Rangeland Exam 1

Know what rangeland is vs. isn’t

A land-use type that has many uses: must have naturally growing ecosystems (grasslands, shrublands, etc.), has the potential to be grazed, variable climates, and storage (of carbon, water, biodiversity, etc.).

Rangelands are NOT: barren desert, closed-canopy forests, highly managed pastures/farmland, covered by rock/concrete or glaciers.

How much of the terrestrial land surface area + Montana is considered rangelands?

54% rangeland covering the terrestrial and surface area

Roughly 70% of Montana considered rangeland

Cultivated pasture vs rangeland

Pasture: high cultivation used to manage vegetation, generally introduced or non-native forage species, usually irrigation or fertilization to increase yield, and managed by agronomic principles.

RM: different interpretations and definitions

Rangeland Management is a planning, implementing, and assessing process that protects or improves the long-term productivity of the resource. \

Different types of RM: traditional/agricultural, ecological/conservational, or multiple-use.

How and why are rangelands considered a multiple-use system?

They simultaneously yield a diverse mic of ecological, economic, and recreational goods and services that must be balanced to prevent resource damage.

Three components of management as discussed in this class

• Planning

• Implementing

• Assessing

What is guiding our management decisions and how we need to balance science and art to do so

Managers use a management framework built on wants, needs, traditions, hunches, etc. Not every rangeland or manager is the same, so management decisions must balance many things depending on the situation.

Broad challenges rangelands face

• Unsustainable grazing practices (overgrazing)

• Damaging fire regimes

• Invasive plant species

• Global climate change

Examples of different types of rangelands

• -Grasslands (dominated by grasses; well-adapted to grazing and fire)

• -Savanna (tropical/subtropical grassland with scattered trees/open canopy; high temps; seasonally dry; abundant rain)

• -Shrubland (shrubs; woody plants; spatiotemporally transitional between grasslands and forests)

• -Woodland (open stands of trees w/ crowns usually not touching; trees usually shorter than “forests”)

• -Tundra (cold, harsh climates w/ freezing temps for most of the year; permafrost soils)

• -Desert/Xeric shrubland

Importance of Rangelands

They are a large portion of the terrestrial surface of Earth and support vital ecological and human livelihood. Provide food security, carbon storage, + houses biodiversity and protects natural wildlife habitats.

Levels of Ecological Organization

Organism → Population → Community → Ecosystem → Biosphere → Biome

Biomes annual precipitation and temps

-Tropical Rainforest: High temps, High precipitation

-Savanna: High temps, avg. precipitation

-Subtropical desert: High temps, low precipitation

-Woodland/shrubland: avg. temps, low precipitation

-Grasslands/desert: avg temps, lower precipitation

-Tundra: Low temps, low precipitation

How many of the WWF 14 terrestrial biomes rangelands fall into

7 of the 14 are considered rangelands

Why deserts are often considered outside of the primary WWF “biome” generalization

classified with their aridity index rather than just rainfall, and they have a severe temperature disconnect from other biomes.

Overlap between rangelands, grasslands, and drylands

Grasslands and drylands can be similar, but are measured differently. Grasslands measured by vegetation + open landscape, drylands measured by aridity levels. All of them can be one or the other, but they do not mean the same thing.

Rangeland Management before Livestock Industry

• -Pastoral tribes in Eurasia and Africa grazed livestock for thousands of years

• -Fire and other management tools used by indigenous people

• -Survival and cultural reasons

Livestock Industry Proliferation RM was formed

• -lots of free public land (treated as “commons”) had no formal ownership or grazing regulations

• -Since grass was free, sheep and cattle barons wanted to graze as many animals as possible

• -led to severe overgrazing and the big “die-up” of these animals since there wasn’t enough food; this birthed RANGELAND MANAGEMENT as an applied science.

Big events that directed RM as we know it today

• -Homestead Act 1852: brought livestock industry to Western US

• Tragedy of the Commons

• -1916 Clement’s Succession; vegetation a complex organism, succession as a developmental process

Succession: primary and secondary

• Succession: orderly process of development involving changes in species composition and community processes over time.

• -Primary Succession: plants and animals first colonize a barren habitat

• -Secondary Succession: begins after a major/moderate disturbance (e.g., fire)

Range Model

A classical ecological framework that is historically used in RM to assess the health and productivity of the rangelands. It fails to follow strict succession because it has irreversible thresholds, soil degradation and loss of ecosystem function, and permanent disruption of invasive species.

• Range condition and trend analysis

• Direct response in vegetation changes to livestock grazing

• Grazing a disturbance causing secondary succession; RETROGRESSION: moving backwards on the successional trajectory.

• Succession isn’t fixed, so the range model might not actually follow the actual successional pathway.

Retrogression

Moving backwards along successional trajectory. Gradual degradation of a plant community away from stable, diverse, and ecological potential. Caused by overgrazing, over-resting, or changes in fire regimes.

