That woody plant cover has increased substantially at expense of original pre-Columbian grass cover due to plus years of overgrazing and consequent reduction or complete cessation of fires is not contested by any knowledgeable, rational range student. It is the quantitative increase that is debated. Curly mesquite and red grama Bouteloua trifida are major species under continued close- and overgrazing as in this shot on a clay loam range site; tobosagrass is a less common dominant. The most common brush species represented here are blackbrush Acacia rigidula and guajillo A.
Not pristine, but typical Fair to Good range condition class. FRES No. Texas Savanna Ecosystem. K Mesquite-Acacia Savanna. This gravely ridge range site is an Acacia complex dominated by blackbrush, guajillo, and screwbean or huischillo A.
This vegetation is often regarded as guajillo ridge and mixed brush uplands. It is a major vegetation subtype of this brush-grass savanna. Chaparrosa Ranch, Zavalla County, Texas. Mesquite Disclimax Series of Brown et al South Texas mixed brush type— Another community of the varied Rio Grande Plains is this range vegetation subtype dominated by guayacan, Berlandier wolfberry Lycium berlandieri , and Texas persimmon Diospyros texana.
Bluewood or brasil Condalia obovata is a widely scattered associate.
The herbaceous understory which should be abundant on this sandy loam range site is limited to red grama, pappusgrass, and the toxic leather-stem or rubber-plant Jatropha dioica , a unique subshrub. SRM Mesquite-Granjeno-Acacia variant; this cover type is extremely diverse with numerous subtypes. Mesquite Disclimax Series of Brown et al. Vegetation typical of much of the Rio Grande Plains under better management not just a brush patch and likely also characteristic of the original legume shrub—mixed prairie savanna.
Live Oak County, Texas.
Huisache form of Mesquite Disclimax Series of Brown et al. Rio Grande Plains Mesquite-Huisache and Mixed Prairie Savanna—Current degree of use is heavy, but except for Texas wintergrass Stipa leucotricha and annual forbs like redstem filaree Erodium cicutarium forage species are dominant. Sparse mesquite and huisache with good cover of conspicuous proper grazing management. Atascosa County, Texas.
South Texas-Tamaulipan Plains Shrub Savanna- With exception of the naturalized buffelgrass Pennisetum ciliare , the tufts of grass in center foreground and at right margin, this is a classic composite shot of what is likely the climax or potential natural vegetation of the Rio Grande Plains. This relict area was sheltered from livestock grazing long enough to recover from range retrogression. Live Oak County, Texas, October after a severe drought.
Rio Grande Plains shrub-grass savanna- The Tamaulipan savanna or brushlands as it likely appeared before three- plus centuries of overgrazing by every species of livestock imaginable , fire suppression, trade routes, oil-gas development, etc. This is a closer view of the remarkably diverse range plant community shown in the previous landscape shot.
The two conspicuous shrubs are: guayacan shorter shrub on left and amargosa taller shrub on right. Live Oak County, Texas, October after severe drought. Mixed Decicuous Series of Brown et al. Apparent homogenity of general appearance physiogonomy and structure of the south Texas shrubland may be a reason why the Society for Range Mangement Shiflet, described only the Mesquite-Granjeno-Acacia rangeland cover type SRM for this farflung range area.
Another reason for this paucity of cover type titles and descriptions is likely that nobody saw fit to "write them up" or submit them for incluision in the official societal publication. Nonetheless, there are many different range plant communities that comprise Rio Grande Plains range vegetation. Many probably most of these range types, including some subtypes and variants of SRM , are disturbance climax types. This fact alone allows for essentially limitless variations in range vegetation.
Photographs show cottonseed oil mill. She was just becoming acquainted with Victor Hugo and his resounding, antithetic phrases, and his humanitarian outcries filled her mind with commotion. Aerial views of grounds, building, people. Two on Gold Flat. The jailer was inclined to allow Harold more liberty after his trial, but the boy said: "I'm not asking any favors from you. The only trees were cottonwoods and cutleaf willow, scattered scantily along the elbows in the river. Photo, Print, Drawing Junction, Texas.
