ADJUSTMENT COSTS OF AGRI-ENVIRONMENTAL POLICY SWITCHINGS - A MULTI-AGENT APPROACH

More powerful computers, the better availability of micro-data, and the development of new modeling techniques, such as multi-agent systems, allows to analyze agricultural policies from the bottom up. We present such an approach that considers the spatial interaction of thousands of individually behaving heterogeneous farms and apply it to analyze agri-environmental policies for a selected intensive production region in the southwest of Germany.Environmental Economics and Policy,

Managing biological control for fruit production in different European climates

Biological pest control in apple orchards is essential and depends on effective and sustainable agricultural management strategies at local and landscape scales. Local measures such as hedgerows, flowering strips, organic management as well as landscapes with a high diversity of cover types and low land-use intensity are assumed to support biological control specifically and ecosystem services in general. However, the influence of local measures, landscape characteristics and their interactions has rarely been studied in perennial crop systems across large latitudinal gradients. Studying ecosystem services across climatic regions is especially important in the face of climate change and induced shifts in species distribution. The present study assesses the effects of local and landscape factors on predatory arthropods and their prey, and on trade-offs between ecosystem services and fruit production in the intensive fruit production systems of three European countries. Local factors included quality of the adjacent habitat (e.g. cover of woody habitat and plant species richness) and two types of orchard management: integrated production (IP; based on the reduced and targeted application of synthetic agrochemicals) and organic management practices. Landscape factors included the amount of orchard cover in the surrounding landscape as a proxy for land-use intensity and landscape diversity. For three years I studied arthropod communities in 30 apple orchards in Germany, with a special focus on natural enemies and herbivores and their impact on tree health and fruit production. I analyzed data from these orchards and from 28 orchards in Spain and 28 orchards in Sweden, provided by collaborators working on the same European BiodivERsA project. As a member of a 17-scientist team, I investigated how agri-environmental schemes, management practices, and landscape composition can be enhanced to support (I) ecosystem services and biodiversity in general, (II) communities of predatory arthropods, and (III) specific predatory arthropod taxa. The first publication (Chapter 2) offers an insight into the complex interactions of functional groups of arthropods (pollinators, predators, and pests) and their influence on fruit production in different environments. It presents natural enemies and their prey in the context of ecosystem service trade-offs. In cooperation with the project partners, I studied the effects of local and landscape factors on functional groups and their services and disservices in 86 European apple orchards in Germany, Sweden, and Spain, during one growing season (from March to October 2015) under a common study design and sampling protocol. Key functions of ecosystem service providers are biological pest control and pollination. Disservices are defined as fruit damage at harvest, and aphid infestation of target trees. Final yield (fruit production and seed set) is assessed as the ultimate measure for ecosystem service provisioning. Using structural equation models, we tested for trade-offs between ecosystem services and for effects of local and landscape variables. Across Europe organic management benefited natural enemies. Higher abundance of natural enemies in organic orchards partly compensated for higher fruit damage and lower yield in these systems. There was no general positive influence of agri-environmental schemes such as hedgerows or flower strips on natural enemies. However, a high flower cover in the understory indirectly increased final fruit yield by improving living conditions for wild bees. Diversity of beneficial arthropods was lower in landscapes with high land-use intensity. The second publication (Chapter 3) focuses on natural enemy communities in apple orchards across all three countries and differences in their responses to local and landscape factors. Together with partners in Spain, Sweden, and Germany, I give a closer look on each of seven groups of predatory arthropods: spiders (Araneae), beetles (Coleoptera), earwigs (Dermaptera), flies (Diptera), bugs (Heteroptera), lacewings (Neuroptera) and harvestmen (Opiliones). In 2015, we took beating samples in all 86 apple orchards to assess the abundance of predatory arthropods. Additionally, we calculated community energy use as a proxy for the communities’ predation potential based on biomass and metabolic rates of predatory arthropods. In both IP and organic orchards, we detected contradicting influences of local and landscape factors on the studied predator groups. Organic management enhanced abundances of five out of seven predatory arthropod groups. It benefited spiders, beetles, earwigs, flies, and bugs, but the response was not consistent across countries. High local woody habitat cover enhanced earwig abundance in Sweden but not in Germany. Plant species richness negatively influenced bug abundance depending on country and management. Predation potential (energy use by the predator community) was higher in organic orchards in Spain but remained largely unaffected by local and landscape factors across Europe. The third publication (Chapter 4) is a case study on a single predatory arthropod group, earwigs, and one of their main prey organisms, woolly apple aphids. Earwigs are expected to be important generalist predators in apple orchards, with woolly apple aphids being a common apple pest. I studied whether local factors such as the presence of woody habitats and organic management and landscapes with low land-use intensity enhance living conditions for earwigs in intensive fruit production systems. Earwigs were sampled using shelters in 30 apple orchards in Germany (2015-2016), and 28 orchards in Spain (2015), subjected to IP or organic management. At the same time, we assessed tree infestation by woolly apple aphids. Correlation analyses served to detect possible interactions between the abundance of earwigs and the availability of potential prey organisms. The results indicate that there is only a weak correlation between abundance of earwigs and tree infestation by woolly apple aphids. Earwigs of the species Forficula auricularia seem to respond indifferently to orchard management. Presence of adjacent woody elements reduced earwig abundance in IP orchards in Germany. In Spain we found two earwig species, Forficula auricularia and F. pubescens, but only F. pubescens, which did not occur in German orchards, profited from organic management. The three different perspectives on predatory arthropods (Chapter 2-4) highlight the importance of local and landscape factors for ecosystem services in general and predatory arthropods in particular. Responses were not consistent between predator groups and countries, stressing the need to develop tailored and country-specific management schemes at the local and landscape scale beyond the promotion of organic management

