Posts Tagged: Hedgerows
Hedgerows enhance wildlife abundance and diversity around farmland without contributing to food safety problems in field crops, according to a new study published by a team of University of California researchers. The UC Agriculture and Natural Resources and UC Davis study documented that field edge plantings around farms are generally too narrow relative to the surrounding landscape to be a source of rodents and foodborne pathogens.
“This study is particularly pertinent right now when FDA's Food Safety Modernization Act (FSMA) is calling for farmers to co-manage wildlife and agriculture, instead of clear cutting wild habitat around their crops,” said co-author Rachael Long, UC Cooperative Extension farm advisor in the Sacramento Valley. “Our paper provides support for this ruling, showing that the presence of hedgerows does increase wildlife diversity, but does not increase wildlife intrusion into the fields and, more importantly, does not increase the prevalence of animals carrying foodborne pathogens.”
This is good news for hedgerows, rows of shrubs, trees, grasses and flowers that are planted on field edges. The plants bordering crop fields provide habitat and floral resources for beneficial insects, such as bees and natural enemies, that help with pollination and biocontrol of pests in adjacent crops. Hedgerows also help enhance biodiversity – especially for insect-eating birds – help reduce wind and soil erosion, and protect water quality.
The two-year study in Sacramento Valley walnut orchards and processing tomato fields was led by Long and Roger Baldwin, UC Cooperative Extension vertebrate pest control specialist at UC Davis, former graduate student Laurel Sellers, the Western Center for Food Safety at UC Davis's Michele Jay-Russell, Xunde Lib and Edward R. Atwill, and Richard M. Engeman of USDA National Wildlife Research Center.
The study, titled “Impact of field-edge habitat on mammalian wildlife abundance, distribution, and vectored foodborne pathogens in adjacent crops,” was published in the February 2018 Crop Protection (Sellers et al. 2018).
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This journal article supports a growing body of literature suggesting that plantings along the edge of fields do not substantially attract wildlife species that intrude on fields and transfer foodborne pathogens. For example, in a 2015 study, UC Davis researchers found more food pathogens when wildlife habitat was reduced on farms. This may be attributed to the vegetation filtering pathogens, a better breakdown of pathogens in diverse environments, and that removing vegetation may not deter wildlife from entering farm fields.
Relative to the larger crop acreage, hedgerows and similar field-edge habitats are generally too linear and small to serve as a significant source of rodents to damage nearby crops. However, cottontail rabbits favor hedgerows, and can sometimes cause damage to adjacent seedling crops.
“Overall, we found risk of crop loss or contamination of foodborne pathogens in crops bordered by hedgerows wasn't significant in our study in the Sacramento Valley, although potential damage could vary by the stage and type of crop and wildlife species present,” Long said. She will be presenting this work at the 28th Vertebrate Pest Control Conference, which will be held in Rohnert Park Feb. 26 to March 1.
In its Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption, the U.S. Food and Drug Administration says, "We continue to encourage the co-management of food safety, conservation, and environmental protection.”
Hedgerow benefits align with food production and sustainability goals. http://calag.ucanr.edu/archive/?article=ca.2017a0020
Comanaging fresh produce for nature conservation and food safety. http://www.pnas.org/content/112/35/11126
UC Agriculture and Natural Resources and UC Berkeley researchers analyzing hedgerows in Yolo County have found that not only are farmers diversifying their land by planting hedgerows, but those hedgerows are attracting natural enemies that provide economic benefits.
The two-year study of hedgerows planted adjacent to processing tomatoes showed higher numbers of natural enemies such as lady beetles (aka lady bugs) and fewer crop pests compared with conventionally managed field crops edged with residual weeds.
The researchers discovered that the increase in natural enemy activity in the hedgerows extended 600-feet into adjacent tomato crops and resulted in a reduction of aphid pests and an increase in stink bug egg predation by parasitoid wasps. Tomato fields adjacent to hedgerows required fewer pesticide treatments than the tomato fields without hedgerows.
The scientists concluded that hedgerow restoration on field edges could enhance pest control, reducing the need for chemical pest control, as reported in the Journal of Agriculture, Ecosystems and the Environment.
Additional research has shown that hedgerows are important for pollinators, such as native wild bees, that feed on flowers and nest in the ground or holes in plant stems. More wild bees are present on farms with hedgerows than with conventionally farmed field edges. Native bees are important in crop pollination, especially with the decline of the honey bee population.
