Monday, April 20, 2015

26-May-2011 Green Lake Park, Seattle, Washington

Bad site: Cone microhabitat buried
under wood chips
Good site: Cone microhabitat
Unable to coordinate with Rod Crawford for another joint collecting trip this month, I settled for a return to Seattle's Green Lake Park to tap cones under a different stand of trees than previously.  Since I'd taken my first sample there back in March, groundskeepers had ruined the fallen cone microhabitat under most tree stands by blanketing the ground with wood chips.  Luckily I found one mixed conifer stand growing next to busy Aurora Ave. that contained white pines (Pinus strobus or P. monticola) and also had been spared the wood chip treatment.

Fallen cones aplenty
Juvenile Enoplognatha sp. in prey
capture web between cone scales
Fallen cones were plentiful, as were arachnids within them.  Tapping 52 cones I collected 27 spiders (wow!), 13 of them the introduced invasive from Europe, Lepthyphantes tenuis (Linyphiidae).  According* to Rod, this species was introduced into Seattle in 1950 but "balloons massively" and so "is now found throughout the Pacific Northwest".  The species does seem to have settled nicely into the city.  An additional 7 spiders were juvenile Enoplognatha sp. (Theridiidae), probably ovata, also introduced from Europe.

Just a few of the many, many juvenile
Paroligolophus sp. harvestmen present
Besides spiders, the cones were also loaded with juvenile harvestmen.  So many, in fact, that I eventually stopped counting, but I estimated about 100 individuals.  Rod identified them as Paroligolophus sp. (Phalangiidae), probably agrestisParoligolophus sp. is a genus native to Europe.

Although the species composition was different this day than in my 25 March 2011 sample, both fallen cones samples contained mainly introduced species.

*Crawford, Rod. 2006. Terrestrial invertebrates: spiders. In: Boersma, P.D., Reichard, S & A.N. Van Buren (eds.) Invasive species in the Pacific Northwest, University of Washington Press, Seattle, 285 pp.

An inquisitive female mallard (Anas platyrhynchos)

No comments:

Post a Comment