City Creek Nature Notes – Salt Lake City

July 21, 2017

July 19th

Crossed Cottonwoods

6:00 p.m. Afternoon thunderclouds threaten, but it is for nothing near City Creek Canyon. Where the road first enters the canyon, it gives vistas of the valley and sheets of water can be seen lowering from the clouds across southern and western ends of the Salt Lake Valley. But at the valley’s northern end, no water falls, and the weather station at the airport records only a trace of moisture. The clouds tease the parched land, dried grass and thirty trees. One canyon tree is well-adapted to this climate; it grows large; it puts down deep roots that search for underground water.

Narrowleaf Rocky Mountain cottonwood (Populus angustifolia J.) are numerous in the first mile and are easily identified by their linear, willow-like leaves. True Freemont’s cottonwoods (Populus fremontii) with their broad triangular cordate leaves are more difficult to spot, and the home range of Freemont’s cottonwoods is further to the south in New Mexico and Arizona. Like the F2 generations of Cottam’s hybird Gambel’s oaks that dominate the drier land of the canyon (July 3rd, 4th and 5th), the Narrowleaf Rocky Mountain cottonwoods and Freemont’s cottonwoods have been hybridizing. Like the Gambel’s oak, it makes numerous hybrids along the canyon’s bottom whose leaves are of intermediate forms between the parent types (Lanner 1984). Their more common cross, Populus angustifolia x fremontii S. Wats, have intermediate ovate leaves that look like a larger version of a Western water or River birch leaf and resemble other common native and introduced trees (Arizona State University and Baker 1993). This confuses identification of trees in the first canyon road mile.

There are many trees in the canyon, and learning tree identification can be eased by examining known exemplars. The following is a list that cross-references some known trees species in the canyon with local examples at the University of Utah and Westminister College in Salt Lake City. The list is weak on conifer exemplars:

List of Exemplars for Trees in City City Creek Canyon at University of Utah, Westminister College Emigration Creek Natural Area and Miscellaneous (2017)

At the University of Utah (University of Utah Tree Tour))

• *Horsechestnut (Aesculus hippocastanum) (University of Utah Tree Tour. No. 5, located at the southwest corner of the George Thomas Building on President’s Circle. Lat. 40.763604, Long. -111.8539387.)

• Rocky Mountain juniper (Juniperus scopulorum) (University of Utah Tree Tour. No. 7, located at the southwest corner of the George Thomas Building on President’s Circle. Lat. 40.763848, Long. -111.8522112.)

• Big Tooth maple (Acer grandidentatum). (University of Utah Tree Tour No. 8. Located south of the George Thomas Building (the old Natural History Museum) and east of University Street. Lat. 40.76375, Long. -111.851917.)

• *Norway maple (Acer platanoides) (University of Utah Tree Tour No. 15. Located north of the George Thomas Building on north side of President’s Circle Drive. Lat. 40.764604, Long. -111.8536557.)

• *Purpleleaf plum (Prunus cerasifera) (University of Utah Tree Tour No. 21. This is similar to the cultivar Newport flowering cherry plum (Prunus cerasifera Newportii) found in the canyon. On the north side of the President’s Circle at the intersection with Lat. 40.7646614, Long. -111.8506819.)

• Gambel’s oak (Quercus gambelii) (University of Utah Tree Tour. No. 24 located northwest of the Talmage Building on President’s Circle Drive. Lat. 40.764621, Long. -111.8521057.).

• *Norway Spruce (Picea abies) (University of Utah Tree Tour. No. 28 located south of the Widtsoe Building on the south side of President’s Circle Drive. Norway spruce were planted in City Creek Canyon around May 1st, 1918 by the City (Salt Lake Tribune). Lat. 40.765321, Long. -111.8526205.)

• *Siberian elm (Ulmus pumila). (McPherson and Graves (1984, 66-67) No. 46. A massive Siberian elm in the quad at the east end of the Bookstore. Lat. 40.764521 Long. -111.8500557. There is also grove of these elms in Lindsey Gardens at the north east corner of M Street and 7th Avenue. Lat. 40.777452 Long. -111.8659852.)

• Serviceberry (Amelanchier x grandiflora) (University of Utah Tree Tour No. 64. Located on the back east side of the Pioneer Memorial Theatre. This is similar to the native Saskatoon serviceberry (Amelanchier alnifolia) found in the canyon. Lat. 40.762741, Long. -111.8512532.)

• Chokecherry (Prunus virginiana) (University of Utah Tree Tour No. 82. Between LINCO and Business Buildings along walkway from Marriott Library. Also along South Campus Drive Traffic Roundabout. Lat. 40.765543, Long. -111.8441142.)

• Cottam’s F1 Hybrid Cross of Gambel’s oak and Arizona shrub oak. (Author taken July 2017 at 1760 South Campus Drive, University of Utah, Lat. 40.760233, Long. -111.8415315.)

At Westminister College Emigration Natural Area Tree Project: Trees)

General directions: At Westminister College on one-eighth mile stretch where Emigration Canyon Creek crosses the campus (Harrison 2002). Park in the main visitor parking area along 1300 East and walk to the starting point in front of Giovale Library at Lat. 40.730536 Long. -111.8558192. Refer to Owens 1999 map for location descriptions.

• Narrowleaf cottonwood (Populus angustifolia). (The Narrowleaf Cottonwood is on the south bank of the stream surrounded by other species in Owen’s Reach No. 2. Look for the narrow leaves from the viewing point. Saplings are closer to the top of the stream bank. Go across the footbridge near Giovale Library and head east to viewing point at Lat. 40.730154 Long. -111.8570887.)

