Longtime head of Jasper Ridge Biological Preserve steps down

By Kate Daly | Special to the Almanac

Philippe Cohen of Menlo Park literally took it as a sign that after serving more than 22 years as executive director of Jasper Ridge Biological Preserve, it’s time to retire.

Standing on the edge of what was called Searsville Lake, he points to a tree where the bark has almost completely grown over a metal sign warning: “No swimming allowed except at the beach.”

Once a popular recreational area, this part of Woodside was closed off to the public in 1975. Stanford University has owned the land dating back to 1892, and has run scientific experiments on the 1,189-acre preserve for decades.

When Mr. Cohen arrived as the second person ever to run the biological field station there, he promised himself he would leave when the old sign disappeared. His last day on the job was Feb. 19.

Mr. Cohen has seen lots of growth over the years. When he started he was the only full-time employee, with a budget of $186,000. Now he oversees a budget of about $1 million and a staff of eight.

“My job is to make sure everybody can do their research and classes can do their work,” he says, listing his duties as a mix of managing land, raising funds, reviewing proposals and overseeing staff scientists. Classes range from East Side Prep to Stanford students.

“I much prefer being out on the trail,” he says, gladly setting off for a hike in the rain from his office overlooking Searsville Reservoir.

His office is located in the Leslie Shao-ming Sun Field Station, one of his proudest achievements. Completed in 2002, the building has earned awards for being a model of sustainability and energy efficiency.

Before the hike he forewarned, “My philosophy about weather and hiking is there is no bad weather, just bad dressing,” so his rain jacket, cargo pants, hat, hiking boots and camera come as no surprise.

What did, though, is the thundering volume of murky water flowing over the Searsville Dam and plummeting 65 feet to meet the San Francisquito Creek downstream.

He stops to take pictures to document the dramatic scene, and talks about what has become a controversial topic what to do with the reservoir. It’s “filling in so rapidly with sediment, right now it has maybe 100 acre-feet of water … and there are lots of questions about the future of steelhead trout downstream.”

Mr. Cohen explains after several years of studies, Stanford is looking “to poke a hole in the bottom of the dam and allow a lot of the sediment through,” but there are federal and state agencies involved in the permitting process and other factors to weigh in such as water rights, endangered species, flooding, wetland habitats “so it’s a really complicated issue.”

After crossing the dam he takes the trail that encircles the reservoir, halting occasionally to provide details about the 65 to 75 research projects going on at any given time in the preserve.

Approximately two-thirds of them are linked to Stanford, but then there’s the Australian who has shown up each spring for 35 years to study fluctuations in a serpentine grassland habitat.

On this wintery day a Stanford student and professor follow the same path and get drawn into Mr. Cohen’s description of how dusky-footed woodrats live in nests divided into sophisticated honeycombs of rooms where the rodents store what they collect.

The subject switches quickly to an examination of coyote scat, a deer carcass, and this season’s explosion of ramalina, the green lace lichen growing in oak woodland forests that is often mistakenly called Spanish Moss.

Mr. Cohen is equally comfortable discussing the sticky monkey flower and hummingbird experiment on plant-pollinator-microbe interactions that has become part of the core curriculum for an undergraduate biology course.

He mentions another experiment, a bat monitoring system to test if their sonar systems interfere with each other. So far 13 species of bats have been detected in the preserve.

Annual bird counts have turned up 178 species. Mr. Cohen wonders out loud why lately he has seen thousands of robins flocking at sunrise.

He ends his hike at the site of the Jasper Ridge Global Change Experiment, “one of the longest continuing studies in the world of climate change and ecosystem response,” Mr. Cohen says.

In 18 years, more than 20 national and international institutions have participated in measuring changes in annual grasslands based on CO2, temperature, precipitation and nitrogen deposition all on the same 2.5-acre plot.

“In some respects it’s one of the best studied landscapes in the world and it’s amazing how much we still don’t know,” he says.

Each year thousands of people visit the preserve for educational purposes. Docents lead small group tours from October to May. Stanford students come through on a regular basis, as do hundreds of local middle and high school students.

Mr. Cohen majored in environmental studies at Pitzer College, then earned his Ph.D. in geography at the University of Minnesota. He managed a field station in the East Mojave Desert for seven and a half years before coming to Stanford.

As for his career, “I’ve loved every minute of it,” he says, but is retiring at 65 because “there are lot of things I want to do in the next five years.” (The search is ongoing for a new executive director.)

His wife, Cindy Stead, retired last June from her reading specialist position at Oak Knoll Elementary. In mid-March they are embarking on a six-week camping trip “chasing desert wild flower blooms” in California, Arizona and Nevada.

After that they want to volunteer to do research in “some remote place” in Costa Rica, Ecuador, South Africa, or possibly all three.