Mountains and Plains

Riparian Landscapes

  • 2-3% of land area 

    • 75% of native animals

  • Filter and store water

  • Continuously varied vegetation 

Physical variables

  • Elevation

  • Climate

  • Grade

  • Soil type and depth

  • Sinuosity

  • Width: Depth

  • Human and animal impacts

  • orientation

*Riparian areas have moving, oxygenated water*

*Hydrophytes: Water-loving plants, legal boundary*


Rivulet to River

  1. First-order stream

    1. Willow, sedges, grass, meadows

  2. Second-order stream

    1. Formed by two first-order streams

  3. Third-order stream

    1. Formed by two second-order streams

    2. Alder, water birch, willow

Abrupt vegetation shifts

  • Point bars

  • Channel bars

  • Cut banks

  • Terraces

  • Islands

  • Dams (log, debris, beaver)

Less sediment now

  • More likely to incise stream beds

Cottonwoods depend on flood-stage rivers to deposit seeds above the typical high water mark

Shifting riparian mosaic

  • Changed by flood suppression

Each pound of plant material uses ~400 lbs of water

People benefit from beaver soils

  • Soil stability

  • Longer flow, bank storage

  • 18x more water storage

Beavers used by people to fill in gullies need appropriate building materials

  • Aspens preferred, will use tires

  • More gullies now than in the 1700s

People love riparian areas!

  • Higher land prices

  • Increased recreation

  • Just plain pretty

Livestock

  • Concentrate where food, water, and shade are (aka riparian)

    • So did bison

  • Fencing, herding, salt licks, keeping cattle out

  • Consequences

    • Bank erosion

      • Lowered bank storage

      • Lowered water quality

      • Decreased habitat

        • Fewer fish

Reservoirs 

“Headwaters of the West”

  • 85% of water goes out of state

  • Decreased riparian habitat

  • Short-lived benefits

    • Sedimentation

    • Flood control

    • Irrigation

    • Power generation

    • Recreation

Great fluctuation in water level

  • No plants can grow

  • Levees reduce the riparian area

  • Dikes increase it


Irrigation

  • Firm need

  • Any means necessary

  • Only 2-3% of Wyoming is arable 

  • Creation of ephemeral streams

    • Lack of protection under the Clean Water Act

    • Poor fish habitat

Return flow

  • More water downstream (+)

  • 90% loss from evapotranspiration (-)

  • Nutrient leaching (-)

  • Eutrophication (-)

  • Salt deposits (-)


Invasives

  • Beavers removed

  • Banks logged

  • Floods created

    • Sluice dam?

  • Species

    • Canada thistle

    • Leafy spurge

    • Yellow sweet clover

    • Kentucky bluegrass

    • Smooth brome

    • Russian live

    • Salt cedar (tamarisk)

      • Non-edible

      • Halophile, salt-secreting 

      • Higher transpiration





Non-Riparian Wetlands

Marshes, playa, wetlands, wet meadows, fens


1974 National Wetlands Inventory

  • 950,000 acres

  • 1.5% of Wyoming 

    • 5% permanently flooded


2,692 Wyoming plant species

  • 12% oblate wetlands

  • 13% facilitative wetlands


Important plants

Sedges (Cyperaceae)

Grasses (Poaceae)

Willow (salicaceae)

Mosses

Algae

Amphibian habitat

Seasonal drying keeps predators to a minimum, which is good for the environment

Prolonged saturation creates oxygen deficiency

“Gleyed horizon” from mineral leaching in soil

  • Carbon sequestration 

Aerenchyma: a spongy tissue in the stem that lets oxygen diffuse

Toxicity

  • Reduced sulfur

  • Reduced iron

  • Reduced manganese

Rhizosphere: mm thick layer adjacent to roots 

  • Oxidation occurs here and renders compounds harmless

  • Red soils are often hydric soils

Diversity maximized at wet/dry fluctuation


Marshes

Med, muck, or sandy bottoms

  • Common in potholes

    • Beheaded streams

    • Old beaver dams

  • Often form rings of various vegetation, sorted by drought tolerance

    • Increases biodiversity

Playa Wetlands

Salt-precipitated wetlands most often occur at low elevations

  • Halophytes (salt > 5 parts per 1000)

    • Greasewood

    • Red swamp fire

    • Saltgrass

  • Devoid of life much of the year


Wet Meadows

  • Where water tables are at or near the surface of the water, but the water table drops in the summer

    • Hard to recognize

    • Hydrophytes

    • Hydric soil

    • Graminoid vegetation

  • Develop below glaciers and snow banks

  • Graduated growth

  • Can be damaged by overgrazing 

    • “Plugged” changes species abundance

  • Desirable real estate 


Fens

Rich in graminoid vegetation, but willow is the most common

  • Not a bog, pH too high (5-8 for basic fen)

  • Different water source

  • Mosses do well

  • Fens can merge with mashes, peat floats

  • Classified based on mineral richness

    • More minerals at a more basic pH


Management issues

  • 35-40% already lost

  • Groundwater contamination

  • Peat mining

  • Invasive plants

    • Reed canary grass

      • Hybrid American-European descent

      • Highly aggressive

    • Broadleaf and Narrow-Leaf Cattail

      • Serile

      • Rhizomes

    • Purple Loosestrife

      • Colorful 3-4ft tall

      • Invasive seasonal springs

  • Climate change

    • Increased droughts

    • conversion into playa

      • Peat deposits decompose by adding carbon dioxide


“Wetlands Reserve Program”

  • Landowners paid to protect wetlands

Artificial wetlands are often built to offset new development on existing wetlands


