City Creek Nature Notes – Salt Lake City

July 30, 2017

July 21st, 2016 – End of Cyclical Year, Revised and Reposted

Microorganisms, Moss, Lichens, Glaciers, and Climate Trends

(Revised and expanded after lichen identification completed.)

3:30 p.m. It is another day intense summer heat, and as I pull into the parking lot, I take notice of a large Limber pine (Pinus flexilis at the lot’s end, south of the row of cultivar Horsechestnut trees. The Limber pine, Narrowleaf cottonwoods and the Horsechestnuts are among the largest plant organisms in the canyon, excepting some of the 50 foot diameter copses of Gambel’s oaks that may be one large, genetically identical sister plant. A bizarrely twisted, immature Limber pine hides behind to the east of side of the Guardhouse Gate building, and just past the gate, another conifer, a mature 70 foot tall native Engelmann spruce (Picea engelmannii). Key taxonomic differences between the two is that round pine needles occur in groups of two and flat fir and spruce needles are single. At mile 1.7 at picnic site no. 12. There a forty foot tall Rocky Mountain juniper (Juniperus scopulorum) is flanked by two taller Engelmann spruce trees. Although native to northern Utah, these three trees have been artificially planted to provide shade for picnic area.

Jogging up canyon about 100 yards up from the gate, I pass a deadly Bittersweet nightshade plant with small 1.5 inch green fruit. Splitting one of the fruit open, it is full of 1 mm bright orange larvae, and testing a few more, they are all infected. Given the number of young children that pass this spot, this is probably not a good place for a poisonous plant.

In the heat, I jog alone through an empty road, except for bicyclists. Near mile 0.3, sounds in the Gambel’s oak forest undergrowth betrays an yearling Mule deer stares back through the leaves. It is waiting for me to pass, so it can reach the stream and water. A bicyclist streaks unaware of its presence. A slight anabatic up-canyon wind provides a brief relief.

Beginning at mile 0.5 and the pond at picnic site 5, I collect the sponges placed in the stream and seeps on July 15th. The sponges have been collecting microorganisms for several days. I have looked at water samples from the stream under a microscope several times since May, but have never seen any microorganisms. That is a testament to how pure City Creek Canyon water is. My microorganism observing guide suggests using the sponges to trap organisms over time. The sponges also provide a protected framework that might appeal to microorganisms by providing shelter. The first sponge was located below the pond at picnic site 5, and it was placed under a cover of rocks such that stream water would continuously flow through the sponge. The first from the stream is a dark brown – a good sign. The second collected from the seep below picnic site 6 and the third is retrieved from the watercress seep also below picnic site 6. All three are a dark brown-grey color; the sponges have worked.

At the seep below picnic site 6, the Horsemint is in full bloom, and I count 32 Cabbage white butterflies feeding on them. A single Central bumble bee (Bombus centralis) collects among the butterflies. These are joined by an orange Mexican queen butterfly. I stand mesmerized by the glade for a few minutes. Nightshade is now also blooms in this glade.

Carpenter bee (Xylocopa californica) reappear after their first spring flight. Uniquely, they fly in a circular pattern closely around me twice, and having rejected me as potential food, they fly off with purposeful intent.

Proceeding again up canyon through the heat, only a few birds are heard at some distance from the stream. I cannot distinguish their calls, except for the nasal cawing of a Red-breasted Nuthatch (Sitta canadensis).

At mile 1.1, I stop where a large rock ledge overhangs the stream and admire a tremendous cottonwood cross, a Populus angustifolia x fremontii S. Wats. This 100 foot tree with a twenty-four inch trunk betrays it hybrid nature through two suckers, each 8 inches in diameter at the base. The parent tree has ovate leaves typical of the cross. Those leaf forms continue on one of the suckers, but at its very tip is one perfectly formed triangular Fremont popular leaf. Mid-way up the second sucker, that is also covered in hybrid leaves, is a bracket of perfectly formed thin Narrowleaf cottonwood leaves. This tree must be at least 100 years old, and perhaps it is older and witnessed the arrival of the Euro-American colonists in 1847. At a few minutes of enjoying this tree, I notice that it is looking back at me. More precisely, another Mule deer is on the rock ledge on the far side of the stream, and it is intently following me. I continue up canyon so it can reach water unmolested.

