GreenTown Los Altos

Resilient Trees


May 2019


~Gary Hedden

Master Arborist Dave Muffly told a packed room at the Los Altos Library about the importance of planting resilient trees, trees that will do well now, and continue to do well in a future shaped by climate change.

A packed room.

He started his talk describing his experience as chief arborist at Apple Park, the new Apple campus in Cupertino. Dave shared how Steve Jobs wanted to incorporate an apricot orchard as part of the campus to reflect the region’s history as the Valley of Heart’s Delight. He described how the final orchard, while incorporating apricots, included 31 varieties of fruit that would ripen throughout the seasons, rather than all at once. Dave went on to describe how the rest of the campus was planted with evergreen varieties indicative of those found throughout California.

Dave Muffly

Why resilient trees? Dave cited an ominous report by the IPCC that predicts climate runaway in 11 years. That’s pretty grim, but Dave says we can buy some time by planting trees. It can’t be any tree though, in California, it has to be a tree that can survive warmer, wetter conditions in addition to being drought tolerant.

One more thing, we need to plant a lot of trees. Trees take up carbon dioxide and to meet the climate change challenge Dave wants to plant one billion trees in California by 2030! Unfortunately, we are losing trees at an alarming rate. In 2018 we lost 18 million from warming, drought, insects, and fires. We have a lot of work to do.

What should we plant? He thinks oaks are part of the answer, but the ones that do well here now, Coast Live Oak, Blue Oak, and Valley Oak don’t thrive with the higher humidity predicted by several climate change models. Dave’s answer is to look to areas that are already warmer and wetter, to the south and east. He thinks Shreve Oak, Island Oak, Engelman Oak, and Southern Live Oak might work. In addition to planting some pilot projects with these varieties, he and others are growing them in nurseries around the state selecting those that do well and resist things like mildew.

A lone oak.

Dave is always on the lookout for oaks and other trees that are good candidates for resilience. One of his favorite spots is Mt. Lemmon, north of Tucson, Arizona. As you climb this mountain you’ll find bands of discrete ecosystems. It is a laboratory for tree selection where he has found Mexican Blue Oak, Silverleaf Oak, and Chisos Red Oak doing well.

There is a lot of interesting information on his website,, including his billion tree challenge and soon, notes from his talk. Check it out.

Asked what we can do, he said to get the city to hire an arborist, replace trees that are dying, plant the resilient trees from his tree list, and remove the dead trees from our forests.

GreenTown wants to help. One billion is a stretch, but maybe we can shoot for 500? Let us know if you want to help.

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