Grasslands

Plains east of the Rocky Mountains

2 Types

  1. Shortgrass prairie

    1. Southeast corner of WY

    2. Buffalo grass, blue grama

  2. Mixed-grass prairie

    1. 17% of the state

    2. Bunch grasses

      1. Blue gramma

      2. June Grass

      3. Sandberg bluegrass

      4. Indian ricegrass 

      5. Forbes, shrubs, and succulents

      6. 50 species per acre

Plant communities are good indicators of soil types

Soil types

  • Sandy

  • Aridisols

  • Mollisols

Grassland invasion

  • All of the world

  • Less frequent fires

  • Overgrazing 

  • Atmospheric changes

Soil Aeration

  • Badgers, ground squirrels, harvester ants, pocket gophers, prairie dogs

Survival

  • 75% of biomass is below the ground

  • Most herbivores are vell

    • Invertebrates are the largest group of herbivores

  • 70% of roots in the first 4 inches of soil

Most perennial buds at or near the soil surface increase protection from fires and grazing

  • Buds will replace blades killed by herbivores or fire

  • Intercalary meristem on a leaf

  • Special meristem below ground

  • Energy stored in roots allows regrowth

Xerophyte

  • Drought-tolerant plant species

  • Small leaves

  • Pubescence

  • Light coloration

  • senescence/ drought deciduous 

Animal adaptations

  • Continuous tooth growth (20 mya)

  • Ruminant digestion

  • Coevolution leads to dissimilar diets

Partitioning Resources

  • Plants use the same resources at different times of the year

  • Use different soil depths

  • Grass vs forb herbivory

  • Physiological differences

    • C3 metabolism in cool weather

    • C4 metabolism in warmer weather

Energy Flow

Photosynthesis <2% efficient

  • Reflected energy

  • Evapotranspiration

  • Soil heating

  • 500-900 g/m2

“Coarse soils have higher percolation rates, meaning greater water need.d”

Patchy rainfall causes episodic growth and large mammal distribution

Pathway of solar energy

  • 65%-85% moved internally

  • 30-40% for maintenance 

  • A large portion of stems and leaves

    • 10%-30% lost to herbivory

    • 33% large herbivores

    • 33% nematodes

    • 33% insects

    • 1% birds and small mammals

  • Energy flows; it doesn’t cycle

Nutrient cycling 

  • Nutrients are lost from a system mainly by erosion

  • Gained by weathering 

Grasses are high in lignin and cellulose and decompose slowly

  • This leads to higher infiltration rates

  • Increases microbial decomposition 

  • Creates beautiful, fertile soils!

  • Low rates of nutrient leaching due to low rainfall

  • Fabaceae plants fix nitrogen

    • 93% of other sources of nitrogen

    • What are they, and how does nitrogen fixation work?


Fertilizing rangelands

  • More forage

  • Higher protein content

  • Selectively graze fertilized areas

  • Favors undesired weeds

  • Not economically viable

Nitrogen that is part of a plant is often stored in the perennial parts of that plant and thus stays in that plant. (50%-80%)

Disturbance and succession

  • Secondary succession: changes that occur after a disturbance that brings the system back to baseline

  • Types

    • Plowing

    • Drought

    • Fire

    • Grazing 

    • Burrowing animals

  • Recovery is often quick if the roots are intact

  • Damages are often cyclical

Effects of Grazing

  • Light grazing makes plants grow faster and with higher ground cover

  • Mechanism:

    • Removal of senescent leaves 

    • Removal of transpiration sites

    • Concentration density in waste

    • Removal of “apical dominance”

    • Compensatory growth hypothesis

      • Little evidence as of 1993

      • Clipping increases photosynthesis by 5-10%

        • Less than the clippings would have added

      • More evidence of bison recently?

  • Some rangeland is still recovering from the 1800s and early 1900s practices

  • Grasslands with native grazers tolerate grazing better

  • Should ranges be managed for ecosystem services?

  • Gnu and impala symbionts on “grazing lawns”

  • Prairie dogs create prime forage

Fire

  • Frequent in pre-fire suppression years, lots of fuel buildup

  • Fire is low in prolonged drought

  • 10-25 lightning fires per 1000 miles in the Great Plains

    • Most frequent in July and August

  • Fires every 2-25 years

    • Less in arid or steep areas

  • Warm-weather species are more tolerant than cool-weather species

  • Natives burned areas to attract game

  • Allows soil to warm quickly 

    • Creates less mulch

  • Very little loss of nitrogen

  • Increases evaporation

  • Patch-burn grazing systems

    • Exposed to both

    • Benefit cattle and birds


Drought

  • Decreased carrying capacity

  • Some plants increase with a lack of competition 

  • Plant cover is reduced to 2% in extreme droughts

  • Prickly pears are the last strongholds for plant survival 

  • Above-average rain can convert the prairie as well


Grasshoppers

  • The most important animals in the western grassland!

  • Outbreak during droughts

    • Unknown reason

    • Correlation, not causation

  • .05% of veg or 65% of vegetation, depending on numbers

    • Cut 25x more than they eat

  • Control measures only last a year

  • All species are native

    • Rocky Mountain locust extinct as of 1900



Burrowing animals

  • Pocket gopher mounds can cover 25% of the grassland

  • Skunks and badgers amplify gopher mounds

  • Burrows provide habitat 

    • Mice, beetles, crickets

  • Prairie dog

    • Black-tailed and white-tailed

    • 3ft-9ft burrows

      • Improves water infiltration

    • Habitat creation

    • Keystone species and ecosystem engineer

    • Build colonies in heavily grazed areas

      • Will clip the grass to better see predators

      • Reduces livestock forage

      • Viewed as a nuisance

      • Provide long-term benefits to the land

    • Sylvatic plague

      • Flea transmitted

      • Deadly to prairie dogs

      • Introduced in the 1800s

      • Kills ferrets too

  • Ground Squirrels 

    • 0-100 per acre

    • Unknown reasons for population variance

  • Harvester ants

    • Pogono 

Invasive Plants

  • Effects

    • Crowding out

    • Altering food availability 

    • Carbon storage capacity reduced

    • Nutrient availability

    • Increased erosion

  • Species

    • Canada thistle

    • Russian thistle

    • Cheatgrass

  • Combatting 

    • Maintenance of native species

    • Finding herbivores

    • Lowering soil nitrogen

    • Herbicides

  • Challenges

    • Nothing that looks original exists

    • Need to establish a park mandate

      • Objections to bears and wolves

      • Increased prairie dogs

      • Increased ferrets

    • More land is needed for agriculture

    • Oil, gas, and wind farms

    • Diseases and invasives

    • Climate change

Sagebrush

Artemisia tridentata

  • ⅓ of Wyoming by area

  • 12 species

  • Indicate deep soils

  • Usually in arid areas

  • Biotic communities similar to grasslands

  • Reliant on deep snow

    • Can reach water at great depths

  • High genetic diversity

    • Low sagebrush

    • Mountain big sagebrush

    • Mountain silver sagebrush

    • Big basin sagebrush

    • Wyoming big sagebrush

    • *All found in the GYE

  • Adaptations:

