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Creators/Authors contains: "Boetzl, Fabian A"

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  1. Abstract 1. In the tropics, smallholder farming characterizes some of the world’s most biodiverse landscapes. Agroecology as a pathway to sustainable agriculture has been proposed and implemented in sub-Saharan Africa, but the effects of agricultural practices in smallholder agriculture on biodiversity and ecosystem services are understudied. Similarly, the contribution of different landscape elements, such as shrub- or grassland cover, on biodiversity and ecosystem services to fields remains unknown. 2. We selected 24 villages situated in landscapes with varying landscape shrub- and grassland cover in Malawi. In each village, we assessed biodiversity of 8 taxa and ecosystem services in relation to crop type, shrub- and grassland cover and the number of agroecological pest management (APM) and agroecological soil management (ASM) on smallholder farm fields of different crop types (maize monoculture, maize-bean intercrop, and bean monoculture). 3. Increasing shrubland cover increased bee richness and altered carabid communities. Increased grassland cover decreased ant richness. Carabid richness increased in maize and intercrop but decreased in bean fields with increasing grassland cover. Carabid and parasitoid activity densities were higher in bean monocultures, but this was mediated by surrounding shrubland cover. Natural enemy activity in beans was especially high in landscapes with little surrounding shrubland. Possibly, this increased activity resulted in lower bean damage in monocultures compared to intercrop, whereas in maize, monocultures where more damaged, especially in landscapes high in grassland cover. In maize, APM was positively related to pest damage, and we find increased carabid activity and richness in fields with high maize damage. Increased ASM resulted in increased carabid richness and wasp activity density. 4. Synthesis and application: Our results suggest that maintaining biodiversity and ecosystem services on smallholder farms is not achievable with a “one size fits all” approach but should instead be adapted to the landscape context and the priorities of smallholders. Shrubland is important to maintain bee and carabid diversity, but legume cultivation beneficial to natural enemies could complement APM in landscapes with a lower shrubland cover. An increased number of ASM practices could lead to improved pest control whilst the effectiveness of APM needs to be re-evaluated. Keywords: agroecology, biodiversity, crop diversity, intercropping, landscape change, pest control, pollination, soil health. 
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  2. Abstract Ecological restoration seeks to reestablish functioning ecosystems, but planning and evaluation often focus on taxonomic community structure and neglect consumers and their functional roles. The functional trait composition of insect assemblages, which make up the majority of animal diversity in many systems, can reveal how they are affected by restoration management and the consequences for ecosystem function. We sampled ground beetle (Coleoptera: Carabidae) assemblages in restored tallgrass prairies varying in management with prescribed fire and reintroduced American bison (Bison bison) to describe their taxonomic and functional trait structure. We also measured seed and arthropod predation to relate management, beetle assemblage characteristics, and function, and to test if function is maximized by trait diversity, dominant trait values, or beetle abundance. Beetle assemblages primarily varied with restoration age, declining over time in richness and both taxonomic and functional diversity, but bison presence also influenced taxonomic composition. Prescribed fire reduced seed predation in summer and arthropod predation in fall. Although seed predation was unrelated to beetle assemblages, arthropod predation was greater in sites with higher abundances of carnivorous ground beetles. The relatively weak impacts of fire and bison on functional assemblage structure is a promising sign that these management disturbances, aimed at supporting a diverse native plant community, are not detrimental to beetle assemblages. The significance of reduced predator function following prescribed fire will depend on the restoration context and whether seed or arthropod predation relates to management goals. 
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