What is an ecosystem

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What is an ecosystem? What are its spatial
dimensions?
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• Landscape ecology
• The patterning of ecological systems across space
  and how this changes over time.
• The consequences of this patterning for the
  functioning of the ecological system.
• The effect of scale on these interactions in
  ecological system pattern and function.
• .

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• Landscape ecology unique in
• Focus on importance of spatial configuration for
  ecological processes
• Focus on spatial extents that are much larger
  than those traditionally studied in ecology.
• The main goal
• Understand how nature works.
• Use knowledge to manage landscapes.

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The Equilibrium View of Nature
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The Equilibrium View of Nature

• Environment is rather constant.
• Evolution is gradual and organisms are well
  adapted to local environment.
• Species distributions are determined by broad
  climate and by competition.
• Vegetation across biomes is rather homogeneous
  except where upset by irregular disturbance.

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The Equilibrium View of Nature
Main contributors von Humboldt
(1770-1860) Merriam (1855-1942) Holdridge
(1960s)
Environment drives broad vegetation patterns
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Savanna
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The Equilibrium View of Nature
Main contributors von Humboldt
(1770-1860) Merriam (1855-1942) Clements
(1900-1930's) Hutchinson (1950's)
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The Equilibrium View of Nature

• Clements (1900-1930's) - succession and
  disturbance create spatial pattern
• vegetation changes over time in response to
  disturbance,
• succession proceeds in orderly way to climax
  community,
• nature of climax determined by climate,
• climate and climax were stable over large areas.
• the general habitat of migration among animals
  insured that serious effects of overgrazing and
  trampling were local and transitory, while the
  influence of fire by Indians was less significant
  in modifying plant cover.

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The Equilibrium View of Nature
Main contributors Gleason (1920s-30s) Whitta
ker (1960s-70s)
Species are distributed along environmental
gradients according to their individual
tolerances.
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Spin-offs of equilibrium view Vegetation
patterns seen by first European settlers had
"always been there" Communities were stable in
composition and patterned by climate and env
gradients Humans were exogenous and cast the
natural system out of balance S. A. Forbes,
"There is a general consent that primeval
nature,, presents a settled harmony of
interaction among organic groups which is in
strong contrast with the many serious
maladjustments of plants and animals found in
countries occupied by man". Conservation could
best be done by setting nature reserves and
leaving them alone
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Origins of Landscape Ecology
European biogeographers/landscape
ecologists Troll (1950s-60s) Sukachef
(1940s-50s)
Focus on human-dominated landscapes Land
classification Land evaluation Mapping Land
planning Landscape architecture
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Disequilibrium View
Paleoecologists showed that environment is not
stable thru time and neither is vegetation.
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Disequilibrium View
Quadrat-scale sampling by ecologists found little
similarity among what were thought to be similar
ecosystems.
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Disequilibrium View
Disturbance was recognized as pervasive and
integral part of ecosystem dynamics, including
strong human presence and influence.
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Disequilibrium View
Pioneering Work Watt (1947) - gap dynamics
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Disequilibrium View
Shifting Steady-State Mosaic
Pioneering Work Likens and Borman (1970s) -
shifting steady-state mosaic
From Turner et al. 2001
Shifting Steady-State Mosaic (Likens and Boreman
1970's) - A landscape where the characteristics
of individual patches are out of phase but the
collective behavior of patches displays
equilibrium.
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Scale Matters What is disequilibrium at the
patch scale Is equilibrium at the landscape
scale.
Single simulated forest plot
Average of 1000 simulated forest plots
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• Current Landscape View
• Synthesis of equilibrium view, European landscape
  ecologists, disequilibrium view

Drivers of Landscape Pattern
Abiotic Factors
Disturbance
Biotic Processes
Landscape Patterns
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• Current Landscape View
• Synthesis of equilibrium view, European landscape
  ecologists, disequilibrium view
• ecological systems are patchy in space and time,
  driven by climate, disturbance, etc.
• neighborhood influences patch and landscape
  properties.
• disturbance and humans are integral parts of
  ecological systems.
• landscapes may either be in dynamic steady-state
  or on new trajectory.
• so human intervention is often necessary to keep
  systems functioning properly, even nature
  reserves may require human management.

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Landscape structure influences landscape function
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Biodiversity Hot Spots

• Bird Richness (gt60 of max)
• lt3 of study area
• low elevation and private lands
• lt3 of hot spots in YNP

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S
H5 Population Viability
N
Yellow Warbler Sources and Sinks
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Tools of Landscape Ecology Remote Sensing
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Tools of Landscape Ecology GIS
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Tools of Landscape Ecology Landscape Metrics
and Spatial Statistics
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Tools of Landscape Ecology Simulation Modeling
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Landscape Management