    • Distribution is determined by delicate seedlings, not adults

      • Most seedlings in wet years

      • Any disturbance to the sage lowers ecosystem productivity

    • Hydraulic redistribution

      • Deep roots bring water to the soil's surface

      • Can reverse this process at any time

      • Nurtures bacterial communities

      • Prolongs growing season

    • Efficient water use

      • Rapid stomata closing lowers transpiration

      • Evergreen

        • No downtime in spring

        • Produce ephemeral leaves as well

      • Pale color and short hairs on leaves

        • Keeps the plant cooler, lowering transpiration rates

    • Carbohydrates are stored in twigs

      • Good food source

      • Evolved terpene defense

        • Vary by species and individuals

    • Cannot sprout from roots

      • Longevity and seed production are important factors in a community

        • 100-year lifespan

        • 50 is very common

      • Produce 1000s of seeds each year

        • Seeds vare iable for 4 years

    • Not salt-tolerant

    • Discontinuous clustered growth

      • Only sprouts in favorable years

The Sagebrush Ecosystem

  1. The presence of aromatic shrubs with deep and shallow roots

  2. A large portion of precipitation occurs during the winter season

*Many similarities to grasslands!*

Hydrology and Plant Growth

  • Makes ecosystems more productive

  • 80-250g per square meter per year

    • > mixed grass prairie

  • Black body effect

    • Causes snow to melt around the plant

    • Fills in with drifts

    • Reduces sublimation

Energy, Carbon, Soil, and Organics

  • ~½ food chain occurs underground

  • Less palatable than grasses

  • Winter forage for:

    • Pronghorn

    • Mule deer

    • Elk

  • Takes >10 years to sprout post-fire

  • Great carbon storage

    • Soil retention is a key to reestablishment

  • Carbon dioxide

    • Sink during wet years

    • Source during dry years

  • NPS manages for:

    • CO2 sequestration

    • Resistance to invasives

    • Habitat for endangered species


Nutrient availability

  • Water is more limiting than nutrient availability

  • Stems reabsorb some nitrogen from deciduous leaves

  • More above-ground biomass than in grasslands

Recovery after Disturbance

  • Increases with precipitation

  • Increases with soil litter depth

  • Decreases with grazing

  • Decreases with herbaceous competition 

  • Increases with more seeds

  • Increases with mycorrhizal nets

  • Decreases with mine tailings

Drought, Frost, Extended Wet

  • Some winter mortality

    • Water stress

    • Late frosts

  • 5 years of wet phase causes extensive die-offs

  • Likely to become more common with climate change

Grasshoppers

  • Potential to kill 50% in warm, dry years


Fires

  • Natural interval of 20-100 years

    • Emerging research says 70-250-year interval 

Cheatgrass (Bromus tectorum)

  • Benefits from disturbance

  • Found above 7,000 feet

    • Climbing with climate change

  • Introduced in the 1800s fromthe  European steppe

  • Grow in late fall and very early spring

    • Gets a head start on native species

  • Lower biological soil crushes

  • Increases fire frequency

  • Increases grazing but only before it flowers

  • Increases with warming temperatures and CO2 levels

Effects on Livestock

  • Grazing is not a disturbance unless there are too many animals or for too great a time

  • Decreases biological crust and leaves areas vulnerable to invasive species colonization

Horses

  • Evolved in North America

  • Died out 10,000 years ago 

  • Reintroduced accidentally in 1539

    • DeSoto dropped 220 around Florida

  • In the 1600s, Indians acquired and freely traded horses

    • Dramatic lifestyle changes followed

  • An estimated 3,500 feral horses in WY as of 1995

    • Periodic round-ups

    • Research on birth control

Sage Grouse

  • Jeopardized and declining

    • Habitat loss is the main driver

    • Inappropriate grazing 

    • Population fragmentation

  • Federally listed as endangered

    • 50% decline in 10 years over the 80s and 90s

  • Eats sagebrush leaves

    • Also, insects and forbs

  • Range of 30 square miles

    • Always use the same lek

    • Will not change and is slow to abandon

    • Noise sensitive

  • Tall structures encourage raptors

    • Increases predation 

  • Vulnerable to West Nile virus (has caused large die-offs)

Escarpments and Foothills

  • Often glacial moraines

  • Small slivers of the ecosystem

  • Important for big game

  • Provide forage and shelter

  • Gros Ventre and Slide Lake

  • Vegetation banding due to soil types

  • Trees grow only on ridges

    • Very little fire fuel


Plants and Adaptations

  • Mountain Mahogany Shrublands (Cerocarpus sp.)

