Scientists Study Ancient Redwoods on Land Trust Preserve Grove

Humboldt State University professor Stephen Sillett and his team recently traveled to a Land Trust of Napa County preserve as part of their collaborative research into the effects of climate change on redwood forests.
The group collected core samples and other measurements from roughly 20 redwoods of various sizes over three days in an effort to not only discover the age of the trees, but also gain insight into their centuries-long history of growth.

During their visit, the research team sampled trees that have now been determined to be over 500 years old, with one tree aged at approximately 800 years. This would make the redwood about as old as the Magna Carta, the historical peace treaty signed in 1215 by King John of England.

The nearly 800 year-old tree also happened to be the shortest and smallest in diameter of all the trees sampled. The tallest tree sampled by the Sillett team measured 201.7 feet (61.5 meters), likely making it one of the tallest trees in Napa County.

“These forests are a mystery to us because they’re so isolated from the rest of the redwood range,” said Sillett.

“The extreme inland location, isolation from other redwood forests, and lack of logging effects in this grove are what caught my eye when I first visited it three years ago,” said Land Trust Stewardship Program Manager Mike Palladini. “I contacted Sillett’s lab and in 2014 a group came down to have a look.”

Using Palladini’s maps and photos as a jumping off point, Sillett’s lab did some leg work of their own, going so far as to approximate heights of individual trees in the groves with LiDAR technology. LiDAR, which stands for light detection and ranging, uses laser light to measure objects on the earth from a plane or helicopter. Sillett’s group pin-pointed one of the tallest trees in the groves, and in 2014 core samples from that tree put its age at over 500 years.

“We’ve noticed in other parts of the redwoods range that most redwoods are producing more wood in recent decades than they have in the past,” said Sillett.


With temperatures rising, growing seasons have extended and evidence of more light and less fog all point to the trees growing faster. The team will use the core samples to quantify rates of wood production.

“We’re not sure how the Napa County trees fall into this spectrum, but from what we discovered two years ago, they’re growing really fast right now,” said Sillett.

The scientific work is ongoing, all core samples have been processed, and data analyses are underway.

And while one redwood grove may be small in the context of the 65,000 acres the Land Trust has protected in Napa County, understanding and caring for unique biological resources such as these is as important to the Land Trust’s mission as protecting the land itself.