Predatory arthropods in apple orchards across Europe: Responses to agricultural management, adjacent habitat, landscape composition and country

Local agri-environmental schemes, including hedgerows, flowering strips, organic management, and a landscape rich in semi-natural habitat patches, are assumed to enhance the presence of beneficial arthropods and their contribution to biological control in fruit crops. We studied the influence of local factors (orchard management and adjacent habitats) and of landscape composition on the abundance and community composition of predatory arthropods in apple orchards in three European countries. To elucidate how local and landscape factors influence natural enemy effectiveness in apple production systems, we calculated community energy use as a proxy for the communities’ predation potential based on biomass and metabolic rates of predatory arthropods. Predator communities were assessed by standardised beating samples taken from apple trees in 86 orchards in Germany, Spain and Sweden. Orchard management included integrated production (IP; i.e. the reduced and targeted application of synthetic agrochemicals), and organic management practices in all three countries. Predator communities differed between management types and countries. Several groups, including beetles (Coleoptera), predatory bugs (Heteroptera), flies (Diptera) and spiders (Araneae) benefited from organic management depending on country. Woody habitat and IP supported harvestmen (Opiliones). In both IP and organic orchards we detected aversive influences of a high-quality surrounding landscape on some predator groups: for example, high covers of woody habitat reduced earwig abundances in German orchards but enhanced their abundance in Sweden, and high natural plant species richness tended to reduce predatory bug abundance in Sweden and IP orchards in Spain. We conclude that predatory arthropod communities and influences of local and landscape factors are strongly shaped by orchard management, and that the influence of management differs between countries. Our results indicate that organic management improves the living conditions for effective predator communities.info:eu-repo/semantics/acceptedVersio

Management trade‐offs on ecosystem services in apple orchards across Europe: Direct and indirect effects of organic production

Apple is considered the most important fruit crop in temperate areas and profitable production depends on multiple ecosystem services, including the reduction of pest damage and the provision of sufficient pollination levels. Management approaches present an inherent trade‐off as each affects species differently. We quantified the direct and indirect effects of management (organic vs. integrated pest management, IPM) on species richness, ecosystem services, and fruit production in 85 apple orchards in three European countries. We also quantified how habit composition influenced these effects at three spatial scales: within orchards, adjacent to orchards, and in the surrounding landscape. Organic management resulted in 48% lower yield than IPM, and also that the variation between orchards was large with some organic orchards having a higher yield than the average yield of IPM orchards. The lower yield in organic orchards resulted directly from management practices, and from higher pest damage in organic orchards. These negative yield effects were partly offset by indirect positive effects from more natural enemies and higher flower visitation rates in organic orchards. Two factors other than management affected species richness and ecosystem services. Higher cover of flowering plants within and adjacent to the apple trees increased flower visitation rates by pollinating insects and a higher cover of apple orchards in the landscape decreased species richness of beneficial arthropods. The species richness of beneficial arthropods in orchards was uncorrelated with fruit production, suggesting that diversity can be increased without large yield loss. At the same time, organic orchards had 38% higher species richness than IPM orchards, an effect that is likely due to differences in pest management. Synthesis and applications. Our results indicate that organic management is more efficient than integrated pest management in developing environmentally friendly apple orchards with higher species richness. We also demonstrate that there is no inherent trade‐off between species richness and yield. Development of more environmentally friendly means for pest control, which do not negatively affect pollination services, needs to be a priority for sustainable apple production.info:eu-repo/semantics/publishedVersio

