Friday Field Trip Notes and Study Questions

Tall Grass Prairie
• 98% of all tall grass prairie is gone – threatened ecosystem
• aesthetics not appreciated by white settlers
• designated Colorado state natural area – very rare
4 Major Grasses
1. Big Blue Stem Grass
2. Switch Grass
3. Yellow Indian Grass
4. Prairie Cord Grass

Climate
• 12000 years ago – climate much cooler and wetter
• Eastern deciduous forest and tall grass Prairie
• 10,000 years ago global warm occurs
o as a result there was high water volume
o helped carve boulder valley
o removed most of tall grass prairie as a result of warming
o this is a relict population of Xeric Tallgrass Prairie
o many past inhabitants are now gone: grizzlies, bison, wolves, Cheyenne-Arapahoe
o people have been part of this ecosystem for a very long time
o Wilderness is a white man’s concept
Trees in the city of Boulder are a new phenomenon--planted by settlers within the last 100 years

Plant Adaptations
o Grazing keeps grasses under control – Boulder Open Space trying to compensate for the Bison that used to graze the prairies—concentrated, intensive grazing
o Fire! Prairie is a fire-adapted ecosystem
o Ecosystem is adapted to a variety of disturbances (fire, drought, grazing)
o Area has seen 6-700 generations of use by people

Plants
o Ute Ladies’ Tresses orchid – endangered native species – choked out by un-grazed grasses
o Orchard Grass and Smooth Brome – invasive European grasses that out compete natural prairie grasses
o Indian Blanket flower- native, pollinated by the gaillardia moth adapted especially to this plant
o Yucca- exclusively pollinated by the Yucca moth

Dog Tags
o Voice and Sight control tags- watch a video and lays out expectations for dog etiquette
o Complicated dog regulations in different areas
o dogs fertilize along trails and encourage growth of invasive weeds

Human recreational use and impacts
o building trails into sensitive habitat is controversial ex: Goshawk Ridge, where remote wildlife cameras have seen Goshawks
o both monitoring of behavior (spies in the woods) and surveys (people lie)
o monitoring wildlife by counting poop in permanent plots
o compliance with regs overall good. mtb=best, dog walkers=worst
o everyone has a different perception and all are valid at some level
o most people want to do the right thing—10% are jerks
o recreation stops being passive when it starts interfering with wildlife

South Mesa Trailhead
o well-developed TH facility with outhouse, picnic tables, multiple trails
o quite busy on a Friday morning
o users in a wide variety of age ranges, plus dogs and horses
o old homestead building and stone walls = cultural “BSO”
o South Boulder Creek and dense riparian vegetation

Doudy Draw Trailhead
o newer parking lot
o trailhead map and handouts
o bottom part of trail has been reworked to remove asphalt, now a highly engineered trail on roadbase with “crusher fines” on surface


1. Name the 4 Major Prairie Grasses.

2. Name 3 other plants that we observed.

3. What is a “code black”?

4. T/F explain – Orchard grass and smooth brome are widespread and native to Colorado.

5. How do OSMP staff monitor user compliance with trail regulations?

6. Why are there cows grazing on remnant tall grass prairie?

7. What are the two elements behind green tags and what do they mean?

8. How much of the tall grass prairie is left?
a. 10% b. 2% c. 15% d. 36%

9. T/F Global warming after the Pleistocene reduced the tall grass prairie’s ability to survive on the front range.
10. Which BSOs did we observe near the South Mesa Trailhead?