Rangeland Mgt Exam 1

Five principles of Range Management

1. Rangeland is a renewable resource

2. Energy capture

3. Low energy food and fiber

4. Range production

5. Products

What does it mean that rangeland is a renewable resource?

Rangelands can safely support removal of 30-50% of their biomass without long-term damage if properly managed.

What are the main traits of sandy soils?

Large particles, fast drainage, low fertility, low water-holding capacity

What are the main traits of clay soils?

Small particles, slow drainage, high nutrient retention, shrink-swell issues

Why is soil organic matter important?

Improves soil fertility, structure, infiltration, and water-holding capacity

How do rhizomes and stolons help plants in soils?

Rhizomes and stolons spread plants vegetatively, improving resilience

How does precipitation amount influence rangelands?

Higher rainfall means more biomass and diversity, lower rainfall means drought-adapted species

How does precipitation timing influence rangelands?

Spring rains mean cool-season plants (C3), summer rains mean warm-season plants (C4)

How does temp. influence plant type?

C3 plants thrive in cooler climates; C4 plants dominate in hotter climates

How does drought influence rangelands?

Reduces cover, increases drought-tolerant plants

How does elevation affect rangelands vegetation?

Higher elevation=cooler temps, more snow, shorter growing season

How does slope/aspect affect plant communities?

South-facing = warmer/drier; North-facing = cooler weather

Where are sagebrush ecosystems found?

Western U.S

What are main traits of the sagebrush steppe?

Cold winters, semi-arid, dominated by shrubs/grasses; fire and grazing are key drivers

Where are grasslands found in the U.S?

Great plains: Tallgrass east, mixed-grass central, shortgrass west

What disturbances shape tallgrass prairies?

Frequent fire, grazing by bison/prairie dogs, drought

What are the three hot desert rangelands in the U.S?

Mojave, Sonoran, Chihuahuan

Key traits of Mojave desert vegetation?

Hottest driest, <10 in. rainfall, Joshua trees, creosote bush

Key traits of Sonoran Desert vegetation?

Two rainy seasons, 3-12 in. rainfall, saguaros palo verde

Key traits of Chihuahuan desert vegetation?

Summer rain, 6-20 in. rainfall, diverse cacti, grasses

Where are western forest ecosystems located?

Rocky mountains and pacific northwest; dominated by conifers

How do soils influence plant communities?

Depth, texture, salinity control/nutrient availability and plant composition

How do disturbances affect plant community composition?

Fire reduces woody plants; grazing alters balance of decreasers/increasers; drought shifts to drought-tolerant species

What role do invasive plants play in altering rangelands?

Species like cheatgrass or red brome alter fire cycles and outcompete natives

What are thresholds in state-and transition models?

Points where ecosystems shift irreversibly

How do rangelands capture energy?

Green plants capture sunlight via photosynthesis, transferring energy to animals when consumed.

Why are rangelands considered sources of low-energy food and fiber?

They provide inexpensive food/fiber; ruminants digest high-fiber plants using microbes.

What determines range production in an area?

Soil, topography, and climate.

What are examples of products harvested from rangelands?

Food, fiber, water, timber, minerals, recreation, wildlife.

What % of U.S. land is rangeland?

~50% U.S., ~70% global, ~85% in Wyoming.

Why will rangelands be more critical in the future?

Human population growth increases demand for food, water, recreation, and ecosystem services.

What are ecosystem services provided by rangelands?

Soil stability, clean water, biodiversity, carbon storage, cultural/aesthetic value.

How is land ownership divided in Wyoming?

~43% private, ~57% public.

Who manages public rangelands?

Agencies like BLM, USFS, USFWS, EPA.

How does management differ between private and public land?

Private = owner-driven, economics-focused. Public = multi-use mandates (grazing, recreation, wildlife).

What did the Homestead Act of 1862 do?

Encouraged western settlement, cultivation, and overuse of rangelands.

What did the Taylor Grazing Act of 1934 establish?

