Common (Translated Scientific) Name: Pecan - Sugarberry - Bur Oak Floodplain Forest & Woodland Macrogroup
Colloquial Name: Southern Great Plains Floodplain Forest & Woodland
Hierarchy Level: Macrogroup
Type Concept: This macrogroup covers floodplain and riparian vegetation ranging from closed-canopy forests of tall stature in the eastern part of its range to open, short-statured woodlands in the western part of its range. Species composition also varies across the east-west range of this macrogroup, but this concept is based on a core set of characteristic species, including Carya illinoinensis, Celtis laevigata var. laevigata, Celtis laevigata var. reticulata, Cephalanthus occidentalis, Cornus drummondii, Elymus virginicus, Justicia americana, Panicum virgatum, Platanus occidentalis, Populus deltoides, Salix nigra, Sapindus saponaria var. drummondii, Sideroxylon lanuginosum, Taxodium distichum, Tripsacum dactyloides, and Ulmus crassifolia. Other characteristic species in eastern examples include Acer negundo, Callicarpa americana, Diospyros virginiana, Forestiera acuminata, Fraxinus pennsylvanica, Gleditsia triacanthos, Ilex decidua, Juglans nigra, Juniperus virginiana, Quercus macrocarpa, Quercus shumardii, Ulmus americana, and Viburnum rufidulum. Other characteristic species in western examples include Diospyros texana, Fraxinus albicans, Juglans microcarpa, Juniperus ashei, Muhlenbergia lindheimeri, Nassella leucotricha, Prosopis glandulosa, Prunus rivularis, Quercus fusiformis, and Ungnadia speciosa. This vegetation is found in the floodplains of medium and larger rivers, as well as along small and intermittent streams of the East Central Texas Plains, Texas Blackland Prairie, Crosstimbers, and Edwards Plateau ecoregions, extending peripherally into adjacent ecoregions. Environmental processes include alluvial sedimentation and erosion associated with perennial and intermittent streams and rivers. It occurs on large and small floodplains, especially in the eastern (and wetter) parts of its range, and on narrow riparian corridors of intermittent streams becoming particularly dry and flashy in the western parts of the range. Periodic, intermediate flooding and deposition (every 5-25 years) dominate the formation and maintenance of examples along better establish floodplains. Further west, in the drier parts of the Edwards Plateau (including the Stockton Plateau) of Texas, examples are open to closed-canopy, low-statured woodlands and shrublands in scoured, rocky riparian settings. These riparian settings are typically intermittently flooded but may be subirrigated.
Diagnostic Characteristics: This macrogroup covers floodplain and riparian vegetation ranging from closed-canopy forests of tall stature in the eastern part of its range to open, short-statured woodlands/shrublands in the western part of its range. Species composition also varies across this east-west range, but this concept is based on a core set of characteristic species, including the trees Carya illinoinensis, Celtis laevigata var. laevigata, Celtis laevigata var. reticulata, Platanus occidentalis, Populus deltoides, Salix nigra, Sapindus saponaria var. drummondii, Sideroxylon lanuginosum, Taxodium distichum, and Ulmus crassifolia, shrubs Cephalanthus occidentalis, Cornus drummondii, and grasses and forbs Elymus virginicus, Justicia americana, Panicum virgatum, and Tripsacum dactyloides.
Rationale for Nominal Species or Physiognomic Features:
Classification Comments: Vegetation in this macrogroup varies across an east-west gradient, with eastern components sharing similarities with vegetation occurring farther east, and western components sharing species with vegetation farther west. The macrogroup is described on a core set of species, but these species also range in importance across an east-west gradient. Further information is needed to better describe the macrogroup and its groups. Southeastern Great Plains Floodplain Forest Group (G784) is distinctive from groups in Southern Coastal Plain Floodplain Forest Macrogroup (M031) at least in part by the lack of species found in the groups of M031 (e.g., Nyssa spp.), and the presence of Quercus macrocarpa, Sapindus saponaria var. drummondii, and Ulmus crassifolia, and the eastern extensions of the range of Celtis laevigata var. reticulata.
