A global synthesis reveals biodiversity-mediated benefits for crop production

Opportunities and obstacles of ecological intensification: Biological pest control in arable cropping systems

Landscape heterogeneity affects arthropod functional diversity and biological pest control

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, measured vegetation characteristics, quantified human activities, and evaluated ant-community responses by grouping ants into service-providing units (SPUs), defined as a group of organisms and their populations that perform specific ecosystem services, to provide an understanding of urbanization impacts on biodiversity and their delivery of ecosystem services. Species richness and abundance peaked at intermediate levels of urban development, as did the richness of 3 types of ant SPUs (aerators, decomposers, and compilers). With increasing land development aerator and decomposer ants significantly declined in abundance, whereas compiler ants significantly increased in abundance. Competing models demonstrated that precipitation was frequently among the strongest influences on ant community structure; however, urban development and human activities also had a strong, negative influence on ants, appearing in most models with DeltaAIC(c) < 2 for species richness and abundance patterns of SPUs and generalists. Response diversity was observed within SPUs, which suggests that the corresponding ecosystem services were maintained until development reached 30-40%. Our data provide evidence that ecosystem functions, such as water infiltration and soil productivity, may be diminished at sites subject to greater levels of urbanization and that conserving ant communities and the ecosystem services they provide could be an important target in land-use planning and conservation efforts.

Insect pollination and biological pest control simultaneously influence crop yield, but are often investigated individually. This can lead to under‐ or over‐estimation of the importance of individual services when they interact to affect yield. Recent, limited evidence from field studies showed contrasting results with both additive and non‐additive positive and negative effects. To disentangle the mechanisms underlying these responses, we conducted a greenhouse experiment and a field study. We tested the potential and realized contribution of insect pollination to cotton boll retention and yield under various pest pressures and biocontrol levels. We found both additive and interactive effects of insect pollination and biocontrol within a single crop system depending on the level of pest pressure. In the greenhouse experiment, pollination did not contribute to cotton boll retention and final yield at low pest pressure. At high pest abundances, boll retention and final yield were higher when pollinators were present. In the field study, pollination was sufficient to alter the negative effect of pests on boll retention. Thus, interactive effect between the two ecosystem services on boll retention was present at high pest pressure in the greenhouse and at natural levels of pest pressure in the field, but not at lower pest abundances in controlled conditions. Although cotton plants partly compensated for bolls shedding by increasing their weight in the greenhouse experiment, this effect was not detected in the field study, likely due to higher environmental variation. Similarly, interactive effect of pollination and biocontrol on the final yield was present only in the greenhouse study. Synthesis and applications. We conclude that the contrasting findings of additive versus non‐additive effects between ecosystem services may be due to the levels of services and disservices tested and environmental variation. Further, this study shows that even when an ecosystem service does not appear to limit crop yield, it can make a substantial contribution to yield and act as insurance when the other service is reduced. For achieving food and fibre security, it is essential that future studies test interactive effects between these ecosystem services in different systems and environmental conditions.

