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Floodplain Management Session 10

BiologyBiological 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 oceans10.2 Describe the 4 dimensions of river

ecosystems10.3 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/figure01.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

A. Early attempt to characterize and classify river ecosystem processes

B. Focuses on longitudinal changes in energy sources and community structure

C. Largely ignored lateral and vertical connectivity

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River

Continuum

Conceptual

Diagram

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Flood Pulse Concept

A. Recognizes lateral connectivity of streams with floodplains and riparian systems

B. Flood pulses are episodic inundation of land adjacent to rivers

- Interconnection of river and floodplain a major driver of energy and nutrient transfer

C. Water fluctuations also drive successional patterns of vegetation

D. Flood pulses recharge aquifersE. Recognizes that floods are a natural part of dynamic

equilibrium in river systemsF. Highest explanatory power in areas where

geomorphology facilitates lateral connectivity

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Hyporheic Corridor Concept

A. Looks at the vertical integration of the streams with surrounding subsurface water

B. Describes importance of vertical exchange of materials

C. 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

A. Recognizes that streams do not change uniformly in longitudinal direction

B. Changes in geomorphology and tributary junctions interrupt Continuum Concepts

C. Dams also create changes in material transport

D. Has been expanded to include vertical and lateral connectivity

E. Highest explanatory power below dams

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Biodiversity Concept

A. Attempts to integrate the many scales of process, function, and community structure into on integrative theme

B. Connectivity of the 3 spatial dimensions changes with water level

C. 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

Surface water Subsurface water Riparian system

Streams

Springs

Lakes

HyporheicZone

GroundWater

ConfinedReaches

UnconfinedReaches

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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

River -------------------- Floodplain Edge

Species Richness

0

50

100

Per

cen

t o

f m

axim

um

ric

hn

ess

fish

Mollusca

Odonata

Amphibia

Macrophytes

Species Richness

Per

cen

t o

f m

ain

stre

am r

ich

nes

s

0

100