    • 4,500ft-8,000ft

    • Curl-leaf: evergreen

    • Birch-leaf: deciduous

    • Nitrogen fixer

    • Curl-leaf controlled by fire

      • 150-year cycle

  • Juniper Woodlands

    • Utah Juniper is common in western WY

    • 3,600ft to 6,000ft

    • Expansion and infilling 

      • Livestock grazing 

      • Fire suppression of >30-60 years

      • Grow well under sagebrush

    • Range expanding with climate change

  • Ponderosa, Limber Pine, and Douglas-fir

    • The 20th century has seen an increase in all 3 species

    • Reduces the forage available

    • Increases transpiration

      • Lowers stream flow volumes

    • Needles are toxic to consume

    • Ponderosa

      • Low elevations

      • Summer rains

      • Eastern Wyoming resident

      • Mowry shale substrate

    • Limber Pines

      • Dryer and cooler environments

      • Extreme elevations

      • Rocky soils and ridges

        • In the lee of boulders

    • Douglas-Fir

      • Dominant species in western WY

      • Fires every few decades

  • Mixed foothill shrubs

    • Many nitrogen-fixing species

    • Serviceberry

      • Utah and Saskatoon

      • Higher fire rate

    • Snowbrush ceanothus

      • Fire obligate

    • Greasewood

      • Water seep obligate

  • Foothill grassland

    • Shallow snows

    • Shallow soils

    • Very windy

      • Cushion plants

  • Deciduous woodlands

    • Aspen, chokecherry, gamble oak, Bur oak

    • Mesic sites: high water content

    • Deep soils

    • Chokecherries

      • Woody draws

      • Eastern Wyoming 

    • Aspen

      • North-facing slopes with snowpack 

      • Water seeps

      • Aspen atoll

        • Ring of aspens around a seasonal drift


Plant and Animal Interactions

  • Elk prefer to winter here

  • Aspen, Elk, Fire community cycle

  • Aspens

    • Clonal species

    • Each clone lives ~150 years

    • Large die-offs

      • Fire suppression 

      • Elk browsing 

        • Linked to hunting, feeding, and few predators

      • Cattle contribute

      • Aging out

      • Wintering grounds for all herbivores

    • Summer forage determines winter survival

      • Used more heavily during the winter months

    • Deep snow uses more energy

      • Shorter growing season

    • Ungulates create browse lines on stems

      • Typically recover quickly

  • Mule Deer die-offs

    • Drought due to climate change

    • Habitat fragmentation

    • Mitigated by feedlots

      • Overgrazing of the surrounding forests

      • Disease transmission

      • Increased hunting opportunities

      • Decreased ranching conflicts

  • Pine seed dispersal by birds

    • Pinyon and Limber pines

      • Large nutritious seeds

    • Clarks nutcrackers

      • 100 seeds per beak pouch

      • Demonstrated moving seeds over 13 miles to caches

      • Collected late summer and buried on south-facing slopes

      • Range overlaps with pines with large wingless seeds

      • Selectively cache seeds in burned areas


Mountain Forests

50 mountains above 13,000ft in Wyoming

No 14,000ft peaks

Important sources of water and timber

Variation in Mountain Environments

  • Elevation

  • Steepness

  • Aspect

  • Bedrock

  • Soil development

  • Snow accumulation

  • Temperature 

    • 2-5 degrees per 1000 feet

  • Growing season

Survival in the Mountains 

  • Short, cool, dry growing season

    • Photosynthesis occurs near 0 degrees

    • Evergreen and wintergreen plants

    • Tolerate cold to -76

  • Low-nutrient-content soils

    • Persistent leaves 

    • 5-18 years on Lodgepoles

    • Mycorrhizae nets

  • Seed establishment

    • Develop early

    • Mycorrhizae attachment at 2 weeks

  • Mammals

    • Migration

    • Insulation

    • Torpor or hibernation

    • Large feet

The Forest Community

  • Buffaloberry

  • Dwarf huckleberry

  • Ground Juniper

  • Heartleaf arnica

  • Lousewort

  • Pyrola

“Mycoheterotrophic”- lacks chlorophyll and obtains energy from dead tree roots via saprophytic fungi. Ex: pinedrops

Undergrowth is inhibited

  • Snow cover

  • Dense tree cover

Plant parasites

  • slow/reduce growth

  • Deform and kill

  • Examples:

    • Dwarf mistletoe

    • Comondra blister rust

      • Requires 3 plants in close proximity

      • Lodgepole, sagebrush, and ribes members

      • Causes top kill, not death

Animal effects

  • Cervid grazing reduces new tree growth

  • Birds increase seed dispersal

  • Red squirrels increase tree germination

    • Prefer serotinous cones

    • Evolved more powerful jaws

    • Reduced serotinous trees

Variation with elevation

  • Creates a beautiful mosaic based on microclimates

Disturbance over time

  • Big and small, swift and slow

  • Forest fires

    • Frequency vs severity

    • Most frequent in the foothills

      • High elevation is more moist 

      • Limited effect of historic fire suppression

    • Intensity: BTU/minute

    • Severity: based on after-effects

      • Litter fires to crown fires

    • Forest can be characterized by their fire prevalence

    • Burn areas attract wildlife

Bark beetle outbreak

  • Many species of beetles

    • Mountain pine beetles are the most common

    • All are native

    • 99% of beetles prey on dead wood

    • Tree-killing species all have similar life histories

    • Attack all pine trees

  • Life cycle

    • Emerge from the bark in July and August

    • Target larger trees

    • Females drill through the bark and cut egg galleries 

      • Healthier trees use resin to expel invaders

      • Also toxic compounds

    • Females secrete aggregating hormones inside infected trees

    • Once colonized, they release a disaggregating hormone

    • Females carry “blue-stain fungus” 

      • Infect and kill in less than one year

      • Larvae eat fungi and the cambium layer

    • Larvae “cold harden” in winter 

      • Vulnerable to early fall freeze

    • Warmer temperatures cause drought stress in trees and kill fewer beetles

    • Positive feedback loop until colder temperatures or fewer trees

    • Never kill small trees

      • Allows smaller trees to grow 2-3 times faster

      • 80 years to reestablish

      • 30 years into the GYE study

Major Forest Types

  • Rexford Daubenmire Habitat Type

  • 2 criteria 

    • Undistributed dominant species

    • Understory plants

  • Ponderosa pine forest

    • The most widespread tree in the West

    • Summer rain dependent 

    • Warmer climate needed

      • Migrating northwards

    • Frequent low-intensity fires

    • Moisture determines density

    • Episodic recruitment 

  • Douglas-Fir Forest

    • Sometimes found with ponderosa

    • <8,500 feet

    • Wetter sites

    • Limestone and sedimentary strata

    • Wet areas burn more often (paradoxical)

    • Become more dense

    • Invading sagebrush

  • Lodgepole Pine Forest

    • The most common tree in WY

    • 6,000-11,500 feet (latitude dependent) 

    • Loves granites and rhyolites

    • Episodic development

    • Infrequent fires (100-200 years)

    • Severe and widespread fires

    • Serotinous cones

    • Not all trees make serotinous cones

      • Trees usually all or none

      • Varies by forest age

      • More non-serotinous cone trees than serotinous ones

      • The red squirrel population influences the cone-type

    • Low-elevation trees have more frequent serotinous cones

      • Fewer in high elevations

      • Due to different rates of crown fires

    • Forest management for both types?

