LS1_LECTURE_21

Climate in these areas is right and the interactions

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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.

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