Shinnery Oak

(Sand Shinnery Oak Scrub)

The sand shinnery oak cover type (SRM 730) is climax vegetation. It is a semiarid shrubland (vs. arid or desert shrubland or scrub) much like the various climax chaparral types in the California Mediterranean climate region and at least some of the encinal shrublands of the southwestern mountains in the Mogollon Rim and Trans Pecos areas. In strict ecological terms (ie. successional status), sand shinnery oak (Quercus havardii) as a species and/or species-dominated community is not an invader or deteriorated range. Shinnery oak scrubland is not the ecological equivalent of overgrazed grasslands or shrub steppe savannas or abandoned old fields ("go-back land") that became depleted ranges dominated, for example, by honey mesquite (Prosopis glandulosa) or big sagebrush (Artemesia tridentata).

In other words, sand shin oak in natural, climax shrubland can be viewed and managed as brush (by definition undesirable woody plants based on management and/or ecological standards) only from the perspective of socioeconomic goals (ie. shin oak scrub can be converted to grassland-- or at least it's cover reduced to allow more grass production-- in order to produce more commodities like beef or, for that matter, certain wildlife species). Designation of sand shinnery oak, a climax species, as a woody weed or noxious range plant is limited to the economic (or human cultural) standards of forage production (or "more cows") and cannot be applied by the criterion of deteriorated range with woody plant invasion except under precisely defined conditions.

These biological standards or ecologic/economic facts (established by range researach and related ecological studies) clearly stated, it must also be underscored that many, if not most, sand shinnery oak-dominated communities have had increases in relative abundance (cover, density, etc.) of this dominant, defining species due to human influence. Many shinnery oak ranges currently have ecologically excessive proportions of shin oak (in excess of that of pristine, natural, virgin, pre- white man, or whatever) due to improper management. The most common of these mismanagement practices probably has been post-settlement changes in the natural fire regimen under which this ecosystem evolved. The most obvious of these has been the reduction of fire frequency: in most cases, the total elimination of fire. This was due largely to human fear of fire (that too is probably "natural") which in Texas for example was institutionalized by laws that since on-set of the settlement era forbid the setting of fires for purposes of "burning-off" forests and all kinds of range.

On sand shinnery oak ranges where oak cover has become excessive-- for whatever reason(s) --restoration of the natural vegetation and ecosystem structure and function requires reduction of this excessive oak canopy. In this context, shinnery oak populations that exceed natural (= climax) proportions are brush in the ecological (as well as economic) sense. In these situations proper, wise use management is synonymous with classic brush control methods. Application of herbicides and prescribed fire have been two of the most commonly used and effective of these methods. The general management objective is reduction of oak cover for the specific purpose of increasing that of native herbaceous plants, most of all indigenous tallgrasses that are major associate species of the potential natural (= climax) vegetation. Examples of these were shown and discussed below. This not only increases beef production through higher stocking rates but may also benefit native animal species like the lesser prairie chicken (Tmpanuchus pallidicinctus), depending on degree of shinnery oak control (proportion of oak canopy remaining).

Proper management of shinnery oak scrub range is reduction of oak not elimination(ie. brush control and not eradication). Complete elimination of shinnery oak (= eradication) is probably not possible without continuing intensive management inputs and it is mutually exclusive of managing shin oak ranges. Destruction of the shinnery oak ecosystem and replacement with domestic field crops, including introduced pasture grasses (or with non-native grasses managed as if they were native) is grazing-type conversion. Type conversion is the changing of one grazing type, shinnery oak rangeland cover type in this case, to another grazing type. The most commonly practiced conversion of sand shinnery oak range is to the introduced perennial, weeping lovergrass (Eragrostis curvula). Weeping lovegrass as an introduced range species was covered under Introduced Forages, Grassland.

One of the conspicuous aspects of the sand shinnry oak range ecosystem is the considerable variation in physiogonomy and diversity in proportions (relative cover) of the few dominant and associate species of local plant communities in this range cover type. This undoubtedly reflects edaphic variation to a large degree. Even though the key adjective "sand" applies to essentially all soils of this general range ecosystem (range cover type) there are different range sites within the general shin oak dominance type. In more eastern parts of the sand shinnery oak range type post oak (Quercus stellata) is an associate woody species. On some of these more easterly shinnery oak ranges post oak hybridizes with shinnery oak resulting in a third distinctive taxon, Q. havardii X Q. stellata (Correll and Johnston, 1979, p.478). On rangeland where all three of these Quercus taxa occur the physiogonomy is distinctive and drastically different from that where Q. havardii is the sole oak taxon.

The physiography and local topography (meso- and micro-relief) create another source of varability among different sand shin oak ranges within the general sand shinnery oak ecosystem. This obviously accounts for some of the edaphic variation, but there are general topographic differences between the Rolling Plains (= Rolling Redlands) and Southern High Plains (Staked Plains or Llano Estacado) sections of the Great Plains physiographic province. The sand shinnery oak rangeland cover type is found on both of these physiographic sections.

Still yet another source of variation among sand shinnery oak range vegetation is that due to a vegetational mosaic of 1) shinnery oak scrub (shrubland), 2) tallgrass or mixed prairie grasslands, and 3) a savanna of shinnery oak (and associated shrubs) and climax grass species, most notably sand bluestem (Andropogon hallii= A. gerardii subsp. hallii) in the ecotone between the former two range plant communities (rangeland cover types). Frequently all three of these climax range plant communities developed and persist in close proximity. In turn, this patchwork of native vegetation has been altered to varying degrees by management (and mismanagement) practices including proper (and improper) livestock grazing, shrub control (cover and density reduction, usually by chemical means), and type conversions (especially to anthropogenetic grasslands of introduced species).

Examples of sand shinnery oak range (and variation therein) across much of the spectrum of this rangeland ecosystem and cover type were presented below.

1. Sand shinnery oak (Quercus havardii) dune type- Some sand sagebrush and even broom snakeweed (Gutierrezia sarothrae) plus sand bluestem and little bluestem are present but "shin oak" is the clear dominant, essentially a consociation, of this climax ecosystem. This is the classic or textbook form of the sand shinnery oak range type.

FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). High Plains- Shinnery Sands Ecoregion, 25j (Omernik and Griffith, 2006). Chaves County, New Mexico. June, estival aspect.

2. Inside a shinnery oak community, or more like a colony of shin oak- Shin oak seen here may be somewhat thicker that true climax type. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al.(1998). Central Great Plains- Red Prairie Ecoregion, 27h (Woods et al., 2005). Beckham County, Oklahoma. June, estival aspect.

3. An example of what pristine shinnery oak scrub probably resembled—Scrub oak (which can include shin oak X post oak hybrids as well as shinnery oak) was likely kept more open due to recurrent fires that reduced oak cover and competitively benefited the bluestems. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Central Great Plains- Red Prairie Ecoregion, 27h (Woods et al., 2005). Beckham County, Oklahoma. June, estival aspect.

