David Kleijn

Wageningen University & Research | WUR · Plant Ecology and Nature Conservation Group

Highbush blueberry production has expanded worldwide in recent decades. To safeguard future yields, it is essential to understand if insect pollination is limiting current blueberry production and which insects contribute to pollination in different production regions. We present a systematic review including a set of meta-analyses on insect-mediat...

BACKGROUND Maximising the effectiveness of natural pest control requires a detailed understanding of how service delivery is affected by natural enemy community diversity and composition. Many studies have investigated the effects of natural enemy abundance and species richness on pest control. Studies examining the effects of evenness and species...

Agricultural expansion and intensification have boosted global food production but have come at the cost of environmental degradation and biodiversity loss. Biodiversity-friendly farming that boosts ecosystem services, such as pollination and natural pest control, is widely being advocated to maintain and improve agricultural productivity while saf...

Agricultural expansion and intensification are key drivers of biodiversity decline. There is mounting evidence that modern farming impacts the effectiveness of protected areas as one of the key instruments of biodiversity conservation through, for example, eutrophication, pesticide emissions or increasing access to remote areas [1]. This is increas...

The abundance and diversity of plants and insects are important indicators of biodiversity, overall ecosystem health and agricultural production. Bees in particular are interesting indicators as they provide a key ecosystem service in many agricultural crops. Worldwide, habitat loss and fragmentation, agricultural intensification and climate change...

While wild pollinators play a key role in global food production, their assessment is currently missing from the most commonly used environmental impact assessment method, Life Cycle Assessment (LCA). This is mainly due to constraints in data availability and compatibility with LCA inventories. To target this gap, relative pollinator abundance esti...

Agricultural intensification has resulted in a decline in insect biodiversity and threatens the provision of valuable ecosystem services. Agri-environment schemes (AESs) have been implemented in an effort to conserve biodiversity on farmland and increase agricultural sustainability, but their effectiveness can vary widely. To better determine which...

Communication and dissemination are key elements to maximise SHOWCASE project impact and ensure long‐term effects. For that, an effective communication strategy is essential to convey the principles and best practices to integrate biodiversity in farm management to favour farmers’ livelihoods while promoting conservation in agricultural landscapes....

One of the most invoked mechanisms mediating the positive effect of pollinator diversity on plant reproduction is pollinator's niche complementarity (i.e. partitioning of resource use by different pollinator species). However, the influence of spatial and temporal pollinator's niche complementarity on crop pollination function is rarely tested. We...

The endangered continental Black-tailed Godwit (Limosa limosa limosa) is a migratory ground-nesting wader breeding in a wide variety of open, wet habitats across Europe. Conservation research has concentrated on the causes of population decline, but we know surprisingly little about whether any resources limit local breeding populations and if so,...

Grassland breeding waders have been steadily declining across Europe. Recent studies indicating a dramatic decline in grassland invertebrates' abundance and biomass, the key food of most grassland wader chicks, suggest a likely driver of the demise of waders. While agricultural intensification is generally inferred as the main cause for arthropod d...

Ecological intensification has been proposed as an alternative paradigm for intensive agriculture to boost yield sustainably through utilizing ecosystem services. A prerequisite to achieving this is to understand the relations between multiple ecosystem services and production, while taking growth conditions such as nutrient availability into consi...

The slow adoption by the agricultural sector of practices to promote biodiversity are thought to originate from three interrelated issues. First, we know little about which incentives effectively motivate farmers to integrate biodiversity into daily farm management. Second, few studies so far have produced evidence that biodiversity-based approache...

Human driven environmental changes increase the concentrations of polluting reactive compounds in the troposphere, such as ozone and nitrogen oxides. These changes lead to biodiversity losses and alter plant physiology and plant-pollinator interactions, essential for pollination services, with potential consequences for agricultural production. Her...

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop y...

Managing ecosystem services might reduce the dependence of modern agriculture on external inputs and increase the sustainability of agricultural production. Insect pollinators and arbuscular mycorrhizal fungi (AMF) provide vital ecosystem services for crop production, but it has not been tested whether their effects on crop yield interact and how t...

Enhancing the diversity of mass‐flowering crops (i.e. crop diversity) in agricultural landscapes is often proposed as a measure to favour pollinators and pollination, but it is uncertain whether crop diversity enhances pollinator richness on the wide landscape level. Here, we surveyed pollinator communities in semi‐natural habitats and mass‐floweri...

Pollinator declines have prompted efforts to assess how land-use change affects insect pollinators and pollination services in agricultural landscapes. Yet many tools to measure insect pollination services, require substantial landscape-scale data and technical expertise. In expert workshops, 3 straightforward methods (desk-based method, field surv...

