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Mammalian herbivores

Week 5 Fire-grazing synergism in grasslands

1

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Grassland Drivers (review)

2

Mammalian

herbivores

Jayne Jonas

Periodic

fire

Mike Bowden

Climate/

periodic

drought

Jayne Jonas

Grassland Ecology

3 of 39

Grassland Drivers (review)

3

Mammalian

herbivores

Jayne Jonas

Periodic

fire

Mike Bowden

Climate/

periodic

drought

Jayne Jonas

Grassland Ecology

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Herbivory-related definitions

Plants being consumed

  • Herbage: all herbaceous biomass
  • Browse: edible leaves and twigs of woody plants
  • Forage: edible herbage and browse

Action of consumers

  • Grazing: consumption of standing forage
  • Browsing: consumption of browse

Society for Range Management (1998)

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Effects of defoliation

Direct

  • Loss of leaf area
  • Consumption of reproductive parts
  • Compensatory processes

Indirect

  • Increased light
  • Altered water and nutrient processes
  • Altered competition

5

P. Meiman

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Plant response depends on

  1. Location of meristems
  2. Growth stage/phenology
  3. Remaining tissues

6

Evolutionary consequences

1. Avoid/resist

2. Tolerate

Elongated tillers

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Plant response depends on

  1. Location of meristems
  2. Growth stage/phenology
  3. Remaining tissues

7

Elongated tillers

Evolutionary consequences

1. Avoid/resist

2. Tolerate

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Community composition

Plant community responses

  1. Decreasers
  2. Increasers

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Community composition

Plant community responses

  1. Decreasers
  2. Increasers

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Community structure

Oñatibia et al.(2018) Oikos

arid

intermediate

semi-arid

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Community structure

Oñatibia et al.(2018) Oikos

Higher productivity site

  • grasses less adapted to grazing
  • negative response to grazing

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Grassland response to grazing

Depends on:

  • climate
  • evolutionary history of grazing
  • productivity
  • plant composition
  • species of herbivore
  • grazing regime
    • duration
    • season
    • intensity

Milchunas et al. (1988) American Naturalist,

water ------------------🡪 light

vertical---------🡪 horizontal

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Grassland response to grazing

Depends on:

  • climate
  • evolutionary history of grazing
  • productivity
  • plant composition
  • species of herbivore
  • grazing regime
    • duration
    • season
    • intensity

Milchunas et al. (1988) American Naturalist,

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Fire vs Grazing

fire

grazing

  • Less selective
  • Preferences/selectivity
  • Litter, senesced biomass
  • Live biomass
  • Nutrients more evenly redistributed
  • Nutrients patchily redistributed
  • No impact on soil density
  • Trampling/compaction

Mike Bowden/Nancy Braker

Jayne Jonas

Jayne Jonas

Jayne Jonas

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Grazing vs Fire

  • Selectivity
  • Amount remaining
  • Redistribution of nutrients
  • Trampling/compaction

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16

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Fire x grazing synergism

Week 5 Fire-grazing synergism in grasslands

17

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Grassland Drivers (review)

18

Mammalian

herbivores

Jayne Jonas

Periodic

fire

Mike Bowden

Climate/

periodic

drought

Jayne Jonas

Grassland Ecology

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Fire effects on forage

Scasta et al. (2016) Renew Food Agricul

Wanchuket al. (2024) Ag Ecosys Environ

Northern mixed-grass prairie

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Fire-grazing feedbacks

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3-yr post-burn

Year of burn

Fuhlendorf and Engle (2004) J Appl Ecol

1-yr post-burn

2-yr post-burn

↓ Pr[Grazing]

Adapted based on

Scasta et al. (2016) Renew Food Agricul

↑ Pr[Fire]

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Fire-grazing feedbacks

21

3-yr post-burn

Year of burn

Fuhlendorf and Engle (2004) J Appl Ecol

1-yr post-burn

2-yr post-burn

Adapted based on

Scasta et al. (2016) Renew Food Agricul

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Shifting mosaic

  • Heterogeneity
    • Plant biomass
    • Composition
    • Habitat structure

22

3-yr post-burn

Year of burn

1-yr post-burn

2-yr post-burn

3-yr post-burn

Year of burn

1-yr post-burn

2-yr post-burn

3-yr post-burn

Year of burn

1-yr post-burn

2-yr post-burn

time

time

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Shifting mosaic

  • Heterogeneity
    • Plant biomass
    • Composition
    • Habitat structure

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Shifting Mosaic - Example

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Patch-burn grazing (PBG)

  • Disturbance-adapted grasslands
    • Fire and grazing
    • Higher precipitation
  • Similar or higher livestock performance
  • Increases diversity and heterogeneity

Scasta et al. (2016) Renew Food Agricul

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Small mammal response to PBG

Ricketts and Sandercock (2016) Ecosphere

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Grassland bird habitat needs

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Bernath-Plaisted et al. (2023) Rangeland Ecol Manag

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Grassland bird response to PBG

Fuhlendorf et al. (2006) Ecological Applications

Abundance per point count

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Traditional ecological knowledge

29

Roos et al. (2018) PNAS

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Fire x grazing x browsing

Week 5 Fire-grazing synergism in grasslands

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Grassland Drivers (review)

32

Mammalian

herbivores

Jayne Jonas

Periodic

fire

Mike Bowden

Climate/

periodic

drought

Jayne Jonas

Grassland Ecology

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Browsers

  • Consume browse
    • Browse = leaves/twigs of woody plants

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Woody plant survival

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Donaldson et al. (2022) Ecology

Jayne Jonas

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Fire-grazing-browsing interactions

Source: Smit and Costsee (2019) The Ecology of Browsing and Grazing II

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Fire-grazing-browsing interactions

Source: Smit and Costsee (2019) The Ecology of Browsing and Grazing II

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Multispecies grazing

  • Stocking domestic grazer and browser species
    • Complementary diets

37

Doyle (2021) SDSU Extension

Jayne Jonas

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Fire + Multispecies grazing

  • Benefits
    • Woody plant control
    • Heterogeneity
    • Wildlife habitat
    • Livestock productivity
    • Climate smart practice

38

Wilcox et al. (2021) Front Ecol Environ

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