4. Climax sand shinnery oak cover type (non-dune form) at landscape-scale- Physiogonomy of shin oak scrub generally remains consistent except for that due to differences in stature among clones and taxa of oak within this range type. Land form (eg. level plain vs. rolling or choppy sand dunes) is responsible for some variation in overall apperance. This slide showed a relatively large expanse of shin oak with considerable intracommunity variation in appearance on land of sandy soil but level topogaphy that is more typical of the High Plains than the dunes shown above. Some of the variation in color and height of the scrub shown here was due to different clones (= genotypes) and taxonomic groups (shinnery oak vs. shinnery oak X post oak hybrids, see immediately below) while other variation was caused by presence of other woody plant species. Shrubs and/or small trees besides oaks included netleaf hackberry (Celtis reticulata= C. laevigata var. reticulata), skunkbush sumac (Rhus aromatica= R. trilobata), wild sand plum (Prunus gracilis) and, especially on deep sand, sand sagebrush (Artemesia filifolia).

There were very few openings among the shrubs that supported herbaceous species and there was no understorey beneath the shrubs (explained below).

The tallest clumps or mottes of oak, like the one in left midground, were shin oak X post oak hybrids (Quercus havardii X Q. stellata). Shinnery oak does not usually attain heights exceeding approximately a yard or meter. Taller oaks within the shin oak scrub community are hybrids between shin oak and various other oak species depending on general area. In western parts of it's biological range Q. havardii hybridizes with Mohr's oak (Q. mohriana), Gambel's oak (Q. gambelii), or wavyleaf oak (Q. undulata). In eastern protions of it's range shinnery oak hybridizes with post oak, a dominant of the Cross Timbers and parts of the western oak-hickory forest as in the Ozark Plateau. These various hybrids reach heights of two to four yards (meters). Two ultimate definitive sources for details of this aspect along with general coverage of the shinnery oak ecosystem are Peterson and Boyd (1998) and Dhillion and Mills (Chapter 16, esp. p. 263) in Anderson et al. (1999). For discussion of management and a general summary of shin oak range, including reduction of woody cover to increase forage production, the short treatment by Pettit (undated) was highly recommendated. This brief summation of the shinnery oak range type is one rangeman's career work and in a league by itself.

Wheeler County, Texas. Estival aspect, June. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Shinnery Sands High Plains Ecoregion, 25j (Griffith et al., 2004).

5. Shinnery oak scrub- Vegetation consisting of clonal mottes of shinnery oak and shinnery oak X post oak hybrids (taller, more robust clumps) with "openings" populated by sand bluestem (Andropogon hallii), giant dropseed (Sporobolus giganteus), and Indiangrass (Sorgastrum nutans). Sand dropseed (S. cryptandrus) was present but less abundant than these threee tallgrass species. Sand bluestem was the large grass-growth in foreground.

The colonal feature and characteristics related to populations of sand-shinnery oak were presented by Mayes et al. (1998). This morphological and genetic aspect has received more study than in other clonal oaks such as Gambel's oak (Quercus gambelii).

Wheeler County, Texas. Estival aspect, June. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Central Great Plains- Red Prairie Ecoregion, 27h (Griffith et al., 2004).

6. Composite of vegetation of sand shinnery oak community- Two views of progressively more detailed focus on species composition of shin oak shrubland. The first slide was a partial fenceline contrast with a routinely mowed highway right-of-way in immediate foreground and an untreated (no mowing, burning, spraying, or livestock grazing) sand shin oak scrub behind the mowed corridor. Ecological status of shinnery oak and associated grass-dominated vegetation was discussed below, but in the upper photograph the presence of tallgrass species (sand bluestem, giant dropseed, and Indiangrass) in a mowed area that was surrounded by a shrub-dominated area gave readers a comprehensive view of the potential natural vegetation of this rangeland cover type.

Shrub species were those listed above: shinnery oak, sand sagebrush, netleaf hackberry, skunkbush sumac, and wild plum.

The second slide was a "closer-in" view of the woody species make-up of this sand shinnery scrub. At local scale of this deep sand microsite sand sagebrush was the associate species with skunkbush, wild plum, and netleaf hackberry subordinate species. Within large communities of shinnery oak shrubland there are smaller communities dominated by sand sagebrush. Sand bluestem and, to a lesser degree, giant dropseed were the unifying or "common denominator" species across both shrubland cover types.

Wheeler County, Texas. Estival aspect, June. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Central Great Plains- Red Prairie Ecoregion, 27h (Griffith et al., 2004).

Note:. At overall landscape-scale in this general area of the southern High Plains there was a vegetation mosaic of sand shinnery oak cover type (SRM 730) interspersed with rangeland cover types SRM 722 (Sand Sagebrush-Mixed Prairie) and SRM 720 (Sand Bluestem-Little Bluestem Dunes) which can be seem herein under Miscellaneous of Shrublands and Mixed Prairie of Grasslands, respectively. Along margins of this landscape-scale mosaic there were other range cover types of mixed prairie and shortgrass plains as well as the postclimax tallgrass prairie dominated by sand bluestem which is the "pure grass" variant of SRM 720.

7.Revealing view of sand shinnery oak vegetation- In addition to sand shinnery oak, shinnery oak X post oak hybrids were conspicuous as four individual taller shrubs each having a single bole. Several individual plants of sand bluestem at peak standing crop and anthesis appeared prominently in foreground accompanied by small individuals of sand sagebrush.

Motley County, Texas. Estival aspect, August. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Southwestern Tablelands- Flat Tablelands and Valleys Ecoregion, 26b (Griffith et al., 2004).

8. Species-rich sample of sand shinnery oak plant community- Sand shin oak had shrub escorts of sand sagebrush and skunkbush sumac (Rhus trilobata= R. aromatica) and the dominant herbaceous species, sand bluestem, was accompanied by little bluestem, giant dropseed, sand dropseed, Wright's threeawn (Aristida wrightii= A. purpurea var. wrightii), and sand paspalum (Paspalum stramineum= P. setaceum var. stramineum). Dominant forb was western ragweed (Ambrosia psilostachya).

Motley County, Texas. Estival aspect, August. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Southwestern Tablelands- Flat Tablelands and Valleys Ecoregion, 26b (Griffith et al., 2004).

9. Flowering shoot of sand bluestem- The dominant herbaceous species at stage of anthesis on a sand shinnery oak range in climax (or close to it) state. When the mature shoots of sand bluestem do "lay down" under their own weight they are often taller than sand shinnery oak. Motley County, Texas. August.

10. Sand bluestem blooming- Panicles of Andropogon hallii at anthesis. The individual branches of the panicle are rames, inflorescence branches bearing some sessile and some pedicellate spikelets.On sand shinnery oak range. Motley County, Texas, August.

11. Basal shoot of sand bluestem- Individual shoots (tillers) of sand bluestem arisinig from its long, stout rhizome ("rootstock") on a sand shinnery oak range community. Motley County, Texas. August..

