Overview

New Posts (please scroll down):

December 2018: request for research proposals, site visit by LSU plant pathologist

October 2018: two experiments, possible insight into mechanisms of spread

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. 

Please add your own observations at our iNaturalist project.

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 (see annotated regional map), 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

• A Lazarus Fern? (March 2018)
• Port Ludlow die-off, some recovery: 2010 - present
• Experimental Plantings at and near Ground Zero (March 2018)
• Hypotheses

• Die-off reported from Snohomish County, Lord Hill Park (January 2018)
• Extensive die-off confirmed on Bainbridge Island and the NE tip of the Olympic Peninsula (December 2017)
• Narrative Essay - an overview
• Soil Analysis (June 2017)
• King 5 video (2 minutes, May 5th 2017)
• KUOW (27 july 2017)
• Sierra Magazine (August 2017) by Sarah DeWeerdt
• Seattle Precipitation Records (2012-2016, evidence against drought/die-off causality)

Contact: Paul Shannon, Forest Steward

RFP: time to issue requests for research proposals?

Research and experimentation on the sword fern die-off has, over the last four years, been  rather unsystematic.  It has taken us a while to realize the nature and extent of the problem.  Seattle Parks, WSU, UW and citizen scientists have cobbled together some low levels of funding and lots of volunteer effort to run studies as they occur to us.  Seattle Parks ecologist Lisa Cieko has consistently supported the work, finding some funding for consultants and experimental restoration.  

A more systematic approach to research and remediation may now be worth a try.  
In the research circles in which I work - my day job is in computational biology at the Institute for Systems Biology - research strategies and priorities are typically set by a central funding agency.  For us, this is usually the NIH, which identifies topics of interest, circulates requests for proposals, then convenes study sections to review, critique and prioritize the submissions.

The central agency’s budget is usually not known in advance. Once the the annual budget is decided, the top-ranked proposals are funded, and the research begins.  In addition, if especially compelling proposals are received, addressing urgent problems,  these can motivate the search for increased funding.

For the sword fern decline, I propose a similar approach:

• The sword fern working group (or a subcommittee) identifies  broad research topics.
• RFPs are drafted and circulated, with full candor about the uncertainty of funding.  
• Research proposals (with budget options) are submitted by prospective researchers.
• The working group then sketches out various budget scenarios, on the assumption of finding zero, moderate or generous funding.  Funding sources are identified and approached.  
• Proposals are scored and ranked and then awarded funding depending on merit and the actual funding available.

Here are some research topics and projects for which RFPs could be issued:

1. What are the causes of the die-off?
2. How best to monitor die-off, at regional scale, and at the scale of selected small sites?
3. Ongoing actual monitoring projects (based on 2)
4. Determine the population structure (age distribution, mortality, natural replacement)  of healthy fern communities in order to establish a baseline against which to assess and understand the die-off.
5. What happens after die-off?  In what circumstances does unassisted regeneration occur?  In what circumstances does it not?   This topic could include strictly observational studies and/or restoration experiments.

Site Visit from Rodrigo Valverde

In early December,  plant pathologist Dr. Rodrigo Valverde visited the sword fern die-off regions at Seward Park.   I first discovered Rodrigo through his 2009 study of viral infection of the Japanese Holly Fern.  He also participates in Lousiana's Roseau Cane Die-Off project.

Rodrigo was startled by the sword fern die-off - echoing Dr. David Barrington's observation that it is novel and deeply worrisome.  Based upon his visit and the tentative results of my bottle experiment, he suggests: 

Water-borne [spread] and the symptoms starting at tips is very typical of a bacterial pathogen. This is because unlike other plant pathogens, bacteria needs an opening/point of entry.  It is possible that water accumulating at tips where “openings” may be present provides a perfect environment for infection.

A small and informal experiment suggests that the agent/s of the die-off can be reproducibly transmitted from an affected frond to a healthy one

This informal experiment suggests that the agent/s are mobile in water, and will affect healthy fronds sharing water with a diseased frond, especially when the diseased fond is at the "crinkly phenotype" stage (which may be the earliest stage of the presumed infection).

Be warned!  This experiment is exceedingly preliminary, undoubtedly naive, suffers from small sample sizes, has not been replicated, and includes no quantitative data nor microbe-scale assays. They  have been carried out by an untrained enthusiast.  

