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 • Waterfowl (prairie potholes and marshes) • Large ungulates (deer, elk, pronghorn) • Smaller mammals and birds
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
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?
RANGELANDS • Grasslands • Desert Shrubland • Shrub Woodland • Tropical - Savanna, campos, llanos • Temperate - prairie, steppes, pampas, veld • Arctic - Tundra (mostly wetland too)
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
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
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
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!!!
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
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
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
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
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
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
Effects of ORV’s on desert fauna(Density per 2 ha plot) • *Even moderate use cuts # species to <11
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
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!
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"