City Creek Nature Notes – Salt Lake City

June 24, 2017

June 23rd

Filed under: Cheat grass, Fire, Guardhouse gate, Jupiter, Stream, Western tent caterpillar moth — canopus56 @ 6:06 am

Canyon Habitat Overview

9:45 p.m. The heat wave has temporarily broken and temperatures fall in the eighties degrees Fahrenheit. I take only a short walk in the canyon’s summer late-evening twilight, and enjoy the coolness of night. The stream has gone down by two-thirds since the end of snowpack melt on June 4th. It must half again before the minimum flows of summer, at about 12 cubic feet per second, are reached. Now the stream runs only from underground water seeping from underneath both halves of Salt Lake salient. True darkness does not come until 10:15 p.m., and when it finally does arrive, bright Jupiter hangs over the road to the south like a guiding star. During the winter, Venus played that role (January 30th).

As I return to Guardhouse Gate, a large 4 inch moth is resting near the guardhouse lights. Its coloration is spectacular gradation of gray and ruddy brown, and it has large green frilled antennae the size of a woman’s pinky finger. It is a Western tent caterpillar moth (Malacosoma californicum). I have seen none of its characteristic tent colonies on trees in the canyon, but looking back through my photographs, I saw the caterpillar form of this moth on May 24th.

Reaching my car, city parking enforcement has left me a warning citation for parking at Guardhouse Gate after 10 p.m. Even five years ago, this would have been laughable, and throughout the winter this parking regulation was never a problem. But now the ridgelines are covered in early two feet tall dry cheat grass. A small spark could cause a brushfire that in the past have burned between 20 to 200 acres, or about one-third of a square mile. The city wants to deter summer nighttime revelers from entering the canyon in order to prevent them from starting campfires or lighting sparklers or other fireworks. Today, there are over 1,500 acres burning in Utah, about half of which I estimate are Cheat grass brush fires, and on arriving home tonight, the news reports a 100 acre grass fire in the Gambel oak chaparral above Farmington, Utah, about 20 miles north of the canyon.

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Per Thoreau’s “Journal” on June 23rd, 1840, he hears a young golden robin. On June 23rd, 1860, he notes that night hawks fly in a path similar to butterflies. He describes three types of cinquefoil. On June 23, 1852, he hears a bobolink and an owl. He sees mountain laurel and partridge berry (Mitchella repens) in bloom. He smells wild rose, sweet briar, blue geranium, and swamp pink. He notes that the undersides of leaves, particularly of the aspen, are lighter than the top side. On June 23rd, 1853, he sees leaf-heart and loose strife. On June 23rd, 1854, he sees three broods of partridges. On June 23rd, 1856, he sees baywings.

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City Creek Canyon is an undeveloped east-west trending canyon that extends 12 miles from Salt Lake City’s downtown business district. The canyon clefts the Salt Lake salient, an east-west trending spur of the north-south running Wasatch Front Mountain Range. The salient was created by an earthquake faults, principally the Pleasant Valley fault, deep below the canyon that is also perpendicular to the main north-south running Wasatch Fault. The canyon defines the northern end of the Salt Lake valley. A similar fault at the south end of the valley created the Traverse Mountains, another east-west salient that defines the boundary between Salt Lake County on the north and Utah County on the south. The difference between the Traverse salient and the Salt Lake salient is that limestone formations that are the bedrock of Salt Lake salient allowed water to flow down the middle of the ridge, and over geologic time, water flows carved out a canyon that clefts the salient in two. The canyon bottom begins at the city near 4,300 feet in elevation and rises to about 6,000 feet in elevation another 8 miles up canyon.

There are four principal habitats in the canyon. At the lowest elevations are grasslands mixed with sagebrush that covered the valley floor before pre-European colonization (Christensen 1963). These grasslands spread up both sides of the canyon walls and ridgelines through canyon mile 6.0 where water is insufficient to support the drought tolerant Gambel’s oak forest. It includes Bluebunch wheatgrass (Pseudoroegneria spicata a.k.a. Agropyron spicatum), Wild bunchgrass (Poa secunda), invasive Cheat grass (Bromus tectorum), and Big sagebrush (Artemisia tridentata) (Christensen 1963, Rogers 1984).