Grazing permits and districts, regulated livestock use on federal lands.

What was the impact of the Dust Bowl (1930s)?

Highlighted poor land use, spurred soil and rangeland conservation.

What did the Multiple Use-Sustained Yield Act (1960) require?

Federal lands managed for grazing, timber, recreation, wildlife, water.

How did the EPA affect rangeland management?

Brought environmental regulation and oversight on issues like pollution and endangered species.

What are increasers?

Plants that increase with grazing mismanagement.

What are decreasers?

Palatable plants that decline under heavy grazing (“ice cream plants”).

What are invaders?

Disturbance-loving plants, often weeds, that colonize degraded sites.

What is browsing?

Consumption of woody plant leaves/twigs.

What is grazing?

Consumption of grasses and forbs.

What disturbances shape tallgrass prairie?

Fire, bison grazing, drought

Define rangeland ecology

Study of interactions between living and nonliving rangeland components

Abiotic vs. biotic factors?

Abiotic = climate, soil, light; Biotic = producers, consumers, decomposers.

How does energy flow?

Sun → plants → herbivores → carnivores → decomposers.

How much solar energy is used in photosynthesis?

Less than 1%.

How does carbon cycle?

CO₂ fixed in plants → stored in biomass/soil → released by respiration/fire.

How does nitrogen cycle?

Fixed by microbes → taken up by plants → consumed by herbivores → recycled.

Define succession.

Orderly plant community change over time.

Primary vs. secondary succession?

Primary = bare substrate; Secondary = disturbance with soil intact.

What is climax community?

Stable, diverse, productive end stage of succession.

Retrogression vs. progression?

Retrogression = away from climax; Progression = toward climax.

Initial Floristic Composition theory?

Succession = reshuffling of species already present.

State-and-Transition model?

Multiple possible states; disturbances shift communities, sometimes irreversibly.

What is an ecological site?

Land defined by soils, precipitation, expected plant communities.

Examples of disturbances?

Grazing, fire, floods, drought, storms, invasives, energy development.

Why is plant physiology important in range science?

Helps predict grazing impacts, manage ecosystems, sustain livestock/wildlife.

Warm-season plant temp needs?

Soil 60–65°F, air 70–90°F.

Cool-season plant temp needs?

Soil 40–45°F, air 65–80°F.

What are CAM plants?

Succulents using CAM photosynthesis (stomates open at night, conserve water).

4 basic plant concepts?

1) Plants = only food source. 2) Photosynthesis forms food. 3) Sun provides energy. 4) Removing leaves/stems reduces food capacity.

What does “take half, leave half” mean?

Safe use principle = 30–50% of biomass removal without harm.

Plant tolerance mechanisms?

Meristems, root reserves, regrowth after defoliation.

Plant avoidance mechanisms?

Spines, toxic chemicals, awns, tannins, low palatability.

Effects of drought on plants?

Favors drought-tolerant species, reduces cover, recovery slow.

Role of fire in grasslands?

Maintains grasses, suppresses woody encroachment.

Is grazing harmful?

Light/moderate = often neutral or positive; overgrazing = harmful.

Why do a range inventory?

Establish baseline of resources for planning.

Common items in an inventory?

Land area, pasture size, water, livestock/wildlife, condition, fences, roads, infrastructure.

Annual vs. biennial vs. perennial plants?

Annual = 1 yr, Biennial = 2 yrs, Perennial = 3+ yrs.

Native vs. introduced plants?

Native = pre-European; Introduced = brought from elsewhere.

Why use scientific names?

Precision; avoids overlap/confusion with common names.

What is monitoring?

Ongoing measurement of vegetation, soil, water to track change.

What are photo points?

Fixed sites for repeat photography to monitor changes

What does density measure?

Number of plants per unit area

What does frequency measure?

How often a species appears in sampling units

Grazing capacity vs. intensity

Capacity: how much forage available

Intensity: effect on plants/land

What is “trend” in range monitoring?

Direction of ecosystem change (improving, declining, stable)