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

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PRESETTLEMENT, EARLY SETTLEMENT CONDITIONS <strong>OF</strong> POST OAK SAVANNAH/INTRODUCTION 115 when rainfall prevents fire throughout the year (e.g., in areas of eastern deciduous forest in the eastern U.S.). Likewise, reduced grass biomass from grazing on the prairies reduces fire likelihood, which in turn enables invasion by trees (Smeins et al. 1982; Scholes and Archer 1997; Van Auken 2000). As noted by Van Auken (2000), “the driving force [for brush encroachment] seems to be chronic, high levels of herbivory by domestic animals. This herbivory has reduced the above ground grass biomass, leading to the reduction of fine fuel and a concomitant reduction or complete elimination of grassland fires. This combination of factors favors the encroachment, establishment, survival and growth of woody plants.” Finally, where relief is extreme, as on scarps or cliffs, woodlands are often present. This is due to both the thin rocky soil (and hence low grass biomass) and the topography (e.g., abrupt scarps), which often creates natural firebreaks (Wells 1965, 1970; Axelrod 1985). Thus, any factor that reduces fire likelihood, frequency, or intensity can be expected to allow trees to invade grasslands in areas where there is sufficient moisture for tree growth. The soil-mediated fire frequency hypothesis for the historical distribution of the prairies and woodlands of North Central and East Texas is consistent with both historical vegetation patterns and recent changes in the vegetation. PRESETTLEMENT AND EARLY SETTLEMENT CONDITIONS IN THE POST OAK SAVANNAH One of the major differences between the Post Oak Savannah of presettlement times and that of the present is that (at least in uncleared areas) there is currently much more woody vegetation than at the time of European contact. With the suppression of naturally recurrent fire, brush encroachment—or as it is sometimes called, thicketization—has occurred, resulting in a reduction in grasses and an increase in trees and shrubs. The term Post Oak Savannah thus does not accurately reflect much of the region’s current woodland/forest vegetation. However, according to early settler and explorer reports, it is a more accurate description of presettlement conditions. For example, McClintock (1930) in 1846 described an area of Post Oak Savannah (Freestone County) as “High rol[l]ing prairie, very sandy and covered in places with low scrubby blackjacks, wholly worthless, except for fuel.” In many areas there was probably a complex mosaic of prairie and woodland varying from quite open to more closed. According to Olmsted (1857), We came to-day upon the first prairie of any extent, and shortly after crossed the Trinity River [probably at the Houston Co.–Leon Co. line]. After having been shut in during so many days by dreary winter forests, we were quite exhilarated at coming out upon an open country and a distant view. During the whole day’s ride the soil improved, and the country grew more attractive. Small prairies alternated agreeably with post-oak woods. The post-oak…forms a very prominent feature in Texas scenery and impressions. It is a somewhat small broad-leaved oak of symmetrical shape, and appears wherever the soil is light and sandy, in a very regular open forest growth. It stands in islands in the large prairies or frequently borders an open prairie through a large tract. In describing another area of Post Oak Savannah in Leon County, Olmsted (1857) said, During the first part of the day we went over small, level, wet prairies, irregularly skirted by heavy timber, with occasional isolated clumps and scattered bushes. Most of the prairies have been burned over. Both yesterday and to-day we have been surrounded by the glare of fires at night.… After a few miles began post-oak, which changed to blackjack, and for the remainder of the day the country was as forbidding as a moor. When fires (whether set by lightning or started by Native Americans), such as those described, were more frequent, there were thus probably significant expanses of prairie vegetation in some places, broken by the occasional area of venerable “giants,” lending a park-like atmosphere to the landscape (Texas Parks and Wildlife 2002a). The following quote by Gregg (in Weniger 1984b), who described the forest in Fayette County in 1846, gives such an impression,
