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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 l.jpg

RANGELANDS:

  • GRASSLANDS, DESERT SHRUBLAND, AND SHRUB WOODLAND  

    • Precipitation = 10-30 inches/yr  

    • 29% of US is rangeland


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TAYLOR GRAZING ACT OF 1934

  • 1. halt deterioration

  • 2. improve range quality

  • 3. stabilize rangeland economy


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IMPORTANT WILDLIFE OF THE GRASSLANDS

  • Waterfowl (prairie potholes and marshes)

  • Large ungulates (deer, elk, pronghorn)

  • Smaller mammals and birds


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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


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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?


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RANGELANDS

  • Grasslands

  • Desert Shrubland

  • Shrub Woodland  

  • Tropical - Savanna, campos, llanos

  • Temperate - prairie, steppes, pampas, veld

  • Arctic - Tundra (mostly wetland too)


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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


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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


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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


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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!!!


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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


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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


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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  


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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  


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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


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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


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Effects of ORV’s on desert fauna(Density per 2 ha plot)

  • *Even moderate use cuts # species to <11


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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


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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!


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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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