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UC Master Gardeners catalyze response to unprecedented tree die-off in California

The Issue

California’s severe drought from 2012 to 2016 led to unprecedented tree mortality. Over 129 million trees died by 2017, 95% of which were in the Sierra Nevada. Mortality was heaviest in the central and southern Sierra, from Tuolumne County south to Fresno County. Trees died from a combination of bark beetle outbreak and drought.

State and federal cost share programs were developed to assist with tree removal and disposal through the Governor’s Tree Mortality Task Force, but these mostly focused on assisting local jurisdictions and owners of 20 acre parcels or more. Owners of small parcels who lost trees had little assistance or information on what to do after removing dead trees.

What Has ANR Done?

UCCE Central Sierra received an ANR Opportunity Grant to develop a train-the-trainer approach to disseminate research-based information to the public through volunteer UC Master Gardeners. The project involved offering professional development workshops for Master Gardeners from the 10 counties affected by severe tree mortality and resources so that they could do outreach to the public.

Between June and October 2017, we trained 170 Master Gardeners on the evolving science of tree mortality, forest succession, reforestation, and climate change so they could then give research-based answers to questions they receive. The gardeners attended one of three all-day workshops with speakers and a field trip to look at tree mortality and forest succession. 77% of participants said they had gotten questions from the public about tree mortality but 71% never had any formal training in tree mortality and replanting topics.

We developed resources to support them in the form of a Tree Mortality Tool Kit, with training materials, a customizable presentation template for their public education classes, and a simple tri-fold brochure for them to distribute at public events.

The Payoff

Small landowners receive critical research-based answers during California’s tree die-off

During an unprecedented forest mortality event in the central and southern Sierra Nevada, Master Gardener volunteers learned from leading experts on tree die-off and disseminated that information to the public in real time. Pre- and post-data show that they were able to learn the key points presented about forest health, bark beetle epidemics, forest succession, and the need to replant native pines in some cases. The training increased their expertise. After the training, nearly 90% of gardeners correctly identified that the bark beetles that are killing trees are native, tree mortality doesn’t require planting a different species afterward, and ponderosa pine can and should be replanted after most have been killed. UC Master Gardeners quickly applied their training and were able to give up-to-date advice to the public and empower landowners to make informed replanting decisions. Their efforts are part of ANR’s commitment to protecting California’s natural resources and building climate-resilient communities and ecosystems.


Supporting Unit: Central Sierra Cooperative Extension

Susie Kocher, sdkocher@ucanr.edu