Wildflower

Abstract: Summary 1. Pollination services from wild insects contribute to crop productivity around the world, but are at risk of decline in agricultural landscapes. Using highbush blueberry as a model system, we tested whether wildflower plantings established adjacent to crop fields would increase the abundance of wild pollinators during crop bloom and enhance pollination and yield. 2. Plantings were seeded in 2009 with a mix of 15 perennial wildflower species that provided season-long bloom and increased plant density and floral area during the subsequent 3 years. 3. Honeybees visiting blueberry flowers had similar abundance in enhanced and control fields in all 4 years of this study, whereas wild bee and syrphid abundance increased annually in the fields adjacent to wildflower plantings. 4. Crop pollination parameters including percentage fruit set, berry weight and mature seeds per berry were significantly greater in fields adjacent to wildflower plantings 3 and 4 years after seeding, leading to higher crop yields and with the associated revenue exceeding the cost of wildflower establishment and maintenance. 5. Synthesis and applications. We suggest that provision of forage habitat for bees adjacent to pollinator-dependent crops can conserve wild pollinators in otherwise resource-poor agricultural landscapes. Over time, these plantings can support higher crop yields and bring a return on the initial investment in wildflower seed and planting establishment, also insuring against loss of managed pollinators. Further understanding of the importance of planting size, location and landscape context will be required to effectively implement this practice to support crop pollination.

Abstract: Sown wildflower strips are increasingly being established in European countries within agri-environmental schemes to enhance biodiversity, especially in intensively used agricultural areas. 2. The regulations vary between countries regarding the seed mixture, intensity of management and period of time over which subsidies are given. Insects in particular are intended to benefit from these schemes. 3. This review treats studies of insect diversity and abundance in sown wildflower strips. Schemes on wildflower strips in several countries in Central and Northern Europe are compared. 4. In a significant majority of studies, sown wildflower strips support higher insect abundances and diversity than cropped habitats. In general, numbers and diversity also tend to be higher than in other margin types such as sown grass margins and natural regeneration, but pollen- and nectar-rich flower mixtures may outperform them. 5. Common species are the main beneficiaries of the establishment of wildflower strips, although some studies point out the presence of rare or declining insect spe-

Abstract: I studied the spring wildflower community of mesic deciduous forests in piedmont North Carolina to determine (a) the extent to which fecundity is pollination-limited in the community, (b) the importance of competition for pollination in affecting seed-set, and (c) the characteristics of plants and their floral visitors that most contribute to full pollination. Although inadequate pollination seems likely in the community, supplemental hand-pollination significantly improved fecundity in just 3 of the 12 species I examined. Pollination-limited reproductive success was evident only in a distinctive subset of the community, species pollinated primarily by queen bumble bees. The majority of wildflower species are pollinated by flies and solitary bees. Measurements of visitation rates and pollinator effectiveness on these plants confirmed that they are usually adequately pollinated in spite of a short blooming season, considerable overlap in flowering times, extensive pollinator sharing by concurrently blooming species, and inclement weather that frequently interrupts insect activity. Many of the flies and solitary bees are inconstant foragers, yet competition for pollination among wildflower species through differential pollinator attraction or interspecific pollinator movements usually does not significantly decrease the seed-set of plants with shared visitors. Competition may act with other causes of insufficient pollination, however, as a selective force to maintain a characteristic set of floral biology traits within the community, including autogamy and self-compatibility, extended receptivity, and pollination by a variety of visitor types. That these floral traits contribute significantly to the successful pollination of vernal herbs was demonstrated by observations of visitor behavior, plant caging experiments that excluded visitors or restricted their access to selected flowers, and measure- ments of floral lifetimes and seed-set for individual plants. These traits are effective regardless of the source of pollination-limited fecundity, and it is the prevalence of such traits, rather than floral specialization or character displacement, that distinguishes the forest spring wildflower community from other communities with potentially inadequate pollinator service.