12. Sand paspalum (Paspalum stramineum= P. setaceum var. stramineum)- Specimen of sand paspalum growing on sand shinnery range ecosystem. Sand paspalum is often an associate herbaceous species to the dominant herb, sand bluestem. Motley County, Texas. August.

13. Inflorescence of sand paspalum- Branches of panicle in sand paspalum complete with caryopses. Motley County, Texas. August.

14. Interior of a clone of sand shinnery oak- Shinnery oak (and other scrub oak species like Gambel's oak) is a clonal or modular plant much like quaking aspen (Populus tremuloides) or buffalograss (Buchloe dactyloides). Each of the shoots the individual shrub boles, is a limb or branch from the underground "trunk" of the individual genotype or genetic organism. Each of these individual shoots is a ramet or module (= a clone) of the genet, the genetic individual. Each of these complete genets (= genotypes) appears as a motte or "thicket" with each of these in turn often coalescing into an entire sand shinnery oak-dominated community of great size.

"Inside" a sand shinnery oak clone the ground surface is typically covered by shed oak leaves and there are few if any other vascular plant species (ie. there is no understorey in a shin oak "thicket" ). Of course, lichens grow on bark of shinnery oak and species of fungi use fallen oak leaves as nutritive substrate. The absence of an understorey beneath shin oak (ie. the characteristic single layer of vegetation) was shown in this photograph.

Wheeler County, Texas. Estival aspect, June. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Central Great Plains- Red Prairie Ecoregion, 27h (Griffith et al., 2004).

15. Re-establishment of native grasses and forbs as components of sand shinnery oak range ecosystem- Re-population of tallgrass and composite species occurred within a shinnery oak-dominated community where highway mowing controlled shrubs. Woody plant species included netleaf hackberry (tallest shrub, right background), sand sagebrush, skunkbush sumac, and wild plum as well as the dominant sand shinnery oak.

Distrubances like defoliation by fire and perhaps heavy browsing by native species (many now extinct), drought, and diseases as well as death at old age or senescence of shin oak clones left bare spots (patches) that could be colonized by other species (typically grasses). This is an example of patch dynamics that partially explains the heterogenous character (albeit very limited) of the shinnery oak ecosystem. Reduction of shinnery oak cover by natural disturbances or similar brush control (= reduction of woody plant cover deemed to be undesirable) practices like prescribed fire, herbicide application, or mechanical treatment allow reinvasion by other native species like the climax tall- and mid-grass species or forbs.

The frontal view of the fenceline contrast shown here illustrated this vegetation development phenomenon. Shredding by use of rotary mowers of vegetation on the highway right-of-way eliminated (at least reduced) shinnery oak thereby enabling the native grasses to outcompete and gain dominance of this treated land. Major grasses were Indiangrass (light-colored or gray-green), giant dropseed (darker green), and sand bluestem (less abundant in this local spot).

Wheeler County, Texas. Estival aspect, June (grasses reduced in size and at kept at premature phenological stage by mowing earlier in growing season). FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Central Great Plains- Red Prairie Ecoregion, 27h (Griffith et al., 2004).

16. Opening dominated by sand bluestem within a sand shinnery scrub community- Shredding of shin oak the previous season allowed this native tallgrass species to regain dominance in a patch within a sand shinnery oak range cover type. Both shin oak and sand bluestem are native climax species with local dominance or relative cover of one or the other being a function of defoliation disturbances.

Both natural (not influenced by man) and scientifically managed shinnery oak ecosystems are patchworks of openings with herbaceous (largely grass) species and shin oak-populated spaces some of which are "solid" stands of "pure" oak while others are oak-dominated-- but sparsely oak-populated-- diverse communities.

Wheeler County, Texas. Estival aspect, June. (In contrast to phenological development of mowed grasses shown in the preceding slide, this sand bluestem had not been mowed in the current growing season.) FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). Central Great Plains- Red Prairie Ecoregion, 27h (Griffith et al., 2004).

17. Shinnery or shin oak- The dark color of shin oak leaves after a hot, dry Texas summer. Mitchell County, Texas, October.

18. Sand shinnery oak (Quercus havardii)- Leaves and fruit (acorns) of sand shinnery oak in early summer. Wheeler County, Texas. Estival aspect, June.

The following series of slides were of a range of sand shinnery oak shrubland on which shinnery oak formed a nearly single species plant community (hence, more a population of shinnery oak) though with sand sagebrush (Artemisia filifolia), soapweed (Yucca glauca), and broom snakeweed (Gutierrezia sarothrae) as associate shrubs while sand bluestem and little bluestem were herbaceous associates. It appeared as if past disturbance (most likely drought and livestock overgrazing) had resulted in reduced herbaceous cover and increased cover of sand shinnery oak.

This successional state (and range condition class of high Fair to low Good) was typical of sand shinnery oak-grass scrubland. It was an example of the sand shinnery oak range type that was capable of continuing secondary plant succession and progression toward increased cover of decreaser (climax) grass species and development into the potential natural plant community or climax state of the sand shinnery oak ecosystem.

Images from this range provided three landscape-scale perspectives and four interior views, these latter of which showed mid-scale topography and species composition.

19. Shinnery oak as far as the eye can see- Physiogonomy and structure at landscape-scale of a sand shinnery oakrange at the western edge of the Southern Great Plains (High Plains, Llano Estacado or Staken Plains). Although this was a consociation--a natural climax plant community--the relatively high cover (foliar and basal) of shinnery oak relative to herbaceous cover was interpreted by the author as excessive, a departure from the natural or potential range plant community. major herbaceous species were sand bluestem and little bluestem. Sand sagebrush was the main woody associate with soapweed or soapweed yucca and broom snakeweed present though less abundant.

This was a Sandhills range site in which sand and little bluestems along with lesser cover of red threeawn (Aristida longiseta) and sand paspalum were important components of the climax range vegetation. The comparatively low cover and herbage standing crop of these grass species indicated that this range was in some state of degradation (departure from climax). Hence your author guaged this scrubland range to be in high Fair to low Good range condition class. As shown below, however, there were enough remnant, vigerous plants of these grasses that natural range improvement via secondary plant succession was still possible. In fact, given the current light degree of use by cattle (= conservative stocking rates) range recovery was evident--and shared with viewers (see shortly below).

Given ongoing recovery of range vegetation and the immense expanse (horizon-to-horizon) of this sand shinnery oak scrubland, this range was a source of imspiration and a testament to natural resource conservation. A well-earned tip of the hat to this obviously conscientious steward of range resources. Salute!

Chaves County, New Mexico. Late June, early estival aspect (prior to onset of summer rainy season). FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). High Plains- Shinnery Sands Ecoregion 25j (Griffith et al., 2006).

20. Not as flat on the inside - Interior of the sand shinnery oak range introduced in the three immediately preceding slides. At smaller spatial scale (closer camera-distance) the characteristic hummocky topography of this climax shrubland that developed on low sand dunes became apparent. In the foreground of this low sandhill or hummock soapweed yucca (left) along with little bluestem and red threeawn (center and right) shared the deep sand with sand shinnery oak.