At mile 1.2, I turn down-canyon on the Pipeline Trial in order to photograph some of the lichens on rocks that line the trail down to where it is perpendicular to the Red Bridge and Chimney Rock. The Gambel’s oaks that border each side of the trail are covered in a ubiquitous dusky orange lichen that is found throughout the canyon. Here the rocks are principally volcanic breccia or limestone conglomerates. The first rock has lichens that are three inch diameter turquoise dollops with raised fruiting centers. The second rock has a large turquoise dollop on one corner and fire yellow bright lichen on one face. This rock also has small dark black lichen circles. The third rock has bright orange circles with darkened brown centers. The fourth has similar bright orange two inch dollops with fruiting orange centers. This same orange rock lichen is common in the canyon. For example, it covers parts of the rock bridge at Weeping Falls near mile 5.2. This bright orange lichen only appears on rocks, and its dusky orange brother keeps to the trees. Near the end of this segment, a gully provides more shade an water. Here, the rocks are covered in complex moss complexes, and unidentified green-black small-onion like moss with fine white hairs.

Continuing up canyon to a western gully near mile 2.3, there is another slope with favored lichen rocks. Here the rocks are sandstone based. In the gully, the first rock is a kaleidoscope of circular lichens colored bright orange, turquoise, and black. The next rock is covered with a bulbous green-black moss with fine white hairs. This is followed by a rock covered in turquoise-green lichen that has a darker brown center. Finally, two foot square areas of an unidentified green-black bulbous lichen attach to a rock ledge’s horizontal surface. Looking over some of my other lichen photographs above milepost 5.0, two prominent upturned limestone ledges stick out next to the road. On these a montane grey-milk lichen that look like delicate leaf petals cling to the stone.

This is all a riot of color mixed with abstract design. Lichen are oldest and, for me, they embody the most alien of terrestrial life. I also hold them in the highest respect because they are all a form of extremophile. They thrive on canyon rocks that both bake to temperatures over 150 degrees during the summer, and they continue to reproduce during the subzero cold of deepest winter. They live on the surface of barren rocks and take all that they need from the passing air and rain. And, what else the need in terms of minerals, they obtain by dissolving the solid rocks to which they attach. Moss are less of an extremophile, but tree moss are one of the few plants that continue photosynthesis through the depths of winter (January 10th).

Returning down-canyon near mile 1.3, ahead, I again here the screeching of a Peregrine falcon. Two falcons are chasing two unidentified hawks away from the sandstone cliffs on the east wall of the canyon near mile 1.0. One falcon easily chases a hawk up canyon and over the ridge. The second hawk begins to climb in lazy, large circles, and the remaining peregrine follows. The peregrine raises higher and then stoops the hawk, all the while screeching loudly. This continues for about 15 minutes. At times I loose sight of the pair as they circle overhead with the Sun behind them. The spring sky is a deep blue, but today, the summer sun makes the atmosphere a white turquoise.

Continuing down-canyon, at picnic site 5 where I collected one sponge, an innovative young couple using long lengths of climbing webbing, have suspended two bright Central American woven hammocks over the stream. They lay side-by-side enjoying the stream-cooled air.

At Guardhouse Gate, there are the cut fireplace-sized remains of a large tree. A quick count of its rings indicates the tree is over one-hundred years old. As the the city cuts down infirm trees in the canyon, they leave the carcasses here as free firewood. The cause of this tree’s demise can be seen in one segment of log – it is riddled to the inner pith with boring beetle tunnels. To supplement my gathering of water borne small life, I also collect from the logs’ surfaces, samples of Green tree moss (probably Orthotrichum sp.) and of orange, black and turquoise lichens.

The lower flood retention pond is full of algae mats. A family of mallards graze on the greenery. The chicks, who a few weeks ago where only four inches long, are now twice that size.

