Foothills Fescue Range Plant Community Guide - Sustainable ...

lowlands, solonetzic soils, some sandy soils). Erosion and sediment production from sites
that are normally unstable is not the focus of this question, but rather the loss of key soil
particles from well developed sites that are normally stable.
Human-caused bare soil is rated by considering the total bare soil on a range site minus
the amount that is normally naturally occurring. For most sites in the Foothills Fescue
grassland, there is normally no bare soil. The following table shows the normal range of
mean soil exposure values observed in the plant community data. Steep slopes, gravelly
soils and thin break sites may have up to about 10% naturally occurring bare soil (Table
12).
Table 12. Soil exposure normals for major range sites in the Foothills Fescue grassland.
Range Sites Soil Exposure
(% canopy cover)
Loamy
• Loamy 1 moist
• Loamy 2 mid
• Loamy 3 dry
• Loamy steep
0-1%
0-5%
0-8%
5-8%
Gravel and Shallow-to-Gravel 5-10%
Thin Breaks 5-10%
7.5 Question 5 - Noxious weed infestation.
Noxious weeds are invasive plants that are alien species to the rangeland plant
community. Weeds are seldom a problem in vigorous, well managed pastures although
weed invasion may occasionally happen in healthy stands. Weeds may be introduced to
relatively healthy stands through rodent burrows, but generally their presence indicates a
degrading plant community. Noxious weeds diminish the agricultural productivity of a
site, and threaten biological diversity and the structure, function, and sustainability of
ecosystems. They diminish the multiple uses and values that range is normally capable of
providing.
Weeds normally provide a strong message about range health. Weeds most often invade
range where grazing practices have resulted in available niche space (bare soil, surplus
moisture); available micro-habitats normally occupied by range plants, but now available
to weeds due to overgrazing or some other land use or natural disturbance. Grazing
management strives to maintain plant vigor and vegetation cover so that all niche space is
filled by one or more plant communities that can occupy the site and thereby minimize
weed invasion.
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