rangeland

is there more work in planning or implementation for fire

implementation

wildfires

uncontrolled and unplanned fires

fire-use or let-burn fires

a fire allowed to burn with monitoring- unlikely to cause human harm

prescribed fires/ controlled burns

planned and implemented fire used to meet management objectives

frequency (fire)

how frequently an area burns

intensity

rate at which fire produces thermal energy

seasonality

time of year when fire is most common to occur naturally

severity

relative amount of alteration, disruption, or damage a site experiences

coexistence era

indigenous peoples fire use

supression era

putting out wildland fires as fast as possible

shadow area

localized prescribed burning

contemporary era

prescribed burning common

3 variable components of fire regimes

time, space, intensity

need to know _________ to understand intensity

fire behavior

fire intensity is dependent on:

• available fuel and composition

• moisture and temperature

• wind

• topography

fire benefits

• manage fuels and reduce wildfire risk

• removes litter and improves forage

• can reduce or eliminate unwanted species

• can be used with herbicide to improve rangeland health

• can be used with grazing to accomplish management objectives

riparian

• water through overland flow, subsurface flow, and groundwater recharge

• boundary of permanent water separates riparian from aquatic zones

• alongside streams/rivers, meadows, bogs, wetlands, springs

riparian make up ___% of western US

1-2%

sheet erosion

Thin layer of soil removed evenly across a surface by rainfall or runoff

rills

channels less than 0.3m deep

gully

channels greater than 0.3m deep

headcuts

occurs at the head (upstream extent) of a channel or side of a wet meadow, and advances backwards with continued erosion

cut banks

erosion and depostion along a meandering stream

channelization

Human-made or modified channels to direct water flow, often accelerating erosion downstream

invasive species

• Non-native (or alien) to the ecosystem under consideration

• Whose introduction causes, or is likely to cause economic or environmental harm or harm to human health

what is the primary cause of invasive species introductions

humans

three phases of invasion process

• arrival and establishment

• spread

• equilibrium and effects

arrival and establishment

• dispersal vectors allow invasive to arrive

• humans, wildlife

Tens hypothesis

• 1 in 10 appear in the wild

• 1 in 10 will establish

• 1 in 10 become an invasive pest

spread

• able to establish and increase in numbers

• rate depends on 

  • species characteristics

  • ecosystem characteristics

  • spatial distribution of individuals or populations

biotic resistance hypothesis

ability of resident species or a community to reduce invasion success

equilibrium and effects

• magnitude of the problem

• eradication possible?

• overall consequences?

3 broad management approaches for invasives

• prevention and education

• eradication

• control

invasive control

manipulation and management to reduce the impact off noxious plants to an acceptable level

methods for managing unwanted plants

• biological control

• prescribed fire

• mechanical control

• chemical control

IWM stands for

invasive weed management

IPM stands for

invasive pest management

fire return interval

average amount of time between fires in a specific area, 3-5 years >100 years

how does fire impact abiotic systems?

• temporarily increases soil temp and nutrient availability

• alters soil pH and moisture levels

• releases carbon and other gasses into the atmosphere

how does fire impact biotic systems?

• removes veg and litter, promoting new plant growth

• creates habitat diversity + early successional stages

• can increase or decrease species richness

time- fire regime component

• how often and win fires occur

• ex. short fire return interval (grasslands every 5-10 years) vs long intervals (boreal forests 100+ years)

• affect regeneration cycles, seed release timing, nutrient turnover

space- fire regime component

• size, pattern, distribution of burned areas

• ex. patchy burns create a mosaic of habitats with varying successional stages

• influences wildlife movement and recolonization periods

intensity- fire regime component

• energy released and its severity on the landscape

• ex. low intensity fires may only burn grasses, high-intensity can kill mature trees

• affects soil chemistry, seed survival, and postfire veg recovery

how can historic burn periods and prescribed burns be mismatched?

• prescribed burns often don’t match historic fire frequency, season, or intensity that ecosystems evolved with

• can cause fuel buildup, alter plant communities, changed nutrient cycling and soil properties

3 sides of fire triangle

• oxygen

• heat

• fuel

3 sides of fire behavior triangle

• weather

• topography

• fuel

how does patch burning influence vegetation

• fire burns one patch at a time, attracting grazers to fresh regrowth

• recently burned areas are heavily grazed = short veg

• unburned are lightly grazed = taller veg

• = mosaic of vegetation structure across landscape

how does patch-burn grazing influence avian communities

• different bird species prefer different vegetation heights and structures

• grassland birds (horned larks) use recently burned, short-grass areas

• shrub or tall-grass birds (Henslow’s sparrow) use older, unburned patches

• patch-burn grazing increases avian diversity by providing nesting and foraging sites for multiple species

why are fire and grazing not the same

• fire- rapidly removes veg and can alter soil nutrients, seed banks, and structure

• grazing- gradual and selective, animals target specific plants and continually disturb soil

• functionally similar, but operate through different mechanisms and timescales

where do riparian areas get their water from?

