moriver historic vegetation change moriverclasses 10-13-11

8/3/2019 MoRiver Historic Vegetation Change MoRiverClasses 10-13-11

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Historic landscape and vegetation

changes along the Missouri

Mark Dixon

Introduction to River Studies

October 13, 2011


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Human Alteration of Riparian Ecosystems

Flow regulation (dams)

~45,000 large (>15 m high) large dams, 800,000 small damsworldwide

Upstream effects inundation, raising water tables

Downstream effectsflow patterns, incision, reduced meanderingreduced sediment

Levees, bank stabilization, channelization

Flow diversion, river dewatering

Groundwater depletion

Land use (e.g., grazing, development)

Other disturbances (e.g., fire)

Non-native species

Climate change

Pollution


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Impounded

Remnant

Channelized


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Impacts of Missouri River

Management on Cottonwood ForestsI. Historic land use/cover change

II. Impacts on flow and sediment regimes

and cottonwood regeneration

III. Changes in species composition in

cottonwood forests

IV. Effects of changes on wildlife (songbirds)

V. Effects of flood of 2011?


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I. Historic Changes in Land Use


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Historic

Changes in

Segment 10


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Time

FlowV

olume

From: Poff et al. 1997

II. Changes in Flow & Sediment Regimes:Dams alter downstream flow patterns and flow-

dependent ecological processes

Flow attenuation

&

stabilization


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-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

740760780800820

WaterSurfaceE

levationC

hange

(m)

Re

lativet

o1960

River Mile (1960)

1965

1986

1994/95

2002

Channel Bed Degradation, Gavins Point Reach


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0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

1930

1933

1937

1940

1943

1946

1949

1953

1956

1959

1962

1965

1969

1972

1975

1978

1981

1985

1988

1991

1994

Water

FlowatYankton(c

ubicfeetpersecon

d)

Date

The Heart Beat of a RiverLostMissouri River Flow at Yankton, SD

1930 - 1995

Ft. Peck 1937 Ft. Randall 1952Garrison 1953Gavins 1955

Oahe 1962Big Bend 1964

Mainstem Dams and Year of Closure

Slide courtesy of Wayne Nelson-Stastny, USFWS


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25 - 10 %

75 - 25 %

90 - 75 %

ROR Natural

Hydrograph

25 - 10 %

75 - 25 %

90 - 75 %

Current Water-Control

Plan

0

10

NovSepJulyMayMarJan

20

30

40

50

60

70

80

Discharge

,kcfs

Hydrologic Alteration, Sioux City, Iowa

km 1,178

Slide courtesy of Wayne Nelson-Stastny, USFWS


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Recruitment Box Conceptmodified from Mahoney and Rood (1998)

RecruitmentBand forSpecies A

DispersalInterval forSpecies A

Day of the Growing Season # of Sandbar Plots

RiverLevel

SandbarTopography

DispersalIntervals forother species

Stage decline


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(adapted from Johnson 1992)

Mathematical Model of Succession inMissouri River floodplain forests


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Projections of Cottonwood Succession Model forGarrison Reach, ND (Johnson 1992)


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Cottonwood Forest Age Map


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>114 yrs

50-114 yrs

25-50 yrs


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III. Changes inSpecies

Composition Non-native & invasive

tree species arecommon (seg. 8 & 10) White mulberry Russian olive Eastern red cedar

Native late successionalspecies are scarce onpost-dam sites

0

10

20

30

40

5060

70

80


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Historic Change in Tree SpeciesComposition on Segment 10 (59-mile MNRR)

1857-1869

(GLO Survey)

2007(field sampling)


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IV. Possible Implications of Missouri River

Changes for Forest Songbirds

Species preferring earlysuccessional (shrub/sapling)

habitats

Bells Vireo, Orchard Oriole, Yellow

Warbler Post-dam non-cottonwood (e.g.,

Russian-olive)also provides suitable

habitat


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Possible Implications of Missouri River


Mature/old forest species Ovenbird, Eastern-Wood Pewee,

Red-eyed Vireo, Wood Thrush

Lower abundance for several in

non-cottonwood


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Possible Implications of Missouri River


Woodpeckers, other cavity nesters Need mature and old forests (>50 years)

other cavity nesters less so

Lower abundance in non-cottonwood


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Changes Affecting Floodplain Forestson Missouri River

Loss of forest to land conversions Reservoir inundation and rising water tables upstream Increased cropland Clearing of forest

