Tree Mortality & Forest Resilience

California’s drought, coupled with climate change, landscape fragmentation, fire suppression, and past forest management have drastically changed the Sierra’s forest landscape. Recent surveys estimate that 66 million trees have died or are dying in the southern and central Sierra Nevada Mountains since 2010. Nearly 40 percent of the mortality occurred between October 2015 and May 2016.

Pacific Forest Trust is participating in the Tree Mortality Task Force, convened by California Governor Jerry Brown to coordinate responses to this state of emergency. With many dead trees located near roads, power lines, and homes, the initial focus has been to remove dead trees that threaten public safety.

Bark beetle infestations have also increased in response to the rise in unhealthy trees, further exacerbating tree death. And, with milder nights and winters from climate change, there are fewer cold spells that keep beetle populations in check.

To reduce tree mortality and increase forest health, the Sierra’s forests need to be restored to more natural composition, structure, and function. Forests are more resilient when they have a diverse mix of tree ages (including large, older trees with fire-resistant bark), open canopies, and other natural forest features. In addition to advocating for restoration to more natural conditions in these forests, Pacific Forest Trust is urging the Tree Mortality Task Force to promote proactive efforts in other at-risk forests to reduce these threats before emergencies occur.

Restoring more natural fire regimes in appropriate areas— where settlements are not at risk—is also a key tool. The U.S. Forest Service has pioneered excellent models of how to bring fire back to the landscape, showing that forest thinnings followed by prescribed burn programs reduce the risk of high-intensity fires and promote more natural low-intensity fires.

More natural forests are better able to survive stresses such as drought and fire. These forests are also more resilient to climate change. A central focus of our work is to encourage natural forest conditions, whether through the Tree Mortality Task Force or by working directly with landowners.

Forests need immediate state investments in restoration to promote health and resilience. This, coupled with Working Forest Conservation Easements, ensures long-term public benefits from these forests. Providing these key economic incentives could improve forest health now and for the future.

More in this Issue of ForestLife

• President’s Letter: All Fired Up!
• Restoring Flourishing Forests
• Heritage & Pioneers – A profile of two supporters of Pacific Forest Trust, Harry and Charlotte Turner.
• Wildlife’s Modest Champion
• Pacific Forest Trust’s 2015 Annual Report
• Realizing the Vision for Conservation Across Boundaries