Friday, May 22, 2015

12-May-2015 Northeast Seattle, Washington

Site location
Having moved back to Seattle the week before, I was by this day more than eager to tap some pine cones.  Although our busy schedule didn't immediately allow for a full field day, I did manage to gain access to a lone pine growing in a relatively undisturbed corner of a nearby parking lot.  With a cone source so conveniently located, I was able to tap 50 cones in 1.5 hours, a very doable time commitment!

Sample site
I suspect that the tree is a black pine (Pinus nigra), a European species widely planted as an ornamental in the United States. I tapped the cones of the maritimus variety of P. nigra last year on Waasdorpervlakte in the Netherlands.  (Fun fact: A black pine growing in the Oxford Botanic Garden was one of J. R. R. Tolkien's favorite trees.)

Pine cone over my "net", a bucket.
The cones beneath the Seattle tree have a fine prickle on each scale, and there are two needles per sheaf.  The cones of ponderosa pine (P. ponderosa) also have prickly scales and two or three needles per sheaf, but I've ruled it out as the species because the cones beneath the Seattle tree would be unusually small if it were a ponderosa, and because the tree doesn't display a ponderosa's typical growth form.  Scots pine (P. sylvestris) is another commonly planted European species that also has prickly cones and 2 needles per sheaf, but its cones are stalked.  The present cones aren't.

Fallen cone microhabitat
The tree was growing in a relatively untended plot (meaning no habitat-smothering wood chips!) on the border of the Burke-Gilman Trail.  This section of the trail constitutes a linear mixed hardwood-conifer forest.  Volunteers have in recent years replaced invasive understory species like Himalayan blackberry and English ivy with native shrubs and herbs.  The pine I tapped is adjacent to one such renovated area, with a wooden fence between.

This tiny crab spider was a
penultimate female
There were no lack of cones to tap, despite the single source.  Had I the time and the inclination, I could have tapped hundreds.  Instead, I tapped the customary 50 and got 20 spiders and 15 juvenile harvestmen.  The vast majority of the spiders were Ozyptila sp. crab spiders from the family Thomisidae, but I also got a few Phrurotimpus sp. ground sac spiders and a juvenile agelenid.  I'll have to re-sample next month, by which time there will hopefully be some mature specimens about.

Juvenile Ozyptila
Although I'm back in Seattle, my spider net isn't yet.  I improvised with a bucket and found it serviceable.  The rigid plastic provided a very nice striking surface, and the light color and light-transmitting plastic contrasted nicely with the darker arachnids.  The main drawback was that it was more difficult to capture specimens on the hard plastic bucket surface than it is from my pliable sailcloth net.
Rhododendron blazing beneath the pine

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