Management trade-offs on ecosystem services in apple orchards across Europe : Direct and indirect effects of organic production

Apple is considered the most important fruit crop in temperate areas and profitable production depends on multiple ecosystem services, including the reduction of pest damage and the provision of sufficient pollination levels. Management approaches present an inherent trade-off as each affects species differently. We quantified the direct and indirect effects of management (organic vs. integrated pest management, IPM) on species richness, ecosystem services, and fruit production in 85 apple orchards in three European countries. We also quantified how habit composition influenced these effects at three spatial scales: within orchards, adjacent to orchards, and in the surrounding landscape. Organic management resulted in 48% lower yield than IPM, and also that the variation between orchards was large with some organic orchards having a higher yield than the average yield of IPM orchards. The lower yield in organic orchards resulted directly from management practices, and from higher pest damage in organic orchards. These negative yield effects were partly offset by indirect positive effects from more natural enemies and higher flower visitation rates in organic orchards. Two factors other than management affected species richness and ecosystem services. Higher cover of flowering plants within and adjacent to the apple trees increased flower visitation rates by pollinating insects and a higher cover of apple orchards in the landscape decreased species richness of beneficial arthropods. The species richness of beneficial arthropods in orchards was uncorrelated with fruit production, suggesting that diversity can be increased without large yield loss. At the same time, organic orchards had 38% higher species richness than IPM orchards, an effect that is likely due to differences in pest management. Synthesis and applications. Our results indicate that organic management is more efficient than integrated pest management in developing environmentally friendly apple orchards with higher species richness. We also demonstrate that there is no inherent trade-off between species richness and yield. Development of more environmentally friendly means for pest control, which do not negatively affect pollination services, needs to be a priority for sustainable apple production

Management-dependent effects of pollinator functional diversity on apple pollination services: A response–effect trait approach

Data available via the Dryad Digital Repository https://doi.org/10.5061/dryad.63xsj3v39 (Roquer-Beni et al., 2021).Functional traits mediate the response of communities to disturbances (response traits) and their contribution to ecosystem functions (effect traits). To predict how anthropogenic disturbances influence ecosystem services requires a dual approach including both trait concepts. Here, we used a response–effect trait conceptual framework to understand how local and landscape features affect pollinator functional diversity and pollination services in apple orchards. We worked in 110 apple orchards across four European regions. Orchards differed in management practices. Low-intensity (LI) orchards were certified organic or followed close-to-organic practices. High-intensity (HI) orchards followed integrated pest management practices. Within each management type, orchards encompassed a range of local (flower diversity, agri-environmental structures) and landscape features (orchard and pollinator-friendly habitat cover). We measured pollinator visitation rates and calculated trait composition metrics based on 10 pollinator traits. We used initial fruit set as a measure of pollination service. Some pollinator traits (body size and hairiness) were negatively related to orchard cover and positively affected by pollinator-friendly habitat cover. Bee functional diversity was lower in HI orchards and decreased with increased landscape orchard cover. Pollination service was not associated with any particular trait but increased with pollinator trait diversity in LI orchards. As a result, LI orchards with high pollinator trait diversity reached levels of pollination service similar to those of HI orchards. Synthesis and applications. Pollinator functional diversity enables pollinator communities to respond to agricultural intensification and to increase pollination function. Our results show that efforts to promote biodiversity provide greater returns in low-intensity than in high-intensity orchards. The fact that low-intensity orchards with high pollinator functional diversity reach levels of pollination services similar to those of high-intensity orchards provides a compelling argument for the conversion of high-intensity into low-intensity farms.This research (EcoFruit project) was funded through the 2013–2014 BiodivERsA/FACCE-JPI joint call (2014-74), Spanish MinECo (PCIN-2014-145-C02), German BMBF (PT-DLR/BMBF, 01LC1403) and Swedish Research Council Formas (2014-1784) by Formas (2013-934 to M.T.), Stiftelsen Lantbruksforskning (H1256150 to M.P.), INIA (RTA2013-00039-C03-00 to G.A. and M.M.), MinECo/FEDER (CGL2015-68963-C2-2-R to D.G.), FI-AGAUR (to L.R.-B.) and MinECo (RYC-2015-18448 to X.A.)

ADJUSTMENT COSTS OF AGRI-ENVIRONMENTAL POLICY SWITCHINGS - A MULTI-AGENT APPROACH

More powerful computers, the better availability of micro-data, and the development of new modeling techniques, such as multi-agent systems, allows to analyze agricultural policies from the bottom up. We present such an approach that considers the spatial interaction of thousands of individually behaving heterogeneous farms and apply it to analyze agri-environmental policies for a selected intensive production region in the southwest of Germany