    • “Canopy seed banks” and fire intensity determine new recruitment

      • 5-100,000 per acre after the ‘88 fire

      • Lodgepole mono-cultures are usually serotinous

      • Mixed stands have fewer serotinous cones

    • “Dog-hair stands”

      • Difficult to walk through

      • Survive for 100 years or so

      • < 4-inch tree diameter

      • Produce seeds

    • Average density of 500 trees per acre

      • 80% of trees in YNP are lodgepoles

    • Other disturbances

      • Blister rust

      • Dwarf mistletoe 

      • Bark beetles

      • Root rot

      • Wind storms

    • Lodgepoles have seen little change with humans in the landscape

      • Climate change is the biggest danger

  • Spruce- Fir forests

    • Engelmann spruce and subalpine fir occur together

      • Lower temperatures for seedlings

      • More water

        • Lower water use efficiency

      • Capable of vegetative reproduction

      • Infrequent fires

        • Those that do come through are hot and stand-replacing 

      • 0-150 years mixed spruce and fir

        • 150-250 fir trees dominate

          • > 250 years spruce dominate

    • Insect outbreaks

      • Spruce beetles

        • Target old stands

        • Can reproduce in recently dead trees

      • Western balsam bark beetle

        • Kill large sections of fir

        • Favors warm, dry conditions

    • Abundance

      • Spruce

        • Dominate older stands

        • Live 500+ years

        • Low establishment rate

      • Fir

        • Dominate young stands

        • Live 250 years

        • Establish quickly

      • Forests today resemble those of the 1800s

  • Aspens

    • Occupy depressions and wetter environments

      • Use less water than lodgepoles, but seedlings need more

    • Grown in places that favor evergreen trees

    • Refixes its carbon dioxide

      • Dwarf Huckleberry does the same

      • “Evergreen- deciduous”

    • Seedling establishment is rare

      • Seedlings are wet-footed

      • Will grow in recently burned areas

    • Individual “trees” (ramets) live 100-150 years

    • 10,000 ramets per acre, 3 feet tall after fire

      • Often replaced by fir 

    • Large ramets suppress new shoots using hormones

    • Fire cycles of decades to centuries 

    • Heavily affected by browsing

    • Photos show aspens in decline

      • Many fires pre-1800s

    • Plants killed by root rot

      • Canker disease

      • Browse and beaver-cutting

    • SAD (sudden asphyxia death) 

      • Severe drought 2000-2003

  • Wildlife

    • Permanent: blue grouse, boreal owl, beaver, lynx, marten, red squirrels, snowshoe hare



The Forest Ecosystem

  • Tree Growth

  • Forest development

  • Soil maintenance

  • Water quality

  • Disturbances

Energy Flow and Productivity

  • 1-3% of solar energy hitting the canopy is used for photosynthesis

    • Most energy is used to evaporate water

  • Low growth rates, relatively 

    • Younger forests have higher growth rates

    • “Primary productivity”

  • Soil litter accumulates quickly 

    • Mostly leaves, branches, and fallen trees

    • High C:N ratio

    • Fire important decomposer

  • 15% of primary productivity is related to mycorrhizal nets

  • 2% of the energy fixed by plants flows through animals

Hydrology of Forest Landscapes

  • High elevation receives more water than can evaporate

    • PE > 1

    • Water towers of the west 

  • 50-75% due to snowfall

  • Surface water drainage

    • Snow drifts

      • 2-5 inches of water per foot

      • National Resource Council estimates total water (“snowtells”)

    • Soil water capacity

      • The amount of water soil doesn’t lose to the downhill flow

      • Depends on the water already in the soil

      • Increases with deep soil

      • Increases with fine soil 

      • Increases in the summer months

    • Weather and Climate

      • Rapid melting means less transpiration

      • Cold springs are better

      • Fall

        • Rains lower capacity

        • Early snow means soil remains unfrozen

      • Little to no moisture from south-facing slopes

    • Percolation percentage

      • Igneous and metamorphic imperious 

        • Increases runoff

      • Farms often occur near sedimentary rocks

    • Vegetation type

      • Total leaf area

      • Leaf type (evergreen vs deciduous) 

      • Increases interception 

      • Increases transpiration

      • Lowest with low area and deciduous

        • 80-90% from meadows

        • 60-65% from forests

        • 20% from lodgepoles

    • Water content

    • Landscape mosaic

      • Most water when forests and meadows mix

      • Maximized when 

        • 30%-40% of the landscape is harvested with patches of 2-5 acres

        • Larger openings have too much wind


Nutrient Cycling in Forests

  • Longer-term cycle

  • Nitrogen most well-studied

    • 78% of the atmosphere

    • Must be converted from nitrogen to ammonium or nitrate

      • Root nodules

      • Lightning

      • Decomposition 

    • Some plants absorb nitrogen from the soil as amino acids

  • Leaching potential 

    • Highest in 3-6 weeks of snowmelt

      • “Spring flush”

    • Nitrogen is retained because plant uptake is extremely rapid

  • Inputs

    • Dryfall

    • Wetfall

    • Rock weathering

    • Animal immigration

    • Runoff

    • Fixation

  • Undisturbed lodgepole forests accumulate nutrients over time

  • Deadwood accumulates nitrogen

    • Critical nutrient source

  • Plants have high retention rates 

    • Withdraw nutrients from sensing tissues, ~half of nitrogen is reabsorbed

      • Higher in lodgepole pine

  • Soil nitrogen is very low, <1%

    • Slows decomposition 

    • 12-22 years for leaf decomposition

    • 100 years for Tree Bole

Effects of Forest Disturbance

  • Fire (depends on temperature)

