Rigor Vitae: Life Unyielding

Saturday, April 28, 2007


Even with the help of global warming, my bioblitz site is still surprisingly sterile and wintery—but a lack of diversity was a blessing in disguise, and some interesting trends were still noticed, but we'll get to that in due time. First, a correction is in order: I previously described my study pond as the result of an anthropogenic excavation in the '50s. This had been my understanding since I was a kid, but after scrutinizing the Google satellite image of the place, it seems clear that it's a classic oxbow, stranded after the creek changed course. I would guess that the construction of the nearby skating rink in the late '40s caused this course change. As scheduled, I spent Wednesday at my study site. The weather couldn't have been more cooperative. It was the warmest day yet this spring—even so, the water is still very cold, with little visible insect life. There was still no sign of new pondweed (Potamogeton sp.) growth, but many new shoots of Broadleaf Cattail (Typha latifolia) pierced the chilly surface.

As I mentioned in my previous post, Perkins Flat was cultivated for nearly a century, and saw the erection of no fewer than six buildings prior to 1950. Since then, the land and ecology have mostly run things for themselves. In the 1970s, I remember the wooden floor that remained from Cannon's warming hut and a WPA outhouse, still in good shape. The wooden roof of the outhouse burned in the '80's, and today the remaining rubble of the sandstone and concrete edifice is inconspicuous. I was unable to find as much as a splinter of wood from the warming hut floor. Only a few chunks of concrete footing remain from the sturdy bridge I crossed the main creek on as a boy. But the chronicling of crumbling architecture isn't my concern here. The flora of the fallow Flat itself has changed steadily, affecting the ecology of the pond and its immediate vicinity.The plant life on each side of the pond is quite different. Not only does the north side receive more sunlight, but it is largely a continuation of the disturbed meadow-grassland system that took over from the adjacent abandoned farmland. The south side, on the other hand, is more a continuation of the native flora of the abutting hillside. Identifying the constituents of the meadow system was a real challenge that I can't claim to have tackled heroically. I purchased a copy of A. S. Hitchcock's excellent Manual of the Grasses, and crammed the night before, but after several hours spent trying to ID the various native and exotic grasses, I threw in the towel and banished the Poaceae from my tally, making myself a promise to develop a better understanding of this important plant family once its members start to flower.
The meadow's dicots weren't much more cooperative. Many of them hadn't sprouted yet, and most of those that had showed little more than a pair of cotyledons to distinguish themselves. Not surprisingly, most of the plants with sufficient growth for identification were invasives: Canada Thistle (Cirsium arvense), Hounds Tongue (Cynoglossum officinale), Dandelions (Taraxacum officianale), Burdock (Arctium minor), and Poison Hemlock (Conium maculatum). Grasses aside, the most conspicuous member of this community right now is one of the newest. Leafy Spurge (Euphorbia escula) invaded Emigration Canyon around 1980, and its range has swollen annually. I could find no specimens of another newcomer, Wild Teasel (Dipsacus sylvestris), on the study site, although it's numerous within ten meters of the west end. The flatter parts of the south end have probably changed much less ecologically. Burdock is plentiful, but so are such natives as Wood's Rose (Rosa woodsii), Arrowleaf Balsamroot (Balsamorhiza sagittata), Oregon Grape (Mahonia repens), Common Rabbitbrush (Chrysothamnus nauseosus), and Utah Serviceberry (Amelanchier utahensis). Gambel's Oak (Quercus gambelii) is the dominant tree on the hillside to the south, but only two small specimens of the species occur on the site itself. A few relicts of the old riparian system still cling to life. Nine very old Bigtooth Maples (Acer granidentum) stand on the pond's east end, and five Fremont Cottonwoods (Populus fremontii) survive on the north shore. While a thick, healthy stand of Peachleaf Willow (Salix amygdaloides) thrives on the pond's sunny west end, shade and a small spring create very different conditions on the east end, where Star Solomon's Plume (Smilacina stellata) mixes with Horsetails (Equisetum arvense) and Short-styled Bluebells (Mertensia brevistyla), which, aside from Dandelions, are the only flowers blooming on the site.

A thick stand of Few-flowered Spikerushes (Eleocharis quinqueflora) lines the northeast shore. I would have liked to include in my tally the nearby stand of invasive Giant Rushes (Arundo donax - left) that appeared a couple of years ago, but it just wouldn't be fair to the other, more humble grasses. On the pond's surface, numerous young Lesser Duckweed plants (Lemna minor) are barely visible, floating amongst the Green Pond Scum (Spirogyra sp.). Within a month the two will claim most of the available surface area between them. The only fungus I was able to find was the Black Knot (Apiosporina morbosum) that grows on Chokecherries throughout the region. In the next post, I'll discuss the animals I cataloged.
Map and all photographs taken by CPBvK at Perkins Flat, April 25, 2007


Blogger Neil said...

Glad to see someone else using Sibley as a 'field' guide. I always feel silly lugging it around...

12:18 AM  
Blogger burning silo said...

That looks like a very interesting site. It must be wonderful a bit later in the season when things really begin to cook. It seems like it might be a good location for odonates(?)
I was actually expecting the flora to be a lot more advanced there, but just looking at your photos, it doesn't seem like we're that far behind.
Btw, glad that you included your map of the site. Very helpful for visualizing the habitat.

4:19 AM  

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