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There is increasing evidence that farmers in many areas are achieving below maximum yields due to insufficient pollination. Practical and effective approaches are needed to maintain wild pollinator populations within agroecosystems so they can deliver critical pollination services that underpin crop production. We established nesting and wildflower habitat interventions in 24 UK apple orchards and measured effects on flower-visiting insects and the pollination they provide, exploring how this was affected by landscape context. We quantified the extent of pollination deficits and assessed whether the management of wild pollinators can reduce deficits and deliver improved outcomes for growers over 3 years. Wildflower interventions increased solitary bee numbers visiting apple flowers by over 20%, but there was no effect of nesting interventions. Other pollinator groups were influenced by both local and landscape-scale factors, with bumblebees and hoverflies responding to the relative proportion of semi-natural habitat at larger spatial scales (1000 m), while honeybees and other flies responded at 500 m or less. By improving fruit number and quality, pollinators contributed more than £16 k per hectare. However, deficits (where maximum potential was not being reached due to a lack of pollination) were recorded and the extent of these varied across orchards, and from year to year, with a 22% deficit in output in the worst (equivalent to ~£14 k/ha) compared to less than 3% (equivalent to ~£2 k/ha) in the best year. Although no direct effect of our habitat interventions on deficits in gross output was observed, initial fruit set and seed set deficits were reduced by abundant bumblebees, and orchards with a greater abundance of solitary bees saw lower deficits in fruit size. The abundance of pollinators in apple orchards is influenced by different local and landscape factors that interact and vary between years. Consequently, pollination, and the extent of economic output deficits, also vary between orchards and years. We highlight how approaches, including establishing wildflower areas and optimizing the ratio of cropped and non-cropped habitats can increase the abundance of key apple pollinators and improve outcomes for growers.

Urban areas are often perceived to have lower biodiversity than the wider countryside, but a few small-scale studies suggest that some urban land uses can support substantial pollinator populations. We present a large-scale, well-replicated study of floral resources and pollinators in 360 sites incorporating all major land uses in four British cities. Using a systems approach, we developed Bayesian network models integrating pollinator dispersal and resource switching to estimate city-scale effects of management interventions on plant-pollinator community robustness to species loss. We show that residential gardens and allotments (community gardens) are pollinator 'hotspots': gardens due to their extensive area, and allotments due to their high pollinator diversity and leverage on city-scale plant-pollinator community robustness. Household income was positively associated with pollinator abundance in gardens, highlighting the influence of socioeconomic factors. Our results underpin urban planning recommendations to enhance pollinator conservation, using increasing city-scale community robustness as our measure of success.

As a K-strategist and comparatively sedentary species, the lesser horseshoe bat Rhinolophus hipposideros is considered sensitive to changes in habitat quality. Knowledge of the species' dietary requirements and use of foraging habitats is thus considered an essential prerequisite to manage its habitats adequately. Based on four large annual samples of faecal pellets from three different nursery colonies, including two consecutive years of sampling from one colony, we studied the diet of Central German populations of R. hipposideros. Consistent with findings of similar studies carried out in other parts of the distribution range of R. hipposideros, in our study, Diptera, Lepidoptera, and Neuroptera represented the most important groups of prey for the studied colonies. However, Hemiptera made a comparatively larger contribution in our study than in others, and so did Hymenoptera in one of the colonies. We found seasonal compositional variation in all four annual samples, as well as compositional variation ...

The resistance of a plant community against herbivore attack may depend on plant species richness, with monocultures often much more severely affected than mixtures of plant species. Here, we used a plant–herbivore system to study the effects of selective herbivory on consumption resistance and recovery after herbivory in 81 experimental grassland plots. Communities were established from seed in 2002 and contained 1, 2, 4, 8, 16 or 60 plant species of 1, 2, 3 or 4 functional groups. In 2004, pairs of enclosure cages (1 m tall, 0.5 m diameter) were set up on all 81 plots. One randomly selected cage of each pair was stocked with 10 male and 10 female nymphs of the meadow grasshopper, Chorthippus parallelus. The grasshoppers fed for 2 months, and the vegetation was monitored over 1 year. Consumption resistance and recovery of vegetation were calculated as proportional changes in vegetation biomass. Overall, grasshopper herbivory averaged 6.8%. Herbivory resistance and recovery were influenced by plant functional group identity, but independent of plant species richness and number of functional groups. However, herbivory induced shifts in vegetation composition that depended on plant species richness. Grasshopper herbivory led to increases in herb cover at the expense of grasses. Herb cover increased more strongly in species-rich mixtures. We conclude that selective herbivory changes the functional composition of plant communities and that compositional changes due to selective herbivory depend on plant species richness. peerReviewed

Summary Seed bank formation plays an important role in plant population dynamics. However, buried seeds face several mortality factors, including the decay caused by microbial activity. Recent seed burial studies involving both fungicide-treated seeds and untreated seeds provide evidence for the importance of saprophytic soil fungi as a seed mortality factor. In this review, we summarize the available evidence. We discuss the influence of abiotic and biotic environmental factors, the specificity of plant-fungal associations at the seed level and mechanisms of resistance to seed decay. Finally, we discuss implications for plant communities and for the biocontrol of agricultural weeds.