  • Low intensity

    • Foothills

    • Ponderosa and Douglas-fir

    • Rapid recovery

    • Burn litter and small trees

  • High intensity

    • Reduce leaf area

    • Spruce and lodgepole

    • Kills everything

  • Erosion

    • Increases with fire intensity

    • Increases with slope angle

    • Increases with area burned

    • Decreases with water infiltration

    • Decreases with understory development

    • Summer rains cause more erosion than snowmelt

  • Leaf area

    • Returns to normal after decades

      • Depends on the number of saplings

    • Leaf area maximum at 250 years

  • Aspens and lodgepoles recover quickly

  • Nutrient cycling

    • Volatilized by heat

    • Higher probability of nutrient loss

    • Higher nitrate levels in streams

    • Post-fire “luxury consumption”

      • Plants take more nitrogen than necessary

    • Nitrogen replacement in 40-70 years

      • Living biomass important

Insects

  • Target the largest trees

    • Reduce total growth for years

    • Other plants grow faster

      • Years- decades of recovery

    • Decreases transpiration

      • Increases in soil moisture

    • Short-term nitrogen boost

  • More research is needed

Timber Harvesting

  • Clear cuts

    • Increases

      • Stream flow

      • Nutrient loss

      • Undergrowth

    • Soil remains intact

    • No shade

    • No “bole wood”

    • 1-4 years for shrub recovery

    • Lower decomposition rates vs fire

    • If a slash is left, nutrient levels are high

    • Deadwood provides a critical habitat for wildlife

    • Better moisture retention with trees

    • Long-term benefits from more slang and large wood (twice the normal)

      • Less burning of slash

    • Erosion is higher with fires

      • Periodic erosion is good for stream biodiversity and productivity

    • Green tree retention 

      • Creates bird perches

    • Half cut means twice the water runoff and no additional nutrients

    • Clear cut means 3 times the water runoff and 6 times more nutrients

    • Dwarf mistletoe 

      • Native species 

      • Lowers productivity 

      • Typically controlled by fire

    • Soil erosion is the largest concern 

    • Windthrow in cut patches


The Future of Mountain Forests

Fragmentation

  • Roads

  • Logging 

  • Homes

Climate change

  • Bark beetles

  • Precipitation

  • Longer fire season

  • Higher evapotranspiration

  • Reduced water for human use

  • Upward shift in forests

  • Type conversions away from forests

Reduced water supply

  • More cutting, more water

  • It would require high-elevation cutting 

  • That wood is valued for other reasons

Fires

  • Upsurge in the last 25 years

  • Inadequate forest management

    • Too much fire suppression

    • Too little harvest

    • Too ubiquitous to be true

Fires and beetles

  • Moderately burned trees are more susceptible 

  • Drought stress is more likely

Beetles and Fire

  • 4 stages

    • Green, red, gray, dead

  • Torching vs crown fires

  • Small to undetectable changes

  • Increase in torching

Management options

  • Allow insects and fires in the backcountry

    • Well-adapted resilient ecosystem

    • More fires are still okay

Nature's resilience against humans

  • From country

    • More homes and infrastructure

    • Timber harvesting

    • Local control

      • Reduce vegetation density

      • Build with non-flammable materials

      • “Firewise” practices

    • Fire or Fuel breaks

      • Large fires from predictable winds

    • Recognize fire risk and discourage homebuilding

    • No clear stance on whether to remove beetle kill

Aspen forests as a bellwether

  • Wonderful biologically and aesthetically 

  • SAD (sudden aspen die-off) 

    • Worst on large old aspen trees

    • Highest from 2003-2007

    • Concentrated in Colorado and Utah 

  • Triggered by drought and high temperatures

    • South-facing slopes are more vulnerable

    • Low elevation 

    • Low water capacity soils

    • Evidence increasing 

  • Recovering very well at higher-than-average elevations

  • Suggests that aspens are already responding to climate change

    • Likely to continue

  • “Bioclimatic Envelope”

  • - shows aspens 1000 feet higher than historically

  • Total decrease in range

  • Similarly, all forests will shift

    • Decline from 15% of WY to 7.5%

  • Yellowstone will convert to all Douglas-fir

  • Increased habitat fragmentation


Mountain Meadows and Snow Glades

Referred to “Parks”

Highly Variable Plant Species

Why no trees?

  • Too much moisture

    • Fire soils, river banks

  • Too much competition from grasses and forbes

  • Soil differences!

Cinnabar Park, Medicine Bow

  • Most well studied

  • Due to the shallow 6-inch fine soils, there is a better grass habitat

  • Trees' habitat means coarser soil and thicker soils

  • Trees are also stressed by blown ice and snow

Subalpine meadows persist where summer frosts are common

  • Caused by direct exposure

  • Reduces sapling recruitment

Snow glades and Ribbon Forests

  • Snow glades: meadows created by late-lying snows

    • The growth season is too cold, wet, and short for trees

    • Favor mold growth on saplings

    • Too many pocket gophers

  • Seedlings have difficulty establishing themselves with too little or too much snow

    • Insufficient moisture

    • Insufficient protection from abrasion

    • 18-56 inches is the sweet spot

Ribbon Forests

  • Initial establishment is a mystery

    • Fire?

