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Forest Resources of the Lower Mississippi Alluvial Valley
1882 Mississippi River “Improvement”
1927 flood 1927 flood
1973 flood 2011 flood
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Mississippi (Coahoma Cty), May 1932 Survey
Louisiana 1951 Survey
Forest Area reported in 1986
1930: 11.8 million acres
1980: 6.6 million acres
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Forest Area Sta s cs
Total Area – 26.7 million acres (Defined by 1986 Publica on)
Forest Area – 7.6 million acres
Percent Forested - 28
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Range: < 3 percent to 70 percent forested
Forest types within the broad “BLH” umbrella
Oak/Gum/Cypress Sweetgum/Nuttall oak/willow oak 1,267.4 Baldcypress/water tupelo 863.5 Overcup oak/water hickory 571.4 Swamp chestnut oak/cherrybark oak 181.3 Sweetbay/swamp tupelo/red maple 179.0 Baldcypress/pondcypress 0.2
Elm/Ash/Cottonwood Sugarberry/hackberry/elm/green ash 1,286.8 Sycamore/pecan/American elm 415.5 Willow 226.6 River birch/sycamore 102.9 Cottonwood 55.5 Cottonwood/willow 50.7 Red maple/lowland 43.4
Forest Type Groups
Other eastern softwoods 0% Oak-hickory 17%
Oak-gum- cypress Oak-pine 41% 2% Loblolly-shortleaf 7% Nonstocked 3% Exotic hardwoods 1%
Other hardwoods Elm-ash- 0% cottonwood 29%
Figure 3—Proportion of forest area by forest-type group. Bottomland hardwood area as defined in this publication consists of the oak-gum-cypress and elm-ash-cottonwood forest-type groups, combined.
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Forest Type Groups and Stand Size
2500
Small diameter 2000 Medium diameter Large diameter 1500
1000
500 Area Area (thousand acres)
0
Oak-pine Oak-hickory
Loblolly-shortleaf Oak-gum-cypress Other hardwoodsExotic hardwoods Elm-ash-cottonwood Other eastern softwoods Forest-type group
Figure 4—Forest area by forest-type group and stand-size class, Lower Mississippi Alluvial Valley, 2010. 68% of all stands are large diameter… 70% of BLH stands are large diameter
Area Trends
14 Total 12 Bottomland hardwood 10
8
6
4 Area Area (million acres) 2
0 1930 1950 1960 1970 1980 1990 2010 Year
Figure 5—Forest area (total and bottomland hardwoods) by year, Lower Mississippi Alluvial Valley.
County Level Change
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County Level Change
Propor on of BLH Rela ve to total forest area
100
80
60
40
20 Area Area (percent of total)
0 1930 1950 1960 1970 1980 1990 2010 Year
Figure 6—Proportion of bottomland hardwoods relative to total forest area by year, Lower Mississippi Alluvial Valley.
What is Going Where…?
Re-measured plots from 2000 to 2010: --- 9 percent of current forest area was agriculture at me 1 --- 1.3 percent of previously forested land diverted to agriculture
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Pecan American sycamore Cherrybark oak 1980 Hawthorn spp. 2010 Willow oak Blackgum White oak Overcup oak Flowering dogwood Texas red oak American hornbeam, musclewood Slippery elm Water-elm, planertree Water hickory Baldcypress Species Common persimmon Water tupelo Eastern hophornbeam Boxelder American elm Water oak Loblolly pine Winged elm Green ash Sugarberry Sweetgum Red maple
0 10 20 30 40 50 60 Number of trees
Figure 11—Number of trees per acre for the most common species, Lower Mississippi Alluvial Valley, 1980 and 2010.
Changes in Rela ve Stocking (1980-2010)
Lolblolly pine Nuttall oak Green ash Water oak Red maple Winged elm American elm Slippery elm Sugarberry Common persimmon Southern red oak Boxelder
Species American hornbeam Eastern hophornbeam Water elm Flowering dogwood Water hickory Baldcypress Willow oak Overcup oak Sweetgum Water tupelo
-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 Stocking (percent change)
Figure 18—Average annual percent change in relative stocking from 1980 to 2010 by species, Lower Mississippi Alluvial Valley.