There are, however, undoubtedly other range cover types that are climax vegetation especially when interpreted from the Tanslian polyclimax perspective. This includes cover types or, probably the most precise designation, subtypes within what has been called generally the "mixed brush type". Two of the more common forms, types, or, according to Scifres , p. Scifres , ps. Some of the most common grasses included Chloris and Paspalum species Scifres, , p. Thomas in Gould, , p. Gould , p. Based on usually brief reference accounts by various authors it appeared that grasses on range types and sites of the Rio Grande Plains brush ranges were less distinctive and diagnostic than major woody species.
In fact, the remarkable rarity of these two ubiquous woody legumes strongly suggsted that this was not an example of the typical brush-infested deteriorated range. Dominance by guajillo and cenizo was consistent with relative scarcity of mesquite and huisache and with the description cited above from Scifres , ps. Guajillo-mixed brush uplands- On this stoney ridge-sandy loam soil habitat a mixed shrub form of South Texas Chaparral was co-dominated by guajillo and cenizo dark-green, compound-leafed shrub at right and grey or silvery shrub at left background, respectively. Grasses were very sparse.
Most common Gramineae species were shortspike windmillgrass Chloris subdolichostachya and silver bluestem. The most common forb was the annual species Texas croton or tinajera Croton texensis. October, autumnal aspect. A diverse brush patch- Another view of range vegetation in the example of the guajillo ridges and mixed brush uplands subtype presented in the preceding slide. In addition to guajillo, cenizo, whitebrush, broom snakeweed, and Torrey croton visible in that photograph, this sample included Spanish dagger, Texas persimmon Diospyros texana , and agarito.
Cover and density of grass species were also greater than in the "photo-plot" of the preceding slide. The most common grasses and these were "few and far between" were silver bluestem and shortspike windmillgrass. Potential grass species were those that were present in strips of grassland vegetation maintained by mechanical treatment which was presented in the immediately succeeding photograph.
Will the real Rio Grande Plains savanna vegetation "please stand up"? Was the mechanically maintained grassland or the otherwise-present shrubland the real climax vegetation. Dominant grasses in the swath of grassland were shortspike windmillgrass and silver bluestem.
Also present was little bluestem, perennial threeawns of the Aristid purpurea complex, buffalograss, curly mesquite, reverchon bristlegrass Setaria reverchonnii , plains bristlegrass S. The following set of three photographs depicted the hardlands vegetation subtype of the Rio Grande Plains general mixed brush type. In describing this range vegetation Scifres , p. Dominant shrubs included blackbrush, guajillo, twisted acacia, and other Acacia spp.
Woody shrubs present in lesser proportions included Berlandier wolfberry, javelina bush, agarito, Texas persimmon, cactuses, Yucca spp. The extremely limited density, cover, and relative proportions of mesquite and huisache suggested that this range plant community was not just another example of an overgrazed, underburned, gone-to-brush, degraded range.
While density and cover of woody plants had almost assuredly increased from pre-Columbian conditions this was afterall Texas with its several centuries tradition of overuse and overgrazing of ranges , this "photo-quadrant" sample probably represented an example of more-or-less natural Rio Grande Plains savanna on a shallow caliche habitat.
The various references cited above for guajillo ridges and mixed brush uplands subtype also applied for the hardlands subtype with specific Gramineae species obviously varying by range site.
Hardlands Rio Grande chaparral- An extremely shallow, primarily clay soil that was overlaid by an interrupted calcareous layer caliche provided an edaphic environment conducive to development of a remarkably diverse range plant community. Guajillo and cenizo were the most abundant species, but there were not obvious dominants.