Aspen atolls

  • U-shaped or doughnut-shaped aspen groves

  • Established by the “snow-fence” effect

    • Center becomes clear

  • Economically important areas

    • Lots of water, no use

      • Increases stream flow

    • Occasionally created artificially 

Livestock grazing on meadows

  • Meadows have a higher carrying capacity than the range

    • Verticality (green wave)

    • Variability in the snowpack

    • Diverse plant communities

  • Ranchers move to high elevations as soon as the soil is dry enough

  • Grazing is restricted to the short summer season

    • Most have a shepherd

    • Fewer animals

  • Meadows are shrinking back to their natural size

    • Reduced by mining 

    • Reduced by logging

    • Increased by fire

  • Forest: meadow ratio is a climate indicator

Forest Expansion into Meadows

  • Reduced by fire

  • Increased by grazing (less competition) 

  • Climate

    • Warmer means less frost and more saplings

    • More vapor means warmer nights

Climate Response

  • Water uncertainties

    • Down prediction accuracy 

    • Minimal effects on growth

    • Large effects on stream flow

    • Water may not be a limiting factor


Upper Treeline and Alpine Tundra

11,500 feet (South facing) to 9,800 feet (North facing)

The slope aspect is a major factor in the treeline and higher on south-facing slopes

Krummholz

  • Common Trees:

    • Engelmann spruce

    • Subalpine fir

    • Limber pine

    • Whitebark pine (GYE only)

  • German for twisted wood

  • Commonly flagged

  • Need:

    • Moderate snowfall

      • Shield trees from winter

    • Other plants

      • Shield from summer and sky

    • Safe when large enough to gather snow 

    • Often grow in slight depressions

      • Increases access to water

    • “Layering branches pressed into the ground by snow grow roots

      • Create tree islands

  • Treeline formation

    • 1000 feet = 300 miles = 5 degrees F

    • Wind

    • Temperature

    • No trees where the growing season is <3 months or below 43 degrees F

    • Shrubs and herbs are better adapted

      • Decreased photosynthesis needs

    • Tree adaptations:

      • Clustered needles

        • Less transpiration

      • Flexible branches

Avalanches

  • Leeward mountain sides

  • End in the “runout zone”

  • Shrubs common as snow movement happen within the snowpack

  • Trees > 4 inches in diameter break

  • Every 50-100 years

Blister Rust

  • Invasive

  • Fungal parasite

  • Mainly kills whitebark, limber, and bristlecone pines (white pines)

  • Secondary Ribes host

  • One two-punch with mountain pine beetles

Survival

  • Many plants are also found in the Arctic

  • Differs from Arctic 

    • High-intensity light

    • Larger temperature swings

    • Shorter days

    • No permafrost

  • Increased evapotranspiration

    • Low pressure

    • High winds

  • Decreased water uptake

    • Poor, cold soil

    • Low nutrients 

  • Rapid freeze-thaw cycles

  • Most plants are herbaceous perennials 

  • Lichens common

  • 40-300 grams per meter per year

  • 30-75 day growing season

  • Adaptations:

    • Cold tolerance

    • Ever and wintergreen leaves

      • Photosynthesis under snow!

    • Shallow, spreading roots

      • Mycorrhizae network

    • Grow and mature more rapidly at higher elevations

    • “Cushion: growth pattern

      • Dense mats, close to the soil

      • Phlox

    • Reproduction largely vegetative

    • Large petals act as windbreaks for insects

    • Apomixis: reproduction without pollination

    • Numerous animal adaptations

      • All warm-blooded

Tundra Mosaic, Frost, and Burrowing

  • Types of tundra

    • Fellfields

    • Alpine turf

    • Wet meadows

    • Willow thickets

    • Abiotic

      • Snow beds

      • Talus slopes

      • Boulder fields

      • Water

  • 3 spatial scales

    • 10’s of miles

      • Changes due to local climate

    • Scale of feet

      • Changes due to boulders and their ability to absorb heat

    • Intermediate scale

      • Topography and tree islands

Cryoturbation

  • Freezing and thawing of moist soils, days to years 

  • Freezes push the largest boulders toward the surface, creating “patterned ground”

Solifluction

  • Soil becomes saturated and moves downhill

Two phenomena combine with the burrowing animals' activity to constantly disturb the soil

“Is there a 'stable' alpine ever?

Nitrogen Deposition

  • Nitrogen is a limiting factor

  • Some nitrogen-fixing plants

  • Nitrous Oxide pollution leads to nitrogen saturation

    • Net 0 nitrogen in the alpine

    • Accumulates in snowbanks

    • Leads to eutrophication 

      • Decreased fish numbers

      • Increased willows

Advancing Treeling

  • Relictual hypothesis

    • Current trees only tolerate our climate as adults, no recruitment 

  • Treeling lags behind the climate by 50-100 years

  • The Uinta Mountains show a treeline increase of up to 550 feet

  • Paradox- early snow melt increases frost damage to plants

    • Snow cover delays development

  • Animal impact

    • American pika

The Greater Yellowstone Ecosystem

Introduction:

  • 40,000 square miles

  • 2 National Parks

  • 7 National Forests

  • 10 Wilderness areas

  • 3 Wildlife refuges

  • 14 mountain ranges

  • 3 major river systems

  • Early Western explorers referred to YNP as Wonderland

  • 631,000 years ago was the last major eruption

    • 3 inches of ash in Iowa

  • 9 million YBP- Teton uplift

    • 50 miles

    • Precambrian rock

    • Flathead sandstone is now 6 miles below the surface

      • 12 inches per century

Pinedale Glaciation: most recent 

  • Began 80,000 years before present

  • 25,000 ybp maximum

    • 4,000 feet thick

    • An ice dam flooded Hayden Valley

  • Glaciers until 9,000 years ago


Primary succession

  • 14,000 ybp park was mostly tundra

  • 11,500 ybp Engelmann spruce colonized

  • 9,000- 11,000 whitebark and subalpine fir

  • 4,500-9,500 ybp douglas-fir

Yellowstone National Park

  • Ancestors of modern tribes 8,000-11,000 years ago

    • Food

    • Obsidian

  • 3,486 miles

  • 150 lakes

    • 5% of the park

  • Mostly rhyolite (infertile soils)

  • 70 inches of precipitation in the south 

  • 10 inches of precipitation in the north

  • “Finest trout fishing in the world”

  • 80% forested

    • Lodgepole pine is the main tree tolerant of poor soils

    • 24 habitat types where lodgepoles are the dominant plant

    • From low to high

      • Whitebark

        • spruce/ fir

          • Lodgepole

            • Douglas-fir

              • Aspen

                • Cottonwood

Grand Teton National Park

  • 1872 Hayden Expedition #2

    • Detachment sent to Jackson Hole

      • Included William Henry Jackson

  • 1897 town of Jackson

  • 1906 Snake River Dam

    • 1989 dam reinforced

  • Pierce Cunningham

    • Circulated a petition in 1925 asking WY to set aside the valley as a national park