If that is not enough to scare you off :} you can find lots of detail and time course photography in this report.

Early data on survival rates of 24 ferns at Seward’s Ground Zero versus 12 at the edge of the active die-off zone

Hypothesis:  the hypothetical agent of the die-off  does not persist in an affected area.

We planted 24 fronds at Ground Zero GZ) at Seward Park (where die-off was complete in 2014) and 12 in an active die-off  (AD) zone about 50 meters north.   I watered all 36 ferns throughout the summer drought.  The experiment will run five years and tests the hypothesis that survival at GZ will be significantly better than at AD.  We have possibly interesting results after only eight months.

Warning: this is informal science,  visual more than quantitative; it must be viewed skeptically.   The results are early and very preliminary,  and they may not stand up to either scrutiny or over the full five-year course of the experiment.

See the report.  

10 apparently long-dead ferns with miniscule fronds sprouting

Following the suggestion of Betsy Dowling of Zanzibar Landscape Design (Betsy contributed the earthworm hypothesis a few months ago) I today found and photographed ten barely resurgent ferns, at Ground Zero and to the south.   I will add these to my weekly rephotography round.  Perhaps some will survive the summer drought.

In this region there are perhaps 500 or 1000 dead crowns, like the one pictured below - a state they reach  roughly  two years after die-off.   The appearance of these few sprouting fronds might be explained by, or at least is consistent with, this model:

1.  The die-off is an epidemic event: a widespread occurrence at a particular time
2.  Some individuals (~2%?) though severely affected, previously judged dead, remain vital, making new small fronds, late in the season, several years after the initial infection.  That this spring has been long-lived, cool and with some rain, may contribute to this phenomenon.  I have noticed only a very few of these tiny sprouts in past years.
3. The hypothetical infection may be cyclical.  Weak support for that possibility is provided by old stubbled fern crowns to the south of Ground Zero which we estimate (without metrics or dependable assays) to  be from about 20 years ago.

Port Ludlow Die-Off History 2008 - present

From:  Ellen Theisen and Ken Thompson 

We are writing to you in the hopes that you have discovered a remedy for the sword fern die-off, and to share with you some information about our experience and experiments, since we were the first to report the die-off to Jenny Glass and Olaf Ribeiro. 

We recently found your blog about the Seward Park sword fern die-off. For 10 years, we have been concerned about the die-off on and around our property, but until now, we didn't know of any others who shared our concern.

1990. The 2.5 acres of our land in Port Ludlow were covered with huge, gorgeous sword ferns, reaching up to nearly six feet high. The 160-acre forest surrounding us was also covered with big, healthy ferns.

2008. We began to notice that the ferns were dying in three or four areas of our property. Within a few years, an entire quarter acre held only dead fern root balls, and no weeds at all, with half an acre more showing severe damage.

July 2013. The die-off had continued to grow with many ferns dying or looking unhealthy. We cleared out a forest of blackberries and salmonberries and discovered another quarter-acre of die-off we had not seen before. 

August 2013. We sent samples of some dead and dying fronds, along with a document of many annotated photos, to Jenny Glass and Marianne Powell at the WSU extension, asking for a diagnosis. They responded that the cause was unknown, and that neither they nor other plant specialists at WSU had heard of any similar problem elsewhere.

April 2014. We contacted Olaf Ribeiro. He examined the ferns, and took soil samples to analyze. He found evidence of a spider-mite infestation, but he said that he had not seen this sword fern die-off anywhere else. We cleared up the spider mites by spraying with CG-Mite.

May 2014. We applied organic products that strengthen roots and kill fungus to the soil around approximately 1000 healthy, dying, and dead ferns. 

April 2015. We repeated the application. We also transplanted 34 ferns into a 1000 square-foot die-off area, and they are still alive and doing fairly well. 

2017. We transplanted 8 ferns into another 400-square-foot area, and they have grown fiddlebacks this spring, and most of them look healthy. 

Current. We have seen signs of improvement. Ferns are even beginning to grow in the first die-back area we observed.  However, an occasional fern still dies or looks unhealthy, and the 160-acre forest surrounding us is showing signs of severe die off. The 10 acres we have walked through are full of dead and dying ferns.

If you find any solution to the die-off, please let us know as soon as possible. We will, of course, be watching your blog and would be happy to send you any of our documentation.