Thursday, January 18, 2018


Since 2014 we have been observing and attempting to understand a dramatic die-off of the dominant understory sword fern species, Polystichum munitum, in the 120-acre old growth "Magnificent Forest" in Seattle's Seward Park Extensive lab and field work, consultations with fern experts throughout the US, and recent reports of die-off from elsewhere in the Puget Lowlands of Washington state, lead us to conclude with considerable confidence: 

  • The die-off is caused by an (as yet unidentified) pathogen 
  • Climate change may be a contributing factor, but until the proximal cause of the die-off is determined, the role of climate change can not be known.  
  • Drought is probably not a cause (see rainfall records below).
  • Is unprecedented, not part of the P.munitum life cycle, in which ferns colonize open ground, do not reproduce under a closed canopy, with individual plants living for hundreds of years.
  • Holds implications for the forest at Seward Park, and for other forests in the region.

Some selected blog entries

Thursday, December 14, 2017

Bainbridge Island Blakely Harbor Die-Off Markedly Worse

In September, Darrell Howe reported some isolated sword fern die-off at one spot on Bainbridge Island, on the trail between Fort Ward and Blakely Harbor Parks - see map below.

This week Darrell reports:

I had a chance to return to Bainbridge and walk back into the sickly fern site I noticed in September.   I will attach a few new photos.   I was way too conservative in my estimate of impacted area earlier in the fall.   I would now guess the total site may be more like 7,500 sf.    I did not see any other signs anywhere else on the Island for now.

Photos below the map.    

Fort Warden Die-Off Update

Erik Kingfisher, Director of the Jefferson Land Trust, along with his daughter Samara, paid a citizen science visit a few weeks ago to Fort Warden State Park, at the northeast tip of the Olympic Peninsula.  They verified observations made by Kitsap resident Heidi Danlicheck in October. 

Follow this link to see the Kingfishers' video and commentary:


Monday, November 20, 2017

Possibly related, at least of interest: diseased and dying western hemlocks at Seward Park

Seven years ago, in 2010, I noticed a cluster of four mature dying hemlocks at the dog-leg bend in the sqebeqsed trail.   I had witnessed the death and disappearance of eastern hemlocks in Shenandoah National Park in the 1990s due to the wooly adelgid.   Concerned that something similar was taking place in this related species, I began an informal survey.   Which I happily abandoned after a few months, discovering that all the hemlocks in other regions of the forest were apparently in good health.

Unfortunately this no longer seems to be true.  Many mature hemlocks have recently been affected by factors unknown, many of them dying.   Perhaps the annosus fungus is responsible, as was suggested to me by UW's Bob Edmonds in 2010.  There is now a loose cluster of tall dead hemlocks on the Huckleberry Trail, and Kramer pointed out many dead or dying hemlocks just south of sword fern ground zero.

Here are my unedited notes from 2010, the result of informal research and email exchanges:

   Notes from 2010

Tuesday, October 31, 2017

Die-off on Hornby Island's Helliwell Provincial Park

Catherine Alexander, the observant citizen scientist who first detected the Seward Park sword fern die-off four years ago, has just returned from Hornby Island - just east of Vancouver Island, 135 miles north of Victoria, between Nanaimo and Campbell River:

Catherine spent most of a day exploring Helliwell Provincial Park, and reports:

Much of the park is old forest, Doug Fir, western red cedar, madrona.  Similar to Seward, Sword fern makes up a good part of the understory. I noticed wilted ferns immediately as we started out, and continued seeing them as we explored. In some places it looked as if most of the ferns visible from the trail were affected. In other areas the ferns on one side of the trail looked healthy while the other side of the trail was affected.  Below are a couple of pictures of small groups of dying ferns, as well as a map of the park with our route through the forested areas marked in red. 

Catherine reports that the islanders became aware of the problem only this year, and considered it the result of an unusually hot and dry summer.   We cannot be sure that that is not so - absent a biological marker of the presumed pathogen - but to both Catherine and me this does not look like a drought affect.   Seattle had less that < 0.1 inch of rain this summer, and Seward's sword ferns weathered this without evident damage.   That is: the effects of the putative pathogen - the die-off - are apparently not difficult to distinguish from drought effects.

Sunday, October 29, 2017

Results of June 2017 Soil Tests

Nelson Salisbury of EarthCorps, assisted by me, collected 10 samples each from three disparate 400 sq.ft. at Seward Park, following the protocol provided by the UMass Extension Service.  Here is a map and site summary, followed by lab reports for each site.
Site #1 is ground zero - no surviving ferns.
Site #2 is just west, across the sqebeqsed trail, where ferns are currently dying.
Site #3 is at the north end, a healthy site, almost exclusively populated by ferns.

Extensive Die-Off at Fort Warden State Park

We received photos and video of a large die-off at Fort Warden State Park.   A representative photo and site map will be found below.

The die-off apparently covers several acres, and is quite dramatic.  This is the most northwesterly die-off report received thus far.  It is about eighteen miles north of Port Ludlow, which was previously the most northerly site.  Fort Warden overlooks both Puget Sound and the Straits of Juan de Fuca.

Our Kitsap citizen scientist, Heidi, reports:

I just spent the afternoon traipsing around Fort Worden State Park in Port Townsend and found extensive fern die-off.  It was in the classic pattern of crispy fern, next to mostly dead, next to sparse flat and failing ferns.  It was everywhere.  We went all around Artillery Hill and found that most of the place is affected.  There’s still “healthy” stands of fern, mostly on the North side, which helped to give a stark contrast to the sad desolation of the remaining hill.

It looks to me like it probably started 2-3 years ago.   It is a very large site and I’ve only explored a small part of the park (2+ miles). 

Interestingly, the first patch of die off I found was near an otter den.   I’m making note of wildlife corridors in case that is a part of the spread. We have a lot of otters that traverse my property to nest across the street. The fern die off seems to follow along their path.