Hedgerows eventually pay for themselves

New research out of the California Central Valley shows that by contributing to pest control and pollination services, native plant pollinator hedgerows end up paying back the cost of their installation and maintenance over time.

The cost of hedgerows used by the authors of the study are higher than those projected by groups such as the Xerces Society for Invertebrate Conservation. Importantly, the authors found that when farmers are able to take advantage of cost share programs funded by the National Research Conservation Service (NRCS), that the amount of time it takes to pay back the initial investment is cut in half. This indicates that the Farm Bill program that supports hedgerows (the Environmental Quality Incentive Program or EQIP) is helping offset installation costs and is a tool farmers should take advantage of if they qualify for assistance.

Learn more about the study details:

Morandin, L.A., R.F. Long, and C. Kremen. 2016. Pest Control and Pollination Cost-Benefit Analysis of Hedgerow Restoration in a Simplified Agricultural Landscape. Journal of Economic Entomology: 1-8.

Best summary of hedgerows I’ve read!

Check out this wonderful, short article on the history and value of hedgerows– it even includes information on hedgerow installation!

Organic Broadcaster

WSARE report on pollinator projects they have funded

Western SARE (which stands for Sustainable Agriculture, Research & Education) just released a report highlighting the pollinator projects they have funded, including short courses on pollinator monitoring put on by the Xerces Society for Invertebrate Conservation (excellent opportunities to learn about different bee species). WSARE funded my graduate research, which was also highlighted.
Check out the details here!

National Pollinator Strategy

Today the White House released it’s National Pollinator Strategy, a comprehensive document outlining the governments’ plans to decrease losses from Colony Collapse Disorder, help Monarch butterflies, and increase acreage for pollinators through restoration and enhancement (goal = 7 million acres in the next 5 years!). How will they accomplish this? Through “USDA resources applied to CRP and EQIP pollinator enhancements, and national forest and grassland acreage; DOI actions to restore or enhance lands through direct restoration action, along with the inclusion of pollinator-friendly native seeds in all post-fire re-vegetation and fuels/green stripping projects; U.S. Army Corps of Engineers (USACE) implementation of pollinator best management practices at its facilities.”

However, the strategy had already been criticized for not doing enough to alter the use of pesticides currently being used today (that are having deleterious effects on pollinator populations).

Read the whole strategy here (pdf).

Hedging our bets: Can hedgerows support native bee conservation and crop pollination?

I recently published a paper in the journal Agriculture, Ecosystems and Environment posing this very question, Can hedgerows support native bee conservation and crop pollination? What I found was that in conventionally managed monoculture sunflower fields, the answer is “mostly no.”  This finding, however, is likely do to a variety of factors unique to sunflower grown in intensively managed agricultural landscapes such as the California Central Valley.

First, hedgerows are just 1% of the size of a sunflower field, so the amount of blooms they provide bees is dwarfed by the number of flowers available in the sunflower field. In addition, I found that the bees visiting sunflower were different species from those visiting the hedgerow. The bees in sunflower fields were mostly sunflower specialists– species that only visit sunflower, taking the pollen and nectar back to their nests as the exclusive source of food for their young. Conversely, the bees in hedgerows were mostly generalists (visit many different species of plants). Hedgerows in my study didn’t contain sunflower due to concerns about contamination with the field varietals. New sunflower species containing a different number of chromosomes than the field plants are being tested. I hypothesize that once sunflower is available in hedgerows, they too will support sunflower specialist bee populations.

I did find that native bees increased sunflower yield- both indirectly, through the interaction between native bees and honey bees, and by having more native bee species present. Native bee species richness likely enhances crop pollination because different species pollinate different parts of the plant, complimenting the efforts of one another. But because hedgerows didn’t increase the number of native bees in fields, these benefits from native bees are likely due to other factors. I am currently exploring what might affect sunflower-pollinating bees through additional analyses.

Past studies have found that hedgerows and other small-scale field-edge habitat enhancements can contribute to increased seed set in canola and blueberry crops in different landscapes. In addition, hedgerows not only increase bee diversity but  also the diversity of different traits the bee community has. I therefore conclude that hedgerows could contribute to both bee conservation and crop pollination, but their efficacy likely depends on their location and crop-context.

In sum, hedgerows are a good idea in some situations but not in others. We ought to hedge our bets and use multiple diversification strategies instead of relying on a single method. Thus, while hedgerows are an important tool in our toolkit, they should be utilized in tandem with other techniques, such as cover cropping, crop rotation, and polyculture.

H.S. Sardiñas and C. Kremen. 2015. Pollination services from field-scale agricultural diversification may be context-dependent. Agriculture, Ecosystems and Environment, 270: 17-25.