Foothills Fescue Range Plant Community Guide - Sustainable ...

7.0 Guidelines for assessing plant community structure, soil exposure and litter
abundance and noxious weeds.
The following guidelines are designed for use with the Range Health Assessment for
Grassland, Forest and Tame Pastures - Field Workbook (Adams et al. 2003). The range
health protocol is available from the Rangeland Management Branch, Public Lands
Division, Alberta Sustainable Resource Development as a field workbook in 2003. The
following comments are to assist the user in interpreting the range health codes and
instructions in the Foothills Fescue grassland.
7.1 Question 1 Integrity and Ecological Status
Why is plant species composition important?
Plant species composition is a fundamental consideration in range health assessment.
Plant species composition will influence a site’s ability to perform functions and provide
products and services. Native plant communities evolve within their environment and
slowly change over time as environmental factors change. Significant short term changes
in plant composition do not normally occur unless caused by significant disturbances like
continuous heavy grazing, prolonged drought, prolonged high periods of precipitation,
exotic species invasion, frequent burning or a timber harvesting treatment.
What changes in plant community may result from disturbance?
Plant species changes due to grazing pressure are predictable:
C Perennial species that tend to be most productive and palatable are also the most
sensitive to grazing and will decline with increased grazing pressure.
C Species with lower forage value and greater adaptation to grazing pressure will
increase in relative abundance.
C Eventually very heavy grazing pressure will lead to weedy species that are adapted to
more constant levels of disturbance.
What successional stages should we manage for?
Range management objectives tend to favor the later stages of plant succession (late-seral
to reference plant community or good to excellent range condition). Late-seral plant
communities tend to be superior in the efficient capture of solar energy, in cycling of
organic matter and nutrients, in retaining moisture, in supporting wildlife habitat values
and in providing the highest potential productivity for the site. Early-seral stages
represent plant communities with diminished ecological processes that are less stable and
more vulnerable to invasion by weeds and non-natives species. They are also
characterized by diminished resource values such as livestock forage production, wildlife
habitat values and watershed protection.
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