Different post-Industrial rangeland management approaches as they have changed over time + relation to sustainability of a system

• -Exploitation: caused the “range problem” →

• -Steady State Management: maximize sustainable yield of specific goods that are highly valued →

• -Ecosystem Management: planning for integrated ecosystems as well as solicitation of more diverse stakeholder feedback →

• -Resilience Based Management: recognizes the inevitability of change and seeks to guide change to sustainably provide multiple ecosystem services for society.

Plant Structure/Pattern and Plant Function/Process

• -Plant Structure: What is there

• -Plant Function: process (cycles, interactions, and mechanisms of change)

Why knowing plant characteristics is important for RM

Plant morphology and function/structure matters because it can describe what is there and what type of life the range can support

Primary plant functional groups

• -Grasses: herbaceous, non-showy flowers)

• -Grass-like: rushes and sedges

• -Forbes: herbaceous, showing flowers

• -Shrubs: woody, several main stems

• -Trees: woody, usually one main stem

Photosynthesis: three pathways

Photosynthesis: convert light energy into chemical energy

• -C3 photosynthesis: most plants; no separation of CO2; high photorespiration

• -C4 photosynthesis: Spatial separation and concentration of CO2; reduced photorespiration adaptation; higher ATP cost

• -CAM photosynthesis: separates and stores photosynthesis processes by time by fixing CO2 at night; slow growth

Plant Phenology and Plant Life Cycles

Phenology: periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate and habitat

Life History: an individual plant’s life, growth, reproduction, and death

How the spatial scale of assessing vegetation can matter for management actions

Evaluating vegetation at the wrong scale can lead to wasted resources/funds or ecological damage, so it’s important to assess the correct scale.

NPP

Net Primary Production: biomass produced, forage available to be grazed/other ecosystem purposes; INorganic matter into ORGANIC matter

How precipitation can impact a system + how total amount vs. seasonal distribution or event characteristics may influence that

Alters the amount of water available for an ecosystem. Certain plants can handle longer seasonal distributions of precipitation; a drought could result in loss of some vegetation.

Average temps don’t tell the full story: min-max better for guiding management

Minimum and Maximum reveal the boundaries the environment and internal systems can handle

Slope/aspect influence vegetation

Both create microclimates:

Slope affects water retention and soil depth

Aspect influences vegetation type due to different exposure to sun, temp, and moisture

why we should consider soil in rangeland management

healthy soil = quality + quantity forage

Healthy soils drive water infiltration, nutrient cycling, and long-term forage productivity in an ecosystem

Main components of soil

Mineral matter, Water, Organic Matter, and Air

Primary Inorganic Particles of Soil (i.e., texture) and SOM

Soil textures: Sand, Silt, and Clay.

SOM: soil organic matter- NOT calculated in soil texture

Basic physical soil properties

Parts of soil are aggregated together through key processes: physical, biological, and chemical

CLORPT

5 forces that create soils

CL = Climate

O = Organisms

R = Relief

P = Parent material

T = Time

Three primary soil orders found in US rangelands

Aridisols - arid, low organic content

Entisols - highly variable, no diagnostic horizon

Mollisols - grassland ecosystem, thick organic surface horizon

Soil Map Units

grouping of soils that occur together, often based geomorphologically

Provide spatial network needed to link underground physical properties with aboveground ecological potential

Site Potential

The inherent ability of a site’s productivity; conditions could be excellent, but productivity could still be low. Site potential guides management actions to the optimal conditions for the site. Potential productivity → a GOAL.

Five major animal types that live on the range

Mammals

Birds

Herps

Fish

Insects

Habitat basic elements:

Biotic, Climatic, Chemical, Edaphic (soil textures)

limited by: food, water, cover, space

Wild, Domestic, vs Feral animals

-Wild: exist in a natural state

-Domestic: accustomed to human control and provision

-Feral: domesticated animals that have reverted to wild state

Habitat Restoration vs Ecological Restoration

Habitat is more specific, ecological is broad-scale

How grazing intensity can influence animal species and our management actions

Grazing intensity shapes habitat structure, plant composition, and the availability of resources for animal species

Different types of animal relationships

• -Mutualism +,+

• -Neutralism 0,0

• -Competition -,-

• -Commensalism +,0

• -Antagonism +,-

• -Amensalism 0,-

Forage and Browse

Forage: plants or parts of plants eaten by livestock/wildlife

Browse: leaf and twig growth of shrubs, woody vines, trees, cacti, and other non-herbaceous vegetation available

How plant phenology relates to forage quality and vegetative phases across different systems and functional groups

Plant phenology directly dictates forage quality: controlling the balance between nutrient concentration and structural fiber as plants mature. As plants transition from young growth to maturity, forage quality declines.

How Forage quantity changes over the season

More linear growth curve, major peak in spring, dip in summer, and decline in fall and winter

Best time to graze (considering forage quality and quantity)

Spring-summer when quality and quantity intersect at their peak.

