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Natural and semi-natural habitats within agricultural landscapes provide food and nesting resources for wild bees, thus promoting crop pollination services. In central Spain, a large network of drove roads (DRs) crosses extensive areas of intensive agricultural fields. DRs are tracks (20⿿75 m wide) with semi-natural vegetation, protected for their priority function of transhumant livestock herding. In this study, we analyse the bee community of one of the main Spanish DRs, and evaluate its effects on flower visitation and seed set in adjacent sunflower fields. We used pan traps to assess bee abundance and richness at 13 sites along the DR and in adjacent sunflower fields at 10, 75 and 150 m from the DR. We also conducted visual counts to assess visitation rates to sunflower heads and measured seed set. Wild bee abundance and richness were significantly higher in the DR than in sunflower fields; but there were no significant differences among distances within sunflower fields. Honey bee abundance did not differ between the DR and sunflower fields. Wild bee visitation to sunflower heads was higher at 10 m compared to 75 and 150 m from the DR, but differences in honey bee visitation were non-significant. Sunflower seed set was significantly higher at 10 m compared to 75 and 150 m, and was associated with wild bee abundance, but not with honey bee abundance. Our results show that livestock DRs act as reservoirs of wild bee diversity within intensive agricultural matrices, enhancing wild bee visitation and seed set in adjacent sunflower crops.

Species flower production and flowering phenology vary from year to year due to extrinsic factors. Inter-annual variability in flowering patterns may have important consequences for attractiveness to pollinators, and ultimately, plant reproductive output. To understand the consequences of flowering pattern variability, a community approach is necessary because pollinator flower choice is highly dependent on flower context. Our objectives were: 1) To quantify yearly variability in flower density and phenology; 2) To evaluate whether changes in flowering patterns result in significant changes in pollen/nectar composition. We monitored weekly flowering patterns in a Mediterranean scrubland community (23 species) over 8 years. Floral resource availability was estimated based on field measures of pollen and nectar production per flower. We analysed inter-annual variation in flowering phenology (duration and date of peak bloom) and flower production, and inter-annual and monthly variability in flower, pollen and nectar species composition. We also investigated potential phylogenetic effects on inter-annual variability of flowering patterns. We found dramatic variation in yearly flower production both at the species and community levels. There was also substantial variation in flowering phenology. Importantly, yearly fluctuations were far from synchronous across species, and resulted in significant changes in floral resources availability and composition at the community level. Changes were especially pronounced late in the season, at a time when flowers are scarce and pollinator visitation rates are particularly high. We discuss the consequences of our findings for pollinator visitation and plant reproductive success in the current scenario of climate change.

Understanding biodiversity distribution is a primary goal of community ecology. At a landscape scale, bee communities are affected by habitat composition, anthropogenic land use, and fragmentation. However, little information is available on local-scale spatial distribution of bee communities within habitats that are uniform at the landscape scale. We studied a bee community along with floral and nesting resources over a 32 km2 area of uninterrupted Mediterranean scrubland. Our objectives were (i) to analyze floral and nesting resource composition at the habitat scale. We ask whether these resources follow a geographical pattern across the scrubland at bee-foraging relevant distances; (ii) to analyze the distribution of bee composition across the scrubland. Bees being highly mobile organisms, we ask whether bee composition shows a homogeneous distribution or else varies spatially. If so, we ask whether this variation is irregular or follows a geographical pattern and whether bees respond primarily to flower or to nesting resources; and (iii) to establish whether body size influences the response to local resource availability and ultimately spatial distribution. We obtained 6580 specimens belonging to 98 species. Despite bee mobility and the absence of environmental barriers, our bee community shows a clear geographical pattern. This pattern is mostly attributable to heterogeneous distribution of small (