116 INTRODUCTION/ PRESETTLEMENT, EARLY SETTLEMENT CONDITIONS <strong>OF</strong> POST OAK SAVANNAH “The timber about our camp resembled, for all the world, an old waste orchard of large apple trees.…” Similarly, Roemer (1849) described the southern Post Oak Savannah (Colorado County) as follows: These forests…have a remarkable resemblance in winter to the cultivated German oak forests…. In other forests of North America many varieties of trees are usually found, but in the post-oak forests all are excluded with the exception of a few walnuts. Underbrush is also lacking. The soil upon which the post-oaks grow is usually of average fertility, but also often sterile and unproductive…. [There] is a wide zone where deposits of gravel and sand are found, and where farming cannot be carried on successfully. Here the land is covered with post-oaks. However, Roemer (1849) described another area in the southern Post Oak Savannah somewhat differently: “Our trail led us several miles along the summit of a range of hills until it descended on the other side and took us into a dense oak forest.” He also described the area between Gonzales and La Grange as “a sandy, hilly country, covered almost entirely with post oak forests.…” Likewise, Captain Domingo Ramón in 1716 noted about an area in what is probably present-day Burleson County that the woods were so dense that “there were not enough hatchets and knives to open a passage” (Foster 1995), and De Córdoba (1858) described a portion of Post Oak Savannah in Robertson County as “heavily set with post-oak timber.” Similarly, Smythe (1852) described part of eastern Limestone County as “… having a more uniform Post Oak growth, and better grass; occasionally a small Prairie begins to make its appearance…” Perhaps more surprisingly, “bottom prairie,” a particularly interesting presettlement community (not known at present), was noted as occurring adjacent to rivers such as the Brazos and Trinity (e.g., in Fayette and Bastrop counties), in some cases occupying thousands of acres (Jordan 1973; Jurney 1987). McClintock (in Jordan 1973) in the 1800s described such a bottom prairie in present-day Anderson or Freestone County as “cover’d with coarse grass as high as a horses [sic] back, yet so level…that when on horse back you can see every part of the plain.” Thus, while descriptions such as the following probably give an accurate broad-scale impression—“widely spaced Quercus stellata (Post Oak) and Q. marilandica (Blackjack Oak) with an understory of tall grasses such as Little Bluestem, Indian Grass, and Switch Grass” (Simpson 1988)—the vegetation of the Post Oak Savannah apparently varied considerably. In fact, the Post Oak Savannah was much more diverse vegetationally than generalizations imply, with a number of well-recognized communities (see discussion in vegetation section) (Bezanson 2000). The early print (a frontispiece probably depicting the Post Oak Savannah) in Olmsted’s (1857) A Journey Through Texas gives a visual impression of this diversity—a forested stream bottom with dwarf palmetto and Spanish moss and a rolling savannah upland with scattered trees (Fig. 69). Analyses of surveyor records from the 1800s (Jurney 1987) and modern vegetational analyses also give insight into presettlement conditions on the Post Oak Savannah. An upland “post oak, blackjack oak, and hickory complex” was found extensively in Post Oak Savannah counties such as Freestone (Jurney 1987), but a variety of other vegetation types were also present (e.g., slope forest, floodplain forest, open prairie, closed prairie, and bottom prairie). Areas of xeric sandylands (MacRoberts et al. 2002b) and various bog and wetland habitats (MacRoberts & MacRoberts 1998e) found today undoubtedly reflect community types that were present long before settlement. For example, core samples from various bogs in the Post Oak Savannah indicate that these wetlands date back to near the end of the last glaciation (approximately 18,000–15,000 years ago) (Bryant 1977; Bryant & Holloway 1985a, 1985b). Further direct evidence about presettlement conditions comes from dendrochronological (tree-ring) research (see page 74 and page 125 for more details). Such studies indicate that old growth remnants of post oak-blackjack oak forest are present in a number of localities,
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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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62 INTRODUCTION/SOILS OF BLACKLAND
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Page 83 and 84: 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 107 and 108: 90 INTRODUCTION/CURRENT VEGETATION
Page 123 and 124: 106 INTRODUCTION/POST OAK SAVANNAH
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Page 147 and 148: 130 INTRODUCTION/BLACKLAND PRAIRIE
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Page 171 and 172: 154 INTRODUCTION/PRESENT AND FUTURE
Page 173 and 174: 156 INTRODUCTION/BIG THICKET THE BI
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Page 177 and 178: 160 INTRODUCTION/NATURAL HISTORY OF
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166 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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