Semi-natural habitats (SNHs) in agricultural landscapes represent important refugia for biodiversity including organisms providing ecosystem services. Their spill-over into agricultural fields may lead to the provision of regulating ecosystem services such as biological pest control ultimately affecting agricultural yield. Still, it remains largely unexplored, how different habitat types and their distributions in the surrounding landscape shape this provision of ecosystem services within arable fields. Hence, in this thesis I investigated the effect of SNHs on biodiversity-driven ecosystem services and disservices affecting wheat production with an emphasis on the role and interplay of habitat type, distance to the habitat and landscape complexity. I established transects from the field border into the wheat field, starting either from a field-to-field border, a hedgerow, or a kettle hole, and assessed beneficial and detrimental organisms and their ecosystem functions as well as wheat yield at several in-field distances. Using this study design, I conducted three studies where I aimed to relate the impacts of SNHs at the field and at the landscape scale on ecosystem service providers to crop production. In the first study, I observed yield losses close to SNHs for all transect types. Woody habitats, such as hedgerows, reduced yields stronger than kettle holes, most likely due to shading from the tall vegetation structure. In order to find the biotic drivers of these yield losses close to SNHs, I measured pest infestation by selected wheat pests as potential ecosystem disservices to crop production in the second study. Besides relating their damage rates to wheat yield of experimental plots, I studied the effect of SNHs on these pest rates at the field and at the landscape scale. Only weed cover could be associated to yield losses, having their strongest impact on wheat yield close to the SNH. While fungal seed infection rates did not respond to SNHs, fungal leaf infection and herbivory rates of cereal leaf beetle larvae were positively influenced by kettle holes. The latter even increased at kettle holes with increasing landscape complexity suggesting a release of natural enemies at isolated habitats within the field interior. In the third study, I found that also ecosystem service providers benefit from the presence of kettle holes. The distance to a SNH decreased species richness of ecosystem service providers, whereby the spatial range depended on species mobility, i.e. arable weeds diminished rapidly while carabids were less affected by the distance to a SNH. Contrarily, weed seed predation increased with distance suggesting that a higher food availability at field borders might have diluted the predation on experimental seeds. Intriguingly, responses to landscape complexity were rather mixed: While weed species richness was generally elevated with increasing landscape complexity, carabids followed a hump-shaped curve with highest species numbers and activity-density in simple landscapes. The latter might give a hint that carabids profit from a minimum endowment of SNHs, while a further increase impedes their mobility. Weed seed predation was affected differently by landscape complexity depending on weed species displayed. However, in habitat-rich landscapes seed predation of the different weed species converged to similar rates, emphasising that landscape complexity can stabilize the provision of ecosystem services. Lastly, I could relate a higher weed seed predation to an increase in wheat yield even though seed predation did not diminish weed cover. The exact mechanisms of the provision of weed control to crop production remain to be investigated in future studies. In conclusion, I found habitat-specific responses of ecosystem (dis)service providers and their functions emphasizing the need to evaluate the effect of different habitat types on the provision of ecosystem services not only at the field scale, but also at the landscape scale. My findings confirm that besides identifying species richness of ecosystem (dis)service providers the assessment of their functions is indispensable to relate the actual delivery of ecosystem (dis)services to crop production.

Habitat management is increasingly considered as a promising approach to favor the ecosystem service of biological control by enhancing natural enemies. However, habitat management, whether at local or landscape scale, remains very uncertain for farmers. Interactions between ecological processes and agricultural practices are indeed uncertain and site-specific, which makes implementation difficult. Thus, prospecting innovations based on habitat management may benefit from integrating local stakeholders and their knowledge. Our objective is to explore with both local and scientific stakeholders how they perceive agricultural practices, ecological processes, and services related to biological pest control and habitat management. We conducted a participatory Bayesian Network modeling approach with five stakeholders in Southwest France around apple orchard cultivation. We co-constructed such Bayesian Networks based on participants’ knowledge. We explored scenarios favoring natural enemies and habitat manipulation with each participant’s Bayesian Network. We compared how different stakeholders perceive the impact of each scenario on the biological control ecosystem service. Our results indicate that a landscape with a high proportion of semi-natural habitats does not translate into significant biological control for most participants even though some stakeholders perceive a significant impact on generalist predators’ activity within orchards. For these local stakeholders, habitat management at the orchard level such as inter-row vegetation seems currently more promising than at the landscape scale. Here, we show for the first time that the use of Bayesian modeling in a participatory manner can give precious insights into the most promising perspectives on habitat management at different scales. These different local perspectives suggest in particular that further dialogue between ecologists and local stakeholders should be sought about inter-row habitat management as the most promising practice to foster biological pest control and other ecosystem services.