• overland flow

• subsurface flow

• groundwater recharge

where do upland areas get their water from?

precipitation

abiotic reasons riparian areas are important

• reduce erosion by stabilizing streambanks with roots

• filter sediments and nutrients from runoff, improving water quality

• regulate streamflow by storing and slowly releasing water

• moderate microclimate through shade and moisture retention

biotic reasons riparian areas are important

• provide critical habitat

• support high plant diversity and productivity

• offer forage and water for livestock

• serve as migration corridors

CAUSES of riparian degradation

• overgrazing by livestock

• deforestation or vegetation clearing

• altered water flow (dams, diversions, channelization)

• invasive species

• pollution and sediment runoff

CONSEQUENCES of riparian degradation

• erosion and streambank collapse

• reduced water quality

• loss of riparian vegetation and shade- higher water temps

• decreased water retention and less resilience to drought and flooding

how does channelization impact floodplains?

• disconnects streams from their floodplains, preventing natural flooding

• without flooding, nutrients aren’t deposited across floodplain, groundwater recharge decreases, riparian plants and wetlands that depend on periodic flooding decline

actions to restore riparian areas

• adjust grazing practices

• restore vegetation

• reestablish natural hydrology- dechannelize, install BDAs

• manage upland runoff

is eradication possible once an invasive species reaches equilibrium?

• usually no, the population is widespread and self-sustaining

• impacts include long-term ecosystem alteration, reduced biodiversity and habitat quality, ongoing management costs

What are the Montana Noxious Weed Classes?

• Class 1A: Not present in Montana.

  • Goal: Eradication and prevention of establishment.

  • Example: Not yet detected species.

• Class 1B: Limited presence in Montana.

  • Goal: Containment and eradication where found.

  • Example: Small, isolated infestations.

• Class 2A: Established but with limited distribution.

  • Goal: Reduce spread and control infestations.

• Class 2B: Widespread and well-established.

  • Goal: Ongoing management to reduce impacts and prevent further spread.

• Class 3 (Regulated Plants): Not designated noxious statewide, but may be managed at local levels to prevent spread.

• Watch List: Species of concern not yet classified as noxious but monitored for potential future issues.

why can removing an invasive species only treat a symptom

• invasions often occur bc of underlying ecosystem disturbances

  • overgrazing or altered fire regimes

  • soil disturbance or erosion

  • hydrologic changes

  • nutrient enrichment (fertilizers or runoff)

biological control

• using living organisms to reduce invasive plants

• ex. introducing a leaf eating beetle to control leafy spurge

mechanical control

• physically removing invasive plants using tools or machinery: hand-pulling, mowing, cutting, tilling

chemical control

• using herbicides to selectively or non-selectively kill invasive plants

IPM approach to invasives

combine control methods based on species, site conditions, and timing to reduce invasives while minimizing harm to env and non-target species

pesticide

any chemical used to ‘control’ some living substance

fundamental principles of herbicide use

• contact plant when the plant is susceptible

• remain in contact long enough to be absorbed

• reach a living cellular site at a concentration sufficient (toxicity) to disrupt a vital process or damage vital structures to kill the plant

why choose herbicides

• can be less expensive than resource-heavy approaches

• terrain has little impact

• can provide selective control

• safe for releasing in situ desirable plants

• low labor requirement

• generally safe when following proper safeguards

why not choose herbicides

• requires precise timing and rates

• may harm non-target, desirable plants

• may increase plant toxicity- alkaloids in tall larkspur

• potential danger to applicator or environment

• unknown or long-term health hazards

herbicide primary modes of action

• growth regulating

• amino acid synthesis inhibitors

• photosynthesis inhibitors

growth regulating herbicides

• chemical mimics auxin, plant hormone that regulates growth and development

• most widely used group of herbicides on rangelands

• selective against broad-leaf plants

amino acid sysnthesis inhibitors

• prevent key amino acid synthesis

• blocks protein and enzyme production

• slow acting but effective

photosynthesis inhibitors

• blocks photosynthesis

• build-up of free radicals destroys cell membranes

• mostly used for perennial weeds

aerial application method

• pros: faster coverage over large areas, terrain doesn’t matter, lower cost per acre, no mechanical disturbance of soils or veg

• cons: more expensive, specialized equipment, susceptible to weather, possible drift from targets

ground application method

pros: adapted to small acreages, less drift, fewer climate limitations, applicator safety higher

cons: labor-intensive, limited coverage in dense or tall vegetation, uneven application

individual plant treatment herbicide method

• pros: common on small scale- portable sprayers, targeted efforts on species of interest, different parts of plant can be targeted

• cons: labor intensive, uneven application

soil application herbicide method

• soil surface is the target

• ground or aerial- usually in dry form, pellets or granules

• pros: less drift, not intercepted by foliage, safer handling, remains active longer

• cons: often more expensive, some are less effective in granular form, difficult to spread evenly, requires rainfall for activation