Conclusions
v Forest Area in the LMAV has increased since 1980
v Bo omland Hardwood forests have not increased propor onally
v Upland areas account for much of the afforesta on
v Changes in LMAV in the last couple of decades are due to diversion to and reversion from agriculture
v Species composi on remains similar to 1980 except: v Trees that typically occupy frequently flooded sites (cypress/tupelo/water hickory) have reduced abundance v Species that typically occupy dry sites (primarily loblolly pine) have increased abundance
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WEST TENNESSEE FLOODPLAIN FORESTS, SEDIMENTATION, AND GEOMORPHOLOGY
Sonja N. Oswalt
S
Outline EDIMENTATION • Brief overview of Basic River Geomorphology and Floodplain Dynamics • Hydrology; Hydroperiod •West Tennessee geography •The Issues and their Impacts on West Tennessee floodplains:
• West Tennessee landuse IN • West Tennessee Soils W • Sedimenta on EST • Normal versus Excessive T ENNESSEE • Channeliza on • Levees • Beavers and other natural processes
• People •Restora on of a river system: what would it take? •Current status •Beyond West Tennessee--A Landscape Perspec ve •Recommended Reading (about W. Tennessee and other Fabulous wetland and river-related books that I highly recommend!)
Factors Impac ng Floodplain Vegeta on Floodplain Geomorphology (study of the origin and evolu on of floodplain landform) • Main channel meanders • Point bars, cut banks • Natural levee • Oxbow lake • Meander scars • Backswamps • Ridges and swales • Flats
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Factors Impac ng Floodplain Vegeta on Floodplain Hydrology (study of the occurrence, movement, distribu on, and proper es of water in the river and surrounding floodplain) • Hydroperiod: • Frequency (how o en flooding occurs) • Dura on (how long floodwater s cks around) • Water Depth • Flow Pa ern Geomorphology + Hydrology = Hydrogeomorpology
Factors Impac ng Floodplain Vegeta on Sedimenta on in Floodplain Systems • Nutrient source for floodplain soils • Builds floodplain topography • Improves water quality as sediments drop out of the water column • Surface for new plant coloniza on Sedimenta on Factors: • Source input (bank erosion, nonpoint source – runoff, etc…) • Grain size (fine-silty, coarse-sandy, etc…) • Flow velocity (fast, slow)
Factors Impac ng Floodplain Vegeta on
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Factors Impac ng Floodplain Vegeta on
Factors Impac ng Floodplain Vegeta on Sedimenta on in Floodplain Systems • Most sedimenta on occurs in/adjacent to the main river channel • Depressions in the floodplain also receive compara vely high sediment rates • Deposi on rates are normally <1 cm/year on the floodplain—and usually consist of FINE/SILTY soils (high nutrient level, high produc vity, good surface for seed establishment)
Factors Impac ng Floodplain Vegeta on
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Floodplain Forest Composi on on intact, naturally-func oning West Tennessee Rivers (i.e. the Hatchie River)
Borrowed from Pierce S
Geography: Rivers in West Tennessee EDIMENTATION •5 Major Tributaries to the Mississippi (North to South): • Obion River (North, Middle, South, and
IN
Rutherford forks) W • Forked Deer River (North, Middle, South forks) EST T
• Hatchie River ENNESSEE • Loosahatchie River (“Loosahatchie Canal”)
• Wolf River
S
Geography: Aerial View EDIMENTATION
IN W EST T ENNESSEE
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Rivers in West Tennessee and the Memphis Sands EDIMENTATION
IN W EST T ENNESSEE
Soil Composi on in West Tennessee (This is very important!) West Tennessee encompasses several ecoregions, including the Mississippi Alluvial Plain and the Loess Bluffs and Loess Plains • Loess is very fine, windblown material that was originally alluvium • Loess is easily eroded when vegeta ve cover is removed—very fragile soil • Underneath the loess is a very deep layer of unconsolidated sand, which is part of the Memphis Sands aquifer—this sand erodes easily
Loess Thickness (feet)
Land use: Pre-se lement •River systems were unaltered •Na ve Americans (general Chickasaw Indians in W. Tennessee) were nomadic, so when floods occurred they moved up to the surrounding bluffs—thus, floodwaters replenished nutrients, fish popula ons, etc… •Wildlife were plen ful • In 1827 Davy Crocke wrote about hun ng the Obion River system—he describes plen ful popula ons of fish, ducks and other birds, panthers, elk, beaver, bears and “every wildlife but buffalo.” He also describes killing 105 bears in one season—a testament to the richness of the ecosystem.