At home, I examine water from the three sponges in under a microscope at 60 power of magnification in order to see some of the smallest plants and animals of the canyon. All of the samples consist mostly of bits of algae, some of which are strung on the ends of mold filament, pulverized bits of plant, and specks of silica. No moving protists are seen. A few rectangular-celled with diatoms with well-defined glass-like walls of the genus Fragellaria are found. Two circular diatoms of the genus Stephanodiscus are seen. Finally, a single, transparent perfectly formed leg of an insect exactly fills the eyepiece and then floats away. This is clean City Creek water.

At home and through the hand-lens, the leaves of the moss, which are present both on trees and on rocks in the stream, reveal their earlier evolution as compared to the leaves of the surrounding trees. They are thin and transparent sheets of green cells, and they lack any vascular features found in true leaves.

Under the hand-lens, where the black lichens interface with the tree’s bark, a separate white hyphae through which digestion occurs. Lichens are composite organisms of algae or green bacteria living symbiotically with fungi. Through the hand-lens, one can see two colors, representing the two organisms in the turquoise and orange lichens. The turquoise portion of the turquoise lichen is also surrounded by white hyphae. The second color is green, and through the lens, these resolve as small bits of algae. That lichens exist on almost all of the trees in the first two miles of road is a good sign. Lichen are sensitive to air pollution and will disappear if Salt Lake’s air quality severely deteriorates over a long period.

The length of the day have changed noticeable from June 20th’s summer solstice. Sunset comes an hour earlier around 9 p.m.

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St. Clair, Newberry and Nebeker (1991 and 1995) provide a comprehensive list of Utah lichens. They and Flowers (1954) describe which species of lichen are common in various northern Utah habitats, including for the scrub oak forest of Gambel’s oaks, the higher subalpine habitat of Quaking aspens, and the montane habitat of conifers. Brodo of the Canadian Nature Museum and Sharnoff and Sharnoff of the Missouri Botanical Gardens published the definite photographic identification guide for lichens: their massive 2001 “Lichens of North America”. They note common lichen species for the Gambel’s oak forest include Lecanora hageni, Phaeoplzyscia orbicu/aris, Physcia adscendens, Physcia dubia, Physcia stellaris, Plzysconia grisea, Xanthoria fallax, and Xanthoria polycarpa. Using these sources, my descriptions and photographs match with the following scientific names:

List of Lichens

• Hooded sunburst lichen (Xanthoria fallax): This is the dusky-orange lichen that covers most of the Gambel’s oak trees in the canyon (Brodo, Sharnoff and Sharnoff, 744).

• Pin-cushion sunburst lichen (Xanthoria polycarpa): This is the bright orange lichen that covers many rocks in the canyon, including the stone bridge at mile 5.2 (Brodo, Sharnoff and Sharnoff, 746).

• Stonewall rim-lichen (Lecanora muralis): This lichen was the even-toned yellow-green (turquoise) circles on rocks along the Pipeline Trail (Brodo, Sharnoff and Sharnoff, 383)

• Sagebrush rim-lichen (Lecanora garovaglii). This is the yellow-green (turquoise) lichen with a darker green center on a rock along the Pipeline Trail (Brodo, Sharnoff and Sharnoff, 380).

• New Mexico rim-lichen ( Lecanora novomexicana): This darker yellow-greenish lichen with yellow fringes was found in the gully near mile 2.2 (Brodo, Sharnoff and Sharnoff, 384).

• Gold cobblestone lichen (Pleopsidium flavum): This is the bright yellow lichen on one rock along the Pipeline Trail. (Brodo, Sharnoff and Sharnoff, 578).

• Powder-tipped rosette lichen (Physcia dubia): This is the delicate leaf-shaped lichen on the limestone vertical fins near mile 5.0 (Brodo, Sharnoff and Sharnoff, 554).

