A wildflower strip is a section of land set aside to grow wildflowers. These can be at the edge of a field to mitigate against agricultural intensification and monoculture; along road medians and verges; or in parkland or other open spaces such as the Coronation Meadows. Such strips provide an attractive amenity and can also improve biodiversity, conserving birds, insects and other wildlife.[1][2][3][4]
General characteristics
editWildflower strips are semi-natural habitats made up of mixtures of native herbaceous species and can be sown on arable field margins to provide multiple ecological, agricultural and conservation benefits. They typically measure 3 – 10 m in width [5] and vary in their plant species composition depending on their intended purpose.
Wildflower strips can serve various purposes. They may provide nectar sources for pollinators, promote biological pest control, or enhance local biodiversity by improving habitat quality and diversity.
Early conceptions of wildflower strips were developed in Switzerland in the 1980s. These ideas were merged under the German name "Buntbrachen" (wildflower strips) and established within Swiss agricultural policy.[6]
Wildflower strips can be naturally regenerated on a range of soil types. On nutrient-rich soils, the plant community is likely to have low species richness and be dominated by vigorous grasses. Therefore, lighter soils may be preferable to give all species present a reasonable chance.[5]
Infield wildflower strips have been trialled as an alternative to traditional wildflower strips that border field margins. This approach involves extending wildflower strips beyond field boundaries to traverse the centre of fields. These measures can be seen as an extension to in-field beetle banks and are primarily aimed at making a larger proportion of arable crops easily accessible to natural enemies of crop pests.[7]
Ecological benefits and conservation value
editWildflower strips not only add colour and aesthetic appeal to the otherwise homogeneous agricultural landscape, but also provide food, shelter and overwintering sites for arthropods.[8] These arthropods can play an important role in controlling insect pests of commercial crops.[9][10] They can also help pollinate crops, as do bumblebees and honeybees, which are attracted to the wildflowers for its source of nectar. Pest-controlling arthropods benefit from the high insulation capacity of the vegetation in the former case, making the wildflower strips suitable as overwintering sites during winter.[11] Wildflower strips can significantly enhance local biodiversity and mitigate declines in economically important invertebrate populations through intensive agriculture. They may be regarded as ecological compensation areas interspersed in a highly disturbed, wildlife-impoverished agroecosystem.[5]
Wildflower strips can also improve habitat connectivity within the agricultural landscape by functioning as wildlife corridors for beneficiary taxa.[6]
Economic benefits
editWildflower strips can benefit agriculture by attracting pollinating insects and pest-controlling arthropods. This can potentially improving crop yields. It is usually worthwhile to sow strips of wildflowers along a given area if the resulting increase in natural pollination improves crop yields beyond those obtained in the absence of wildflower strips. Investing in relatively inexpensive seed mixtures to create wildflower strips is an effective way for farmers to promote natural pollination and reduce reliance on commercially sourced pollinators, such as bumblebees. This also ensures against potential market supply failures.[12]
Restoring semi-natural habitats for pollinators can help offset the loss of pollination services caused by declines in pollinating insects, for example by establishing wildflower strips along field margins..[13]
Effectiveness
editWhile generally beneficial to wildlife, the success of a wildflower strip, from both an ecological and an agricultural perspective, depends on several important factors, such as the right plant species composition and the local landscape context in which the strip is established.[13] Ultimately however, the right choice of plant species to sow in the right place depends on the specific conservation goals of the wildflower strip. In an intensive agricultural landscape, for example, the best option may be to sow wildflower strips with a mixture of seeds from different species to attract a more taxonomically diverse range of pollinators. On the other hand, wildflower strips can be planted with a smaller range of species in a targeted approach to help save endangered pollinating insect species. In this case, seed mixtures should primarily contain the preferred host plants of the species in question[14]
To ensure a viable network of natural or near-natural habitats within the landscape to support wildlife movement, it is important to connect multiple wildflower strips to each other and to elements in the wider landscape elements.[5] However, it can take several years of vegetation growth and development before the ecological benefits appear..[10]