We investigated the influence of fungivorous soil invertebrates on seedling emergence from soil mesocosms buried in a ruderal grassland. Two out of three tested plant species, Centaurea nigra and Origanum vulgare, had a higher seedling emergence when we added the fungivorous collembolan Protaphorura fimata to mesocosms, compared to a control treatment where we excluded soil mesofauna by using defaunated soil and preventing re-colonization from the ambient soil. P. fimata increased seedling emergence to a similar extent as a treatment of the seeds with the fungicide Aathiram. In contrast, a treatment designed to allow re-colonization of defaunated soil from the ambient soil did not result in increased seedling emergence compared to the control treatment. In a third plant species, Anthriscus sylvestris, overall seedling emergence was too low for any significant treatment effects to be detected. This study corroborates the findings of a previous experiment carried out in the laboratory to explore th...

Insect pollinators provide a crucial ecosystem service, but are under threat. Urban areas could be important for pollinators, though their value relative to other habitats is poorly known. We compared pollinator communities using quantified flower-visitation networks in 36 sites (each 1 km(2)) in three landscapes: urban, farmland and nature reserves. Overall, flower-visitor abundance and species richness did not differ significantly between the three landscape types. Bee abundance did not differ between landscapes, but bee species richness was higher in urban areas than farmland. Hoverfly abundance was higher in farmland and nature reserves than urban sites, but species richness did not differ significantly. While urban pollinator assemblages were more homogeneous across space than those in farmland or nature reserves, there was no significant difference in the numbers of rarer species between the three landscapes. Network-level specialization was higher in farmland than urban sites. Relative to other habitats, urban visitors foraged from a greater number of plant species (higher generality) but also visited a lower proportion of available plant species (higher specialization), both possibly driven by higher urban plant richness. Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators.

Summary 1 Seeds in soil seed banks are exposed to a number of mortality factors, including fungal attack. The composition of the soil fungal community is affected by fungus-feeding soil invertebrates, suggesting that fungus-feeding soil animals may affect losses of seeds caused by fungal attack. We tested this assumption with a full factorial experiment that examined the effects of fungivorous Collembola and of seed coating with a fungicide on seed longevity of four grassland plant species. 2 Seeds of Centaurea nigra, Dactylis glomerata, Origanum vulgare and Taraxacum officinale were kept in Petri dishes filled with soil under conditions that stimulate fungal growth but not seed germination. Treatment factors were (i) addition of the collembolan Protaphorura fimata, a soil-dwelling fungus feeder; and (ii) seed treatment with the fungicide chitosan. After 5 weeks, germination was recorded and viability of the remaining ungerminated seeds was determined. 3 In three species, the addition of P. fimata resulted in an increase in the number of remaining ungerminated viable seeds. This was due to reduced seed mortality (C. nigra, O. vulgare) or to reduced germination (D. glomerata). Seeds of T. officinale remained unaffected. 4 For the fungicide treatment, no significant main effect was found in any species, although in two species there was a significant interaction between the addition of Collembola and seed coating with chitosan. There is circumstantial evidence that this interaction may have resulted from a negative effect of chitosan on adult survival of P. fimata. 5 These results show that fungus-feeding soil invertebrates affect not only the performance of live plants, as shown in previous studies, but also the persistence of seeds in the soil, and that this effect varies between different plant species. 6 Our results suggest that by reducing the mortality of seeds due to fungal decay, fungal grazers may influence the dynamics of plant populations and the assembly of plant communities. Further experimentation under more realistic conditions is, however, required to investigate the importance of this process under field conditions.

Evidence for effects of saprophytic fungi on buried seed demography is usually obtained from studies involving the simultaneous burial of fungicide-treated seeds and of untreated seeds. However, any potential influence of fungicide treatment on seed dormancy levels is generally ignored in these studies. Also, some studies assume that a combination of several fungicidal compounds provides better protection against a broader range of fungi, ignoring chemical interactions that may potentially occur between different compounds. To investigate these issues, we carried out a 6-month burial experiment using seeds ofAnthriscus sylvestris(L.) Hoffm.,Centaurea nigraL. andDaucus carotaL., and three substrates differing in organic matter content. Three fungicidal compounds, captan, iprodione and mancozeb, were applied alone and in combination, including an untreated control. All fungicidal compounds and combinations thereof provided protection against fungal-induced seed mortality and, except for a low efficacy of iprodione in protecting seeds ofAnthriscus, there were no pronounced differences in seed mortality between different fungicide treatments. Captan temporarily inhibited germination inCentaurea, whereas a similar inhibition inDaucusseeds caused by mancozeb was more long lasting, suggesting an induction of secondary dormancy. Organic matter content had only a negligible influence on these results. Our results suggest that the basic conclusions from most seed burial studies are robust with respect to their choice of fungicide. We conclude by discussing further implications of our findings for the design and interpretation of seed burial studies.