Like today’s Great Salt Lake (May 26th), ancient Lake Bonneville’s water levels and glaciation of the Salt Lake’s canyons at the end of the last ice age gives clues as to the climate of the Salt Lake valley and the canyon. That record is hidden within the valley’s rocks and trees. In 2015 and updating a prior study from 1997, Oviatt at the University of Kansas reconstructed date ranges in which ancient lake rose and fell by radiocarbon dating organic material in tufa deposits along the lake’s former shorelines. He concluded that Lake Bonneville began its rise about 30,000 years ago (id., Table 1). Between 15,000 and 18,000 years ago, Lake Bonneville reached its maximum height at about 5,100 feet, or near the northern end of Pleasant Valley in the canyon near mile 1.7. Following the failure of the Red Rock ice dam in Idaho, the Lake drained to the Provo Shoreline, which is Bonneville Drive and 11th Avenue in the City. Other the next 15,000 years, the lake gradually declined to the current level of the Great Salt Lake (id).

In 2011, Laabs, Marchetti, and Munroe and colleagues used residual Beryllium 10 isotopes in rocks, taken from the glacial moraines in Little Cottonwood Canyon in Salt Lake valley and American Fork Canyon in Utah valley, in order to date when glaciers retreated up from the ancient lake’s shores. An ongoing question existed amongst geologists, based on conflicting earlier studies, concerning whether the Salt Lake glaciers receded before, coincident with or after the end of the last Ice Age and-or before, coincident with or after the end of the peak level of Lake Bonneville. Figure 1 of their study shows the area of glaciation stretching from American Fork to the south and Farmington, Utah in the north, thus, including City Creek Canyon. They concluded that glaciers covering the Salt Lake valley canyons started to retreat 15,700 plus or minus 1,300 years before the present, either during or shortly after the maximum 5,100 foot shoreline height of ancient Lake Bonneville. Their confidence interval overlaps the 15,000 to 18,000 years before the present found by Oviatt for the maximum height of Lake Bonneville. Deglaciation started about 4,000 years after the end of the continental Ice Age at 18,000 years ago. Because the lake reached its maximum and retreat of the local glaciers started after the end of the Ice Age, Laabs, Marchetti, and Munroe et al concluded that the local climate between 18,000 and 15,000 years ago was wetter than thought by prior geologists.

That there were glaciers in City Creek Canyon below Grandview Peak and at the canyon’s final hanging valley (September 8th) seems evident from an examination of any terrain map and hiking the canyon. But to my knowledge, there are no studies dating the glacial deposits in City Creek Canyon. Van Horn and Crittenden’s geologic map shows no surficial glacier features (Van Horn and Crittenden, 1987, U.S.G.S. I-1762). Perhaps there was a lighter ice sheet over the canyon 15,000 years ago, but it was insufficient to crave the bedrock.

The Engelmann spruces and other pine trees that live in association with the spruces, tell the history of Salt Lake valley’s and the canyon’s climate for the last 13,000 years before the present. In Little Cottonwood Canyon, Engelmann spruce share the glacial scoured hillsides with Limber pine (Pinus flexilis). Engelmann spruce is more tolerant of wet earth and colder soil temperatures, and Limber pine is more tolerant of dry earth and warmer soil temperatures. Thus, as climate changes occur over thousands of years, the relative amount of pollen left in soil layers beneath their canopy gives a general indication of weather in the distant past. In 1979, Madsen and Currey at the University of Utah used a bog in Gad Valley near Snowbird Ski Resort to reconstruct Utah’s late Holocene climate (Madsen and Currey 1979). Based on moraine deposits, the maximum extent of glaciation that extruded glaciers into the Salt Lake valley floor occurred about 25,000 years ago. After a period of warming, a second smaller glacial period ensued and Madsen and Currey, using the bog at Gad Valley places that around 12,500 years ago. Then glaciers within Little Cottonwood Canyon retreated and disappeared. A similar bog in Albion Basin at the top of Little Cottonwood is dated at 9,500 years (id, 258). Using the ratio of Engelmann spruce and Limber pine in the Gad Valley bog, Madsen and Currey were able to reconstruct the relative climate of the canyon, and by extension the Salt Lake Valley and City Creek Canyon, for the past 12,500 years. Between 13,000 and 8,000 years before the present, the valley’s climate was cooler and wetter than today. Between 8,000 and 5,000 before the present, advancing Limber pines indicate a warmer and drier climate than today. Then there was a brief period in which temperatures greatly declined, followed by a quick warming and a gradual decline to today’s cooler temperatures with respect to the 13,000 year mean (id, at Fig. 6 and 265). In contrast, precipitation has been on a gradual decline for the last 6,500 years and is currently near the 13,000 year mean (id). These are consistent with Grayson’s climate divisions for the Great Basin Holocene generally: 10,000 to 7,500 years before the present (early), 7,500 to 4,500 years before the present (middle), and 4,500 years before the present until today (late) (Grayson, Chap. 8).