Hedgerows cost about $4 per linear foot to plant and manage for the first three years for a single row of shrubs and native grasses about fifteen feet wide. The Natural Resources Conservation Service (NRCS) offers cost-share programs through USDA's Environmental Quality Incentives Program (EQIP) that covers about 50 percent of the establishment costs. However, due to less pesticide use, a hedgerow can pay off in about 15 years. Add pollination services in areas without an adequate number of honey bees for crop pollination, and that time can be significantly reduced.
With a grant from the California Department of Pesticide Regulation, the Yolo County Cooperative Extension Service seeks to spread the word about the ecosystem service benefits provided by hedgerows planted on farmland. During the past two-years, the researchers hosted workshops in Northern California on the value of hedgerows on farms, reaching hundreds of farmers and landowners. The researchers also offer advice on hedgerow plantings, including plant selection and how to establish and manage hedgerows. Planting hedgerows does not take land out of production; it's using areas that cannot be farmed, such as along fence lines or terraces from land leveling, and providing economic benefits.
Additional examples of hedgerows on Yolo County farms:
Hedgerow planted in western Yolo County.
All birds depend on habitat for food, shelter and nesting sites. With a decline in habitat in the Central Valley, primarily due to agricultural expansion, urbanization and water diversions, there has been a significant decrease in the numbers and types of birds. Many bird species are now endangered, threatened or listed as species of special concern. Approximately 36 percent of our state’s historical grasslands, 9 percent of the original wetlands, and 2 to 7 percent of the original riparian forests remain. The Central Valley alone has lost more than 90 percent of the riparian, oak woodland and shrub land habitats.
In a recent study by UC Cooperative Extension and Audubon California in Yolo County, researchers determined that hedgerow plantings along field margins helped increase the abundance and species richness of birds on farms, both for winter migrants and year-round species. Their data analyses, examining farms with and without hedgerows, showed that the presence of hedgerows tripled bird abundance and doubled bird species richness in these linear habitat features, but did not increase the bird abundance in the adjacent crops. Of the 2,203 birds counted during the winter and spring of 2011-12, hedgerows drew 41 species of birds, as compared to 22 species in control areas (weedy, semi-managed field edges). In addition, more than three times as many birds used the hedgerows during wintertime, compared to the spring breeding season. This highlights the importance of this habitat for migrating and overwintering birds.
Hedgerows provide a variety of ecosystem services in agricultural landscapes, such as attracting native bees to enhance pollination and natural enemies to control pests in adjacent crops. Birds also feed on insects and rodents, potentially helping with pest control in crops. The value of hedgerows on farms for enhanced biodiversity and ecosystem services will hopefully encourage more landowners to establish them on field edges for conservation purposes.
They’ve been in existence for thousands of years with many benefits including serving as wind breaks, helping to reduce soil erosion, and providing habitat for wildlife. All of this helps protect our water and air quality as well as enhances biodiversity.
More recently, studies have shown that hedgerows of California native flowering shrubs planted on field crop edges can enhance beneficial insect activity on farms, possibly leading to biological pest control in adjacent crops. This valuable ecosystem service could lead to reduced insecticide use on farms, possibly enhancing environmental and worker health and safety issues and provide cost savings to growers. for thousands of years with many benefits including serving as wind breaks, helping to reduce soil erosion and providing habitat for wildlife. All of this helps protect our water and air quality as well as enhance biodiversity.
The extent to which enhanced pest control occurs in adjacent crops is still under investigation. However, research to date shows that hedgerows aren’t concentrating beneficial insects; instead they’re actually exporting them into adjacent crops. That is, higher numbers of beneficial insects have been found in crops adjacent to hedgerows of flowering shrubs than weedy field edges. Data are still being collected on impacts to pest control.
The enhanced biodiversity and potential ecosystem service benefits of hedgerows have prompted the USDA Natural Resource Conservation Service to support growers in planting native shrubs and perennial grasses on their farms. In 2009, 13 miles of hedgerows were established on California farms compared to 3 miles in 2005, so interest is growing. In particular, planting California native flowering shrubs and forbs for attracting native bee pollinators for enhanced pollination in adjacent crops is gaining significant attention. Recently the USDA approved 90 percent cost-share programs for pollinator hedgerows.
More information on plant selection, establishment practices and costs for planting hedgerows on farms can be found in UC ANR publication number 8390, available as a PDF or e-book: Establishing hedgerows on farms in California.