Exam 1 Flashcards
Describe biotic and abiotic changes that occur when pinyon/juniper trees encroach on a sagebrush ecosystem
Biotic- outcompetes sagebrush and understory dies
Abiotic- connecting canopies can lead to megafires
Mean fire intervals for Mountain Big Sagebrush and Wyoming Big Sagebrush
Mountain Big- 15 years
Wyoming big- 60-100 yrs
How has decreases in fire attributed to degradation of sagebrush?
Too little fire allows woody plants to outcompete sagebrush
How has increases in fire attributed to degradation of sagebrush?
Too many fires allows invasive weeds to establish before native ones can
What makes cheatgrass a good fire fuel?
1 It is a fine fuel
2 It dries out early in spring
3 It’s a continuous fuel source (no fire breaks)
What can be don to decrease cheatgrass?
- controlled burns
- seeding native plants
- grazing
- introduce bunch grass species
How are perennial bunchgrasses opponents to cheatgrass?
Vast root systems occupy bare ground
List 6 sagebrush obligate species
Sagebrush lizard, pygmy rabbit, greater sage grouse, sagebrush vole, sagebrush thrasher
List 3 sagebrush obligate species
Mule deer, burrowing owls, Merriam’s shrew
Define fragmentation in regards to sagebrush systems
Sagebrush communities are not continuous. Sagebrush obligate species isolated
How are pasturelands different from rangelands?
Rangelands are not highly cultivated. No plowing, no tilling.
What % of earth’s land surface is covered by rangeland?
40-50%
List and explain five basic concepts on which range management is based
- Rangeland is a renewable resource
- Energy captured by green plants can only be harvested by animals
- Rangelands supply humans with food at comparatively low energy costs
- Productivity varies depending on soils, topography and climate
What are some agencies that manage public land in the United States? (4)
Bureau of Land Management
Forest Service
National Park Service
Department of Defense
Describe at least 8 uses for rangelands
- Grazing cattle
- Recreation
- Water
- Energy
- Minerals
- Open space
- Wildlife habitat
- Forage
- Native plants
How does occupied bare ground benefit a site?
Perennial grasses utilize nutrients and water in that space, making it unsuitable for annual grasses
How have seeding practices changed regarding native and introduced species?
We have shifted away from planting introduced species, and towards planting natives
Pros of seeding natives
Habitat for wildlife, increased polinators
Cons of seeding natives
Doesn’t survive as well, seed is more costly, not strong against weeds
Pros of seeding introduced
Better against weeds, quick to establish
Cons of seeding introduced
Outcompete natives, leads to monoculture, could spread into non-target areas
How do roots respond to above-ground defoliation?
0%- no effect
50%- small effect
70%- less than half of roots remain
90%- very few roots remain
What are non-structural carbohydrates?
carbohydrates that are easily transported within plant, good forage, important for recovery of plant
What are structural carbohydrates?
Carbohydrates found in the form of cellulose and ligden, not easily digested
How do non-structural carbohydrate levels vary with growth phase of plants?
When grass is dormant, NSC recede to roots of plants. When active, NSC found in leaves.
List four ways grazing promotes plant growth
- Stimulates compensatory photosynthesis
- Improves light levels
- Disrupts carbon/nitrogen ratio
- Reduces influence of apical dominance
List 3 negative impacts of grazing
- Reduced root mass
- Prevent seed propagation
- Takes carbohydrate reserves
Name three sources for growth from a grass plant
- Apical meristem
- Intercalary meristem
- Axillary bud
What is an apical meristem and how does its location change in a grass plant?
Apical meristem is the growing point for main upward growth.
In the vegetative stage, the apical meristem is near the ground
In the boot stage, the meristem is high
Once the plant has gone to seed, the meristem is near the ground again
Difference between cool and warm season grasses
Cool season grasses grow the most in the spring and fall, semi-dormant in summer
Warm season grassed grow in the summer
Accordin to Joel Slatin, what is the role of the herbivore in influencing the carbon cycle?
They stimulate biomass production by pruning grasses to bring them back to the growth stage and continue carbon sequestration
Describe three ways vegetation influence water movement in soil
- Creates macropores
- Strenghtens soil aggragates
- Absorbs water and shields ground
What is carbon sequestration?
