Category: Forest Restoration

Catherine spotted these last year: small but healthy young sword ferns, a rare welcome and hopeful exception to what we have seen in eight years of the sword fern die-off – which is that sword ferns do not naturally re-establish themselves from spore in the forest at Seward.

For the most part, sword ferns colonize open ground on mineralized soil before the forest canopy forms, then plants each live very long lives (“a thousand years is not out of the question” – D. Barrington). Direct sunlight and bare, rich soil are the usual preconditions.

Years of close observation throughout Seward’s fern dead zones fits this model. (The research on germination and establishment are summarized here.) Catherine’s observations complicate the received wisdom – and offer some hope.

February 6th, 2022: Holly and ivy, popular at Christmas, are year-round deadly in Seward’s forest. Left to propagate and grow, they out-compete native species. Most of the forest was cleared of ivy between 2002 and 2006 in a massive and partly volunteer effort. But some eastside slopes north of the Fish Hatchery are seeing a resurgence. Here is a pile including both species, pulled and dug out this afternoon:

Seattle Parks/GSP plant ecologist Michael Yadrick found funds to hire Signature Landscape Services of Redmond Washington to do more restoration in Seward’s old-growth forest. Last year, Signature did lots of planting, and subsequent irrigation in several acres of sword fern die-off near the cisterns, at the intersection of the sqebeqsed and Hatchery trails. The crew, led by Hamilton, is skilled, industrious, committed to the forest, and a pleasure to deal with.

This year, with yet more support from Michael, Signature installed about 200 young sword ferns in depleted areas on either side of the sqebeqsed trail. Half of these young ferns are the offspring of the Lazarus Fern, so-called because it was one of the few survivors of the initial die-off at Ground Zero – and unlike most of the other survivors, is located at a distance from large trees or downed wood. Volunteer David Perasso collected spores from the Lazarus Fern, grew them out in flats, then transferred them to the Parks nursery/greenhouse (thank you Johan!).

Michael, Johan, Eric Sterner and FoSP designed a simple experiment on the hypothesis that these Lazarus offspring may have an allele protective against the (still unknown) agent of the die-off, and therefore will have better survival than generic nursery ferns planted nearby. Hamilton and the Signature crew platned the Lazarus ferns and the generic controls into the latest dramatic die-off zone, described here. FoSP will monitor survival over the next five years. Many confounding factors muddy the picture, but perhaps some useful pattern will emerge.