How Rainforest Conversion to Agricultural Systems in Sumatra (Indonesia) Affects Active Soil Bacterial Communities

Palm oil production in Indonesia increased constantly over the last decades, which led to massive deforestation, especially on Sumatra island. The ongoing conversion of rainforest to agricultural systems results in high biodiversity loss. Here, we present the first RNA-based study on the effects of rainforest transformation to rubber and oil palm plantations in Indonesia for the active soil bacterial communities. For this purpose, bacterial communities of three different converted systems (jungle rubber, rubber plantation, and oil palm plantation) were studied in two landscapes with rainforest as reference by RT-PCR amplicon-based analysis of 16S rRNA gene transcripts. Active soil bacterial communities were dominated by Frankiales (Actinobacteria), subgroup 2 of the Acidobacteria and Alphaproteobacteria (mainly Rhizobiales and Rhodospirillales). Community composition differed significantly between the converted land use systems and rainforest reference sites. Alphaproteobacteria decreased significantly in oil palm samples compared to rainforest samples. In contrast, relative abundances of taxa within the Acidobacteria increased. Most important abiotic drivers for shaping soil bacterial communities were pH, calcium concentration, base saturation and C:N ratio. Indicator species analysis showed distinct association patterns for the analyzed land use systems. Nitrogen-fixing taxa including members of Rhizobiales and Rhodospirillales were associated with rainforest soils while nitrifiers and heat-resistant taxa including members of Actinobacteria were associated with oil palm soils. Predicted metabolic profiles revealed that the relative abundances of genes associated with fixation of nitrogen significantly decreased in plantation soils. Furthermore, predicted gene abundances regarding motility, competition or gene transfer ability indicated rainforest conversion-induced changes as well

Balancing economic and ecological functions in smallholder and industrial oil palm plantations

The expansion of the oil palm industry in Indonesia has improved livelihoods in rural communities, but comes at the cost of biodiversity and ecosystem degradation. Here, we investigated ways to balance ecological and economic outcomes of oil palm cultivation. We compared a wide range of production systems, including smallholder plantations, industrialized company estates, estates with improved agronomic management, and estates with native tree enrichment. Across all management types, we assessed multiple indicators of biodiversity, ecosystem functions, management, and landscape structure to identify factors that facilitate economic-ecological win-wins, using palm yields as measure of economic performance. Although, we found that yields in industrialized estates were, on average, twice as high as those in smallholder plantations, ecological indicators displayed substantial variability across systems, regardless of yield variations, highlighting potential for economic-ecological win-wins. Reducing management intensity (e.g., mechanical weeding instead of herbicide application) did not lower yields but improved ecological outcomes at moderate costs, making it a potential measure for balancing economic and ecological demands. Additionally, maintaining forest cover in the landscape generally enhanced local biodiversity and ecosystem functioning within plantations. Enriching plantations with native trees is also a promising strategy to increase ecological value without reducing productivity. Overall, we recommend closing yield gaps in smallholder cultivation through careful intensification, whereas conventional plantations could reduce management intensity without sacrificing yield. Our study highlights various pathways to reconcile the economics and ecology of palm oil production and identifies management practices for a more sustainable future of oil palm cultivation.</p

Unravelling the effects of tropical land use conversion on the soil microbiome

Open-Access-Publikationsfonds 202

Tumour-treating fields (TTFields): Investigations on the mechanism of action by electromagnetic exposure of cells in telophase/cytokinesis

Tumour-treating fields (TTFields) use alternating electric fields which interfere with dividing cells, thereby reducing tumour growth. Previous reports suggest that electrical forces on cell structure proteins interfered with the chromosome separation during mitosis and induced apoptosis. In the present report we evaluate electromagnetic exposure of cells in telophase/cytokinesis in order to further analyse the mechanism of action on cells. We performed numerical electromagnetic simulations to analyse the field distribution in a cell during different mitotic phases. Based thereon, we developed an electric lumped element model of the mitotic cell. Both the electromagnetic simulation and the lumped element model predict a local increase of the specific absorption rate (SAR) as a measure of the electromagnetically induced power absorption density at the mitotic furrow which may help to explain the anti-proliferative effect. In accordance with other reports, cell culture experiments confirmed that TTFields reduce the proliferation of different glioma cell lines in a field strength- and frequency-dependent manner. Furthermore, we found an additional dependence on the commutation time of the electrical fields. The report gives new insights into TTFields’ anti-proliferative effect on tumours, which could help to improve future TTFields application system

Landscape heterogeneity and soil biota are central to multi-taxa diversity for landscape restoration

How to enhance biodiversity in monoculture-dominated landscapes is a key sustainability question that requires considering the spatial organization of ecological communities (beta diversity). Here, we experimentally tested if increasing landscape heterogeneity – through tree islands – is a suitable landscape restoration strategy when aiming to enhance multi-taxa diversity. We found that multi-taxa diversity resulted from islands fostering unique species (turnover: between 0.18 - 0.73) rather than species losses and gains (nestedness: between 0.03 - 0.34), suggesting that tree islands enhance diversity at the landscape scale. Through partial correlation networks, we revealed that landscape heterogeneity is associated with multi-taxa diversity (strength = 0.84). Soil biota were also central to the overall community by connecting beta diversity patterns across taxa. Our results show that increasing landscape heterogeneity enhances multi-taxa diversity in monoculture-dominant landscapes. Furthermore, we highlight that strategies aiming to enhance multi-taxa diversity should consider that spatial distributions of above- and below-ground communities are associated

Mechanical weeding enhances ecosystem multifunctionality and profit in industrial oil palm

A full factorial experiment in a state-owned industrial oil palm plantation in Indonesia evaluates whether reduced management via reduced fertilization rates and mechanical weeding can decrease the negative impacts on ecosystem functions and biodiversity while maintaining profitability of the plantation.Oil palm is the most productive oil crop, but its high productivity is associated with conventional management (that is, high fertilization rates and herbicide application), causing deleterious environmental impacts. Using a 2(2) factorial experiment, we assessed the effects of conventional vs reduced (equal to nutrients removed by fruit harvest) fertilization rates and herbicide vs mechanical weeding on ecosystem functions, biodiversity and profitability. Analysing across multiple ecosystem functions, mechanical weeding exhibited higher multifunctionality than herbicide treatment, although this effect was concealed when evaluating only for individual functions. Biodiversity was also enhanced, driven by 33% more plant species under mechanical weeding. Compared with conventional management, reduced fertilization and mechanical weeding increased profit by 12% and relative gross margin by 11% due to reductions in material costs, while attaining similar yields. Mechanical weeding with reduced, compensatory fertilization in mature oil palm plantations is a tenable management option for enhancing ecosystem multifunctionality and biodiversity and increasing profit, providing win-win situations