Patches of bare soil interspersed with the predominant space plant-covered soil was most likely a natural arrangement that resulted in a mosaic pattern of this native vegetation that served as range for species ranging from beef cattle to lesser prairie chichen (Tympanuchus pallidicinctus) to various invertebrates.

21.Not as uniform as it appeared- In the "deep core" of the sand shinnery oak range being reconnoitered in this section range plant species of much less cover and biomass were more obvious. Plants of sand sagebrush, sand bluestem, and little bluestem were present in these two 'photo-plots". This was more the case for the closer camera view of the second slide where a fine specimen of still-mostly dormant sand bluestem adorned center foreground with plants of sand sagebrush in front of and behind it. Relative proportions of cover of sand sagebrush and the two bunchgrass bluestem species were presented in the first slide to show a representative sample of species composition and structure of this shrubland range community.

Given relative cover of grass species compared to that of sand shinnery oak it was apparent that some range retrogression (departure from climax vegetation) had taken place on this scrub range. It was also apparent that with this much cover of vigerous plants of climax (decreaser) grasses, range improvement--measured as upward range trend--was possible. On this range that had recently (and was currently being) lightly grazed by beef cattle, range restoration through the process of secondary plant succession was highly probable. Degree of use on this range served as an example of proper grazing management for the goal of range improvement and wise use of range and ranch resources. This was a textbook example of range conservation.

22. Potential for range improvement- Large robust specimen of sand bluestem (with a young plant of broom snakeweed to its left rear) growing on the high fair to low Good range condition class sand shinnery oak range being featured in this section.

23. Insuring enough images- General view of sand shinnery oak foliage with abundant acorn crop (first slide) and closer view of three acorn-bearing leaders (woody shoots or branches) of sand shinnery oak (second slide) that grew on the high Fair to low Good range condition class sand shinnery oak range featured in this section.

This was an extraordinarily heavy acorn crop that blessed human onlookers--including those studying this book--as well as mast-feeding range brutes, both vertebrate and invertebrate.

Chaves County, New Mexico. Late June; growing-maturing fruit stage of phenology.

24. The skinny on shinnery oak- Leader of sand shinnery oak with two acorns (first slide) and a close-up view of those two acorns (second slide) that grew on the sand shinnery oak scrub range featured in this section. Quercus havardii is in the white oak group (Leucobalanus subgenus) members of which take only one year or growing season to produce mature acorns (versus two years for the red oak group). Heavy acorn crops are not an uncommon phenomenon for sand shinnery oak-- and this mast (fruit of woody range plants) is a very valuable concentrate for most range animal species.

Chaves County, New Mexico. Late June; growing-maturing fruit stage of phenology.

25. Small but adaptable- Smallflower or Nuttall's milk vetch (Astragalus nuttallianus) graowing on one of the many harsh microhabitats it calls "home". Several small, pre-bloom plants of smallflower milkvetch were growing on the dry, deep sand of the sand shinnery oak range treated in this short section. Smallflower milkvetch was the most common forb on that range. Given the early phenological stage of milkvetch plants growing in the sand shinnery oak range community the author "burrowed" some slides of this widely distributed species that was growing on a shallow, rocky environment on the Grand Prairie in northcentral Texas.

Astragalus nuttallianus has a species range extending from Oklahoma westward to California and from Utah south to Durango, Mexico with nine or more taxonomic varieties (Correll and Johnston, 1979, p. 850). Allred and Ivey (2012, p. 310) described "four intergrading varieties" of A. nuttallianus in New Mexico. Smallflower or Nuttall's milkvetch is an annual, often a cool-season annual (Correll and Johnston, 1979, p. 849; Allred and Ivey, 2012, p. 310) that is often dimunitive in size.

Erath County, Texas. Early May; full-bloom and young fruit stages.

26. One at home on the shinnery sands (and on other homes)- Upper shoot (first slide), cluster of papilionaceous flowers (second slide), and inflorescence and immature legumes (third slide) of smallflower or Nuttall's milkvetch, a small (dwarf-like) annual Astragalus species that makes its home on varied--though usually harsh--microhabitats. Littleflower milkvetch was the most common forb on a large sand shinnery oak shrubland on the western Llano Estacado (Staked Plains) in southeastern New Mexico.

It was explained in the preceding caption that specimens of Nuttall's milkvetch found on that sand shinnery oak range ecosystem were still in their immature growth stage such that your author was compelled to "transplant' images of this species that was growing in the Grand Prairie of northcentral Texas (fittingly enough on a stoney, shallow soil).

Erath County, Texas. Early May; full-bloom and young fruit stages.

The following series of slides was taken on a range of relict climax (actually, postclimax) or potential natural vegetation on two range sites the soils of which were deep sand. One of these range sites consisted of low sand dunes while the other was of more nearly level or typical High Plains topography. Climax range vegetation on the low sand dunes site was sand shinnery oak-sand bluestem scrubland. The climax plant community on the more level or very gently sloping sand was sand bluestem-little bluestem tallgrass prairie. There was a transition zone--an ecotone--between these two distinctive climax range plant communities that was a sand shinnery oak-sand bluestem savannnah. Past application of tebuthiron reduced cover of shinnery oak except on the deeper sand of the low dunes. This chemical control treatment--in conjuction with improved grazing management--had been a factor that aided restoration of this range which had been previously overgrazed by cattle. This and adjoining ranges on this ranch were being managed for restoration of the lesser prairie chicken (Tympanuchus pallidicinctus).

The range vegetation was pristine. It was interpreted as postclimax vegetation (in the Clementsian monoclimax theory) because soil-moisture storage (Clements' chresard) was greater than the moisture-capacity that was typical for most soils in this semiarid precipitation zone.

27. Landscape-scale scope of sand shinnery oak scrubland- Panarama of sand shinnery oak range on the Llano Estacado, the Staked Plains, as Clovis Man and Conquistadors likely saw it. This range vegetation was on low dunes of deep sand where sand shinnery oak generally dominated the plant community to such degree as to exclude almost all other species. Greater water-holding capacity of sand on this range site in this semiarid region created an edaphic climax that was postclimax to the general vegetation (monoclimax) of mixed prairie. Specific climax vegetation on this specific range consisted of three potential natural plant communities: 1) sand shinnery oak scrub, 2) tallgrass prairie, and 3) sand shinnery oak-tallgrass savanna, the ecotone of the former two range plant communities. Examples of these three were presented below.

This photograph was taken under an overcast sky and provided a good example of why slow film like Kodachrome 64 needs (certainly does best)under full-sun. (More examples of this situation included immediately below).

28. Major players in the sand (full sun shots)- Two photographs of range vegetation in the interior of a climax (postclimax) sand shinnery oak scrubland community that developed on deep sand on the Southern High Plains (Staked Plains). Sand shinnery oak was the obvious dominant species, but sand bluestem was a strong associate species. Sand sagebrush (conspicuous in both of these slides) was a far-distant associate shrub species that was clearly secondary to sand bluestem, the overall associate. There was also substantial cover of little bluestem and sand dropseed (Sporobolus cryptandrus) locally (in microsites) within the sand shinnery oak-dominated scrub.

