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RANGELANDS:

RANGELANDS:. GRASSLANDS, DESERT SHRUBLAND, AND SHRUB WOODLAND   Precipitation = 10-30 inches/yr   29% of US is rangeland . TAYLOR GRAZING ACT OF 1934. 1. halt deterioration 2. improve range quality 3. stabilize rangeland economy . IMPORTANT WILDLIFE OF THE GRASSLANDS .

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RANGELANDS:

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  1. RANGELANDS: • GRASSLANDS, DESERT SHRUBLAND, AND SHRUB WOODLAND   • Precipitation = 10-30 inches/yr   • 29% of US is rangeland

  2. TAYLOR GRAZING ACT OF 1934 • 1. halt deterioration • 2. improve range quality • 3. stabilize rangeland economy

  3. IMPORTANT WILDLIFE OF THE GRASSLANDS • Waterfowl (prairie potholes and marshes) • Large ungulates (deer, elk, pronghorn) • Smaller mammals and birds

  4. GRAZING PERMIT CONTROVERSY • Nearly 5 million cattle and sheep graze on 80% of public rangelands annually   • Permits cost one-fifth that charged by private landowners • Federal subsidy = $100 million/yr over the water subsidy they get • In 45 National Parks, 150 National Wildlife Refuges, and BLM lands • http://www.sagebrushsea.org/pdf/factsheet_Grazing_Economic_Contributions.pdf

  5. GRAZING PERMIT CONTROVERSY, continued • Current fee doesn't even pay for administration of program • Ecosystem is being damaged by overgrazing and miss-management: wildlife suffer • Ranchers benefit, but land belongs to everyone • The paradox persists. Why?

  6. RANGELANDS • Grasslands • Desert Shrubland • Shrub Woodland   • Tropical - Savanna, campos, llanos • Temperate - prairie, steppes, pampas, veld • Arctic - Tundra (mostly wetland too)

  7. ECOLOGY OF RANGELANDS   • Metabolic reserve = lower half of grass plant   • Decreasers - plants favored by grazing animals; subject to decline when grazed • Increasers - avoided by grazers; abundance increases upon grazing • Invaders - dominate overgrazed areas

  8. ECOLOGY, continued • Overgrazing: • Too many animals for too long • grasses replaced by woody plants and forbs • reduces water and nutrients • reduces litter, exposes soil • more wind erosion   • Undergrazing:   • brown leaf and stem left to age (poor food quality) • kills off (chokes) grasses and favors woody vegetation • reduces water and nutrients • reduced root mass leads to soil erosion

  9. MANAGEMENT OF RANGELANDS: • Control amount of grazing • periods of grazing and rest (deferred rotation) • continuous grazing • holistic grazing (6 paddock rotation) • Control vegetation • fire • herbicides

  10. MANAGEMENT OF RANGELANDS, continued  • Control rodents and predators • Rodent control: • Controls don't last (temporary relief • Ecology gives long-term solution • Predator control: • controls don't work (temporary relief) • Ecology gives long-term solution   • Coyotes eat Rodents!!!

  11. COYOTE PROBLEMS  • The federal government kills coyotes! • '1080' in collars • cyanide in "coyote getter" • costs about $1,000 per coyote! • ineffective in reducing coyotes • Other methods to deal with coyotes: • fencing • guard dogs • good animal husbandry practices • Kansas model program only costs 5% of nearby states' programs

  12. NORTH AMERICAN GRASSLANDS: • tall-grass prairie: southeastern edge • mid-grass (mixed-grass) prairie: north and west of tallgrass prairie • short-grass prairie: western plains • Palouse prairie: great basin country • Valley grasslands: California's Central Valley • Desert grasslands: Arizona and New Mexico and Mexico

  13. MORE ECOLOGY • Most grasslands are subject to great variability in temperature, precipitation, grazing, and fire, leading to "multiple stable states" rather than one climax community type   • Global warming and grasslands: • may increase decomposition rate and thus increase CO2 release (positive feedback)   • Grassland restoration is in progress  

  14. TEMPERATE AND TROPICAL DESERTS   • Characteristics • Hot vs. Cool deserts: • temperatures below freezing may be rare or common • What creates the desert environment? • Rain shadow - mountains • Cold upwelling - oceans  

  15. SPECIAL FEATURES OF DESERT ECOSYSTEMS • caliche - cement-like subsoil of calcium carbonates   • desert pavement - hard, protective surface layer   • cryptobiotic crust - algae, fungi, and lichens form a fine organic tissue • may take 200 years to reform if disturbed

  16. DESERTS, ecological problems • Desertification- drying of arid ecosystems is a global concern • Other Problems: • Overgrazing by livestock • Competition with feral ungulates • ORV's • compact soil, disrupt surface • first pass does most of damage   • Reptiles, mammals, and birds are all reduced in number of species and number of individuals per species under heavy and very heavy ORV use*   • *Even moderate use cuts # species to <11

  17. Effects of ORV’s on desert fauna(Density per 2 ha plot) • *Even moderate use cuts # species to <11

  18. Problems, continued • Invasion of exotic plants:   • Annual grasses of genus Bromus that choke out native plants after a rain, die, and carry fire (native species evolved w/o fire)   • Salt cedar - shrub replacing willow and cottonwood in riparian areas • Deep-rooted, high transpiration: dries soil • Carries fire; resprouts vigorously after fire, outcompeting native species   • Beaver and deer do not feed on it

  19. Problems, continued • Global warming will increase desertification   • Desert soils are a source of carbon in the atmosphere; more desert surface and weaker cryptobiotic crusts will add to the greenhouse effect!

  20. Management of arid/desert systems: • Need to limit use of ORV's • California Desert Protection Act • 1994 - upgraded several deserts to National Parks, enlarged areas of protection, and designated more "wilderness"

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