Reduced cottonwood regeneration Increasing proportion of older forests

Changes in species composition Successional change:

Decreases in cottonwood, increases in later successional trees

Terrestrialization increases in upland species

Increase in introduced and invasive species

Floodplain disconnected from river processes Channel down-cutting, flood control, levees, declining water tables


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Restoring the Missouri

Degradation of the Missouri River ecosystem will

continue unless some portion of the hydrologicand geomorphic processes that sustained the

pre-regulation Missouri River and floodplainecosystem are restored including flow pulsesthat emulate the natural hydrograph

National Research Council (2002) The Missouri River

Ecosystem: Exploring the Prospects for Recovery


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Restoring the Missouri

Native biota are keyed in to natural flowtiming and periodic floods

Fish spawning

Sandbars for plover and tern nesting Productivity of aquatic insects

Cottonwood reproduction

Replenishment of cottonwood forests foreagle nesting

Floodplain-river connections

Photo by Tim Cowman


26/49From Brian Richter The Nature Conservanc


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Ecological Functions and Flow-RegimeNaturalization

SPRING PULSE(S): BUILD BARS CONNECT FLOOD PLAIN SPAWNING CUE

SUMMER LOW: EXPOSE BARS PROVIDE SWH

NESTING TERNS AND PLOVERS


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Challenges in Missouri RiverFlow Restoration

Large, multi-purpose river, subject to socio-economic, legal and political constraints Stakeholders navigation, hydropower, land use, etc.

Endangered Species Act, Biological Opinion

Restoring or mimicking natural flows may not

restore other critical processes (e.g., sediment)

Uncertainty of ecological linkages to flowcomponents (vs. certainty of socioeconomic costs) E.g., pallid sturgeon


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Effects of Flood of 2011?


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Effects of Flood of 2011? Erosion of banks

Loss of forest?

Deposition in new areas May increase sandbar habitat

But, may also be more channel down-cutting

Prolonged inundation May cause mortality of trees

Redcedar, Cottonwood?

Effects on delta?

Policies, Other? More land set aside for conservation? New policies?

Backlash against environmental management?


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Platte River in Nebraska


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Morphology, Landforms of aBraided River


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1938 1998


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Historic Channel Changes on the PlatteRiver near Shelton, Nebraska

1938

2001

Channel Change 1938-2001


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Platte River

NEED NEW SLIDES PHRAGMITES

ALSO NEED SOME SUMMARY TEXTSLIDES FOR BOTH??? AT LEAST GIVE STUDENTS AN OUTLINE


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Platte River




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Platte River




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Least Tern

Sandhill Crane

Whooping CranePiping PloverPhoto by Chris Gondahl Photo by Rocky Hoffman

Photo by Jim Rathbert


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Vegetation Clearing on the Platte


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Platte River Riparian vegetation has increased with flow

regulation (dams, flow diversion) Flood not large enough to scour vegetation out of active

channel bed

Increase in low flows from irrigation returns, may increase

seedling survival during droughts

Cottonwood regeneration and area have increased! (oppositeof Missouri)

Channel has narrowed considerably since 1930s (sometimes>70%)

River morphology has become less braided, more meandering


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Platte River

Recent increases in exotic grass (Phragmites) Concerns about geomorphic effects, sandbar stabilization

Good at binding sediments and resisting floods

Could lead to further channel narrowing and loss of

sandbar habitat

Management to restore braided channel byclearing vegetation, prescribing floods, & adding

sediment Trying to restore open sandbar habitat for Whooping andSandhill cranes, Piping Plover, Least Tern

Di er ent Responses of Misso ri and


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Divergent Responses of Missouri and

Platte to Flow Regulation

Meandering rivers (Missouri) Flow regulation reduces channel meandering, creation of point bars

Recruitment of cottonwoods decreases

Long-term decline in cottonwood projected, increase in latersuccessional species

Braided rivers (Platte) Flow regulation may enhance low flows (help persistence) and reduce

high flows (reduce scour)

Facilitates colonization of the active channel bed by vegetation

Channel narrows and may shift morphology

River morphology influences response to flow regulation


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NarrowedMigration ReducedIntermediate Case

Glacial DepositLocally Derived DepositAncient Fluvial Deposit

Aeolian Deposits:

LoessSand

Friedman et al. 1998,

Wetlands, 18, 619-633


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moriver historic vegetation change moriverclasses 10-13-11

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