ILLUSTRATED FLORA OF EAST TEXAS - Brit - Botanical Research ...

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VEGETATION OF POST OAK SAVANNAH/INTRODUCTION 119 FIG.70/PRAIRIE INCLUSION IN THE POST OAK SAVANNAH,LICK CREEK PARK,BRAZOS,CO.(PHOTO BY JIM MANHART). Sorghastrum nutans (Indian grass), and Panicum virgatum (switch grass). Rather than a zone of homogeneous vegetation, areas such as prairie inclusions (Fig. 70) were interspersed with woody vegetation of various types, including savannah/woodland/forest. Limited areas of somewhat similar vegetation can still be found today in the Post Oak Savannah and also to the west in the East and West cross timbers and to the east in well-drained xeric areas of the Pineywoods (Bezanson 2000). DRY-MESIC MIXED PINE-HARDWOOD UPLANDS—Wilson (1989) described a community in Franklin County (northern Post Oak Savannah) where the canopy layer was dominated by (in order) Pinus echinata (shortleaf pine), Quercus alba (white oak), Liquidambar styraciflua (sweetgum), Quercus falcata (southern red oak), and Quercus stellata (post oak). Somewhat similar dry-mesic mixed forests have been documented from Sanders Cove in Lamar County (Wilson & Hacker 1986) and are found in other portions of the Red River Area (an area often included in the Post Oak Savannah, but treated separately here—see page 127). Such forests correspond to the Dry-Mesic Mixed Pine-Hardwood Uplands as described by Van Kley (page 95) for the Pineywoods. XERIC SANDYLANDS—This distinctive vegetation type is developed primarily on the extremely droughty, rapidly draining, deep, loose, sandy soils of the Carrizo Formation (McBryde 1933; MacRoberts et al. 2002b), with some occurrences on sandy soils developed from other layers such as the Queen City and Sparta formations (Yantis 1998). Even though rainfall can be plentiful, surface moisture lasts only a few days (Price & Singhurst 2001), and the typically white to tan sands (sometimes called “sugar sand”) support species able to withstand very dry conditions. It is similar to and sometimes lumped with the post oakblackjack oak upland forests and woodlands (e.g., Bezanson 2000), but differs significantly from that community. The Xeric Sandylands are equivalent to the “Dry Uplands on Deep Coarse Sands” discussed by Van Kley as occurring in the Pineywoods (see page 92). The Xeric Sandylands (also called the Deep Sands Ecosystem—Yantis 1998) are characterized
120 INTRODUCTION/VEGETATION OF POST OAK SAVANNAH by such tree species as Quercus incana (sandjack oak), Q. margaretta (sand post oak), Q. stellata (post oak), and Carya texana (black hickory), as well as a variety of typical herbaceous/understory species including (to name a few) Asimina parviflora (small-flower pawpaw), Brazoria truncata (blunt-sepal brazoria), Cnidoscolus texanus (Texas bull-nettle), Cyperus grayoides (Mohlenbrock’s sedge), Opuntia humifusa (eastern prickly-pear), Polanisia erosa (large clammy weed), Selaginella arenicola subsp. riddellii (riddell’s spike-moss), and Yucca louisianensis (Louisiana yucca) (MacRoberts et al. 2002b, 2002c). An indication of the rather extreme edaphic conditions is that in undisturbed areas soils are often cryptogamic—with lichens (Cladonia spp.) common (MacRoberts et al. 2002c). Because of the porous nature of the deep sands underlying this vegetation type, Herbaceous Seeps and Bogs (discussed below) and other types of wetlands are typically found in close proximity to (topographically below) the Xeric Sandylands. LOBLOLLY PINE-POST OAK UPLAND FOREST—Small disjunct areas of Pinus taeda (loblolly pine) are found in the southern Post Oak Savannah, primarily in the “Lost Pines” area of Bastrop County, but also on the north banks of the Colorado River in Fayette County and near Carlos in Grimes County (Jackson & Garner 1982). The Bastrop forest is characterized by loblolly pine, post oak, blackjack oak, and Ilex vomitoria (yaupon holly), with associated species including Vaccinium arboreum (farkleberry) and Pteridium aquilinum (bracken fern) (Bezanson 2000). The deep sandy soils and hilly topography apparently combine to allow the survival of these isolated loblolly pines approximately 100 miles to the west of most populations of this species (Texas Parks and Wildlife 2002b). The stand is considered a relict of a much more extensive Ice Age forest (Maxwell 1970). This unusual habitat is one of the last refuges for the endangered Houston Toad, Bufo houstonensis (Texas Parks and Wildlife 2002a). EASTERN RED-CEDAR CHALK GLADES—Bezanson (2000) indicated that “Glades communities occur very infrequently at scattered sites in the Post Oak Savannahs and Blackland Prairies on ridges where the Annona, Gober, and Austin chalk formations are exposed.” “Cedar glades” are well known in the southeastern U.S. and adjacent areas (see e.g., Baskin & Baskin 1985, 2000), and a comparison of glades in the Post Oak Savannah with the better studied areas to the east is needed. A detailed comparison with the “chalkland prairie biome” described by Stanford (1995) for areas of very thin soil on exposed outcrops of the Austin Chalk on the Blackland Prairie is also needed. The glades of the Post Oak Savannah may support thin-soiled grassland communities with Bouteloua rigidiseta (Texas grama), Bouteloua curtipendula (side-oats grama), Sporobolus vaginiflorus (poverty dropseed), Schizachyrium scoparium (little bluestem), and other grasses (Bezanson 2000). Bezanson (2000) also