Degradation of Terrestrial and Aquatic Ecosystems

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Degradation of Terrestrial and Aquatic Ecosystems
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A first step in understanding how to restore or
repair damaged ecosystems is to understand how
Wildland Degradation occurs (forests,
grasslands, savannahs, deserts, shrublands,
wetlands, marshlands)
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Stages

• Initially -- altered species composition (some
  species are being selected out)
• Ecosystem still has control over essential
  resources (soil, water, nutrients and organic
  materials)

http//www.wwf.it/summit/images/19061_germany20Ac
id20rain.jpg
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• Degradation becomes more severe as the area loses
  control over its essential resources
• What does this mean?

Russia
http//www.iiasa.ac.at/collections/IIASA_Research/
Research/FOR/russia_cd/pictures/final_pics/degrada
tion/05_deg_des1.jpg
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• Eventually the ecosystem loses capability for
  self-repair.
• System unravels leads to such factors as
  desertification
• Degradation continues in the absence of the
  original causal factor!

Tajikistan
http//enrin.grida.no/htmls/tadjik/soe2001/eng/htm
ls/erosion/press.htm
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• In other words removing a stress or disturbance
  often does not result in recovery.
• Irreversible changes have occurred to the
  ecosytem.
• Thresholds of irreversibility have been
  crossed.

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83500.jpg
Van Andel and Aronson 2005
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Degradation Model
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Water Capture Efficiency
High
Low
Energy Capture Efficiency
High
Low
Nutrient Retention Efficiency
Low
High
Resource Flows Captured by Organic Materials
High
Low
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Relative Value of Landform Features in Resource
Capture
High
Low
Relative Value of Microtopographic Features in
Resource Capture
Low
High
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Favorability of Microclimate to Promote Primary
Processes
Low
High
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How about Riparian and Aquatic Ecosystems??

• That is how are they different, how are they
  similar to what has just been described?

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Connectivity

• Guess what?
• Water runs downhill.
• Streams and rivers are NETWORKS.
• If you change the ecological conditions at a
  site, you potentially affect the entire network .
  . .
• Both downstream AND upstream.

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Oak Creek
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Depth of Channel Incision
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Stream Network

• So where do you start to reverse the degradation
  caused by incision or gullying?

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Ash Swale
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Gully Where Ash Swale Was Removed
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Lower End of Gully at Oak Creek
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53rd Street Road Crossing
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53rd Street Road Crossing
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Dairy Reach of Oak Creek
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Mouth of Oak Creek
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Mouth of Oak Creek
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Willamette River
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Begin to Conceptualize Cause and Effect and
Relationship to Degradation

• How do we evaluate where we are in the
  degradation process
• What steps need to be taken to repair the
  ecosystem

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Stepwise Degradation of Terrestrial Wildland
Landscapes (adapted from Whisenant 1999Table 1.1)

• Baseline Reference Ecosystem
• Biomass and composition of vegetation varies with
  climatic cycles and stochastic events.
• Perennial vegetation changes are associated with
  varying climatic conditions (precipitation or
  temperature) rather than with consumption of
  primary production. Primary processes are
  undamaged.
• Management options
• Adaptive management of herbivory, wood
  harvesting, hay or fodder removal.
• Appropriate focus for initial repair activities
  is on Secondary producers (consumers of the
  ecosystems primary production)

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What is a Reference Ecosystem?

• Planning and evaluation
• a point of advanced development along intended
  trajectory.
• The restored ecosystem is eventually expected to
  emulate its attributes.
• Consists of one or several locations, a written
  description, or a combination of both.
• Information includes both biotic and abiotic
  components.

Adapted from Society for Ecological Restoration
The SER International Primer on Ecological
Restoration. Section 4.
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Terrestrial Degradation Step 1

• Selective removal of keystone species reduces
  recruitment, allowing expansion of populations of
  less preferred species.
• Age distribution of plant populations changes to
  older plants. Primary processes are undamaged.
• Management Options
• Stricter control of selective consumption of
  plants.
• Focus restoration on causal factors affecting
  keystones ecosystems processes.

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Terrestrial Degradation Step 2

• Plant species are lost, as are their specialized
  predators and symbiots.
• Reduced secondary productivity (dependent plants
  and animals). Primary processes are damaged, but
  functioning.
• Manage vegetation (e.g., add, remove, or modify)
  with planting, fire, herbicides, biological,
  cultural or other methods.
• Focus on primary producers for repair activities

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Terrestrial Degradation Step 3

• Biomass and productivity of vegetation fluctuates
  as ephemerals benefit from loss of perennial
  cover
• Perennial biomass reduced (short-lived plants and
  instability increase), resident birds decrease,
  and nomads increase. Primary processes are only
  partially functional.
• Management
• Manipulate soil cover (e.g., mulching, erosion
  barriers, roughen soil surface).
• Use carefully selected vegetation to modify micro
  environmental conditions
• Focus for initial repair activities Physical
  environment

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Degradation Step 4

• Denudation and desertification involve changes in
  soil function and detritivore activity.
• Bare ground, erosion, and aridification. Primary
  processes are nonfunctional.
• Management
• Manipulate soil cover (e.g., mulching, erosion
  barriers, roughen soil surface).
• Use woody vegetation to modify microenvironmental
  conditions.
• Focus for initial repair activities Physical
  environment (moderate microclimate).
• Recognize chances of recovery are slim!

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Assess Risk
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Cookbooks Are Not Substitutes for Understanding
Ecological Processes
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Ecologically Unsound Restoration Practices Are
No Joke
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Halting Degradation of Terrestrial and Aquatic
Ecosystems Requires You to be a Student of the
Ecosystem.

• Learn about your ecosystems.
• Degradation occurs in response to different and
  often interacting perturbations.
• Changes in a disturbances
• Changes in climate
• Introduction of new species
• Intentional actions by humans

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Challenge determine where one is at in the
degradation process and act accordingly!!

• The farther the degradation, the more it will
  cost to repair it!
• Complete restoration possibilities diminish.
• Recognize and plan for ecological, sociologic and
  economic realities!