Changes to Rangelands Over Time

1
Changes to Rangelands Over Time
2
Range Change Factors

• Grazing
• Fire
• Invasive Species
• Weather/Climate
• Human Activities

3
Goal of ecosystem management

• Efficiently capture sunlight
• Reduce losses of nutrients and water from system

Land managers will have more specific goals
4
Forces of Ecosystem Change

• Immigration and establishment of plants
• Competition between plants
• Fire
• Grazing
• Site modification
• Stabilization

5
How does grazing affect plants

• Some plants are extremely sensitive to grazing
  (A)
• Most plants are somewhat tolerant of grazing (B)
• A few plants actually benefit from grazing,
  especially light grazing (C )

6
How does fire affect plants

• Some plants are extremely sensitive to fire (A)
• Most plants are somewhat tolerant of fire (B)
• Other plants actually benefit from fire
  especially light grazing (C )

7
Adaptations to Fire and Grazing
Grazing Fire

Grasses
Woody Plants
8
Location of Growing Points - Grasses

• Also called
• Buds
• Meristems

From How Pasture Plants Grow by Stephen K.
Barnhart Iowa State Cooperative Extension
9
Location of Growing Points - Grasses
Grasses push growth from the growing point ---
old growth at tips of leaves
10
Location of Growing Points - Grasses

• As long as the growing point is present growth
  continues.
• If removed - growth stops and new growth has to
  initiate from a dormant bud.

From National Range and Pasture
Handbookswww.glti.nrcs.usda.gov/technical/publica
tions/nrph.htmlChapter 5 page 2-13
11
Location of Growing Points - Grasses
Stolon
Rhizome
New growth can come from below Stolons Rhizomes
12
Location of Growing Points - Grasses
Culmed
Apical Meristem
Culmless
Axillary Buds
13
Location of Growing Points - Grasses

• Location depends on season
• Early in the growing season - close to the
  ground and protected.
• As the season progresses - elevates and subject
  to removal.

14
Location of Growing Points Shrubs Trees
Forbs and shrubs initiate growth outermost points
15
Location of Growing Points Shrubs Trees
Meristem
J. Peterson
16
Location of Growing Points Shrubs Trees
May have basal buds and be able to resprout form
base after fire
17
Other fire adaptations Shrubs Trees
fs.fed.us
J. Peterson
Insulating bark
Serotinous Cones
18
Differences between fire grazing?

• Grazing

• Fire

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19
Differences between fire grazing?

• Grazing

• Fire

• Not selective for specific plants
• Removes dead and live tissue
• Produces heat
• Recycles nutrients in inorganic form
• Recycles nutrients in a relatively even layer
  across the landscape
• Patchiness on a landscape scale
• Most likely in dry-hot season
• May create hydrophobic soil layer but, doesnt
  yield compaction
• Generally reduces seed viability, though some
  seeds require fire to be viable.

• Selects palatable over unpalatable
• Live tissue preferentially removed
• No heat produced
• Recycles nutrients in organic (feces) and
  inorganic (urine) forms
• Recycles nutrient in patches
• Patchiness on a plant-scale
• Occurs year round
• Can cause compaction through hoof action
• Generally reduces seed viability though some
  seeds require consumption to become viable

20
Weather/Climate

• Most important factor in long-term changes to
  rangeland plant communities
• Normal variation
• Year-to-year (annual)
• Long-Term
• Drought
• Impacts on plant composition

21
Exotic of Introduced Species

• Definition plants that are not native to a
  region that have been brought in either
  intentionally or unintentionally
• Invasive vs. weed
• Response to disturbance
• How do they increase?
• Negative environmental impacts

22
Invasive Species

• Species that that increase in a community in a
  way the suppresses other plants in the community
  and reduces there abundance or fitness.
• Can native or introduced
• Negative environmental impacts
• Have characteristics, such as high seed
  production or root sprouting, that allow them to
  increase with disturbance.

23
Human Activities

• Included development, recreation, subdivision
• Humans affects other forces of nature
• Invasion
• Fire
• Grazing
• Climate/weather?

24
Current Issue of Ecological Change

• The Pristine Dream - many environmentally
  concerned people wish that rangelands could
  return to pristine conditions similar to what
  Lewis and Clark observed.
• Possible or Not?

25
Current Issue of Ecological Change

• Sustainability (or Sustained-yield) is the
  concept that we can graze or otherwise use the
  rangeland resource in such a way as to not
  jeopardize future productivity.
• Possible or Not?

26
Current Issue of Ecological Change

• Biodiversity (or Biological Diversity) is an
  attribute that describes for the variety of
  organisms the genetic variation they contain and
  the variety of communities, ecosystems and
  landscape pattern in which they occur.
• Believed that more diverse ecosystems are
  generally more stable and able to cope with
  disturbance than less diverse ecosystems.
• Many agencies and environmental organizations
  espouse the concept that we should manage for
  high biodiversity.
• Yes or No?