noted that some glades could be dominated by “rock moss” (Sedum pulchellum[?]) and that the bluegreen bacterium, Nostoc commune, was often abundant. Common forbs include Penstemon cobaea (cobaea penstemon), Echinacea spp. (coneflowers), Paronychia virginica (Parks’ nailwort), and numerous others. As indicated by the name of the community, scattered individuals of Juniperus virginiana (eastern red-cedar) are usually present. Bezanson (2000) pointed out that these “communities are uncommon and further study is warranted.” Given the importance of fire during presettlement times and the susceptibility of Juniperus virginiana to fire, such glade communities probably occupied very limited areas. In this regard, it is interesting that Amos A. Parker (1968), who traveled through the area in 1834, noted for an area west of the Trinity River and east of the Brazos, that “Among the trees in the swamps, I noticed the red cedar, today, for the first time.” Roemer (1849) also noted that red-cedars “are found singly among other trees in the lowlands of Texas, but nowhere forming a continuous forest of their own.” These statements would suggest that Juniperus virginiana was somewhat limited in occurrence during presettlement times, apparently being more common in less fire-prone areas.
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ILLUSTRATED FLORA OF EAST TEXAS
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ALLDREDGE, LINDA & JACK BATTERBAE,
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We would like to recognize and expr
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ISSN 0833-1475 ISBN 1-889878-12-X S
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“DEEP EAST TEXAS IS AN OLD, QUIET
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Elray S. Nixon E lray Nixon was bor
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ILLUSTRATED FLORA OF EAST TEXAS TAB
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TABLE OFCONTENTS/ PAGE APPENDICES A
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Hymenocallis liriosme
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ILLUSTRATED FLORA OF EAST TEXAS OVE
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4 INTRODUCTION/GEOGRAPHIC AREA OF E
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10 INTRODUCTION/MAJOR RIVERS OF EAS
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12 INTRODUCTION/PLANTS TREATED The
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14 INTRODUCTION/GUIDE TO ARRANGEMEN
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16 INTRODUCTION/GUIDE TO SOURCES OF
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18 INTRODUCTION/GUIDE TO GEOGRAPHIC
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20 INTRODUCTION/GUIDE TO ENDANGERED
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22 INTRODUCTION/GUIDE TO GLOSSARY,
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24 INTRODUCTION/GUIDE TO ABBREVIATI
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26 INTRODUCTION/SUMMARY DATA ON FLO
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28 INTRODUCTION/ACKNOWLEDGMENTS Kar
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30 INTRODUCTION/AUTHORS’ NOTE Pre
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32 INTRODUCTION/GENERAL GEOLOGY OF
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46 INTRODUCTION/SOILS SOIL ORDER DE
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48 INTRODUCTION/SOILS, EAST TEXAS B
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50 INTRODUCTION/SOIL-RELATED GEOLOG
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60 INTRODUCTION/SOILS OF BLACKLAND
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66 INTRODUCTION/CLIMATE OF EAST TEX
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Page 95 and 96: 78 INTRODUCTION/GEOLOGY OF PINEYWOO
Page 97 and 98: 80 INTRODUCTION/PRESETTLEMENT, EARL
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Page 123 and 124: 106 INTRODUCTION/POST OAK SAVANNAH
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170 INTRODUCTION/NATURAL HISTORY OF
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172 INTRODUCTION/SUMMARY DEFINITION
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174 INTRODUCTION/PRESETTLEMENT AND
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184 INTRODUCTION/HISTORY OF BIG THI
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190 INTRODUCTION/CONSERVATION IN BI
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200 INTRODUCTION/ORIGIN AND DIVERSI
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228 INTRODUCTION/CONSERVATION IN EA
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234 INTRODUCTION/HISTORY OF BOTANY
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244 INTRODUCTION/BOTANY IN NORTH CE
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246 INTRODUCTION/BOTANY IN NORTH CE
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248 INTRODUCTION/BOTANY AT UNIVERSI
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250 INTRODUCTION/BOTANY AT TEXAS A&
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252 INTRODUCTION/BOTANY AT TEXAS A&
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254 INTRODUCTION/OTHER CONTRIBUTION
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256 INTRODUCTION/CURRENT BOTANICAL
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258 INTRODUCTION/BOTANICAL ART IN E
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