It must be remembered when contemplating and estimating productivity and standing crop at a point in time that shrub species have aboveground perennial (woody) shoots whereas herbaceous species like sand bluestem have only annual shoots. In other words, much of the aboveground oak biomass (other than leaves) visible in these slides is the accumulation of many years' growth while almost all herbaceous biomass was produced in the current year (only one growing season's production). Thus, dominance of this range plant community by shinnery oak is not as great or to the degree that it superficially (surfacially) appears. Furthermore, it is generally acknowledged (based on limited research) that herbaceous perennials, especially grasses, produce a proportionately greater quantity of their currrent annual production (net primary productivity) in roots as compared to shoots than is the case for woody plants. When used as rough indications of dominance based on cover and biomass (standing crop of herbage and browse) snapshots of range vegetation underestimate herbaceous plants or, same thing, overestimate woody components of vegetation.

These two photographs were full-sun shots (in contrast to the immediately preceding and the two immediately succeeding photographs taken under an overcast sky) that portrayed plant species composition of this range vegetation to good advantage. Comparison of these two slides with those taken with overcast conditions clearly illustrated why full-sun shots are superior when using high-quality slow-speed film like Kodachrome.

29. Major players in the sand (overcast shots)- Two photographs of the same sand shinnery oak scrubland as shown in the two preceding slides except that these shots were under an overcast sky. Sometimes light-colored plants such as shoots of dormant bluestems and dropseeds show up more clearly under dimmer light. This is due to the photographic phenomenon whereby bright light of full-sun exposure "bleaches out" lighter browns tans, greys, and white (as in the "silver" coloration of bluestem awns). For this reason photographers welcome the opportunity to take photographs under both a cloudless sky and a cloudy (at least a somewhat overcast) sky. Such an opportunity existed on occasion of this visit to this relict range vegetation. Photographs under both light conditions were presented here and in photographs above and below.

The dominant grass was the decreaser tallgrass species, sand bluestem, which was the overall associate plant species to the dominant sand shinnery oak. Other common grasses included little bluestem, sand dropseed and sand paspalum. Other major shrub species included sand sagebrush and broom snakeweed.

30. Patches of sand shinnery oak scrub- Two photographs of sand shinnery oak scrub on deep sand of low dunes of the Llano Estacado (Staked or High Plains). The associate species was sand bluestem. The first of these two slides presented a view of the heights or "humps" of the sand dunes with a depression (midground) situated within higher parts of dunes. The second of these two slides presented the local range vegetation on the top of a dune.

The soil of this duneland complex was primarily Tivoli, a series conosisting of almost pure sand up to depths of five feet. This is a textbook example of an edaphic basis for range vegetation that is postclimax. Tivoli will frequently hold so much water that one can literally squeeze out this liquid as if from a sponge. In this semiarid range area having an average of 17 inches of annual precipitation the enhanced water-holding capacity of Tivoli soil results in an edaphic-determined habitat of closer to 25 inches average precipitation (Russ Pettit, personal communication). This is primary basis for a shrubland range community developing in a region where the zonal rangeland community (the monoclimax) is mixed prairie or shortgrass plains grassland.

31. Shinnery oak shoots, new and old- A portion of dead shoot with attached root of sand shinnery oak (center foreground) that had been exposed by wind erosion was surrounded by live shinnery oak shoots. This close-in shot revealed a common feature of shinnery oak colonies on sand dunes. From a distance (sometimes even eye-level when standing) a stand of sand shin oak appears rather dense, but at closer glance (say, eye-level when kneeling or squatting) the extent of soil surface not under foliar cover of oak shoots becomes glaringly obvious.

This degree of uncovered land surface is the area of soil surface exposed to erosional agents, especially wind, and available for colonizing by other plant species. The extent of openness of the land surface is also the space available for travel by certain animal species such as the lesser prairie chicken, the main range animal for whose restoration this range was being managed.

32. Dune rolls- Gently rolling relief of duneland supporting postclimax sand shinnery oak range. Larger view of low sand dunes from atop highest point (foreground) descending off to a depression or low point in the dune complex (right midground). This was a consociation of sand shin oak with but occasional plants of sand bluestem and even fewer individuals of sand paspalum, little bluestem, and sand dropseed.

This rangeland landscape provided an example of units (hierarchial levels) of range vegetation from range types through range sites down to range microsites. Forground and close midground vegetation was sand shinnery oak scrubland on low sand dunes of Tivoli soil. Background vegetation was sand bluestem-little bluestem tallgrass prairie. Distant midground vegetation was an ecotone (transition zone) between the shubland and grasssland types that was a shinnery oak-bluestem savanna. These three range plant communities were range types, the largest-scale range plant communities. There was generally only one range site within each of these range types. The basin or depression within the dune complex was a local or microsite (= microhabitat).

Details of the depression or basin in these dunes was featured in the next slide.

33. Depression in the dunes- Close-up view of the low-lying microsite (a basin or depression) introduced in the immediately preceding slide. The small patch of bare soil (sand) in bottom of this depression area or basin suggested wind erosion. This small blowout appeared to be of relatively little importance except that it provided a favorable microhabitat for sand bluestem (larger specimens of bunchgrass) and little bluestem (smaller individuals of bunchgrass form).

The next four photographs (presented as two two-photographic caption sets) presented postclimax range vegetation moving progressively outward from a sand shinnery oak scrubland ecosystem on a dune complex to sand bluestem-little bluestem tallgrass prairie ecosystem with an ecotonal sand shinnery oak-sand bluestem savanna that developed between scrub and grassland range communities. All this range vegetation.was postclimax in a semiarid region of the Llano Estacado (Staked or Southern High Plains) where the zonal or regional (climatic climax) vegetation was mixed prairie, the monoclimax of the region.. Increased water-holding capacity (enhanced chresard) of soils was the major factor responsible for postclimax phenomenon. This is a textbook case of the Clementsian monoclimax theory (Clements, 1916; Clements, 1920; Weaver and Clements, 1938).

Alternatively in the Tanslian polyclimax theory (Tansley, 1926) each of these three general range cover types could be viewed simply as climaxes in their own right, most logically edaphic climaxes. The polyclimax perspective is obviously most consistent with recognition of different soil series and range sites based thereon, the Dyksterhuis (1949) theory and method for determing range condition (range condition/trend analysis).

The third perspective in which to view this rangeland vegetation is as or by the climax pattern theory of Whittaker (1953) in which relative proportions of shinnery oak, bluestems, and various forbs (annuals, biennials, perennials were all represented in this vegetation) had developed along gradients of various habitat factors, including soil moisture levels. Patterns reflecting gradients of soil water (and perhaps other factors as well) were readily apparent in the mosaic or patchwork spatial arrangement of this rangeland vegetation.

