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Fern Watch

Main Project Information
Goal Help track the health of redwood forests
Task Volunteer to monitor ferns in our forests
Where California

Help Track the Health of Redwood Forests

In 2008, League scientist Emily Burns discovered that the height of the most common plant in the coast redwood forest is affected by how much rain and fog fall in the woods. Western sword fern (Polystichum munitum) has tall fronds in wet redwood forests and much shorter fronds in dry forests. For this reason, sword fern is an important indicator of climate change and we are studying these ferns to detect drought in the redwood forest.

Just by monitoring the ferns on the forest floor, you can help League scientists learn how changes in climate may be affecting redwood forest habitats. You can help us track changes in these ferns in your local forest by photographing and taking measurements of ferns through our Fern Watch Project on the free iNaturalist App

How to Join

How to Get Involved

Locate Western sword fern on the forest floor throughout the coast redwood ecosystem and other Californian forests. Its fronds reach lengths of more than 1 meter and typically live for approximately 30 months. Fiddleheads emerge in spring.

Add pictures and frond measurements of your fern observations through iNaturalist. Download the iNaturalist app on your iPhone or Android. Create an iNaturalist account and join the Fern Watch project.

Photograph the fern up close so the frond characteristics are documented. Use multiple photos if necessary to show presence of fiddleheads and sori.

What Did You See?
Identify the species or leave it blank if unknown. Use our Fern Watch Species Guide if you need help.

Select Fern Watch and note additional traits about the fern:

Fiddleheads—Do you see any new leaves emerging as curled fiddleheads? If you see at least one fiddlehead record YES.
Number of Green Fronds—Count the number of green fronds including fiddleheads. Record the number of living fronds.
Presence of Sori—Sori are the round spots on the underside of fronds which produce spores. Do you see any of these reproductive structures? If brown or green sori are present, record YES.
Frond Length—Measure the length in centimeters of one uncurled green frond from the tip down to its lowest leaflet (pinna). Record the length to the closest whole centimeter. Repeat length measurements on four more fronds.

Ideal Age Group Elementary school (6 - 10 years), Middle school (11 - 13 years), High school (14 - 17 years), College, Graduate students, Adults, Families
Ideal Frequency Per month
Average Time Less than an hour
Spend the Time outdoors
Type of Activity On a walk, run, On a hike
Media Mentions
and Publications
Tags climate, drought, fern, fog, redwoods, sword ferns
Project Updated 05/23/2018