Floodplain Management Session 10 Biology Biological Landscape Prepared by Susan Bolton, PhD, PE

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Floodplain Management Session
10BiologyBiological Landscape Prepared by
Susan Bolton, PhD, PE

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Session 10 Biological Landscape Its impact on
the floodplain and floodplain management

• Objectives
• 10.1 Explain the importance river systems and
• their connectivity to oceans
• 10.2 Describe the 4 dimensions of river
  ecosystems
• 10.3 Describe major conceptual theories in
  stream ecology and how energy flow and nutrient
  cycling vary among them
• 10.4 Describe how species are distributed in
  space and time

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Objective 10.1

• Explain the importance of
• freshwater river systems and
• their connectivity
• to oceans.

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Importance of freshwater streamflow

• More water moves through ecosystems than any
  other material
• Streamflow provides both human and ecosystem
  services
• Freshwater and marine ecosystems are
  interconnected

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National water use
http//pubs.usgs.gov/circ/2004/circ1268/htdocs/fig
ure01.html
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Rivers and Oceans

• Marine areas with high levels of freshwater
  inflow usually have significant fisheries
• e.g.,
• Mississippi River
• Columbia River
• Northern Gulf of Alaska

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Ecosystem effects of rivers on oceans

• Salinity
• Organic matter
• Nutrients
• Sediment
• Pollution
• Light

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Ecosystem effects of rivers on oceans

• Evidence of increase number of algal blooms and
  toxic blooms related to river inputs to marine
  systems
• Changes in nutrient ratios can alter community
  composition
• Alterations of streamflow from flood management
  activities or river restoration may ultimately
  affect marine ecosystems

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Objective 10.2

• Describe the 4 dimensions of river ecosystems

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Four dimensions of river ecosystems
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Objective 10.3

• Describe major conceptual theories in stream
  ecology and how energy flow and nutrient cycling
  concepts vary among them

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River Continuum Concept

1. Early attempt to characterize and classify river
   ecosystem processes
2. Focuses on longitudinal changes in energy sources
   and community structure
3. Largely ignored lateral and vertical connectivity

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• River
• Continuum
• Conceptual
• Diagram

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Flood Pulse Concept

• Recognizes lateral connectivity of streams with
  floodplains and riparian systems
• Flood pulses are episodic inundation of land
  adjacent to rivers
• - Interconnection of river and floodplain a
  major driver of energy and nutrient transfer
• Water fluctuations also drive successional
  patterns of vegetation
• Flood pulses recharge aquifers
• Recognizes that floods are a natural part of
  dynamic equilibrium in river systems
• Highest explanatory power in areas where
  geomorphology facilitates lateral connectivity

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Hyporheic Corridor Concept

• Looks at the vertical integration of the streams
  with surrounding subsurface water
• Describes importance of vertical exchange of
  materials
• Look at separately from longer, slower exchanges
  via ground water
• - Microbial activity enhanced by frequent
  exchanges
• D. Highest explanatory power where
  geomorphology facilitates vertical and lateral
  exchange

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Serial Discontinuity Concept

1. Recognizes that streams do not change uniformly
   in longitudinal direction
2. Changes in geomorphology and tributary junctions
   interrupt Continuum Concepts
3. Dams also create changes in material transport
4. Has been expanded to include vertical and lateral
   connectivity
5. Highest explanatory power below dams

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Biodiversity Concept

1. Attempts to integrate the many scales of process,
   function, and community structure into on
   integrative theme
2. Connectivity of the 3 spatial dimensions changes
   with water level
3. Biodiversity is broader than community, links
   ecology with evolution, genetics and biogeography

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Objective 10.4

• Describe how species are distributed in space
  and time

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How species are distributed in space and time --
Environments contributing to riverine biodiversity
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Selected Important Habitat Factors

• Substrate
• Temperature
• Oxygen levels
• Flow velocity
• Food availability
• pH
• Nutrient and sediment regimes
• Organic input and transport

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How species are distributed in space and time
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