• Hybrid cross between Freemont’s poplar and Narrowleaf cottonwood (Populus angustifolia x fremontii). (Go down the stairs to the west of Giovale Library to the trail that overlooks Emigration Creek. Go to the Nunemaker Amphitheater along the trail in Owen’s Reach No. 3. Hybrids are along the back of the stage. Compare the intermediate forms of these leaves that are between the parent Narrowleaf and Freemont poplars. Lat. 40.730537 Long. -111.8585217.)

• Freemont’s poplar (Populus fremontii). (Freemont’s poplar is located further west along the trail near the end of the parking lot structure on the north border of the trail in Owen’s Reach No. 6. Lat. 40.730521, Long. -111.8588057.)

• Box elder (Acer negundo). (Box Elder trees are prevalent in Salt Lake City An exemplar can be found east of the footbridge. From in front of Giovale Library, go along the sidewalk at the east of the residence hall to the east. Lat. 40.73029, Long. -111.8552372.)

Other

• Coyote willow (Salix exigua) (There is Coyote willow along east Bonneville Drive about one-quarter mile after the turning on to the one-way Bonneville Drive from 11th Ave. Lat. 40.7826391 Long. -111.8825331.)

Source: University of Utah, Department of Facilities Management (2017). Tree Tour (Web). Link (GIS Map Tour of trees in the Walter Cottam Tree Collection spread throughout the University of Utah campus.), McPherson and Graves 1984, Harrison 2002, Boogert 2017, Owens 2000, and Author. * – Cultivar or invasive.

The Westminister College Emigration Creek Natural Area is a deep gulch about 1,000 feet long that holds one of the Salt Lake Valley canyon streams. The four streams flowing from the north and east of the City, Red Butte, Emigration, Parley’s and City Creek, are for the most part encased in underground conduits, but where Red Butte, Emigration and Parley’s Creeks cross soft soils on the elevated east bench of the City, they cut small gorges in which it was impractical to build. There four mini-canyon parks provide short, cool walks under the shade of native trees during the oppressive heat of afternoon summers. Red Butte Creek runs through the Miller Natural Park near 1100 South and 1700 East and from there it continues on bordered by private lands to Liberty Park. Emigration Canyon Creek runs through Wasatch Hollow Nature Area near 1500 South and 1700 East, then the Blaine Street Nature Area, and then on through the Westminister College Natural Area described above. Parley’s Canyon Creek flows through a small gorge Hidden Hollow Nature Area surrounded by office towers and a shopping center near 2100 South and 1300 East. In this way, City residents always have some form of City Creek Canyon always close at hand.

The Westminister College Emigration Creek Natural Area is a deep gulch about 1,000 feet long that holds one of the Salt Lake Valley canyon streams. The four streams flowing from the north and east of the City, Red Butte, Emigration, Parley’s and City Creek, are for the most part encased in underground conduits, but where Red Butte, Emigration and Parley’s Creeks cross soft soils on the elevated east bench of the City, they cut small gorges in which it was impractical to build. There four mini-canyon parks provide short, cool walks under the shade of native trees during the oppressive heat of afternoon summers. Red Butte Creek runs through the Miller Natural Park near 1100 South and 1700 East and from there it continues on bordered by private lands to Liberty Park. Emigration Canyon Creek runs through Wasatch Hollow Nature Area near 1500 South and 1700 East, then the Blaine Street Nature Area, and then on through the Westminister College Natural Area described above. Parley’s Canyon Creek flows through a small gorge Hidden Hollow Nature Area surrounded by office towers and a shopping center near 2100 South and 1300 East. In this way, City residents always have some form of City Creek Canyon always close at hand.

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Eckenwalder at the University of Toronto is credited demonstrating prolific ability of poplar’s to hybridize, including Fremont’s poplar-cottonwood (Eckenwalder 1984), but he did specifically cross-breed Fremont’s cottonwood and the Narrowleaf cottonwood. In 2002, Schweitzer, Martinsen and Whitham at the University of Northern Arizona crossed and back-crossed Fremont’s poplar and the Narrowleaf cottonwood (Populus fremontii x P. angustifolia) using trees along northern Utah’s Weber River. They found that in terms of seed mass and seed weight, the F2 back-crosses fell between the more productive Fremont’s poplar and the less productive Narrowleaf cottonwood. Thus, they concluded that the hybrids were at least as productive as one of the parent trees.

Sparks and Ehleringer at the University of Utah used Narrowleaf cottonwood, Fremont’s poplar-cottonwood and Coyote Willow to investigate whether trees maintain lower or higher levels of photosynthesis at different elevations (Sparks and Ehleringer 1984). This is a deceptively simple question. As elevation increases, carbon dioxide is less dense and leaves may thicken to protect against harmful ultra-violet radiation. The stoma (pores) in leaves may also restrict in order to better retain water at the lower pressure of higher altitudes. Conversely, higher altitude mountain plants get more water. How do these factors balance? Contrary to other studies, Sparks and Ehleringer found that Fremont’s poplar and Narrowleaf cottonwoods in Big Cottonwood Canyon do more photosynthesis as altitude increases.

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On July 19th, 1895, a Mr. Taylor reported to the city council that he intended to develop 26 mining claims in the canyon and then force the city to buy him out in order to protect its water supply (Salt Lake Herald).

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