Wildflower strips have been heralded as a promising way to enhance ecosystem services by providing organisms which may help make farming less dependent on external inputs. However, recent studies show inconsistent effects on delivery of ecosystem services and crop yield, warranting a more detailed analysis of the factors determining the effects of...

The importance of wild bees for crop pollination is well established, but less is known about which species contribute to service delivery to inform agricultural management, monitoring and conservation. Using sites in Great Britain as a case study, we use a novel qualitative approach combining ecological information and field survey data to establi...

Establishing wildflower strips has been suggested as an effective measure to promote pollination services, pest control or general insect biodiversity, but little is known about the integration of these different objectives when selecting flower seed mixtures. In ten agricultural landscapes in the Netherlands, we established a wildflower strip (0.4...

Global biodiversity is declining under pressure of agricultural intensification and land-use change. Two-thirds of the agricultural lands is directly or indirectly devoted to the production of animal products. Replacing animal-based proteins by plant-based proteins can be an important step to a more sustainable agricultural system. Lupins (Lupinus...

Bumble bees ( Bombus ) are a group of eusocial bees with a strongly generalised feeding pattern, collecting pollen from many different botanical families. Though predominantly generalists, some bumble bee species seem to have restricted dietary choices. It is unclear whether restricted diets in bumble bees are inherent or a function of local condit...

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Intensive agriculture faces the challenge of contributing to feeding the increasing global population while minimizing its adverse effects on the environment. Ecological intensification can help achieve this as it proposes to supplement artificial inputs with ecosystem services such as pollination, nutrient cycling and water retention. The mixed re...

While an increasing number of studies indicate that the range, diversity and abundance of many wild pollinators has declined, the global area of pollinator-dependent crops has significantly increased over the last few decades. Crop pollination studies to date have mainly focused on either identifying different guilds pollinating various crops, or o...

Managing ecosystem services may reduce the dependence of modern agriculture on external inputs and increase the sustainability of agricultural production. Insect pollinators and arbuscular mycorrhizal fungi (AMF) provide vital ecosystem services for crop production, but it remains unknown whether their effects on crop yield interact and how their e...

Wild bee populations are threatened by current agricultural practices in many parts of the world, which may put pollination services and crop yields at risk. Loss of pollination services can potentially be predicted by models that link bee abundances with landscape‐scale land‐use, but there is little knowledge on the degree to which these statistic...

Floral plantings are promoted to foster ecological intensification of agriculture through provision-ing of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest...

Agricultural expansion and intensification have resulted in strong declines in farmland biodiversity across Europe. In many intensively farmed landscapes, linear landscape elements such as field boundaries, road verges and ditch banks are the main remaining green infrastructures providing refuge for biodiversity, and as such play a pivotal role in...

Ecological intensification of farming proposes that more effective use of ecosystem services can, in part, replace external inputs allowing farmers to maintain high crop yields while reducing adverse effects on the environment. However, uptake of ecological intensification among farmers is currently hampered by a lack of realistic studies on the ag...

Agricultural intensification and associated loss of high‐quality habitats are key drivers of insect pollinator declines. With the aim of decreasing the environmental impact of agriculture, the 2014 EU Common Agricultural Policy (CAP) defined a set of habitat and landscape features (Ecological Focus Areas: EFAs) farmers could select from as a requir...

There is widespread concern regarding declines in bee populations given their importance for the functioning of both natural and managed ecosystems. An increasing number of studies find negative relations between bee species richness and simplification of agricultural landscapes, but the role of land-use intensity and its relative importance compar...

Current conservation instruments, which for most species rely heavily on protected areas, are insufficient to halt biodiversity loss. Conservation initiatives in the wider landscape surrounding protected areas are needed to achieve the impact required for reversing negative biodiversity trends. Focussing on intensively used north-western European l...

Pollination by insects is a key input into many crops, with managed honeybees often being hired to support pollination services. Despite substantial research into pollination management, no European studies have yet explored how and why farmers managed pollination services and few have explored why beekeepers use certain crops. Using paired surveys...

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance...

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance...

Interactions between aboveground and belowground organisms are important drivers of plant growth and performance in natural ecosystems. Making practical use of such above-belowground biotic interactions offers important opportunities for enhancing the sustainability of agriculture, as it could favor crop growth, nutrient supply, and defense against...

Agri‐environment management (AEM) started in the 1980s in Europe to mitigate biodiversity decline, but the effectiveness of AEM has been questioned. We hypothesize that this is caused by a lack of a large enough ecological contrast between AEM and non‐treated control sites. The effectiveness of AEM may be moderated by landscape structure and land‐u...