Animal Maintenance Requirement

Maintenance = basic metabolism + minimum movement + foraging

How maintenance requirements differ across animals and seasons

Animals have different physiological adaptations for body temps, activity levels, and reproductive cycles.

Different requirements that put animals above the maintenance phase and how this differs across animal and environmental characteristics

Level of activity = standing 15% greater than lying down

Range animals 40-46% greater than stall-fed

Cold environments require energy for maintenance

Hot environments require water for perspiration

Growth of young and gestating females (+ lactation) = 10-15% greater requirements

Supply and Demand of reproductive females

Demand greater than supply in spring and winter, supply greater than demand in summer and fall.

Potential ways to meet demands if supply is below

• -Manipulate vegetation to meet animal needs

• -Feed supplements

• -Stock conservatively

Stocking rate vs Carrying Capactiy

Stocking rate = forage demand

Carrying Capacity = forage produced (The number of animals that a piece of land can support LONG-TERM without causing damage to the ecosystem)

Ruminants vs Hind-gut fermenters

Ruminants eat 2.5% of body weight in forage/day

Hind-gut fermenters eat 3.0% of body weight in forage/day

AU and AUE

AU = Animal Unit (1AU = 1000 lbs of grazing animals)

AUE = Animal Unit Equivalent

AUM

Animal Unit Month

amount of forage AU will eat in a month

(Ruminants: 1000 lbs x 2.5% = 25 lbs/day x 30 days = 750 lbs)

Four steps of Forage-demand method used for setting stocking rates

1) Calculate useable forage supply (weight of biomass/acre x proper use factor)

2) Adjust for accessibility

3) Calculate forage demands of animals (forage demand/animal/year)

4) Calculate stocking rate (supply/demand)

Proper Use Factor

Set stocking rate well below carrying capacity and total forage availability. Based on maintaining sufficient plant residue for health/regrowth, wild forage and habitat, and erosion prevention.

Guidelines for range types

How to adjust for accessibility

Prevent localized overgrazing by accounting for new terrain, water, and vegetation that limit animal movement; distance to water, slope percent, vegetation density, physical barriers

How to calculate forage demand

Weight of biomass x total area = total biomass supply →

Weight of biomass/acre x proper use percentage x area = Useable Forage Supply

How to calculate stocking rate

Useable forage supply / AU demand = number of stock

What happens to animal production when we increase stocking rates

Initially increases total production per acre, but eventually causes individual animal behavior and total yield to decline if too high (less selection and lower forage quality)

How environmental variability may influence stocking rates how we account for this

Stocking rates must be flexible to account for potential drought/forage fluctuations. herd size must be able to be sustained if rainfall was 25% below average

5000 acre cattle ranch in a shortgrass prairie (proper use 40-50%). total production is 900lbs/acre and 90 day active grazing season.

What is your useable forage supply/year?

What is your forage demand for each cow?

With an AUM of 750 lbs, how many AUM are there in this ranch?

How many cows is appropriate stocking rate?

Useable forage supply: 5000 acres x 900 lbs/acre = 4,500,000 × 40% = 1,800,000 lbs

Forage demand for each cow: 90 days = 3 months x 750 lbs/month = 2,250 lbs/cow

Total AUMS: 1,800,000 lbs / 750 lbs = 2,400 AUMS

Appropriate stocking rate: 2,400 AUMS / 3 months = 800 AU (cows)

Primary terms of grazing methods

Grazing System: a planned effort guide grazing timelines and if/how to leave areas unused

Grazing period: season/time period/number of days when a pasture/location is grazed

Deferment vs. Rest

Deferment: delay of livestock grazing until seed has set and gets past the susceptible phase

Rest: complete absence of livestock grazing for an entire year (or set timeframe)

Principles of Grazing Management

Balance forage supply and demand, provide effective rest periods, avoid sensitive time periods, and manage livestock distributions

Continuous grazing

whole area, whole season

PROS: simple + low input, maximized choice

CONS: high preference areas are used excessively and can become degraded

Deferred Rotation

Every pasture grazed in rotation to allow seed to set

PROS: pastures not grazed when they are sensitive

CONS: reduced performance and choice, requires fencing and management

Rest Rotation

Once pasture gets complete rest for a full year

PROS: pastures set seed every few years

CONS: reduced animal performance, higher stocking rate on grazed pastures, dormant stems on pastures not recently grazed mixed in with green growth

Short-duration grazing

each pasture in the unit is grazed for a short time rotated through all available pastures at least two times every year.

PROS: high stocking rates, higher forage quality, all plants often grazed

CONS: plants never get rest or deferments, animal performance usually low

Seasonal suitability

Moving livestock to different areas of range depending on growth patterns of different vegetation types (following the green)

PROS: animals have green forage most of the year, plants mostly grazed in earlier seasons before seed sets

CONS: high management/herding input, summer range may not get deferment