As global consumption increases, there is a growing emphasis on the production of food and the use of other resources necessary for life. Consequently, many ecosystems are stressed because their ability to produce market goods is favoured over other critical functions and services that ecosystems provide such as energy transfer, water regulation, nutrient filtering, and carbon sequestration. Capturing these benefits using ecosystem services thinking offers decision makers a methodology for considering the multiple benefits that ecosystems provide. However, gaps in our understanding of how we can make the ecosystem services concept operational remain. Recognising the relationship between natural capital stocks and the provision of ecosystem processes and services is a crucial step in operationalising ecosystem services thinking. I advance this concept by identifying that attributes of natural capital are not uniform in their amenability to change. Hence, the central tenet of this thesis is that management actions targeted at manageable attributes of natural capital stocks is effective for influencing provision of ecosystem services and benefits. I test how management practices influence natural capital stocks that contribute to the provision of required ecosystem services, using a ‘provider group’ approach. Provider groups are sets of species which exhibit attributes which contribute to ecosystem services and benefits. The traditionally farmed grassland system in the Southeastern Carpathians, Romania, is a good example of a multifunctional landscape providing provisioning, regulating, and cultural ecosystem services and thus a useful case study to test this approach. I assigned grassland plant species to provider groups (quality fodder, medical and aromatic compounds, honey, pollen, nitrogen fixation, and conservation concern) based on their characteristics and tested the impact of management practices (abandonment of hay meadows, grazing, and mowing) on species diversity and abundance within each group. Over three quarters (77%) of the 210 unique species sampled during this study contributed to at least one provider group and over a third (36%) contributed to more than one group. I found that different management practices favour certain provider groups over others, and thus supply of certain ecosystem services over others. A more nuanced understanding of the influence of management practices on natural capital stocks can better inform agricultural and conservation policies targeted at sustaining multifunctional landscapes. Incorporation of social data, particularly that describing human behaviour and decision making, is critical to embed the ecosystem services concept into natural resource management policy and practice. Riparian management is a common policy option for mitigating the externalities of land use. A riparian management programme has been running in Taranaki Region, New Zealand for over 20 years providing a useful case study to elicit farmers perceptions and experiences of the pros and cons of planting riparian margins. I found the views of dairy farmers farming the Taranaki ring plain to be varied. Farmers with planted margins reported experiencing many on and off-farm benefits from multi-tier riparian plantings including production, environmental, and social values. This group of farmers identified 32 aspects of riparian vegetation across nine categories, 65% of which were positive aspects and 35% of which were negative aspects. Farmers who had fenced but not planted their riparian margins also believe benefits for water quality, animal safety, and farm management can be achieved from fenced grass strip riparian margins but were less convinced about additional benefits from planting. This group of farmers identified 15 aspects of riparian vegetation across four categories, all of which (100%) were negative aspects. Recognising that farmer’s perceptions and/or experiences vary can help inform how best to structure and deliver policies for sustaining provision of multiple ecosystem services and benefits. Biodiversity offsetting represents a critical application of the ecosystem services concept as trading biodiversity also inherently trades the associated ecosystem service values. Further, trading biodiversity in an offset exchange embodies the manipulation of natural capital stocks, in both the removal of species and habitats and in their replacement or enhancement elsewhere. Currencies used to evaluate offset proposals can either aggregate (combine measures of biodiversity attributes into a composite unit) or disaggregate (individually account for each measured biodiversity attribute of interest). I developed a disaggregated accounting model that balances like-for-like biodiversity trades using a suite of area by condition currencies to individually calculate the net present biodiversity value (NPBV) by which to evaluate no net loss for each biodiversity attribute inputted into the model. The model improves on more aggregated models by enabling increased transparency of biodiversity offsetting proposals, and thus improved decision making processes. This thesis provides an increased understanding of the relationship between management actions and ecosystem services and associated benefits at local scales, and a collection of tools and methods to support decision making targeted at sustaining multifunctional landscapes. Overall, this research illustrates that a natural capital focussed ecosystem services approach provides an opportunity to shift land management towards practices that sustain rather than deplete the natural capacity of ecosystems.

Large-scale use of the persistent and potent neonicotinoid and fipronil insecticides has raised concerns about risks to ecosystem functions provided by a wide range of species and environments affected by these insecticides. The concept of ecosystem services is widely used in decision making in the context of valuing the service potentials, benefits, and use values that well-functioning ecosystems provide to humans and the biosphere and, as an endpoint (value to be protected), in ecological risk assessment of chemicals. Neonicotinoid insecticides are frequently detected in soil and water and are also found in air, as dust particles during sowing of crops and aerosols during spraying. These environmental media provide essential resources to support biodiversity, but are known to be threatened by long-term or repeated contamination by neonicotinoids and fipronil. We review the state of knowledge regarding the potential impacts of these insecticides on ecosystem functioning and services provided by terrestrial and aquatic ecosystems including soil and freshwater functions, fisheries, biological pest control, and pollination services. Empirical studies examining the specific impacts of neonicotinoids and fipronil to ecosystem services have focused largely on the negative impacts to beneficial insect species (honeybees) and the impact on pollination service of food crops. However, here we document broader evidence of the effects on ecosystem functions regulating soil and water quality, pest control, pollination, ecosystem resilience, and community diversity. In particular, microbes, invertebrates, and fish play critical roles as decomposers, pollinators, consumers, and predators, which collectively maintain healthy communities and ecosystem integrity. Several examples in this review demonstrate evidence of the negative impacts of systemic insecticides on decomposition, nutrient cycling, soil respiration, and invertebrate populations valued by humans. Invertebrates, particularly earthworms that are important for soil processes, wild and domestic insect pollinators which are important for plant and crop production, and several freshwater taxa which are involved in aquatic nutrient cycling, were all found to be highly susceptible to lethal and sublethal effects of neonicotinoids and/or fipronil at environmentally relevant concentrations. By contrast, most microbes and fish do not appear to be as sensitive under normal exposure scenarios, though the effects on fish may be important in certain realms such as combined fish-rice farming systems and through food chain effects. We highlight the economic and cultural concerns around agriculture and aquaculture production and the role these insecticides may have in threatening food security. Overall, we recommend improved sustainable agricultural practices that restrict systemic insecticide use to maintain and support several ecosystem services that humans fundamentally depend on.