Over the last 4,500 years, a picture of trends in Salt Lake City’s local climate can be developed from tree ring, Gad Valley bog pollen, and other climate research. Since 4,500 years before the present, there was a brief period in which temperatures greatly declined, followed by a quick warming and a gradual decline to today’s cooler temperatures with respect to the 13,000 year mean (Madsen and Currey, Fig. 6 and 265). It is now colder than average than over the last 13,000 years. The Little Ice lasted from about 1300 C.E. to 1850 B.C. There were highly variable swings in temperature during this time, but those changes were not global, but regional (Solomon et al 2007; Houghton et al 2001). In Utah, the Little Ice Age ended in 1850 and was followed by the most severe winter in Utah history, the winter of 1855-1856.

Since 4,500 years before the present, precipitation has been on a gradual decline for the last 6,500 years and is currently near the 13,000 year mean (Madsen and Currey). From 1492 to the present, the tree rings show that persistent, severe droughts were far more prevalent in the distant past than in the 150 years of Euro-American presence in northern Utah (Bekker et al 2014). Variability in Salt Lake City precipitation since the 1960s, including severe drought in the 1960s and peak flooding in the 1980s, is tied to the Pacific Quasi-Decadal Oscillation, an 11 year cycle of drought and heavy precipitation tied to ocean temperatures off the coast of California and Japan. The level of the Great Salt Lake acts as a recorder of climate, and the Lake’s level has been recorded continuously since 1875 (USGS, 2017a, USGS, 2017b). In the summer of 2016, it dropped to a new historical low of 4,190.1 feet (id).

In 2010, Wang and colleagues at the Utah State University associated the Pacific Quasi-Decadal Oscillation (PQDO) with a northern Utah three-year leading precipitation and a six year leading level of the Great Salt Lake (Wang, Fig. 4 at 2166). In the association with the level of the Great Salt Lake, PQDO warm phase peaks are associated with the lowest lake levels and PQDO cool phase troughs are associated with the highest lake levels. In 2013, DeRose, Wang and colleagues used tree rings to reconstruct the level of the Great Salt Lake back to 1429, and they associated the lake’s level to the pacific oscillation back to 1700 (DeRose 2013). In recent years, the PQDO has been good for Utah. While California has suffered severe drought, the PQDO has kept annual precipitation relatively higher in Utah (IWWA Project).

The PQDO has not had a phase change since 1997 and the change to a heavy precipitation pattern is overdue. Despite heavy winter snowfall in the high mountains during the winter of 2016-2107, Utah remains in an extended drought with unseasonably warm summers.

Future uncertainty is added by the effect of global warming. Has global warming disrupted the Pacific Quasi-Decadal Oscillation? What will its future impact be? However, even excluding global warming, Salt Lake City and Utah are on a path towards relatively hotter weather and declining water supplies as compared to the past.

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On July 21st, 1942, the City banned the entire north bench of Salt Lake City to entry due to fire hazard, but access to City Creek Canyon would remain open (Salt Lake Telegram). On July 21st, 1906, the Deseret Evening News published a picture of a 10 foot snow bridge across City Creek Canyon about nine miles up the canyon. On July 21st, prize fighter Tommy Reilly trained by taking a long run up City Creek Canyon (Salt Lake Telegram). On July 21st, 1903, about 100 Ute Tribe members gathered for an annual celebration at the mouth of City Creek Canyon (Salt Lake Herald). (In the present, the Ute Tribe holds an annual meet at Liberty Park.)

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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