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Land use: Rich, produc ve soils = Prime Farmland •State boundaries established 1818; Memphis se led around 1819; Dyersburg around 1850 •Widespread clearing in the loess bluffs and floodplain (exploit and move west was the mindset —ambi on with li le thought to the future) •Timber and agriculture prevailed—then the big soybean boom of the 1960s and 70s •Dyer County is #1 soybean producing county in the state
Land use: Rich, produc ve soils = Prime Farmland
West Tennessee’s Fragile Soils Meet Civiliza on….
When Sediment load exceeds flow capacity to carry the sediment, it is deposited in the stream bed & floodplain
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More Examples from West Tennessee
More Examples from West Tennessee
More Examples from West Tennessee
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The “Solu on” = Channeliza on •First ins tuted using levees and je es along with “shortcuts” through meanders in the 1860s on the Mississippi River by Andrew Humphreys and James Buchanan Eads (read more about them in “Rising Tide”)
•Was “successful” on the Mississippi (at least, it seemed so at the me) at scouring the channel bedload by increasing water velocity—thus deepening the channel for naviga on purposes and flood control
• It was only natural that, seeing the successes of Humphreys and Eads in scouring the Mississippi, West Tennesseans would give it a try on the clogged Tennessee streams
•Channeliza on = • Straightening and shortening the channel by cu ng off meanders • Deepening the channel through dredging and/or scouring • Widening the channel
•Ini ally began by small groups of landowners, local governments
Channeliza on: What is it? Unchannelized Hatchie River:
Channeliza on: What is it? Channelized Forked Deer River:
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Channeliza on: What is it? Channelized Obion River:
Channeliza on—The Problems with the “Solu on” •West Tennessee’s soils are not stable – unconsolidated material •Rivers want to meander •Requires constant maintenance = constant money! •Upstream draining = downstream flooding •Levees – inten onal and uninten onal •Someone always loses…..and that someone is your neighbor….
Channeliza on video
Channelized Rivers in West Tennessee
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Levees—Adding to the Growing Problem •The dirt from channel excava on has to go somewhere = Spoil Banks (otherwise known as an uninten onal levee) •Road construc on •Levees built for duck hun ng •What happens when you squeeze the river?? • Water has to go somewhere • Levee wars
Landowner A Landowner B
Levees: Adding to the problem Levee on the Middle Fork Forked Deer River, just upstream from a channel blockage
Sedimenta on from the River Itself…
The system has no equilibrium Unconsolidated Sediments + Straight channel + High flow events = Headcu ng
•Headcu ng and Aggrada on • Progresses from downstream to upstream • Water flow is scouring the channel, carrying sediment downstream • Flow slows, and sediment is deposited • River widens, flow slows further • More sediment is deposited • If sediment load is higher than can be transported and/or something blocks or slows the river flow (e.g. beaver or a fallen log, confluence with a tributary), then a plug forms
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The Culmina on of Problems
Sand Deposi on in the River Systems
Valley Plug •The result of excessive sedimenta on •Fills in the channel •Forces the River onto the surrounding floodplain (increases flooding) •Sedimenta on on the floodplain surrounding the plug •Can stretch for up to a mile as sediments con nue to deposit •Braiding can occur as the river tries to “escape”
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Channelized Ditch Gullies
Anastamosing Stream
Sand Splay
Ponding
Old Meander
Valley Plug (Happ et al.1940)
Valley Plug—2 examples on the Forked Deer River
Valley Plug
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Valley Plug close-up
Some Known Valley Plug loca ons
More Examples
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Same plug
Zoomed out – look just south
Closeup of Spring Creek Swamp
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Close-up of Spring Creek swamp
Beaver are also playing a role in the forma on of these swamps throughout West Tennessee, along with highway crossings that constrict the river
More examples
More Examples
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More Examples
More Examples
More Examples
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Valley Plugs– the bo om line •Deposi on is as much as 10 mes greater than where plugs don’t exist •Soil composi on is extremely different than on an unaffected floodplain •Affects vegeta on composi on and floodplain hydrology •Impacts wildlife • What are the possible impacts on herps? Birds? Mammals? Insects? •Renders the river virtually unusable by people (it’s inaccessible and un-navigable)
Impacts to Vegeta on •Where headcu ng is occuring: • Floodplain gets drier so compe on is more prevalent (not limited by moisture) • Less diversity a possibility as micro-topography becomes less important • Loss of hydroperiod connec vity—understory vegeta on changes drama cally
•Where aggrada on is occuring: • Flooplain gets we er so some species are unable to persist • Hydroperiod changes drama cally
•On/adjacent to valley plug: • Sedimenta on buries trees • Nutrient content is low, so only a handful of disturbance-related species establish (e.g. red maple, black willow, green ash) • Moisture content is lower because sand does not retain moisture as well as silt • Water table may be higher, resul ng in a change in species composi on
