Fort Worden Recovery

Darrell Howe reports on a recent visit to Fort Worden that the ferns we thought were dying in 2017 are in fact recovering, sprouting new fiddleheads.   See his iNaturalist report and photos.   Last year's blog post of what we then interpreted as die-off is here.

This suggests a few different possibilities:

1. The putative pathogen which we think causes the die-off is not always fatal: it can also cause a die-back from which ferns can recover.  We may see this phenomenon at Ground Zero in Seward Park, where two ferns (out of ~100),  which I previously judged to be dead, are now recovering.
2. Some other phenomenon lies behind last year's apparently dead ferns at Ford Worden.  

Whatever the explanation - and ongoing observation may clarify - this recovery is very good news.

This recovery at least partially fits the pattern reported by the Pitterman Lab describing sword fern die-back due to drought in the redwood forests of California.   See the blog post here.  In brief:  fern response to drought includes stomatal closure followed by xylem embolisms followed by die back.  The ferns return in successive years, but continued cycles of drought + embolism lead to die-off.

Note that the California drought was more severe and lasted longer than what we have seen in the Pacific Northwest.  See precipitation records and California comparion here.