Forestry Research and Outreach

Tree Mortality Data Collection Network

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The drought of 2012 to 2016 resulted in unprecedented tree mortality across California, with the most severe impacts occurring in the southern Sierra Nevada. Prolonged drought stress weakened trees, reducing their ability to defend against native bark beetles. This led to widespread bark beetle outbreaks, during which beetles burrowed under the bark, laid eggs, and ultimately girdled and killed millions of trees. A CalEco video, Ponderosa Pine Mortality, the Western Pine Beetle and Drought provides a succinct explanation of this event. 

The consequences of this mass die-off event will persist for decades. As dead trees fall, surface fuels will increase, vastly outpacing the resources of local, state and federal jurisdictions to remove it. Additionally, tree regeneration and species composition is significantly disrupted.  In response, University of California scientists, forest managers, and public agencies developed a data collection network to monitor, identify and project future trajectory of affected stands.  This work supported improved management of impacted forests to increase their resiliency to future droughts. 

Additional information may be found in this published summary of the Tree Mortality Data Network, California Agriculture.

The California Tree Mortality Data Collection Network, led by UC Berkeley and UC ANR academics, and supported by CAL FIRE, brought bring together scientists from various agencies conducting field and remote-sensing studies across the Sierra Nevada.  Additionally, researchers collected data at eight Drought Mortality (DX) sites throughout the Sierra Nevada in 2017, 2018, 2019 and 2021 to address the following questions:

  • What is the future course of the bark beetle outbreak?
  • What is the impact of tree mortality on forest carbon storage?
  • What are the likely successional trajectories in impacted stands? Is forest regeneration occurring and what are the implications for future forest composition?
  • How does the increase in standing, and eventual downed, dead trees affect the timing and magnitude of wildfire hazard?

Network Meetings

A key outcome of the Tree Mortality Data Collection Network was to quickly collect and present results to a diverse audience of resource decision makers, policy makers, practitioners, and private landowners.  Annual meetings were held from 2018-2021 to share key information about tree mortality and its effects on wildfire risks, carbon, and more broadly on ecosystem services across this region. 

2021 Network meeting (Summary) - Held in March 10-11, 2021, this workshop 1) Shared latest results on live and dead trees, tree fall rates, fuels, regeneration, and post-mortality management and 2) Discussed frameworks for incorporating data into forest management planning and identify management challenges and opportunities.  

2019 Network Meeting (Summary) - Held in March 14th, 2019, Wildfire Training Center in McClellan, CA, this workshop 1) Shared results of the field season on live and dead trees, bark beetle attacks, regeneration, and fuels 2) Solicited input from partners and managers on useful data summary products 3) Discussed on-going collaboration on field data collection, interpretation and use

2018 Network Meeting (Summary) - Held on March 12th, 2018, Wildfire Training Center in McClellan, CA, this workshop 1) Shared results of the field season on live and dead trees, bark beetle attacks, regeneration, and fuels 2) Solicited input from partners and managers on useful data summary products 3) Discussed on-going collaboration on field data collection, interpretation and use

Other Resources:

Collaborators: CAL FIRE, National Park Service, US Forest Service (Forest Health Protection, Pacific Northwest Research Station, Pacific Southwest Research Station, Rocky Mountain Research Station, Region 5), US Geological Service, University of California (Berkeley, Davis, and Cooperative Extension), University of Washington.