There are two groups (in two different macrogroups, in two divisions) which may need to be more clearly distinguished from one another floristically and (as much as is possible) biogeographically. These are Southeastern Great Plains Floodplain Forest Group (G784) in Southern Great Plains Floodplain Forest & Woodland Macrogroup (M154); and Great Plains Cottonwood - Green Ash Floodplain Forest Group (G147) in Great Plains Flooded & Swamp Forest Macrogroup (M028). The first of these is in 1.B.3.Nb Southeastern North American Flooded & Swamp Forest Division (D062), the latter one in 1.B.3.Na Eastern North American-Great Plains Flooded & Swamp Forest Division (D011). One problem area is Oklahoma, where G784 and G147 overlap.
Several associations in Carya illinoinensis - Ulmus crassifolia - Celtis laevigata Floodplain Forest Alliance (A3679) extend this group into Arkansas, Kansas, and Louisiana which is beyond the conceptual boundary of this group and macrogroup. This is peripheral to the core geographic distribution of this group, i.e., the East Central Texas Plains, Texas Blackland Prairie regions, Crosstimbers, and Edwards Plateau ecoregions centered on Texas. More information is needed to determine if the vegetation in Arkansas, Kansas, and Louisiana represents a new association that would be better classified elsewhere.
Similar NVC Types:
M029 Central Hardwood Floodplain Forest, note:
M031 Southern Coastal Plain Floodplain Forest, note:
M028 Great Plains Flooded & Swamp Forest, note:
M310 Southeastern North American Ruderal Flooded & Swamp Forest, note:
Physiognomy and Structure: This macrogroup covers floodplain and riparian vegetation ranging from closed-canopy forests of tall stature in the eastern part of its range to open, short-statured woodlands/shrublands in the western part of its range. Depending on the degree of soil development, herbaceous species may occur as clumps or as a continuous herbaceous layer, and may be quite high, especially in situations where shrub cover is low.
Floristics: Species composition varies across the east-west range of this macrogroup, but its concept is based on a core set of characteristic species, including the trees Carya illinoinensis, Celtis laevigata var. laevigata, Celtis laevigata var. reticulata, Platanus occidentalis, Populus deltoides, Salix nigra, Sapindus saponaria var. drummondii (= Sapindus drummondii), Sideroxylon lanuginosum, Taxodium distichum, and Ulmus crassifolia, shrubs Cephalanthus occidentalis, Cornus drummondii, Amorpha fruticosa, and grasses and forbs Andropogon glomeratus, Elymus virginicus, Justicia americana, Panicum virgatum, Tripsacum dactyloides, and Verbesina virginica. Associates of these characteristic species vary across an east-west gradient, with eastern components sharing similarities with vegetation occurring farther east, and western components sharing species with vegetation farther west. Other characteristic species in eastern examples include the trees Acer negundo, Fraxinus pennsylvanica, Gleditsia triacanthos, Juglans nigra, Quercus macrocarpa, Quercus shumardii, and Ulmus americana, shrubs Callicarpa americana, Diospyros virginiana, Forestiera acuminata, Ilex decidua, Juniperus virginiana, and Viburnum rufidulum, and vines Nekemias arborea (= Ampelopsis arborea), Berchemia scandens, Campsis radicans, Parthenocissus quinquefolia, and Vitis spp., and grasses and forbs Carex sp., Chasmanthium latifolium, Chasmanthium sessiliflorum, Clematis pitcheri, Galium spp., Geum canadense, Sanicula canadensis, and Symphyotrichum drummondii var. texanum. Other characteristic species in western examples include the trees Fraxinus albicans (= Fraxinus texensis), Juglans microcarpa, Prosopis glandulosa, and Quercus fusiformis, shrubs Diospyros texana, Juniperus ashei, Prunus rivularis, and Ungnadia speciosa, vines Ampelopsis cordata, and Parthenocissus heptaphylla, and grasses and forbs Cladium mariscus ssp. jamaicense, Eleocharis spp., Hydrocotyle spp., Muhlenbergia lindheimeri, Nassella leucotricha, and Setaria scheelei. Herbaceous species of the adjacent uplands may also be present, including Bothriochloa barbinodis (= var. barbinodis), Bouteloua curtipendula, Indigofera lindheimeriana, Leptochloa dubia, and Schizachyrium scoparium var. scoparium (= Schizachyrium scoparium ssp. neomexicanum).
