Tuesday, January 8, 2019

Tim Billo's Presentation to the Washington Native Plant Society, January 3rd 2019

Tim, assisted by Kramer Canup, gave a masterful and comprehensive report on the regional die-off last Thursday.   Here are his slides - accompanied by extensive notes. 

Get the pdf.

Monday, December 31, 2018


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

Saturday, December 29, 2018

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.

Saturday, October 6, 2018

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 

Sunday, July 1, 2018

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.