Download Rangelands Lectures

Managing Rangelands
rangeland: landscape
of grasses and/or
scattered trees
- uncultivated &
provides forage
for large
animals
- gradient in
precipitation, soil
structure,
topography
Rangelands
- few inputs (contrast with cropland)
forage: standing plant material (grasses,
forbs, shrubs) that is edible
Herbivory:
grazing: consuming
grasses & forbs
browsing: consuming
leaves/twigs of woody
plants
* Manipulate grazing system of large
herbivores for plant & animal
production
* Maintain healthy rangeland by
controlling # grazing livestock
* Rangeland Mgt & Wildlife
* Grazing on Public Lands & Endangered
Species
* Sage Grouse – 40 to 80% population declines
(overgrazing, invasion of cheat grass)
* Rangeland Mgt & Predators / Wildlife
Damage / Predator Control
Rangelands:
1) are a renewable resources if managed
properly (ecosystem mgt)
2) important site of energy flow / nutrient
cycling
ruminants: herbivores
with microbes in
digestive system
needed to digest
cellulose (fiber) –
transfer plant fiber
to another energy
source
Native vs. Domestic Grazing Systems
• Differences in selection & competition
among species
Horses
Grass Forbs & Cacti
Browse
100%
Cattle
90%
10%
Sheep
40%
60%
Pronghorn 6%
83%
11%
117 pronghorns = 1 horse
105 pronghorns = 1 cow
7 pronghorns = 1 sheep
Selectivity among some N.American
ungulates
Pronghorn
Most
Sheep
Cattle
Least
Bison
Types of Rangelands
* differences in climate (precipitation/
temperature), vegetation, fauna
1) Grassland
2) Forest
3) Savanna
4) Chaparral / Desert Shrubland
5) Tundra
Types of Rangelands
Grassland (prairie, pampas, steppe, veld)
-
High productivity of forage
Grasses (family Gramineae) & forbs (broad-leaved)
Fibrous root, soil & water conservation, soil
Grazers:
cattle, elk, bison, musk oxen,
Types of Rangelands
Forest (shrub, temperate, tropical)
-
Compared to grassland: wetter conditions/lower
fertility
Browsing habitat, but little grazing benefit
National Forest, Bureau of Land Mgt (BLM) lands
Browers:
moose, pronghorn, goats, deer
Types of Rangelands
Savanna (barrens)
-
Grasslands with scattered shrubs/trees
Influence of fire / transitional area
Types of Rangelands
Chaparral / Desert Shrubland
-
arid climate
low-growing shrubs with deep-root systems
sensitivity to domestic grazing & riparian zones
Types of Rangelands
Tundra
-
Low-growing vegetation, “tree-less”
permafrost
highly sensitive / native herbivores & migration
Intermediate feeders: sheep, caribou, burros
Rangeland Ecology
* How does range management (grazing
by domestic livestock impact the
rangeland community in the long-term?
* Excessive grazing & retrogression
Rangeland Ecology
• Wet rangelands, such as
southern pine forest or the
tallgrass prairie = quicker
recovery after
retrogression (<5 years)
Rangeland Ecology
• Drier rangelands, such as the
Chihuahuan desert, slower
recovery after retrogression
(20+ years)
Rangeland Ecology
• Those plants that
collectively occupy a site
in the absence of severe
disturbances – such as
excessive grazing, fire and
cultivation – are
collectively referred to as
the climax.
Grazing & metabolic reserve
Decreasers = high nutritional value, palatable,
decrease with moderate grazing
e.g., sideoats grama, little bluestem
Increasers= high nutritional value, less palatable,
initial increase with heavy grazing pressure
e.g., blue grama, Nebraska sedge
Invaders = low nutritional value, less (or not)
palatable (poisonous), increase with heavy
grazing pressure
e.g., Canada thistle, ragweed
Grazing Systems
• Continuous Grazing: animals graze
one area during growing season
• Pros = less labor, cheaper
• Cons = overgrazing possible, damage
riparian areas
• Rotational Grazing: alternate grazing
between multiple areas within or among
growing season(s)
• Pros = better range condition, protect
riparian areas
• Cons = more work, more planning
• Precision Grazing Systems
• similar to precision farming
• GPS technology….map grazing units
• Develop grazing system plan
accordingly….
Protecting Riparian Zones