RNR Test 3

RNR Test 3 - Test 3 • Grasslands – rangelands o...

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Unformatted text preview: Test 3 • Grasslands – rangelands o Grasslands cover about 26% of the world’s land surface o 10% classified as rangelands Rangeland > used to graze livestock o ¼ of rangeland is in developing countries – cleared forests, abandon cropland o 80% of annual production of beef and mutton o Extremely important in grain-poor nations • Rangelands o From 1950 – 2001 World population from 2.5 to 6.1 billion Cattle 720 mil to 1.53 bil Sheep and goats from 1.04 to 1.75 bil Degraded rangeland 680 mil and increasing o How can rangeland be managed sustainably? Population pressure Climate Change o 10 billion domesticated animals worldwide 30% of ruminates • Multi-chambered stomachs ¾ of the world’s domesticated ruminates feed on rangelands, the rest on feedlots 200 million people graze livestock on rangeland Bulk of that is Africa and asia (85%) o <5% of the world’s population, 9% of the world’s cattle o Live stock graze >33% of North America o More than ½ us croplands planted with livestock feed o Focus mainly on cattle o Side Note: Livestock production – 50% of annual water consumption in the US 1 pound of feedlot fattened beef – 5 pounds and 280 gallons of water 1000 lb cow = 280,000 gallons of water o Minimal use land without irrigation o Renewable resource for many materials Produce food Can produce wool leather, etc o Vegetation collectively known as forage o Forbs – broad-leaved flowering plants Sun flowers o Sedges – perennial herb with triangular stems o Rushes – grass-like herbs with round stems Hollow stems o Grasses – high quality forage Buffalo grass o Most grasses, sedges, rushes, perennial, forbs often annual, biennial o Deep fibrous root systems o Highly tolerant of low moisture conditions o Highly tolerant of fire o Grasses grow from base of the plant o The lower part (around 50%) metabolic reserve Most important part of the grasses o Needed for nourishment of extensive root system o Chronic loss of the metabolic reserve from overgrazing can destroy rangeland sustainability o Decreasers – highly palatable, declin in abundance with grazing o Increasiners Increaser 1 – moderately palatable, secondary forage, slight increase or stable levels under moderate grazing, at higher grazing levels, these species also declin o Invaders – non palatable ; invader 1 – grazed as a last resort ; invader 2 – unpalatabgle o Abundant on overgrazed and undergrazed land • Rangeland Grazing o Not just grazing but trampling as well o Rangeland sustainability is a function of grazing pressure, grazing and trampling and is a function of: Type of animal Number of animals Grazing time o Many grazers are defoliators o Remove entire plants and branches o Populations regulated by predation, parasitism, starvation- overgrazing o Population movement, selective herbivory, and predatory key to historical rangeland health o Land use changes important...
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RNR Test 3 - Test 3 • Grasslands – rangelands o...

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