•Above the valley plug: • Ponding eventually kills the trees, new seedling establishment is impaired Basically, the whole system has changed
Impacts to Vegeta on—examples of various findings Diehl (2004): Plugs “increase depth and area of seasonal flooding…promo ng the development of open water communi es, marshes, shrub communi es in place of bo omland hardwood swamps…”
Weins (2003): On the Wolf River, headcu ng has resulted in drier floodplains, which has translated into abnormal growth rates and an increase in flood-intolerant species
Franklin et al. (2009): Absence or reduc on in Baldcypress and tupelo, increase in early successional species, par cularly red maple, in channelized systems
Pierce and King: Larger numbers of maple, willow, and sweetgum on valley plugs compared to control sites where baldcypress and oaks were prevalent
Oswalt and King (2005): Larger numbers of maple and willow on valley plugs, dead and dying cypress in associated swamps, bo omland hardwoods with elevated floodplains in areas with head cu ng
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The People Factor •The real challenge begins and ends with people •The majority of land in west Tennessee is privately owned •Coopera on across mul ple ownerships is difficult •The people along west Tennessee Rivers are a broad cross- sec on; many of them: • Are highly educated • Are second or third genera on landowners • Love the rivers and their land • Are absentee • Are hunters, fishermen, or farmers • Are leery of government and governmental interven on
1970 J. Clark Akers III (a wealthy, poli cally connected Nashville businessman and duck hunter) sues the Corps of Engineers, claiming that 1985 channeliza on work was Akers lawsuit was se led, elimina ng wetland and and 32,000 acres was to 1883 waterfowl habitat on the 1973 be developed and 1994-1996 Channeliza on on the MS 1950s Obion and Forked Deer (he The Akers lawsuit causes managed by TWRA as OFDRBA disbanded and River; sedimenta on Duck hun ng clubs owned a farm on the WTTP to shut down a er waterfowl habitat as was reorganized into the already a problem in West 1920s 1938 prosper in W. Tennessee 1960s-1970s Obion, and channeliza on only 32 percent of the mi ga on for the damage West Tennessee River Tennessee, rivers become Large scale dredging Flood Control Act results in and begin construc ng Soil conserva on goes out drained much of his project had been caused by WTTP—in Basin Authority—new goal clogged up—Channel campaigns demanded- 245 miles of clearing and ar ficial swamps using the window with rising waterfowl unit). Federal completed—the lawsuit return, channeliza on was was to restore and 1818-1850 improvement projects channeliza on at the local snagging on Obion-Forked levees—soybean prices soybean prices—wide 1965 Court issues a stop-work would con nue for 15 to con nue, and was to be 1990 preserve natural flow and Se lement begin, headed by USACOE level begins Deer begin to rise scale clearing again occurs World Soybean Prices Peak order. years managed by the OFDRBA WTTP shut down, officially func on of rivers
Late 1800s 1886 1930s 1948 1956 1961 1970 1972 1980 1987 1992-1994 Current Timber boom, widespread Channel naviga on project Dust bowl era—soil West Tennessee Highest flood on record for West Tennessee 8 severe blockages noted Obion-Forked Deer River Addi onal lawsuit filed for Shrinking budgets and WTTP re-ini ated at WTRBA func oning, clearing---Cypress, Oak, of 1883 stops because conserva on becomes Tributaries Project Obion-Forked Deer Tributaries Project on the Forked Deer River Basin Authority formed to non-compliance with NEPA con nuing controversy le governor’s request, but though much effort is and Sweetgum are alterna ve transporta on important na onally, Soil authorized for flood channeliza on work address drainage issues wetland laws the state to more or less new focus was on water focused on repairing flood important commodi es becomes available Conserva on Service (now control on Obion and begins again as a response resul ng form the abandon channeliza on quality control structures and NRCS) formed Forked Deer, with plans to to public outcries about abandoned West efforts—everyone was ed removing debris. Other dredge and re-channelize increasing flooding, Tennessee Tributaries up in lawsuits organiza ons (e.g. The (but work didn’t begin on a increasing clogs on the Project Nature Conservancy, large scale un l 1960s) rivers—the Corps of TWRA) have been Engineers was to undertaking restora on channelize 225 miles of projects. Obion/Forked Deer and Soil Conserva on Service would ditch the tributaries
Restora on of a whole river system: What would it take? •Sedimenta on control • October 4, 2000—from the Na onal Resources Inventory (Southeast Farm Press = source) : Erosion levels on TN cropland are half as high as 20 years ago (due to no- ll systems and CRP) BUT, Tennessee has the highest rate of erosion of cul vated cropland in the United States—it is twice the tolerance level of 2-4 tons/ac every year • Revegeta on • Bank stabiliza on • Sediment fencing/mats •Upstream to downstream approach • Why would star ng mid-stream or downstream be problema c? •Re-establishing hydrology through meanders • Landowner concerns about boundary lines, losing property, privacy, security • Why won’t the river “fix itself” by flowing through the old abandoned meanders? •Levee breaks • Removing levees, including WMA levees, on “first bo oms” immediately adjacent to the river • Managing levees in the “second bo oms” not immediately adjacent to the river for hun ng purposes •Leaving valley plugs in place • Why does this make sense?
