Rangeland

Aridisols

Arid, low organic content

Entisols

highly variable in setting and land use, no diagnostic horizon

Mollisols

grassland ecosystem, thick organic surface horizon

Soil series

A group of soils that are similar in texture and profile

Soil Map Units

A grouping of soils that occur together (often geomorphologically)

Site potential

Inherent ability of a site’s productivity

Habitat factors

Biotic, Climatic, Chemical, Edaphic (soil textures)

Habitat limiting factors

• food,

water,

cover,

space

Mutualism

+,+

(cattle egrets and bison)

Neutralism

0,0

(mason bees and pronghorn)

Competition

-,-

(coyotes and wolves)

Commensalism

+,0

(ravens and wolves)

Antagonism

+,-

(ticks and elk)

Amensalism

0,+

(domestic sheep and bighorn sheep)

Maintenance

Basal metabolism + Minimum Movement + Foraging

Animal Requirements for Grazing

• Grazing

• Level of Activity

• Environment conditions

• Growth, lactation, reproduction

Livestock Production Principles

• Which animals? (type/age/gender)

• Stocking rate (how many)

• Distribution (where)

Animal Unit

1 AU = 1000 lbs of grazing animals (cow w/ calf = 1 AU)

Animal Unit Month

amount of forage AU will eat in a month

Ruminants eat 2.5% of body weight in forage/day

1000lbs x 2.5% = 25lbs/day x 30 = 750lbs

Stocking Rate: how to balance forage supply with demand

1) calculate useable forage supply

2) adjust for accessibility (distance from water / slope percent)

3) calculate forage demand (forage demand / animal/year)

4) calculate stocking rate (supply / demand)

Proper Use Factor

Set stocking rate well below carrying capacity and total forage availability

Calculate useable forage supply

weight of biomass/acre x proper use factor = useable forage

Stocking rates must be:

Flexible (no more than 60% of herd in breeding stock) and Constant (herd size that could be sustained if rainfall was 25% below average)

Grazing System

A planned effort to guide grazing timelines and if/how to leave areas ungrazed

Grazing Period

Season/time-period when grazed factoring

• maintaining/improving vegetation

• improve uniform use of grazing units

• stabilize forage supply

• enhance forage quality

• improve function of ecological processes

Deferment vs. Rest

Defer = get past susceptible phase of plants before allowing grazing

Rest = no grazing for an entire year