Download Xeric Tallgrass Prairie Study - Jefferson Conservation District

Xeric Tallgrass Prairie Study
Importance of Piedmont Grasslands
Jefferson County and Boulder County to the north have some of the largest occurrences
of Piedmont grasslands in Colorado. These grasslands harbor some of the richest species
diversity in Jefferson County. In general, grasslands are regarded as among the most
imperiled ecosystems in North America.
Tallgrass prairies were once commonplace in Colorado, especially along the Front Range
foothills. Today only remnants of the original prairies remain.
Threats to Grasslands
In 1969, rare tallgrass tracts were examined in both counties. These included big and little
bluestem plant communities as well as needlegrass types (including Nasella and
Hesperostipa dominated expressions). In 1998, researchers reported that less than half of
the tallgrass sites remained.
Many tallgrass communities were lost to urbanization or incompatible grazing and others
were in marginal condition. Other risks include mining and invasive plants. There is a
clear need for managing and protecting these rare grassland communities for biological
integrity and for public enjoyment.
Cooperative Study of Remaining Grasslands
A high quality xeric tallgrass prairie located in Section 16 at Rocky Flats (T2S R70W)
has long been a grassland of great interest to ecologists and others. For this reason, the
Jefferson Conservation District spearheaded an intensive 5-year botanical study of
Section 16 and surrounding grasslands to assess the uniqueness of Section 16.
Five stakeholders groups participated in the study, which was conducted by ESCO
Associates. Funding for the study was provided by the conservation district and
LaFarge Corporation, with the Jefferson County Nature Association providing field
assistance to ESCO Associates.
The work began in 1996 and was completed five years later with a Draft Report prepared
in April 2002. In all some 47 sites containing significant amounts of big bluestem
throughout Jefferson County were examined intensively. Six of these sites were located
in Section 16. The prairie there proved to be a mix of eastern and western species,
including big and little bluestem, common eastern prairie species; and mountain muhly
and Porter’s aster, prevalent western species. A total of over 50 native species were
found on the site. The report notes on page 21 “that this ecosystem does possess unique
qualities consistent with its very old environment.”
Results of Study (Draft)
The uniqueness of the xeric tallgrass prairie in the western 106 acres of Section 16 was
clearly established by this intensive plant ecological study. This unusual resource can
provide a rare example for study by students, the public, research scientists, and
reclamation experts that seek to establish this unique ecosystem in similar habitats that
have been disturbed.
Information and data provided by Paul Kilburn, Jefferson County Nature Association and
Survey of Critical Biological Resources in Boulder County, Colorado 2007-2008,
Colorado Natural Heritage Program.
Tallgrass prairie in Jefferson and Boulder Counties is a remnant of a once-extensive area of tall
prairie occupying floodplains and much of the glacial outwash plateaus of the Front Range.
These tallgrass prairie remnants support flora similar to the prairies of South Dakota, Kansas,
and the Midwest, including big bluestem (Andropogon gerardii), switchgrass (Panicum
virgatum), and yellow Indiangrass (Sorgastrum nutans). Photo: Colorado Department of
Parks