December 9, 2002
Gretchen LeBuhn, SFSU assistant professor of biology, is teaming with Napa and Sonoma winemakers to improve practices that sustain agriculture and the native woodlands. Her strongest allies? Legions of Northern California bees.
With the wine country’s growth, California’s native oak woodlands have shrunk dramatically. Native trees and plantings that once spanned the north coast are now isolated islands in a sea of development, grazing and grape growing. Ecologists, valley residents and the winegrowers themselves have become concerned with maintaining the area’s natural beauty while allowing agriculture to continue.
Bees and woodlands need one another to thrive, so tracking and understanding changes in bee/plant relationships can yield important insights. Bees need trees and flowers for nectar that feeds them and for pollen that nurtures their eggs. The native plants and trees need bees’ pollen-spreading activities to reproduce.
A key focus of LeBuhn’s research is to get a solid understanding of the baseline relationships between bees and plants. Looking at paired locations that can be compared and contrasted, her team will note changes in the types and abundance of bees, and experiment with modifications, to discover which bees are the best pollinators for at-risk native plants.
Because the once lush woodlands are now fragmented and isolated, they may lack sufficient bee populations to pollinate and thrive effectively. By examining both woodlands surrounded by vineyard and woodlands surrounded by greater woodland, LeBuhn will be able to determine what processes and interventions can best maintain and restore woodlands.
One theory is that vineyards can serve as bridges between the fragmented woodlands, providing breeding environments that produce bees that benefit native plants.
“There are some pretty simple things people can do to increase bee population,” LeBuhn says, like adding native plants to gardens and cover crops or leaving some dead wood or bare dirt for bees to nest in. Creating these “pollinator refuges” may go a long way toward woodland restoration.
That’s especially important, given the role that bees play in pollinating wine country grapes, right? Wrong. Grapes are wind-pollinating, needing little to no bee pollination to reproduce. Vineyards are drawn to LeBuhn’s work out of concern for the environment, and the growing focus on sustainable farming.
“I think virtually all vineyard people would like to have a property that has good ecological function,” says LeBuhn, noting that “I haven’t had a winery turn me down.” There’s currently a strong interest among wine growers in social responsibility and environmental stewardship. The Wine Institute and the California Association of Winegrape Growers recently introduced a 490-page workbook that helps vintners and growers assess their practices, conserve natural resources and protect the environment. Knowing the connection between a healthy bee population and healthy native woodlands, LeBuhn is working with vineyards to determine which cover crops will attract and sustain the right amounts and types of bees.
Baseline data collection is taking place now, and the first round of experimental cover crops will be planted in the fall. The team will look at costs and benefits of different cover crops and combinations. They hope to develop a mix that supports the right bee populations needed to pollinate and propagate the nearby woodlands, but are also a win for vineyard management because they, for example, live longer and require less re-seeding, control pests or suppress weeds.
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