    • Accomplished in 1950

      • Compromises on grazing and hunting 

Vegetation of Jackson Hole

  • 58% non-forested

    • Tundra, boulder fields, meadows, grasses, and shrubland) 

  • 28% lodgepole

  • 7% Spruce/Fir

  • 4% Douglas-fir

  • 1% Aspen

  • Whitebark pine is common on higher slopes 

  • Much of the Tetons are above the treeline

    • Lichens only

Sagebrush Mosaic

  • Glacial outwash plain

    • Deposits of glacial melt 80,000 to 12,000 years ago

  • Mountain big sage and Idaho fescue

    • East of Snake River

    • Deep soils, more water

  • Mountain big sage and bitterbrush

    • Sandy soils and gravel

  • Low sage and mountain big sage

    • Shallow infertile soils

Gros Ventre Landslide

  • Mountains are diverse

    • Volcanics (50 million years old)

    • Gravel conglomerates

    • Sedimentary strata

    • Granites and gneiss of Jackson Peak

  • June 23, 1925

    • 1 mile long

    • Half a mile wide

    • 300 feet deep

    • 900 x 200 ft dam

    • 3-mile-long lake

  • The dam failed 2 years later

    • 6 people died

    • The top 20 feet of the dam washed away

    • 20 20-foot wall of water hit Wilson 2 hours later


Management Issues in GYE

Initial objectives

  • Protect the hydrothermal from vandalism

  • Protect wildlife from poachers and predators

  • Protect vegetation from fire and overgrazing 

Elk proliferated: threatened the persistence of aspen, willow, and grasslands on winter range

Grizzly neared local extinction

1963 Leopold report

  • Wildlife management in the national parks

  • “Let ecological processes operate to the greatest degree possible, with human intervention allowed as needed for safety or to correct problems caused by previous human activity.”

  • 1968 elk culling (all culling) stopped

  • Continuing debate onthe  long-term effects of Native Americans

The Elk Problem

  • By 1912, we had 30,000 elk in Yellowstone

    • Trapped and shipped to other places

    • Cullings

  • Loss of willow and aspen habitat

    • Important habitat for migrating birds

    • Competition with deer and beavers

  • 1912 National Elk Refuge

    • Reduced agricultural conflicts

    • Increased herd sizes

    • Decreased starving animals

    • Increased habitat destruction

    • Increased disease transmission

    • Decreased habitat conservation

The key winter range north of Yellowstone National Park was purchased or protected

Do elk harm northern range vegetation?

  • “Northern range is different from when Europeans arrived, but the ecosystem is not in imminent danger of losing any major piece.s”

    • National Academy of Science (1998)

  • Less dramatic damage than the  Aspen and Willow communities

  • Increased compensatory grass growth

    • 35-85% higher than enclosures

  • Most grazing takes place in winter and fall when vegetation is dormant

1982, Biologist Doug Houston concluded that no herd reduction was necessary

  • 85% of aspens established before 1920

  • Neither fire nor climate was sufficient to explain this

  • 40,000 elk in 1968

  • 19,000 elk in 1998

Fire management

  • The systematic elimination of fires started in 1886 with the arrival of the US calvary

    • Ineffective in more remote regions of the park

  • 1963 Leopold report 

    • Set theme

    • 1972

      • Lightning caused fires to burn without interference in a remote portion of the park during moderate weather conditions, when the risk of human injury or  serious resource damage is minimal

    • 1972- 1987

      • 235 fires

      • 1- 7,500 acres in size

      • Only 27 are  larger than 1 acre

    • 1988

      • 1.4 million acres

      • 25,000 firefighters

      • $120 million 

      • More by drought and wind than fuel build-up

      • North Fork Fire 490,000 acres 

    • The cost of fuel reduction would be reasonable compared to the cost of fire

    • Increase in aspen seedlings in burned areas

      • TRUE SEEDLINGS!

    • Increased visitation 

      • Today’s policy is similar to 1989

    • Climate models 

      • By 2050, large fires could occur nearly every year

      • The fire cycle of 120-300 years could shift to <20 years

        • Fire Cycle: the time for a whole system to burn

      • Decreases in old growth

      • Type conservation of major species

Beetles, blister rust, white-bark pine

White-bark pine: common at high elevation

  • Important grizzly food

  • Recover from fire via distribution by Clarks nut-crackers

White pine blister rust:

  • Non-native

Global warming

  • Mountain pine beetles invade at high elevations

  • Whitebark pines lack most chemical defenses

    • Rely on cold

  • Target larger trees

    • More cambium for larvae

Invasive Eurasian blister rust

  • Fungi

  • Introduced in 1900

  • Kills all sizes of whitebark pine

  • Makes trees more susceptible to beetles

    • Decreases their resin

The combination creates ghost forests

Grizzly connection

  • < 1% of the former range

  • Whitebark pine only mast every 3-5 years

    • Grizzly bears need large areas of trees

  • Decrease in cutthroat trout 

    • Whirling disease?

      • Causes odd bony growths

    • Invasive trout

  • Decreasing winter-killed elk and bison

    • Increasing predation on elk calves

Wolves, Elk, and Aspen

  • Functional extinct since 1929

  • Protected in 1973 by the Endangered Species Act

  • Predator control was questioned in the 1930s

  • 1960s too many elk

    • 19,000- 6,000

  • Willow and aspens increase

  • Wolf behavior modification is just a hypothesis, not confirmed

    • Very little effect in winter

  • Willow is noticeably taller in many places

    • Not all

    • Elk kill all willow → beavers die from lack of willow → water table lowers from lack of dams → willows can’t regenerate → beavers can’t recover 

Wolves and pronghorn

  • Increase in wolves → Decrease in coyotes → increased fawn survival

The greatest biodiversity exists on the private lands of low-elevation