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 of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

To address the challenges of biodiversity conservation and commodity production, a framework has been proposed that distinguishes between the integration ("land sharing") and separation ("land sparing") of conservation and production. Controversy has arisen around this framework partly because many scholars have focused specifically on food production rather than more encompassing notions such as land scarcity or food security. Controversy further surrounds the practical value of partial trade-off analyses, the ways in which biodiversity should be quantified, and a series of scale effects that are not readily accounted for. We see key priorities for the future in (1) addressing these issues when using the existing framework, and (2) developing alternative, holistic ways to conceptualise challenges related to food, biodiversity, and land scarcity.

Summary1. Landscape simplification and habitat fragmentation may cause severe declines of less mobile and habitat specialist species and lead to biotic homogenization of species communities, but largescale empirical evidence on biotic homogenization remains sparse. 2. We sampled butterfly and day-active geometrid moth communities within 134 differently fragmented landscapes in Finland situated in five geographical regions. Overall species richness was partitioned into alpha and beta diversity and butterflies were assigned a species-specific mobility rank and habitat specificity score based on published ecological trait classifications. 3. Alpha and beta diversity of butterflies and geometrid moths decreased with increasing agricultural intensity, independently of geographical position. The responses were either linear or nonlinear with accelerating decrease of diversity when arable field cover exceeded 60%. 4. Mobility rank and percentage generalists of butterfly communities increased linearly with increasing field cover. 5. In landscapes with high agricultural intensity (>60% field coverage), the decrease in beta diversity of butterflies was strongly associated with an increasing proportion of habitat generalists and increasing average mobility in the butterfly communities. However, there was no such relationship in landscapes with low or moderate agricultural intensity. 6. Synthesis and applications. We demonstrate that biotic homogenization caused by land-use change arises as a consequence of the loss of habitat specialists and poor dispersers in intensively cultivated landscapes with simplified landscape structure. Agri-environment schemes will therefore be inefficient in protecting high beta diversity unless they explicitly increase habitat availability and connectivity for habitat specialists and poor dispersers.

Co-flowering plant species commonly share flower visitors, and thus have the potential to influence each other's pollination. In this study we analysed 750 quantitative plant-pollinator networks from 28 studies representing diverse biomes worldwide. We show that the potential for one plant species to influence another indirectly via shared pollinators was greater for plants whose resources were more abundant (higher floral unit number and nectar sugar content) and more accessible. The potential indirect influence was also stronger between phylogenetically closer plant species and was independent of plant geographic origin (native vs. non-native). The positive effect of nectar sugar content and phylogenetic proximity was much more accentuated for bees than for other groups. Consequently, the impact of these factors depends on the pollination mode of plants, e.g. bee or fly pollinated. Our findings may help predict which plant species have the greatest importance in the functioning of plant-pollination networks.

Original Citation:A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes Published version:DOI:10.1111/gcb.13714 Terms of use:Open Access (Article begins on next page) Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law. Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species richness, and whether impacts differ across spatial scales and landscape contexts. Using a global meta-dataset, we quantified the effects of organic farming and plant diversification on abundance, local diversity (communities within fields), and regional diversity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in-field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in-field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem service providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacommunities that may provide temporal and spatial stability of ecosystem service provisioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes. Availability: This is the author's manuscript

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Because population size is sensitive to changes in adult survival, adult survival may be buffered against environmental variability. Philopatry may be adaptive in changing environments, but it could also constrain breeding habitat selection under changing conditions such as shifting predation regimes. Habitat preference and quality could become decoupled in long-lived philopatric species that evolved in stable environments when suddenly faced by increased adult predation risk, as dispersal may be triggered by past reproductive failure. We evaluated whether the Baltic eider (Somateria m. mollissima) population may currently face a predation-induced ecological trap. Eiders are philopatric and nest on open and forested islands. We hypothesized that open-nesting females would be disproportionately affected by increased predation. We compared female annual survival in these two habitats in 1996-2010. We also tested for effects of time trends, winter severity (NAO), female body condition, and habitat-specific predation pressure on survival. Our results revealed the lowest survival recorded for this species (Φ = 0.720), and survival on open islands was significantly lower (Φ = 0.679) than on forested islands (Φ = 0.761). Nonetheless, only 0.7 % of females changed breeding habitat type despite ample availability of alternative islands, and breeding phenology in both habitats was similar. Female survival increased with body condition, while it was unrelated to winter climate and stable over time. Open islands had a higher predation pressure on incubating females. Breeding philopatry results in a predator-mediated ecological trap for open-nesting eiders. Our results contribute to explaining the drastic decline of the Baltic eider population.