Why study ferns?  In 2008, I discovered that the height of the most common plant in the coast redwood forest is affected by how much rain and fog fall among the coast redwoods. In wetter forests, like the temperate rainforests of Humboldt and Del Norte Counties,Western sword fern (Polystichum munitum), grows in patches so tall and thick on the forest floor that the ferns are hard to walk through. In drier forests, like the coast redwood forests of Santa Cruz and Monterey Counties, sword ferns grow more sparsely and the fronds on these ferns are shorter. In dry years, sword ferns lose many of their fronds and show signs of stress before other species — like the redwoods themselves — do. For this reason, sword fern is an important indicator of climate change and can help detect drought in the redwood forest to identify areas of climate refuge as the environment continues to change. 

When fertile, the underside of Western sword fern fronds display colorful sori – reproductive structures that release wind-borne spore when mature.

Dr. Fern giving these sword ferns a summertime health check up.

Las Positas Community College students get their fern on and collect Fern Watch data.

Frond height measurements by students at Redwood Regional Park.

Fern Watch is powered by amazing volunteers like Eric Havel, Mary-Ellen Hannibal, Deborah Zierten, and Cat Morris (left to right).

Oakland Tech high school students collect Fern Watch data at Redwood Regional Park.

Architectural beauty of fronds make me smile from any perspective.

Dr. Fern and Marie Antoine finding fern paradise.

Dr. Fern encourages this crunchy sword fern to hang in there a little longer.

Dry sword fern, June 2014.

A brightly-colored new sword fern frond has been munched by a hungry sawfly larva.

Aphid, sooty mold, and lichen covered weather station at Samuel P. Taylor State Park.

A fuzzy sword fern fiddlehead declares spring has sprung at the Grove of Old Trees in Sonoma County.

Sword fern loves having wet leaves and soaks this water up.

Betsy Franson records Fern Watch data at Prairie Creek Redwoods State Park

A fiddlehead emerges after fire

A sword fern returns to normal with a new flush of fronds after the fire.