Storing carbon from the atmosphere in the soil
What does the decomposition of organic matter result in?
Humus- stable carbon in soil
How can grazing improve soil carbon sequestration?
Stimulates bioproduction of grasses
How can grazing improve soil carbon sequestration?
Stimulates bioproduction of grasses
In Rangeland Rehabilitation and Carbon Credits in Kenya, what was done to improve the health of their rangelands?
The scattered animals were herded together, and they did planned grazing on pre-determined plots
What are the two major motivating factors for landowners to adopt carbon sequestration practices on rangelands?
- Improved productivity/production of grasses biomass
2. Carbon credits
When would be the best time to remove wolf plants through heavy grazing?
During dormancy. Plants are less susceptible. Easier to get cattle to eat them.
With respect to plant physiological development explain four different strategies strategies land managers could implement to promote/sustain grazing productivity?
- Change duration of grazing
- Change season of grazing
- Provide opportunity for leaves to regrow
- Avoid annual use during reproduction
- Periodic heavy use during dormant to address wolfy plants
Explain what factors make some grasses more grazing tolerant than others
- Height of growing points
2. Ability to perform compensatory photosynthesis
How is Green and Brown strategy used to control cheat grass?
Graze when perennials are brown. Graze when cheat grass is green.
How does the green and brown strategy contribute toward the overall reduction of cheatgrass?
- Keep annual grasses from flowering (green)
2. Keep perennial species strong and healthy (brown)
Give two examples of morphological and biochemical avoidance mechanisms of plants
Morphological - Spines, tensile strength
Biochemical - Reduce digestive benefit, Terpenes in sagebrush
Give two examples of morphological and biochemical tolerance mechanisms
Morphological - Location of meristem, leaf replacement potential
Biochemical - Compensatory photosynthesis
Why do warm season grasses grow little above ground in it’s first few years?
They focus most of their energy on establishing a root system
What are three ways we are losing sagebrush
- More frequent, larger fires
- More trees moving into landscape
- Introduction of weeds
Describe the 3 functional groups of sagebrush-stepp
- Forbes - tall flowering plants
- Grasses - low plants with many tillers and leaves from ground
- Shrubs - sagebrush and other low, woody species
Describe 4 purposes native americans used fire for
- Increase availability of desireable plants
- Maintain habitat for animals
- Driving game for hunts
- Warfare
What are fire scars and what do they teach us about fire frequencies?
We know what year the fire happened, how often it happened. Dark marks in tree rings left over from fires
What is a potential reason for fire frequencies decline in 1900’s
Overgrazing took fuel away
What did the railroad do for livestock production in the west?
It made it easier to transport livestock from Texas
Homestead Act
160 acres per family
1905 Transfer Act
Established Forest Service. Permits to use public land to run livestock
Who brought cattle to America?
Cortez and Coronado
Who was John Wesley Powell?
The guy that understood native American prescribed burning principles. Soldier, explorer, geologist.
Who was Arthur Sampson?
Father of range science. Started in Ephraim Canyon.
Explain tragedy of the commons
Everyone had the opportunity to use the finite resource of the grass growing in the Wasatch Plateau.
List consequences from uncontrolled livestock grazing
Bad erosion, destructive floods, people became sick from run-off water from grazing areas, fires stopped
Enlarged Homestead Act
320 acres per family, 1/4 cultivated
Stock Raisers Homestead Act
640 acres per family
Taylor Grazing Act
Put remaining public land under BLM management
Multiple Use Act
You can use lands for more than just livestock
Wilderness Act
Protected some areas against profit-ventures
National Environmental Policy Act (NEPA)
Must prepare impact of policy and publish it to the public
Federal Land Policy and Mgmt Act
Ends homestead act
Range Improvement Act
Federal grazing fee ($1.35 per AUM)
Who was Gifford Pinchot
1st chief of Forest Service, against forest fires, from Europe.
What are other potential reasons for fire frequency decline?
The Smokey the Bear/ Bambi effect
Removed native americans
overgrazing
fire repression policies