As a response to concerns for the conservation of pollinator diversity, mitigation measures are being initiated in the Netherlands by a wide variety of organizations and private individuals. Most of these efforts focus on the restoration of floral resources, by sowing wildflower mixtures and/or improving terrain management. Such initiatives are, ho...

Insect pollination is a well-studied ecosystem service that supports production in 75% of globally important crops. Although yield is known to be sustained and regulated by a bundle of ecosystem services and management factors, the contribution of pollination to yield has been mostly studied in isolation. Here, we compiled and reviewed research on...

Conserving and restoring semi-natural habitat, i.e. enhancing landscape complexity, is one of the main strategies to mitigate pollinator decline in agricultural landscapes. However, we still have limited understanding of how landscape complexity shapes pollinator communities in both crop and non-crop habitat, and whether pollinator responses to lan...

Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects...

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and s...

Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects...

The current worldwide pollinator decline is caused by the interplay of different drivers. Several strategies have been undertaken to counteract or halt this decline, one of which is the implementation of wildflower fields. These supplementary flowers provide extra food resources and have proven their success in increasing pollinator biodiversity an...

Soil organic matter (SOM) is declining in most agricultural ecosystems, impacting multiple ecosystem services including erosion and flood prevention, climate and greenhouse gas regulation as well as other services that underpin crop production, such as nutrient cycling and pest control. Ecological intensification aims to enhance crop productivity b...

There is worldwide concern about the environmental costs of conventional intensification of agriculture. Growing evidence suggests that ecological intensification of mainstream farming can safeguard food production, with accompanying environmental benefits; however, the approach is rarely adopted by farmers. Our review of the evidence for replacing...

The sustainability of agriculture can be improved by integrating management of ecosystem services, such as insect pollination, into farming practices. However, large‐scale adoption of ecosystem services‐based practices in agriculture is lacking, possibly because growers undervalue the benefits of ecosystem services compared to those of conventional...

Agricultural landscapes rich in natural and semi-natural habitats promote biodiversity and important ecosystem services for crops such as pest control. However, semi-natural habitats may fail to deliver these services if agricultural pests are disconnected from the available pool of natural enemies, as may be the case with invasive species. This st...

Understanding how ecosystem services interact to support crop yield is essential for achieving food security. Here we evaluate the interactions among biotic pest regulation, pollination, and nutrient cycling. We found only 16 studies providing 20 analyses of two-way interactions. These studies show that multiple services limit crop yield simultaneo...

THIS IS A CONFERENCE PRESENTATION ABSTRACT Although agriculture depends critically on biodiversity-based ecosystem services such as insect pollination, conservation of biodiversity in agricultural landscapes has seen little uptake by the agricultural sector. We argue that this is largely because we lack knowledge on the relative importance of polli...

Declining pollinator populations have caused concern about consequences for food production, and have initiated an increasing number of initiatives that aim to mitigate pollinator loss through enhancement of floral resources. Studies evaluating effects of mitigation measures generally demonstrate positive responses of pollinators to floral resource...

Pollinator communities exhibit variable responses to changing landscape composition. A general expectation is that a decreasing cover of semi-natural habitats negatively affects pollinator reproduction, population size and pollination services, but few studies have investigated the simultaneous effects of landscape complexity on different aspects o...

Simultaneously enhancing ecosystem services provided by biodiversity below and above ground is recommended to reduce dependence on chemical pesticides and mineral fertilisers in agriculture. However, consequences for crop yield have been poorly evaluated. Above ground, increased landscape complexity is assumed to enhance biological pest control, wh...

There is increasing evidence showing that microbes can influence plant-insect interactions. In addition, various studies have shown that aboveground pathogens can alter the interactions between plants and insects. However, little is known about the role of soil-borne pathogens in plant-insect interactions. It is also not known how environmental con...

Effects of soil organic matter (SOM) content (low, high) on fresh aphid biomass in both sterilized and unsterilized soil. (DOC)

Effects of soil organic matter (SOM) content (low, high) on aboveground plant biomass in both sterilized and unsterilized soil. (DOC)

Fresh aphid biomass, aboveground plant biomass, and C:N ratio explained by soil sterilization, soil organic matter content and Rhizoctonia solani addition. (DOC)

Effects of soil sterilization, soil organic matter (SOM) content (low, high) and Rhizoctonia solani addition on C:N ratio of Triticum aestivum leaves. (DOC)

Linear models explaining fresh aphid biomass (Sitobion avenae, √(ln+1) transformed), aboveground dried plant biomass (stem and flower biomass) of wheat (Triticum aestivum) and plant C:N ratio (√ transformed) by soil sterilization, soil organic matter (SOM) content, Rhizoctonia solani addition and all possible interactions. (DOC)

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