These three theoretical perspectives reach the same end-point conclusion: the natural vegetation of duneland and adjacent sandy lands is more mesic than that of the surrounding "hard land" or "tight land", the predominate or zonal range habitat of the Llano Estacado region, the general edaphic features of which are less moist and hence less favorable for range plant growth.

A major management factor (treatment) that affected this range vegetation had been soil application of tebuthiron, a substituted urea herbicide that is usualy very effective in control of sand shinnery oak. On the deeper, more mesic sand of the Tivoli dunes tebuthiron was not effective in reduction of shinnery oak cover. On the rangeland surrounding and situated among the dune complex the predominate soil was Brownfield (with some small, local areas of Patricia). The later series are shallower soils on which tebuthiron drastically reduced shinnery oak, perhaps being the determining factor for nearly complete absence of this shrub from the bluestem tallgrass prairie. Even if tebuthiron had been responsible (or primarily so) for local eradication of sand shinnery oak the overall impact of brush control appeared to have been restoration of this range vegetation to the state of its natural potential. All of this range vegetation (types, sites, microsites) generally was postclimax. Brush control (and improved grazing management) served to restore the potential natural vegetation (monoclimax, polyclimax, climax pattern, whatever).

34. At scrub's edge- Two photo-stops with two photo-spots showed rangeland plant communities moving from the interior of sand shinnery oak scrub on a duneland complex toward a sand bluestem-dominated tallgrass prairie off of the dunes (background). A shinnery oak-sand bluestem savanna was the natural ecotonal range vegetation between the grassland and shrubland types. The second of these two photographs portrayed the progressively and proportionately greater cover of sand bluestem farther into the ecotone and closer to the bluestem tallgrass prairie. Cover and density of sand sagebrush was also greater farther into the ecotone. In fact, sand sagebrush was more abundant/commonof on the transition zone than in either the shrubland or grassland range types.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). High Plains- Shinnery Sands Ecoregion, 25j (Griffith et al., 2006). Background range vegetation was sand bluestem-little bluestem tallgrass prairie which had the classification units that follow. In theory the grassland would be (or could be seen as) FRES No.39 (Prairie Grassland Ecosystem) and K-66 (Bluestem Prairie) as a postclimax or a smaller-scale edaphic climax in a region the zonal vegetation of which is FRES No. 38 (Plains Grassland). This is problematic however because there is no Kuchler unit of tallgrass prairie in FRES No. 38. Itstead this was mapped as K-58 (Grama-Buffalograss). SRM 720 (Sand Bluestem-Little Bluestem [Dunes]). Bluestem "Tall-Grass" Series 142.11 in Plains Grassland biotic community 142.1 of Brown et al. (1998). High Plains- Llano Estacado Ecoregion, 25i (Griffith et al., 2006). Note: at this scale there was an intermixing of two level III ecoregions, perhaps best described as islands of two ecoregions.

35. Intermingled- Moving farther away from the sand shinnery oak on duneland range and into the heart of an ecotonal plant community between shinnery oak scrub and bluestem-dominated tallgrass prairie showed rangeland vegetation that is a sand shinnery oak-bluestem (sand bluestem is the dominant) savanna. The first of these two slides was of range vegetation nearer to the shinnery oak scrubland while the second slide was farther from the duneland scrub and closer to the bluestem-tallgrass prairie that was featured below. Sand sagebrush was the associate shrub species on savanna nearer (as well as in) the shinnery oak scrubland. Sagebrush cover and general abundance was greater on the savanna than in the shinnery oak scrubland.

The range vegetation in the second of these photographs was that at outer edges of the savanna (distinguishable in right midground) and tallgrass prairie (left foreground back to entire background). Species composition of this exterior of the tallgrass prairie was locally approximately equal abundance and production of sand bluestem and little bluestem as co-dominants with broom snakeweed the major shrub (the only woody species of other than incidental cover and presence) and annual wild buckwheat the major forb. Riddell's groundsel was present in trace proportion as the second major forb. Southwestern rabbitbrush edged out sand sagebrush as "runner-up" shrub to broom snakeweed on this "mint-condition" grassland.

It was reinterated that all this range vegetation was, in monoclimax theory, postclimax (due primarily to greater water-holding capacity of sandy soils) to the regional (climatic) climax of gramagrass-buffalograss (Bouteloua spp.-Buchloe dactyloides) mixed prairie (Kuchler unit 58; Kuchler, 1964, Kuchler, 1966). Alternatively, this natural vegetation could be viewed from the polyclimax perspective as an edaphic climax or from climax pattern theory as range plant communities that developed along gradients of variables, of which soil water was most determinative. "Same difference". All three theories lead to the same final conclusion.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October. FRES No. 31 (Shinnery Ecosystem). K-64 (Shinnery). SRM 730 (Sand Shinnery Oak). Oak-Scrub Series 132.41 in Plains Deciduous Scrub biotic community 132.4 of Brown et al. (1998). High Plains- Shinnery Sands Ecoregion, 25j (Griffith et al., 2006). Background range vegetation was sand bluestem-little bluestem tallgrass prairie. FRES No. 38 (Plains Grassland), but no appropriate K unit for this postclimax tallgrass prairie within regional mixed prairie. SRM 720 (Sand Bluestem-Little Bluestem [Dunes]). Bluestem "Tall-Grass" Series 142.11 in Plains Grassland biotic community 142.1 of Brown et al. (1998). Shinnery oak vegetation corresponded to High Plains- Shinnery Sands Ecoregion, 25j (Griffith et al., 2006); sand bluestem-little bluestem tallgrass prairie corresponded to High Plains- Llano Estacado Ecoregion, 25i (Griffith et al., 2006). Note: at this scale there was an intermixing of two level III ecoregions, perhaps best described as islands of two ecoregions.

36. Beyond ecotone edge and into the prairie- Two photo-plots of postclimax tallgrass (sand bluestem and little bluestem) prairie at farthest extrme of the sand shinnery oak-sand bluestem-little bluestem savanna, the transition zone or ecotone between tallgrass prairie and sand shinnery oak range ecosystems. At this point the savannah was left to the rear with advance into the tallgrass prairie at peak standing crop and grain-ripe with onset of dormancy in bluestems.