Along the eastern and northeastern margins of the range of this macrogroup, some stands belonging to more eastern groups may exhibit dominance by eastern taxa such as Quercus alba, Quercus lyrata, Quercus phellos, and Quercus pagoda; the environment becomes generally and correspondingly drier from east to west with communities containing these moister representatives being constrained to riverbanks and floodplains. Representatives of this macrogroup may vary in the openness of the habitat and physiognomy. There may be an open canopy resulting from flood events and rare fire events. Along the Red River and a few of its tributaries, thin bands of riparian vegetation occurring on sandy floodplain terraces, bluffs and sandbars are significantly different in species composition from riparian communities elsewhere in the region. Occurrences may include Acer saccharinum (which probably does not occur in any other basin in Texas), Juniperus virginiana, Populus deltoides, and Salix spp. (especially Salix exigua).
Dynamics: In eastern examples, periodic and intermediate flooding are the most significant processes, and are expected every 5 to 25 years. Grazing and conversion to agriculture can significantly impact this vegetation, and can lead to its degradation or extirpation. Fire occurs infrequently relative to surrounding systems. Fuels tend to stay moister due to shady conditions and low topographic position. Other disturbances include ice storms/blowdowns, which are capable of setting back small to large patches, as well as beaver pond flooding, which, even though a small-patch event, is expected to cycle throughout the forest over the long term, perhaps at a scale of hundreds or thousands of years. Overgrazing and/or overbrowsing may influence recruitment of overstory species and composition of the understory and herbaceous layers.
Environmental Description: Some examples of this type occupy relatively broad flats at low topographic positions, along large streams where alluvial deposition dominates, as well as on medium to very small, intermittent to ephemeral drainages, minor intermittent streams, and tributaries. Species composition of these forests are variable and are thought to be dependent on soil and geologic substrates. Some examples may be influenced by fire. Others occur on flashy streams, or frequently inundated floodplains where flooding, rather than fire, is the dominant process. Fuels are variable, and fire-return interval is partially determined by that of the adjacent and surrounding matrix upland vegetation, where consistent fuels are present. The "riparian" components are driven primarily by erosional processes and are affiliated with smaller, higher-gradient streams that may occur on limestone cobbles or flat-bedded limestone of streambeds that are typically intermittently flooded but may be subirrigated by shallow groundwater. "Floodplain terrace" components are driven primarily by depositional processes and are affiliated with larger, lower-gradient rivers and streams. This vegetation is ubiquitous (in appropriate habitats) in the East Central Texas Plains, Texas Blackland Prairie Regions, Crosstimbers, and Edwards Plateau (Level 3 Ecoregions 33, 32, 29 and 30, respectively, sensu Griffith et al. (2004)).
Geographic Range: This macrogroup encompasses the floodplain vegetation along large and small rivers in north and south-central Texas in the Edwards Plateau, Texas Blackland Prairies, and East Central Texas Plains ecoregions, and extending peripherally into adjacent ecoregions. The type occurs in portions of the floodplains and tributaries of the Red, Trinity, San Jacinto, Brazos, Colorado, Guadalupe, San Antonio, Nueces, and Lavaca rivers, as well as along minor streams and tributaries in the Colorado, Rio Grande, Guadalupe, San Antonio, and Nueces river drainage basins in the western Edwards and Stockton plateaus of Texas.
States/Provinces: OK, TX
|US Forest Service Ecoregions (2007)|
Southwest Plateau and Plains Dry Steppe and Shrub Province
Confident or certain
Texas Cross Timbers and Prairie Section
Confident or certain
Omernik Ecoregions: 29:C, 30:C, 32:C, 33:C
Confidence Level: Moderate
Confidence Level Comments:
Concept Lineage: This macrogroup has been rescoped in geographic range to include Edwards Plateau (G172) and a new southern Great Plains (784), distinct from the Texas Coastal Plain Forests of G171 in M031.
Synonomy: > Sawgrass - Willow (Webster 1950)
Concept Author(s): J. Teague, in Faber-Langendoen et al. (2014)
Author of Description: J. Teague and M. Pyne
Acknowledgements: We have incorporated significant descriptive information previously compiled by J. Teague, D. Diamond, and L. Elliott.
Version Date: 15Jun2015
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