Table Lu02: Descriptions of land type association (LTA) groups and condensed descriptions of the 11 LTAs (underlined in bold) within the South Grand River Watershed
Alluvial Plains Group
Landform: The Alluvial Plains group represents the broad floodplains of the Osage and South Grand Rivers. The floodplains included in this group are at least on mile wide with essentially no local relief other than that associated with terraces.
Soils: Soils are, for the most part, very deep and formed in alluvial materials of variable loamy, sandy, silty, and clayey textures. Both moderately drained and poorly drained hydric soils are common. The rivers have been extensively channelized and siltation related to agricultural runoff is prevalent.
Historic Vegetation: Historic vegetation included extensive bottomland prairie (39-54%) and numerous wetlands, including marshes, shrub swamps, and oxbow lakes. Substantial bottomland forest also occured, especially on the higher, more well drained bottoms. Flooding and fire were important disturbance regimes which created and maintained a unique and diverse ecosystem.
Current Conditions: Current land cover varies with LTA. The Scared Osage Alluvial Plains support extensive row crop agriculture (57%). In the South Grand and Four Rivers Alluvial Plains LTAs, extensive flooding and wetlands are more common. Consequently, cropland cover is lower (20-30%) and forest (28-33%) and water (17-19%) cover is higher. Widespread channelization, draining and levee systems are in place throughout, altering the natural hydrology and stream quality. While there are more remaining wetlands in these LTAs than the others, most have been drained or eliminated and existing wetlands suffer from severely altered hydrology, siltation, and agricultural runoff.
Scarped Osage Alluvial Plains: Valleys more narrow with higher gradient streams and more extensive cropland.
South Grand Alluvial Plains: Very broad bottoms; Truman Lake high water zone; some large blocks of remaining timber.
Landform: The Prairie Plains consist of broad flat uplands sloping gently down to very broad and flat bottoms. Local relief is less than 75 feet. Streams are mainly low gradient.
Geology: Geology primarily consists of Pennsylvanian limestone, sandstone, or shale overlain by a layer of loess.
Soils: Soils are primarily deep and somewhat poorly drained, especially on the smoothest landscapes. Streams deeply entrenched in silty substrates.
HistoricVegetation: The Prairie Plains represented some of the largest, most continuous expanses of prarie in Missouri. Historic prairie cover was greater than 80% for most LTAs in this group. Savannas occurred as isolated groves or narrow ribbon-like areas along streams. Wetlands occurred in lower more poorly drained areas.
Current Conditions: Currently the Prairie Plains consist of a mosaic of cropland and grassland. The grasslands are primarily fescue pasture and hay land. Less than 15% of these LTAs are timbered. Areas that are timbered consist primarily of invasive tree species such as elm, hackberry, and shingle oak. Few quality native prairies or oak savannas are known. Existing prairie remnants are traditionally native prairie hay meadows. Streams are often deeply encised and suffer heavy siltation and altered hydrology.
Belton High Prairie Plain: High, flat, loess covered upland divide at the head of the South Grand River drainage.
Four Rivers Low Prairie Plains: Low plains flanking the middle Osage River and tributaries. These plains occur mainly on shale.
Osage Prairie Plains: The flattest upland surfaces within the Scarped Osage Plains subsection. These occur mainly on Kansas City shale and limestone.
South Grand Smooth Low Prairie Plains: Low, very flat plains flanking the lower South Grand and occuring mainly on shale.
Southern Pettis County Prairie Plain: At the edge of the Ozarks with portions underlain by Jefferson City-Cotter dolomite and having common prairie remnants. Very little of this LTA occurs within the South Grand River Watershed.
Scarped and Dissected Prairie/Savanna Plains Group
Landform: Rolling to moderately dissected topography with local relief between 75-150 feet. Broad, flat divides give way to more rolling and dissected lands with gentle sideslopes and moderately broad stream valleys.
Geology: Geologic parent materials are Pennsylvanian-aged limestones, shales and sandstones.
Soils: Soils are variable, ranging from shallow to bedrock, to deep, well drained, sandy loams. Numerous streams with variable gradient and substrates occur.
Historic Vegetation: Originally, prairie dominated the higher, flatter ground and graded into oak savanna and open oak woodlands in the more dissected areas near streams. Historic fire as well as grazing by bison, elk, and deer likely played and important role in maintaining the prairie and open woodlands.
Current Conditions: These LTAs currently have the largest blocks and greatest acreage of existing grassland with approximately 40-55% of the land cover being grassland. Most of this grassland consists of fescue pasture and hayfields. The remainder of the land in these LTAs consist of cropland (29%) or forest (21%). Cropland is mainly in smaller and more fragmented blocks than in the Prairie Plains. The dense second growth woodlands have been over grazed and in the absence of fire have very little ground flora. Stream quality varies, but some of the least altered streams occur in these LTAs.
Inner Osage Prairie/Savanna Dissected Plain: Scarped limestone dissected plain along the boundary of the Osage and Cherokee Plains.
Outer Osage Prairie/Savanna Dissected Plain: Scarped limestone dissected plain at outer edge of Osage Plains.
Windsor Prairie/Savanna Dissected Plain: Similar to, but less dissected and scarped than the Inner Osage Scarped Plain.
Ozark Oak Woodland Hills
Landform: Gently rolling to well-dissected hills with 150-250 feet of local relief. Broad ridges give way to moderately steep sides slopes (<25%) and moderately broad to rather narrow, entrenched valleys.
Geology: Cherty Mississippian limestones in the highest parts of the landscape with the stream valleys cutting through it into Jefferson City-Cotter dolomite.
Soils: Soils are often very cherty and shallow to moderately deep, with frequent bedrock outcrops. Streams are mainly moderate in gradient and widely meandering in moderately broad to narrow valleys with gravel and bedrock substrates.
HistoricVegetation: Oak savanna and open oak woodlands dominated the uplands, with dolomite and sandstone glades and occasional prairie openings scattered throughout. Fires from the prairie country to the west likely swept frequently through these woodlands and played and important role in their maintenance. Oak forest was confined to the steepest, most protected areas.
Current Conditions: A high percentage of these LTAs (57%) are currently forest consisting mainly of the post oak-black oak and mixed forest types. Substantial cedar-hardwood forest on shallow glade and woodland soils occurs, especially in the Lower Osage and Pomme de Terre Hills. Grassland makes up about 30% of these LTAs; less than 10% cropland occurs. Former savannas and woodlands are now dense, with a sparse ground flora. Most glades are overgrown with eastern red cedar. Streams are generally high quality with minimum impact relative to the prairie streams to the west.
Truman Lake Oak Woodland Hills: Rolling hills surrounding much of the main body of Truman Lake.