The first of these two photographs was at edge of the savanna just outward from the photo-point of second photograph in the immediately preceding pair of photographs. This first slide featured the surface of the Tivoli deep sands soil. The second of the current pair of slides showed sand bluestem and little bluestem on the shallower Brownfield soil. Here at the edge of grassland and away from savannah and, farther yet, shrubland the only shrub of much consequence was broom snakeweed, a local associate species. Another shrub, though one of much less cover and density than broom snakeweed, was sand sagebrush. Sagebrush was also present in the sand shinnery oak shrubland as seen above. Southwestern (Chyrsothamnus pulchellus) was a widely scattered shrub present in trace amounts in both the savanna and grassland and not, to any notable extent, in the shinnery oak range ecosystem.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October. Early dormancy and fruit-ripe pehnology of climax grasses. In theory this grassland would be (or could be seen as) FRES No.39 (Prairie Grassland Ecosystem) and K-66 (Bluestem Prairie) as a postclimax or a smaller-scale edaphic climax in a region the zonal vegetation of which is FRES No. 38 (Plains Grassland). This is problematic however because there is no Kuchler unit of tallgrass prairie in FRES No. 38. Itstead this was mapped as K-58 (Grama-Buffalograss). SRM 720 (Sand Bluestem-Little Bluestem [Dunes]). Bluestem "Tall-Grass" Series 142.11 in Plains Grassland biotic community 142.1 of Brown et al. (1998). High Plains- Llano Estacado Ecoregion, 25i (Griffith et al., 2006).

37. Postclimax prairie- Tallgrass prairie of sand bluestem and little bluestem in a semiarid zone in which the region climax range vegetation is mixed prairie and where there is far more "shortgrass country" than tallgrass range. This pair of photographs provided another study in light and color contrasts resulting from different conditions of natural light. The first slide (taken in full sun; under a completely cloudness sky) was of a stand of postclimax tallgrass prairie that was a consociation of sand bluestem, for all practical purposes the only grass species present in this stand. The shrub was broom snakeweed and the forb (a specimen in right, immediate foreground) was annual wild buckwheat (Eriogonum annuum). The second slide (under an overcast sky) featured a range community of more species diversity including sand bluestem, little bluestem, Indiangrass (Sorgastrum nutans), broom snakeweed, and annual wild buckwheat. In the instance of this second slide, grass panicles with their pale or silvery pubescence showed up to much better advantage under conditions of reduced light.

It was explained above why range photographers benefit from different light conditions depending on what aspects and characteristics they wish to feature. Atmospheric conditions with cloud cover that varies dramatically over a short period of time, while a source of aggravation if not frustration (especially with moment-to-moment light dynamics) to the shutterbug, is ideal for most kinds of range photography. These two photographs, as well as others in this series, provided examples of that lesson.

Anyway, this was a beautiful postclimax tallgrass prairie amid an otherwise "vast sea" of mixed prairie. Even the crotchiest ole range professor can fight at least half a semester's battle with university Pharisees treasuring scenes like these in his soul.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October. Tallgrass species were at pehnological stage of grain-ripe and beginning dormancy. In theory this grassland would be (or could be seen as) FRES No.39 (Prairie Grassland Ecosystem) and K-66 (Bluestem Prairie) as a postclimax or a smaller-scale edaphic climax in a region the zonal vegetation of which is FRES No. 38 (Plains Grassland). This is problematic however because there is no Kuchler unit of tallgrass prairie in FRES No. 38. Itstead this was mapped as K-58 (Grama-Buffalograss). SRM 720 (Sand Bluestem-Little Bluestem [Dunes]). Bluestem "Tall-Grass" Series 142.11 in Plains Grassland biotic community 142.1 of Brown et al. (1998). High Plains- Llano Estacado Ecoregion, 25i (Griffith et al., 2006).

38. In prairie and in scrub- Sand bluestem is the climax dominant grass (major decreaser) species on both postclimax tallgrass prairie (first or upper slide) and sand shinnery oak scrubland (second or lower slide). Shoots of sand bluestem in these (and above) photographs were in dormancy or near-dormancy stage with ripe grain. Associate species on grassland was broom snakeweed.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October. Early dormancy; grain-ripe phenology.

39. Details of the dominant decreaser grass- Sand bluestem was the dominant herbaceous species on sand shinnery oak duneland range (Tivoli deep sands) and co-dominant with little bluestem on tallgrass prairie that developed near shinnery oak shrubland. Sand bluestem was introduced above growing on another shinnery oak range and at stage of antheseis and it seemed advisable to present it again here at phenology of grain-ripe and onset of dormancy. (The fact that sand and big bluestem happen to be the author's favorite grasses had nothing to do with the dual presentation.)

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

40. Duo of another decreaser grass- Two plants of little bluestem loaded with pubescent spikelets. Little bluestem was locally co-dominant with sand bluestem on tallgrass prairie, especially on Brownfield soil. On deeper Tivoli sands, as on sand shinnery oak shrubland, little bluestem was the associate grass species with sand bluestem the dominant grass and major herbaceous species.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

41. How about another grass of shinnery oak scrubland?- Sand paspalum (Paspalum stramineum= P. setaceum var. stramineum) was introduced above with another example of sand shinnery oak scrub range, but another example seemed warrented here where it could enhance presentation of another shin oak range ecosystem. Sand paspalum does well on disturbed areas, but its presence with sand shinnery oak is an indicator that cattle grazing was not excessive by large.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

42. A blooming broom snakeweed- Broom snakeweed is a common and widespread woody composite, often viewed as a subshrub, that is common on semiarid or even subhumid grasslands to arid scrub such as the Chihuhuan Desert. It is important as a major component of various range plant communities and vilified as a poisonous range plant.

Broom snakeweed is more important as in invasive native plant on ranges, often even those in high ecological status, but especially those that have been abused by overgrazing and/orsuffering from drought. The New Mexico Agricultural Experiment Station conducted extensive studies over a number of years on the broom snakeweed problem on the ranges of its state. Findings from these concerted studies (part of the New Mexico Range Improvement Task Force) were published variously including as a proceedings (Huddleston and Pieper, 1989).

There have been several toxic substances implicated to one degree of the other as the source of livestock poisoning by broom snakeweed. The most commonly and strongly suggested principle is a saponin, but other substances have been considered including volatile monoterpenes. Major sources concerning broom snakeweed as a poisonous plant included Kingsbury (1964, ps. 406-408), Cheeke (1985, p. 198), James et al. (1988, ps. 57-69), Colegate and Dorling (1994, 345-349, 468-469, 495), Garland and Barr (1998, ps.307-311), Burrows and Tyrl (2001, ps. 167-170), and Hart et al. (2003, ps. 98-99).

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

43. Blooms of broom snakeweed- The basis of "DYC" (Damn Yellow Composite) as a designation for many members of Compositae was obvious from these photographs.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

44. An "also-ran" woody composite- Good example of southwestern rabbitbrush (Chrysothamnus pulchellus) growing on postclimax tallgrass prairie on the Staked Plains of eastern New Mexico. This species was sparse on the bluestem-dominated grassland featured above. Tthis range was without any doubt in Excellent range condition class and one would expect woody plants to "few and far between" in such a pristine range plant community. The presence of some rabbitbrush plants added species diversity and served as an indication of the relict nature of this range vegetation.

Powell (1988, p. 442) reported that southwestern rabbitbrush was most common on deeper sandy soils. This was clearly the edaphic habitat this happy specimen called home.