Ecosystem Services in Agricultural and Urban Landscapes, edited by SteveWratten, HarpinderSandhu, RossCullen, and RobertCostanza. Published by Wiley‐Blackwell, Queensland, Australia,2013, pp. 200, ISBN: 978‐1‐4051‐7008‐6, AU$ 124.95 (hardcover), AU$99.99 (E‐book).

Optimizing intermediate ecosystem services in agriculture using rules based on landscape composition and configuration indices

Selective flowers to enhance biological control of cabbage pests by parasitoids

Increasing plant diversity in agricultural systems is a promising way to balance food production and biodiversity conservation. Biological pest control, a crucial ecosystem service delivered by natural enemies, could particularly benefit from increased plant diversity at the local scale. Such positive effects however often depend on the landscape context that shapes the pool of natural enemy species available and their ability to colonize newly created habitats. However, how the landscape context modulates the local effect of plant diversity on natural enemies and pest control services remains unclear. Here, we manipulated the diversity of cover crops (2 versus 20 plant species) in nine pairs of vineyards located along a landscape gradient ranging from 20 to 60% of semi‐natural habitats. We sampled natural enemy communities in the soil and foliage and measured the predation rate of an important moth pest in European vineyards ( Lobesia botrana ). Diverse cover crops enhanced the abundance of natural enemies by 140% across the experiment, but without changing their taxonomic richness and composition. We further found a distance‐decay effect of cover crops on natural enemy abundance across cover crop types. The landscape context remarkably modulated the effects of local plant diversity on natural enemy abundance and predation rates. While predation rates were on average similar in the low and high cover crop diversity treatments across the experiment, diverse cover crops had higher positive effects on predation and natural enemies in simple (&lt;50% semi‐natural habitats) than complex landscapes. Predation rates increased from 11 to 42% in the high compared with low cover crop diversity treatments in simple landscapes. Synthesis and applications : Our study demonstrates the benefits of increasing plant diversity at the local scale to enhance the abundance of natural enemies as well as the level of biological pest control services in vineyard agroecosystems. Diverse cover crops mostly benefit natural enemies and biological pest control in simplified landscapes, highlighting that the success of local agroecological practices in improving biodiversity and ecosystem services depends on the landscape context. Thus, we suggest that a strategic spatial arrangement of agricultural practices increasing local plant diversity is necessary to maximize beneficial effects on biodiversity and ecosystem services.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

Conservation practices in agriculture—such as biological pest control, provision of pollinator habitat and cover cropping—may provide ecosystem services that are beneficial to both farmers and wildlife. Despite these benefits, however, their use is not yet widespread and the factors that may limit adoption are not well-understood. In this study we tested potential associations between farmers' beliefs about ecosystem services and their management practices using data collected from questionnaires and cognitive maps from 31 Michigan blueberry and cherry farmers describing their farming systems. We found that farmers who included key biological pest control concepts in their mental model representations reported the use of more conservation practices, and/or participation in conservation programs, than those who did not. In addition, the timing of management practices was a more central factor in the mental models of farmers who included both natural predators and beneficial insects than those omitting these factors. Finally, the farmers who included those two factors showed higher degrees of systems thinking based on mental model metric analysis. We suggest that outreach emphasizing the relationships between ecosystem services and the factors farmers view as most important may positively influence communication and potential of adoption of conservation practices and preventative pest management strategies.

Relationship between stoichiometry and ecosystem services: A case study of organic farming systems