum RH. Still, conditions were hotter and drier in several experimental plots compared to conventional oil palm plantations, considering a higher transpiration in the latest. We conclude that stand structural complexity and tree island size control microclimate and LST in the experimental oil palm agroforests, but alleviating the harsh microclimate conditions in oil palm plantations might take longer to occur.
  • Publication
    Accès libre
    Dataset on microclimate and drone-based thermal patterns within an oil palm agroforestry system
    (2021)
    Laura Somenguem Donfack
    ;
    Alexander Röll
    ;
    Florian Ellsäßer
    ;
    Martin Ehbrecht
    ;
    Bambang Irawan
    ;
    Dirk Hölscher
    ;
    Alexander Knohl
    ;
    Holger Kreft
    ;
    Eduard J. Siahaan
    ;
    Leti Sundawati
    ;
    Christian Stiegler
    ;
    Zemp, Clara 
    Microclimate and Land Surface Temperature (LST) are important analytical variables used to understand complex oil palm agroforestry systems and their effects on biodiversity and ecosystem functions. In order to examine experimental effects of tree species richness (0, 1, 2, 3 or 6), plot size (25 m2, 100 m2, 400 m2, 1600 m2) and stand structural complexity on microclimate and Land Surface Temperature, related data were collected following a strict design. The experiment was carried out in the Jambi province, in Sumatra (Indonesia), as part of the collaborative project EFForTS [Ecological and Socioeconomic Functions of Tropical Lowland Rainforest Transformation Systems]. Microclimate data collected using miniaturized data loggers combined with drone-based thermal data were considered within an oil palm plantation enriched with six target tree species. The timeframe considered for data analysis was 20th September 2017 to 26th September 2017. The experiment data can be used for comparison with data from conventional oil palm agroforestry systems in the tropics. They can more specifically be used as reference to assess microclimate and Land Surface Temperature patterns within similar agroforestry systems.
  • Publication
    Accès libre
    Flooding and land use change in Jambi Province, Sumatra: integrating local knowledge and scientific inquiry
    (2020)
    Jennifer Merten
    ;
    Christian Stiegler
    ;
    Nina Hennings
    ;
    Edwine S. Purnama
    ;
    Alexander Röll
    ;
    Herdhata Agusta
    ;
    Michaela A. Dippold
    ;
    Lutz Fehrmann
    ;
    Dodo Gunawan
    ;
    Dirk Hölscher
    ;
    Alexander Knohl
    ;
    Johanna Kückes
    ;
    Fenna Otten
    ;
    Zemp, Clara 
    ;
    Heiko Faust
    The rapid expansion of rubber and oil palm plantations in Jambi Province, Sumatra, Indonesia, is associated with largescale deforestation and the impairment of many ecosystem services. According to villagers’ observations, this land use change has, together with climate change, led to an increase in the magnitude and frequency of river flood events, which constrain village and plantation development. Based on this empirical societal problem, we investigate whether we can find measurable indications for the presumed linkages between land use change, climate change, and changing flooding regimes. We follow an explorative, bottom-up research approach that builds on a review of multidisciplinary datasets, integrating local ecological knowledge with scientific measurements from soil science, climatology, hydrology, and remote sensing. We found that water levels of one of the largest rivers in Jambi Province, the Tembesi, have increased significantly during the last two decades. Data of local and regional meteorological stations show that alterations in rainfall patterns may only partly explain these changes. Rather, increased soil densities and decreased water infiltration rates in monoculture plantations suggest an increase in surface runoff following forest conversion. Moreover, additional interview data reveal that an increasing encroachment of wetlands in Jambi Province may contribute to changes in local flooding regimes, as the construction of drainage and flood control infrastructure redistributes floodwater at the local scale. We conclude that changing flooding regimes are the result of multiple interacting social-ecological processes associated with the expansion of rubber and oil palm plantations in Jambi Province. Although ecohydrological changes are likely to contribute to an increase of flood occurrence, their social impacts are increasingly mediated through flood control infrastructure on industrial oil palm plantations.