In some of the earlier sources Chrysothamnus was shown as Bibelovia or Linosyris. Thus, for example in the classic Botany of Western Texas (Coulter, 1891-1894, p. 187) designated this species as B. pulcella (= L. pulchella) and with the common name of rayless golden-rod. Sometimes rangemen have to be amateur detectives when working in the seminal literature, works that often prove indespensible in interpreting early accounts of pioneer botanists. L. pulchella was the binominal assigned by Asa Gray of Harvard.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

45. Fluffy fruits- Shoots and shoot apices with former inflorescences fully filled with fruit. Powell (1988, p. 440) described the heads of rabbitbrush as being borne in "dense clusters" with ray flowers typically absent. Thus with only disk flowers present on the capitulum (head), the flower type in Chrysothamnus species is tubular. The grey-colored, long or silky pubescence resembling fine bristles make up the pappus, "the modified calyx of the flower in the Compositae" (Smith, 1977, p. 303).

The Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

46. Another DYC and another poisonous one- Riddell's groundsel (Senecio riddellii) growing on postclimax bluestem tallgrass prairie displayed composite heads with features characteristic of this genus. Presence of this biennial forb also afforded and opportunity to describe a poisonous range species (one of this author's favorite topics).

Poisonous principle is pyrrolizidine alkaloid, specifically riddelliine, Kingsbury (1964, ps. 427-435), Cheeke (1985, ps. 94-95), Seawright et al. (1985, ps. 209-218), James et al. (1988, ps. 182-183), Garland and Barrr (1998, ps. 304-305), Weathers (1998, ps. 44-45, 64, 192, 202), Burrows and Tyrl (2001, ps. 193-205), Hart et al. (2003, p. 188-189), and Acamovic et al. (2004, ps.50, 387-393).

Senecio includes annual, biennial, and perennial life cycles as adaptations to the extreme range of habitats (niches) occupied by the members of this genus. S. riddellii is a biennial. The biennial life cycle permits Riddell's groundsel to thrive on disturbed areas, including local blowouts on the sandy Tivoli and Brownfield soils of the Staked Plains. On large areas of disturbance, such as on degraded ranges, high cover and density of Riddell's groundsel is more likely to result in livestock poisoning.

Weaver Ranch, Roosevelt County, New Mexico. Autumnal aspect, October.

47. An annual for the sand- Annual wild buckwheat (Eriogonum annuum) is a forb whose annual life cycle serves it well in sandy soils like the Tivoli and Brownfield of the Southern High Plains. Frequent, localized blowouts create relatively short-term microhabitats of disturbance that can be exploited by pioneering annuals. These small-sized (tiny compared to immense blowouts such as those of the Nebraska Sandhills or Gulf Coast dunes) local disturbances exist even within pristine plant communities of postclimax sand shinnery oak shrubland and sand and little bluestem-dominated tallgrass prairie. Such products of natural or geologic erosion (mostly by wind) provide ideal environments for disturbance-dependent species like annuals (E. annuum featured here) and biennials (Riddell's groundsel introduced above).

Presence of naturally disturbed microsites on postclimax or edaphic/topographic climax plant communities is a major reason for as much plant species diversity as occurrs on these range types. In such potential natural vegetation the presence of annual and biennial forbs serves as an indicator of high successional (including climax) states of these seres. These annual and biennial forbs that grow and complete their life cycles on localized areas (spots) of disturbance--denudation at small spatial and short temporal scale-- are not weeds. They are actually part of the climax vegetation even though by their successional response they are invaders. This is an example of patch dynamics where local blowouts are gaps (the equivalent of openings in forest canopies due to tree blowdown or limb loss from ice storms). It is secondary plant succession taking place on microsites within the overall sere at climax (at least high seral) stage. A major authority with thorough treatment of patch dynamics, including that of grasslands, is Pickett and White (1985). The natural retrogression and subsequent plant succession of patch or gap dynamics is "part and parcel" of the Clementsian paradigm of dynamic vegetation of which the first step is denudation.

If, "on the other hand", mismanagement of ranges (eg. overgrazing, over- or underburning) or of adjacent land (eg. cropland, oil fields, roads) permitted unnatural (oversized or prolonged) disturbances on ranges resulting in retrogrsssion over large portions of (or the entire) grazing unit and range plant community (ies) such disturbance would constitute range abuse which, if continued, would result in range degradation or, ultimately, range depletion. A symptom of such range degeneration is large denuded areas supporting only annual and biennial species like annual wild buckwheat and Riddell's groundsel. At this spatial scale of anthropogenetic degradation expensive, input-intensive remedial treatment (= restoration management) would be required. On sandy land in the semiarid zone such efforts at remediation are risky at best (the Dust Bowl equivalent of a "river boat gamble"; high stakes sand dune poker). The alternative is to hope Mother Nature will restore the range at successional time scale before all the soil blows away or, stated in realistic terms, return to the Dust Bowl.

Annual and biennial forbs are important plant indicators, especially on fragile range lands and under harsh or extreme environmental conditions.

48. Spectacle-pod (Dithyrea wislizeni= Biscutella wislizeni)- Spectacle pod is not only one of the most apt-named range plants it is also one of most common species of the Cruciferae native to the ranges of the Southern Great Plains and Tran-Pecos Basin and Range. Coulter (1891-1894) wrote of this species as native to the Staked Plains (High Plains portion of the Southern Great Plains) and sandy soils along the Rio Grande. Wooton and Stanley (1915) presented the species range as from Colorado and Utan to west Texas and south into the Mexican states. Spectacle-pod is thus a species of both Mixed Prarire and Shortgrass Plains grasslands as well as of the Chihuhuan Desert,It is especially abundant in the shinnery oak (Quercus harvardii) shrubland ecosystem and, at somewhat lesser cover and density, in the postclimax tallgrass prairie of the Southern Great Plains. Spectacle-pod has a high preference for habitat with sandy soils.

Spectacle-pod appears to have a very versatile life cycle having been described by various taxonomists as annual, biennial, or perennial. This pattern of resource allocation is characteristic of plants of harsh habitats. Whle conducting reserch for his Master's thesis this author found spectacle-pod to one of the most densly populated of the larger forb species on the disclimax Chihuhuan Desert of the New Mexico State Universtiy College Ranch. This was during a period (the years of 1972-1973) of average or higher precipitation. Sebsequent visits to the same study ranges of the College Ranch following dry periods and severe drought revealed little and no evidence, respectively, of this cricifer. These findings were consistent with an opportunistic range species.

The specimen shown here was growing in a typically dense population in a sand shinnery oak (Quercus haavardii) shrubland in which there had been a recent surface fire. (Note small shinnery oak resprouts.)

Beckham County, Oklahoma. June.

49. Inflorescence and fruit of spectacle-pod- The fruit type of is a silique, defined by Smith (1977, p. 307) as a broad, longitudinally dihiscent fruit in which fruit walls part from a persistent internal partition called the replum.

The photographs of the flower cluster showed the prominent and clearly separate or unjoined four petals of the corolla.

These examples were in the same sand shinnery oak scrub range as the specimen presented in the preceding slide.

Beckham County, Oklahoma. June.

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