Wildflower strips should be designed to ensure seasonal continuity of floral resources for as long as possible in any given year. This can be achieved by sowing a mixture of annuals, biennials, and perennials at high densities and with differing flowering times.[5] By sowing species with different individual flowering times next to each other, the resulting wildflower strip will be available for use by a range of arthropods for more of the year.[15] This design also benefits insects with long colony cycles such as bumblebees.[13]
Ideal dominant plants within wildflower strips include species in the Fabaceae, which are especially favoured by pollinating bees, or Apiaceae (carrot family), which attract pest-controlling arthropods.[16] It is important to avoid choosing dominant species that are sensitive to herbivory by slugs and snails, such as Centaurea cyanus or Papaver rhoeas, since this can affect the growth and development of the wildflower strip.[17]
The economic practicality of planting and maintaining wildflower strips at the farmer's end is another consideration. Farmers will need to invest in the initial seed mixture for sowing and account for the cost of maintaining the wildflower strip in subsequent years to prevent invasion of vigorous grass species or other perennial weeds..[5]
The larva of target species may benefit from the selective sowing of food plants in wildflower strips, which can help achieve conservation goals. However, this aspect is often overlooked when designing agri-environment schemes.[18]
References
edit- ^ Ganser, Dominik; Mayr, Barbara; Albrecht, Matthias; Knop, Eva (December 2018), "Wildflower strips enhance pollination in adjacent strawberry crops at the small scale", Ecology and Evolution, 8 (23): 11775–11784, doi:10.1002/ece3.4631, ISSN 2045-7758, PMC 6303775, PMID 30598775
- ^ Grass, Ingo; Albrecht, Jörg; Farwig, Nina; Jauker, Frank (1 December 2021), "Plant traits and landscape simplification drive intraspecific trait diversity of Bombus terrestris in wildflower plantings", Basic and Applied Ecology, 57: 91–101, doi:10.1016/j.baae.2021.10.002, ISSN 1439-1791, S2CID 240241322
- ^ Haaland, Christine; Naisbit, Russell E.; Bersier, Louis-Félix (2011), "Sown wildflower strips for insect conservation: a review" (PDF), Insect Conservation and Diversity, 4 (1): 60–80, doi:10.1111/j.1752-4598.2010.00098.x, ISSN 1752-4598, S2CID 55210072
- ^ Schmidt, Annika; Fartmann, Thomas; Kiehl, Kathrin; Kirmer, Anita; Tischew, Sabine (1 February 2022), "Effects of perennial wildflower strips and landscape structure on birds in intensively farmed agricultural landscapes", Basic and Applied Ecology, 58: 15–25, doi:10.1016/j.baae.2021.10.005, ISSN 1439-1791, S2CID 240256023
- ^ a b c d e f Pfiffner L, Wyss E. 2004. Use of sown wildflower strips to enhance natural enemies of agricultural pests. In: Gurr GM, Wratten SD, Altieri MA. Ecological Engineering for Pest management: Advances in Habitat Manipulation for Arthropods, pp.165-186. CSIRO Publishing.
- ^ a b Keller M. 1999. The importance of seed source in programmes to increase species diversity in arable systems. Doctoral Thesis, University of Zurich.
- ^ UK Centre for Ecology and Hydrology. Infield wildflower strips. Blog available at:[1] (Accessed 26/06/2022).
- ^ Sandau N, Naisbit RE, Fabian Y, Bruggisser OT, Kehrli P, Aebi A, Rohr RP, Bersier L-F. 2019. Understanding negative biodiversity-ecosystem functioning relationships in semi-natural wildflower strips. Oecologia 189(1): 185 – 197.
- ^ Marshall EJP, Moonen AC. 2002. Field margins in northern Europe: their functions interactions with agriculture. Agriculture, Ecosystems and Environment 89: 5 – 21.
- ^ a b Frank T, Reichhart B. 2004. Staphylinidae and Carabidae overwintering in wheat and sown wildflower areas of different age. Bulletin of Entomological Research 94: 209 – 217.
- ^ Sotherton NW. 1985. The distribution and abundance of predatory Coleoptera overwintering in field boundaries. Annals of Applied Biology 106: 17–21.
- ^ Feltham H, Park K, Minderman J, Goulson D. 2015. Experimental evidence that wildflower strips increase pollinator visits to crops. Ecology and Evolution 5(16): 3523 – 3530.
- ^ a b c Scheper J et al. 2015. Local and landscape-level floral resources explain effects of wildflower strips on wild bees across four European Countries. Journal of Applied Ecology 52: 1165 – 1175.
- ^ Pywell, RF, Heard MS, Bradbury RB, Hinsley S, Nowakowski M, Walker KJ, Bullock JM. 2012. Wildlife-friendly farming benefits rare birds, bees, and plants. Biology Letters 8: 772 – 775.
- ^ Balzan MV, Bocci G, Moonen A-C. 2014. Augmenting flower trait diversity in wildflower strips to optimise the conservation of arthropod functional groups for multiple agroecosystem services. Journal of Insect Conservation 18(4): 713 – 728.
- ^ Campbell AJ, Biesmeijer JC, Varma V, Wäckers FL. 2012. Realising multiple ecosystem services based on the response of three beneficial insect groups to floral traits and trait diversity. Basic Applied Ecology 13: 363–370
- ^ Barone M, Frank T. 2003. Habitat age increases reproduction and nutritional condition in a generalist predator. Oecologia 135: 78 – 83.
- ^ Haaland C, Bersier LF. 2011. What can sown wildflower strips contribute to butterfly conservation? An example from a Swiss lowland agricultural landscape. Journal of Insect Conservation 15(1-2): 301 - 309