Ecology « The Friends of the Florissant Fossil Beds

Exceptional diversity of fossil algae at Florissant

Filed under: Ecology, Events, Lectures, Paleontology, Research, Science — The Friends of the Florissant Fossil Beds, Inc. @ 11:40 pm

The ancestors of these modern marine diatoms coexisted with the dinosaurs. Photo Credit: Dr. Neil Sullivan, University of Southern California/NOAA

University of Colorado at Boulder graduate student Mary Ellen Benson, M.S., gave a talk about her doctoral research at the University of Colorado Museum of Natural History (UCM) on February 7.

Benson’s talk, titled “Exceptional Diversity of Late Eocene Freshwater Diatoms from the Florissant Formation, Teller County, Colorado,” summarized some of her work to date on the previously unstudied fossil diatoms of the Florissant Formation.

Diatoms are microscopic, single-celled, golden-brown algae with hard silica shells (frustules). These shells are extremely tiny, only 10-100 microns (1 micron = 1/1000 millimeter). Scientists use the shapes, sizes, and ornamentation of the frustules to identify diatom species. Diatoms can be divided into two major groups according to shape, centric (round) and pennate (elongated).

Although marine diatoms are known as far back as the Jurassic Period (200 million years ago), confirmed reports of freshwater diatoms in North America are much more recent. The diatoms of the Florissant Formation represent one of the earliest occurrences of freshwater diatoms in North America.

Fossil diatoms are most abundant in thin “paper shale” layers within the Florissant Formation, such as those found at the Scudder Pit Interpretive Site. Photo Credit: Melissa Barton

Benson’s research, which is partially funded by visitor fees from the Federal Lands Recreation Enhancement Act (formerly Fee Demo Program), is currently focused on identifying the fossil diatoms and comparing the Florissant assemblage to other Eocene assemblages from western North America. Additional funding sources include the Paleontological Society, Walker Van Riper Fund at UCM, Evolving Earth Foundation, Colorado Scientific Society, Colorado Mountain Club, and the Sam Van Landingham Fellowship at the California Academy of Sciences.

In order to examine the diatoms with a light microscope, Benson must break up the matrix of the rock, make a slurry, dry the slurry on cover slips, and then mount the slips on slides. However, many important identifying characteristics cannot be seen without the higher-powered scanning electron microscope (SEM). Taking a good micrograph is difficult and time-consuming.

These SEM micrographs of modern diatoms show the whole frustule of a centric diatom (A), two whole pennate diatom frustules (B), a single valve of a centric diatom (C), and another centric diatom frustule (D). Relatives of some of these diatoms are known from the fossil record. Photo Credit: Mary Ann Tiffany, San Diego State University

The Florissant diatoms are extremely diverse compared to other Eocene sites, Benson has found. Many of the Florissant genera have not been recorded in other Eocene or earlier deposits. Benson hopes to find and describe new species within these genera.

“Although the diatoms are relatively well-preserved, they are not as well-preserved [as the plant and insect fossils of Florissant],” Benson said at the talk, “so their claim to fame will be their diversity, not their preservation.”

Since diatom frustules can dissolve in alkaline water, they are not always preserved in lake deposits, even if diatoms lived in the lake. Diatomaceous sediments can also be replaced by chert if additional silica is introduced after burial.

Florissant presents an exceptional opportunity for scientists like Benson to study the evolutionary history of diatoms and what diatoms can tell us about the ecology and chemistry of ancient lakes.

-Melissa Barton

Acknowledgements: Thanks to Mary Ellen Benson and Dr. Dena M. Smith for assistance in writing this article.

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February 12, 2008

Species Spotlight: Ponderosa Pine

Filed under: Biology, Ecology, Science, Species Spotlight — The Friends of the Florissant Fossil Beds, Inc. @ 12:00 pm

Read former Florissant Fossil Beds National Monument intern J.J. Huie’s full article in the Spring 2008 Friends newsletter!

With Deep Roots in Colorado: The Ponderosa Pine

by J.J. Huie

I like running in Colorado when the sound of my breathing is drowned out by a wind so violent it causes the arms of the ponderosa pines (Pinus ponderosa) to thrash about wildly. Hundreds of miles from the Pacific, in the foothills next to Rampart Range near Colorado Springs, I feel like Iâ€™m sailing through an ocean storm. In crossing this ocean, however, there is no salty scent or giant, looming swells; instead, I have the waving motion of the ponderosas and the rich aroma they exude.

In Colorado, the ponderosa pine ecosystem can be found at an elevation range of 5,600 feet to 9,000 feet on both sides of the Continental Divide, with ponderosas dominating on sunny, south-facing slopes. Throughout much of the elevation range of the ponderosa, Douglas-firs predominate on the shadier, north-facing slopes. Direct solar radiation is critical to the ponderosa, which germinates best on soils with unobstructed sunlight. Standing close to a mature tree, I enjoy the scent of vanilla that the orange-brown bark gives off as itâ€™s warmed by the sun.

A distinctive feature of ponderosas is their long needles (up to 7 inches in length), which come in bundles of two or three needles. The needles of ponderosas are the longest among conifers in Colorado. Some ponderosas are among the largest trees in the Southern Rockies (the area from southern Wyoming through Colorado to northern New Mexico), growing up to 150 feet in height and more than 3 feet in diameter.

Mature trees usually have rounded crowns, while the oldest trees can have flat-topped crowns, unlike most other conifer species. Mature cones are globe shaped and can be up to 6 inches long; each of the coneâ€™s thick scales is tipped with a sharp bristle.