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Ongoing restora on projects: Crooked Creek (South Fork Obion Watershed)- completed 2010 WTRBA Circa 1997:
Ongoing restora on projects: Crooked Creek (South Fork Obion Watershed) Circa 2007:
Ongoing restora on projects: Crooked Creek (South Fork Obion Watershed) Circa 2008:
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Canal at restora on segment
New meanders right a er construc on
Erosion control blankets at the new meandering channel inlet
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Inlet and erosion blankets
Flow diversion into the new channel
Crooked Creek restora on segment one year later
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Restora on segment 1 year later
•Canal length at restora on segment: 1.5 mi
•Restored channel length: 2.3 mi
Old Canal—downstream of restora on—note the bank collapse on both sides that had been occurring.
Examples of Ongoing Restora on projects Nature Conservancy, WTRBA coopera ve: Porters Creek, Reedy Creek, Oxford-Muddy Creek; 5 more channels proposed for restora on • Grade Stabiliza on • Outlet protec on • Streambank Stabiliza on
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Grade stabiliza on and channel erosion control
Before A er
Sediment reten on ponds
Before A er
Revegeta on with na ve warm season grasses
Before A er
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Channel stabiliza on, revegeta on, ca le exclusions
Before A er
More Ongoing projects •USDA Mississippi River Basin Ini a ve project driving force • $320 million desginated in 2009 for conserva on in the Mississippi River Basin—designed to improve the heath of the river, wildlife habitat, and reducing hypoxia in the Gulf of Mexico •158 projects designated in the Obion and SF Obion watershed •20 grade stabilliza on structures, 18 plan ngs, 5 access control sites (ca le), 25 sediment control basins, others •Pays por ons of the restora on costs ( costshare) •Stokes Creek (some controversy about the goals, steps) •Black Swamp (controversial)
Importance beyond Tennessee’s borders: Landscape Perspec ve •Mississippi River Basin is a cri cal ecosystem for people and wildlife •Excess sediment = excess nutrient input = contribu ons to the Gulf of Mexico hypoxic zone •Loss of habitat = impacts on the Mississippi Flyway—an extraordinarily important migratory pathway, par cularly for waterfowl and shorebirds. •Sixty percent of all the bird species in the United States use the Mississippi River as a migra on corridor, and 40 percent of all the waterfowl in North America use the river basin during migra on. The flyway is considered the most significant flyway in the world. •The en re MS alluvial valley in Tennessee is designated as an Important Bird Area by Audubon.
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Recommended Reading •Rivers Under Siege: The Troubled Saga of West Tennessee Wetlands: Jim W. Johnson •Rising Tide: The Great Mississippi Flood of 1927 and How it Changed America: John M. Barry •Discovering the Unknown Landscape: A History of America’s Wetlands: Ann Vileisis
Thank You for Updates, Photos, Conversa ons… •Dr. Sammy King, USGS Louisiana Coopera ve Fish and Wildlife Research Unit •Christopher Bridges, West Tennessee Project Director, The Nature Conservancy •Dr. Sco Franklin, University of Colorado •Carl Wirwa, Wildlife Manager II, Tennessee Wildlife Resources Agency •Dr. Aaron Pierce, Nicholls State University •Larry Smith, Wolf River Conservancy and Shelby County Government •David Salyers, West Tennessee River Basin Authority
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