Thursday Cooperative Extension Free Weekly Webinars

Courtsey photo Dr Lauren M. Porensky to discuss ‘Greenstripping and Grazing for Cheatgrass

Once-a-week gardening and horticulture webinars this summer have explored a wide range of topics: container gardening, FireWise landscaping, making your own compost tea -- even agritourism. You’re welcome to join a growing audience for these informal online chats, arranged and moderated by our local Extension Agent Chris Jones, with University of Arizona’s Gila County Cooperative Extension. Convenient online links for each Thursday’s 11 a.m. one-hour session are posted at extension.arizona.edu/gila, a website you should bookmark as a favorite for updates and links to connect with Gila County Cooperative Extension for other programs, talks and resources for Globe-Miami gardeners. Links are also conveniently posted each week on Facebook, where you can join a local network of gardeners and green-thumbed followers at facebook.com/gilaextension. Want to be added to Mr. Jones invite list for future gardening and horticulture workshops? Call Chris at 928-402-8586  or email    [email protected]

Aug. 27 the topic is ‘Greenstripping and Grazing for Cheatgrass’ with Dr Lauren M. Porensky. Research Ecologist, Rangeland Resources and Systems Research Unit USDA Agricultural Research Service, Fort Collins, CO. Dr. Porensky is an ecologist interested in plant communities and herbivores. Her research focuses on balancing livestock production with conservation and restoration in semi-arid rangelands. Porensky got her PhD at UC Davis working on livestock management and wildlife conservation in central Kenya. She currently investigates the interactive effects of grazing, fire, prairie dogs, and variable weather on plants, livestock, and humans in the northern Great Plains.

Millions of hectares in western North America have been negatively impacted by cheatgrass invasion. Post-wildfire restoration generally involves spreading limited resources over extensive areas, and this approach often fails to meet restoration objectives. We investigated an alternative approach that may be able to weaken cheatgrass-fire feedbacks, protect remnant and restored sites, and reduce further invasion by focusing restoration resources in small, spatially strategic locations. We tested multiple methods for creating native greenstrips (fuelbreaks made of native plants), subjected experimental greenstrips to targeted grazing treatments, and monitored seedling densities over two years. At a highly invaded Great Basin site, we found that planting and grazing treatments had strong effects on seedling densities. Plots planted with a doubled seed rate had 50 percent more seedlings than those planted with an average seed rate. Ungrazed plots had 40 percent and 90 percent more seedlings than spring- and fall-grazed plots, respectively. However, results were primarily driven by one planted species (Elymus trachycaulus) which was both highly successful and susceptible to grazing. At a minimally invaded Colorado Plateau site, planted seedling densities were much lower (1-2 per m2) and planting techniques had weaker effects, though seed rate was still an important driver of results. At this site, targeted spring grazing tended to enhance seeded species densities and reduce cheatgrass biomass. Early results suggest that high rate native grass seedings and short-duration spring grazing should be further evaluated as potential tools for addressing cheatgrass invasion, though results may strongly depend on ecosystem context.

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