Why Plant Elderberries in Multi-species Hedgerows?
Hedgerows are defined as managed rows of trees and shrubs, which can include perennial and/or annual forbs as well as grasses. 1, 2 Hedgerows are an ancient feature of agricultural landscapes throughout the world and have been used in many ways. However, Europe and North America saw an increase in the removal of hedgerows in the 1900s as farmland industrialized. Hedgerows are less common today but are increasingly being recognized for their significant ecological benefits.
As semi-wild places in otherwise very intensively-managed agricultural landscapes, including much of the lowland cropland acreage in California, hedgerows provide numerous ecological benefits. They provide natural habitat and travel corridors for wildlife, support beneficial insect populations with pollen, nectar, and shelter, can act as windbreaks for crops and shelter for livestock, and, if designed appropriately, can also serve as living fences and boundary markers. Hedgerows provide many ecosystem services in support of agriculture.
Hedgerows can significantly increase biodiversity and natural habitats to agricultural landscapes that have often been over-simplified compared to the original natural landscapes. Mixed species hedgerows composed primarily of California native species support significantly higher populations of common and rare bird species, compared to bare or weedy field margins.3 In addition, the use of hedgerows can support growers that run organic operations and are required to meet requirements of conserving biodiversity through the USDA National Organic Program (NOP). For more information on using practices such as hedgerows for meeting USDA organic requirements for biodiversity conservation, please refer to the Natural Resources Conservation Service’s portal for organic farmers.
Hedgerows provide shelter as well as pollen and nectar to support significant populations of insects. Many of these insects serve as natural enemies of crop pests or as crop pollinators. Recent studies in the Central Valley have shown that natural enemies move up to at least 600 feet from a hedgerow into adjacent crop field and can reduce the overall pesticide applications required in a growing season (Morandin et al. 2016). Hedgerows also support large populations of honey bees and other pollinators that can increase yields of adjacent crops. 4, 5
Hedgerows that are rich in long-lived woody perennial species such as elderberry can provide additional environmental benefits by storing carbon long-term. One study in Yolo County found that hedgerows on annual crop farms stored 18% of the total carbon on the farm, while only occupying 6% of the land area. 6
Hedgerows with tall perennials provide cooling shade and increase stream bank stability when located alongside water courses such as streams and ditches. Cooler water temperatures are important for maintaining native fish species.
Mixed species hedgerows that include grasses can substantially improve the quality of both surface water runoff and groundwater coming from agricultural fields. Hedgerows with only tree and shrub species can improve groundwater quality (but not surface water quality as much). Studies around the world have shown that nitrate can be reduced by an average of 33% in surface water and 70% in groundwater, although results vary widely from case to case. 7
Blue elderberry (Sambucus nigra spp. cerulea) is native to California and other western states and is often included as a component of hedgerows. Elderberry serves many beneficial functions in hedgerows including providing a canopy which creates cooling shade, contributing to soil structure (particularly along stream banks), and providing food for wildlife. Wildlife that feed on elderberry foliage and fruit include game birds, deer, bear, and elk.
Elderberry also serves as a nesting habitat for many songbird species and hosts a range of insects including pollinators. Elderberry is the sole host for the threatened Valley Elderberry Longhorn Beetle, a species that occurs only in the Central Valley of California (see Valley Elderberry Longhorn Beetle page).
- Baudry J., Bunce R.G.H., Burel F. 2000. Hedgerows: an international perspective on their origin, function, and management. Journal of Environmental Management 60: 7-22. doi:10.1006/jema.2000.035
- Earnshaw, Sam. 2018. Hedgerows and Farmscaping for California Agriculture: A Resource Guide for Farmers. Community Alliance with Family Farmers.
- Heath S.K., Soykan C.U., Velas K.L., Kelsey, R., Kross S.M. 2017. A bustle in the hedgerow: Woody field margins boost on farm avian diversity and abundance in an intensive agricultural landscape. Biological Conservation 212(Part A): 153-161.
- Morandin L.A., Long R.F., Kremen C. 2016. Pest control and pollination cost benefit analysis of hedgerow restoration in a simplified agricultural landscape. Journal of Economic Entomology 109(3): 1020–27.
- Williams N.M., Ward K.L., Pope N., Isaacs R., Wilson J., May E.A., Ellis J., Daniels J., Pence A., Ullmann K., Peters, J. 2015. Native wildflower plantings support wild bee abundance and diversity in agricultural landscapes across the United States. Ecological Applications 25(8): 2119 – 2131.
- Smukler S.M., Sánchez-Morenoc S., Fonted S.J., Ferris H., Klonsky K., O’Geen A.T., Scow K.M, Steenwerth K.L., Jackson L.E. 2010. Biodiversity and multiple ecosystem functions in an organic farmscape. Agriculture, Ecosystems and Environment 139: 80-97.
- Valkama E., Usva K., Saarinen M., Uusi-Kämppä, J. 2019. meta-analysis on nitrogen retention by bu?er zones. Journal of Environmental Quality 48:270–279.