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October 9, 2007

Species Spotlight: Wapiti or American Elk

Filed under: Biology, Ecology, Species Spotlight — The Friends of the Florissant Fossil Beds, Inc. @ 12:00 pm

It’s hard to forget the eerie sound of an American bull elk bugling–the sound is almost completely unlike a bugle, but rather a high, unearthly wail. Elk bugling is a common sound at Florissant Fossil Beds National Monument in the fall, when elk rut (seek mates).

American elk (Cervus canadensis*), which once numbered 10 million in North America and which lived in grasslands from coast to coast, today are mostly confined to last remaining wild spaces in the mountains. In Colorado, according to seasonal park ranger Harv Burman, wildland is developed at a rate of 4 acres per hour. That doesnâ€™t leave much space for the elk, but in September and early October you still have a good chance of hearing or seeing elk at the park, particularly at the south end and along Lower Twin Rock Road.

During the rut, or mating season, cow elk focus on eating. They need the fuel to carry calves through the winter. The bulls, however, are often too busy to eatâ€“the successful are busy gathering and keeping harems of 10-15 cows. They shed the velvet from their antlers in August, and polish them on trees. Struggles between males usually involve only pushing and shoving, and the antlers are more for display than combat. The bugling is also a warning to other males.

The Rocky Mountain elk (C. canadensis nelsoni) is the largest of the North American elk and the largest of the red deer species worldwide. In Europe, â€œelkâ€ refers to the American moose (Alces alces), and â€œred deerâ€ to C. elaphus, although European and Asian red deer are much smaller than American elk. There has been a largely unsuccessful push in North America to call C. canadensis by its Shawnee name, â€œwapiti,â€ meaning â€œwhite rump.â€ Like â€œbuffaloâ€ for the American bison (Bison bison), the name â€œelkâ€ has centuries of inertia behind it.

Signs of elk–tracks, scat, scarred aspens, and broken ponderosa saplings–are common sights in the Front Range, but elk themselves are more elusive. Hundreds of elk graze and mate in the park in fall. In September and early October, park rangers at Florissant Fossil Beds National Monument lead evening programs to listen and look for elk. The chances of hearing the elk are very good, but elk sightings occur less often.

Many quaking aspen (Populus tremuloides) trunks in the park are scarred from elk eating the bark. Aspen bark is photosynthetic and a favorite of elk, especially in winter when nutritious grazing is hard to come by. Unfortunately for the aspens, elk chew makes them vulnerable to infection. Canker-invading fungi such as sooty-bark canker (Encoelia pruinosa) attack the trees, often killing them. Because aspens stands are â€œclonesâ€ with a common root system, fungus spreads rapidly from tree to tree. Sometimes a combination of overgrazing and fungus can kill an entire aspen clone.

The last elk walk this year will be on October 13, but you can always visit the park to listen and look for elk yourself. Nearby Mueller State Park is also a good place to spot elk.

ELK-SPOTTING TIPS

Early morning and late evening in fall are the best times to see elk in the Front Range.
Elk are color-blind, so it doesnâ€™t matter what you wear, but try to stay in the cover of the trees.
If you spot a herd, approach quietly and slowly from downwind. Elk have excellent senses of hearing and smell.
Stop and listen frequently for the distinctive wailing bugles of the bulls. Elk herds can travel and change direction quickly.
If you want a virtual guarantee of seeing elk and donâ€™t mind them being practically tame, visit Rocky Mountain National Park. In this area, elk are so used to humans they have become pests.

-Melissa Barton

Photo Credits: PDPhoto.org/Jon Sullivan (elk at Yellowstone), Melissa Barton (broken sapling and Ranger Burman giving a talk)

*Some biologists classify American elk as belonging to the same species as European and Asian red deer, C. elaphus. Recent genetic studies suggest that American elk belong to a different species from red deer. Further studies will clarify the relationship of different species and subspecies of red deer and American elk (returnÂ to article).

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August 16, 2007

Park fights to stop spread of yellow sweetclover

Filed under: Conservation, Ecology, Park Changes, Resource Management, Species Spotlight — The Friends of the Florissant Fossil Beds, Inc. @ 12:00 pm

Student Conservation Association intern Lindsey Stecker pulling sweetclover.

Yellow sweetclover (Melilotus officinalis), an introduced European plant, grows profusely along roadways, trails, and in other disturbed areas throughout the plains and montane regions of North America, including Florissant Fossil Beds National Monument. Sweetclover is a hardy biennial that is used as fodder for livestock and for producing clover honey. Outside of cultivation, sweetclover can out-compete native plants, as well as overrun pastureland.Â Sweetclover is aggressive and difficult to eradicate, and seeds can remain viable in the soil for up to 30 years.

Yellow sweetclover bushes can grow from 2 to 5 feet tall and have strong taproots. At right, sweetclover grows densely along the road to the Visitor Center. Park staff, particularly Student Conservation Association interpretive intern Lindsey Stecker (Boston University) and Chief Ranger Rick Wilson,Â have been working hard to control the spread of sweetclover this summer.

-Melissa Barton

Photo Credits: Melissa Barton

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The Friends of the Florissant Fossil Beds

May 14, 2009

Florissant diatoms in the news

More on Mary Ellen Benson’s research…

February 19, 2008

Exceptional diversity of fossil algae at Florissant

February 12, 2008

Species Spotlight: Ponderosa Pine

With Deep Roots in Colorado: The Ponderosa Pine

October 9, 2007

Species Spotlight: Wapiti or American Elk

August 16, 2007

Park fights to stop spread of yellow sweetclover

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