Rather this example of the hardlands chaparral subtype of "mixed brush" was mostly an "equal parts" mixture of knifeleaf condalia, Berlandier woldberry, cilindrillo or tomatillo, javelina bush, granjeno, agarito, Spanish dagger, blackbrush, myrtle-croton or southwest bernardia Bernardia myricifolia , and the cactus known variously as Texas or Englemann or Lindheimer pricklypear Opuntia englemannia var.
There was an herbaceous understorey made up almost exclusively of buffalograss.
Rio Grande Plains mixed shrub-shortgrass savanna- Range vegetation portrayed here represented the deciduous shrub-mixed prairie savanna in something resembling what was interpreted by prominent ecologists Kuchler, , p. Shrubs were almost certainly somewhat more plentiful than in the virgin vegetation, but this was about as good an approximation as can usually be found. The herbaceous understorey was a consociation of buffalograss. Past overgrazing may have greatly reduced less grazing-tolerant grasses like little bluestem, silver bluestem, sideoats grama, pink pappusgrass, and bristlegrasses leaving an herbaceous layer consisting exclusively of a shortgrass species.
Buffalograss might likely have been the predominant --though not the only-- grass even in pristine condition on this shallow clay soil. Physiogonomy, species composition, and range community structure appeared to approach what was described as virgin range vegetation. This example of the hardlands subtype of Rio Grande Plains savanna matched closely the description of Class 2 of the Texaas Savanna Ecosystem given by Garrison et al.
The range vegetation presented in this present photograph and in the close-up photograph immediately below matched closely the vegetation in the photograph used by Kuchler , p. The example shown by Kuchler , p. Interior of hardlands subtype of Rio Grande Plains mixed shrub chaparral- Close-in view of Tamaulipian Thornscrub vegetation that developed on a caliche outcrop, shallow, clay soil in South Texas Plains vegetational area.
Herbaceous layer was a consociation of buffalograss. It was likely that taller, less grazing-tolerant grasses like little bluestem, silver bluestem, sideoats grama, and plains bristlegrass had been reduced to near elimination by overgrazing, but there was no scientific proof of such range retrogression. Conspicuous shrubs were nopal or Texas or Lindheimer pricklypear and Spanish dagger. Other woody species included granjillo, Berlandier wolfberry, agarito, knifeleaf condalia, cenizo, granjeno or spiny hackberry, and javelina bush.
The first two of these three images presented in this unit showed the overall or synopsis view of the classic "south Texas mixed brush type", a man-made range type resulting from various combinations of overgrazing, underburning, cultivation, transportation, i. Most abundant forbs were bristleleaf dogweed Dyssodia tenuifolia and western ragweed Ambrosia psilostachya.
Grasses were limited but the main species included Hall's panicgrass Panicum hallii subsp. The third image presented a closer-in view of fewer plant species including Lindheimer's pricklypear, blackbrush, guajillo, guayacan, leatherstem, western ragweed, Hall's panicgrass, red grama, and silver bluestem. This range vegetation was an example of the Rio Grande mixed brush-grass savanna that had gone mostly to shrub cover ie.
Yes, the vast majority of Texas range--in all vegetational or land resource areas--is brush-infested Scifres, , ps. This is the epitome of brush invasion and noxious range plant communities. Furthermore, it has been shown by many studies and now widely recognized that grassland or grass-shrub savanna range in the Rio Grande Plains that through human action or inaction has been converted to brush woodlands that become "steady states" much like the pre-Columbian climax grasslands or shrub savannahs Hamilton et al.
Actually, it was relatively early in Range Management education and our understanding of range degradation that the static nature of Rio Grande Plains brushlands was described and regarded as human-induced vegetation. Specifically, this more-or-less permanent state of retrogression became textbook knowledge by the second edition of the classic McGraw-Hill text, Plant Ecology Weaver and Clements, These two giants of early plant succession wrote that while this range vegetation " The "proclimax associes" was terminology of the then-prevalent Clementsian monoclimax theory. In this context, the Rio Grande Plains brush community was most specifically a "disturbance climax" or, simply, "disclimax" Clements, , p.