Redwoods line the drive to the Chabot Space and Science Center, located in the hills of Oakland, California. These trees are an icon of Northern California, but this particular Oakland patch is essentially an island ecosystem. And it’s vulnerable to a changing climate.
Enter an army of “citizen scientist” students and teachers, who visit Chabot (and the two adjacent urban parks) with a mission to monitor… sword ferns.
Both redwoods and sword ferns thrive in a Mediterranean climate, rare but treasured worldwide for their characteristic blue skies and mild temperatures. The “blue skies” also means limited rain. In fact, on the US West Coast, much of the moisture available to plants comes in the form of fog. As part of the Communicating Climate Change initiative, students at Chabot are keeping an eye out for how this Mediterranean climate may be changing, and what that means for the Redwood forests.
Even though rainfall and fog-drip moisture is limited, plants in these ecosystems are highly dependent on it. Sword ferns in particular are known to be indicators of the amount of moisture available in Redwood forests. They’re such good indicators that researchers can use the length of sword fern fronds (their “leaves”) to almost perfectly graph the amount of moisture available in their particular forest. The further north the forest, the more moisture they usually receive… and, the longer the fronds on the ferns!
Research and images courtesy of Emily Limm, Save the Redwoods League. Link to research.
Nobody had ever measured the ferns in the Redwood forests surrounding Chabot until educator Eric Havel and Redwood scientist Emily Limm (PhD, Director of Science at Save the Redwoods League) reached out to teachers and students for their help. The forests surrounding Chabot are of particular interest, because they’re an isolated patch on the drier southern and inland edge of California’s Redwood Ecosystem zone. The lengths of the fern fronds could tell Emily whether this particular patch fit the pattern she was seeing of ferns and fog drip… and repeat measures over time can tell how this pattern might be changing.
With the global climate changing, Northern California winter rainfall and summer fog drip moisture patterns may also change. As an isolated forest patch, already on the edge of ideal conditions, the Chabot redwoods are particularly vulnerable to changes. Students monitoring sword ferns are on the front lines of keeping watch for the health of not just the sword ferns, but also the salamanders and other animals and plants dependent on a certain moisture and temperature range, including the iconic Redwoods themselves.
Chabot is actively working with partners Save the Redwoods League and the East Bay Regional Park District to find further funding and resources to support and expand this project.