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Unformatted text preview: pecies’ range. ! Cheatgrass has been able to invade two important types of biomes in North America: the arid, shrub-dominated habitats
known as sage-steppe, and dry temperate grasslands. Climate in
these areas is right, and the interactions with other species
facilitated it’s spread. The Role of Fire & Overgrazing
in Cheatgrass’s Spread
! Grazing cattle depleted the bunchgrass in arid areas of the American West.
! Cheatgrass arrived and was 1) able to outcompete re-emerging bunchgrass in
the graslands, and 2) able to invade sage-steppe habitats with the aid of fire. ! If a fire gets started, it does not affect the cheatgrass because cheatgrass is
an annual, so there is no living tissue exposed once the growing season is
over and because cheatgrass seeds sprout readily in soils that have been
depleted of organic matter by fire....
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This note was uploaded on 12/04/2013 for the course LIFE SCIEN 1 taught by Professor Lloyd-smith during the Winter '11 term at UCLA.
- Winter '11