The second habitat by elevation is Wasatch chaparral that is dominated by pure stands of Gambel’s oak trees (Quercus gambelii) (Hayward 1945; Christensen 1949). Such stands can be found around the base of and to the north of Ensign Peak. They continue below the western ridgeline of the Salt Lake salient to milepost 2.0.

The third habitat is Wasatch lower montane (Hayward 1945, p. 10; Hayward 1948; Rogers 1984). This habitat is a mid-elevation association between 4,500 feet and 8,000 feet above sea level that consists primarily of dwarf Gambel’s oak trees mixed with Norway maple trees (Acer platanoides), and Big Tooth maple trees (Acer grandidentatum) (Hayward 1948; Ream 1960). In City Creek Canyon, this habitat begins at the Guardhouse Gate and continues up to approximately milepost 4.0. On the shaded north facing slopes of the canyon, water-loving maple trees dominate. On the sun-exposed south facing slopes, Gambel’s oak trees that have deep water-seeking tap roots dominate. Between the two slopes and surrounding the canyon’s stream is a mixed community of oaks, maples, Box Elder trees (Acer negundo), Rocky Mountain narrowleaf cottonwood trees (Populus angustifolia), and Western water or River birch trees (Betula occidentalis). Bohs at the University of Utah has prepared an extensive list of plant species in City Creek Canyon near the Guardhouse Gate (Bohs 201).

The fourth habitat begins about 6 miles up canyon, or four miles above the Guardhouse Gate above Bonneville Drive, where the Wasatch oak community gives way to Wasatch upper montane habitat (Hayward, 1945). This habitat is includes Lodgepole pine (Pinus contorta Dougl.), Douglas fir (Pseudotsuga menziesli) and Quaking aspen trees (Populus tremuloides) (Hayward 1945, Hayward 1948). On shaded north-facing slopes conifers dominate, and on sunny south-facing slopes Aspens dominate with some Utah juniper trees (Juniperus osteosperma.

The Gambel’s oak trees in the vicinity of City Creek Canyon are all dwarfs. Gambel’s oaks can grow to be mature trees thirty or forty feet in height, but where they are limited by water or other environmental stresses, then they reach only about ten feet in height (Christensen 1949). Christensen also noted that the seeds of these oaks while not germinate if they fall under the shade of an existing tree, but that does not limit the rate of their expansion. He observed many species distributing Gambel oak acorns, such as Western scrub jays, rock squirrel (Spermophilus variegatus), and Lewis woodpeckers (Melanerpes lewis) (Christensen 1949). In the canyon during the winter, I have also seen mule deer (Odocoileus hemionus) and Wild turkeys (Meleagris gallopavo) browsing for acorns. Thus, the oak’s acorns are widely distributed, and other constraints like lack of water must constraint its growth. Because the Gambel’s oak’s acorns are randomly distributed around the perimeter of copse, copses of these oaks have a characteristic inverted bowl shape. The oaks are found either in these bowl shaped groups on chaparrals or in uniformly covered broad sections of hillsides. The Gambel’s oaks around Salt Lake City are at the northern limit of that specie, and so, their development is under constant limiting pressure from northern Utah’s climate.

This journal primarily concerns the Wasatch lower montane habitat in the first two canyon miles above Guardhouse Gate within 500 feet on either side of the stream. Over the course of a year, all of the four habitats are visited.

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On June 23rd, 2012, Smith’s Food King, a dominant supermarket chain in the valley, decides to no longer sell fireworks because of the risk they pose to starting fires on valley benches and in valley canyons, including City Creek Canyon (Salt Lake Tribune). On June 23rd, 2010, the 31st Wasatch Steeplechase run over Black Mountain was run (Salt Lake Tribune). The Steeplechase was begun in 1979 by McKay Edwards as a summer solstice celebration (id). On June 23rd, 1918, the Salt Lake Tribune featured a photographic story-advertisement extolling the pleasures of automobile driving up City Creek Canyon (Salt Lake Tribune). On June 23rd, 1899, a City Committee will investigate the lack of water on the east side due to problems in the distribution system for City Creek water (Salt Lake Tribune).

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