@article {50553, title = {Vegetation changes in the Jornada Basin from 1858 to 1998}, journal = {Journal of Arid Environments}, volume = {61}, number = {4}, year = {2005}, month = {June 1, 2005}, pages = {651-668}, abstract = {

Notes made by land surveyors in 1858 were utilized to estimate cover of grasses and shrubs on the Jornada Experimental Range (JER) and the Chihuahuan Desert Range Research Center (CDRRC) in the northern Chihuahuan Desert, southern New Mexico, USA. Portions of these areas have previously been assessed for historical vegetation dynamics, but the entire 84,271 ha assessed in the 19th century has not been examined in total. In 1858, fair to very good grass cover occurred on 98 and 67 percent of the JER and CDRRC, respectively. Shrubs were present throughout both properties, but 45 percent of the JER and 18 percent of the CDRRC were shrub free. Reconnaissance surveys to determine carrying capacity for livestock, made in 1915-16 and 1928-29 on the JER and in 1938 on the CDRRC, show that shrubs had made large increases in area occupied at the time of the surveys. Vegetation-type maps were made of both properties in 1998. Mesquite (Prosopis glandulosa Torrey) was the primary dominant on 59 percent of the JER in 1998, and creosotebush [Larrea tridentate (Sess. \& Moc. Ex DC.) Cov.] was the primary dominant on 27 percent of the area. On the CDRRC, mesquite and creosotebush were primary dominants on 37 and 46 percent of the area, respectively. Grass cover has decreased greatly with the increase in shrubs, and only shrub control efforts have maintained the once abundant black grama [Bouteloua eriopoda (Torrey) Torrey] as a primary dominant on 1 percent or less of the area on both properties. Sustainable use as grazing land will require low levels of use because grasses cannot increase unless shrubs are eradicated and shrub control is likely to remain economically unfeasible for the foreseeable future. http://www.sciencedirect.com/science/article/pii/S0140196304002150

}, keywords = {changes, Jornada Basin, vegetation}, doi = {10.1016/j.jaridenv.2004.10.001}, url = {/files/bibliography/05-023.pdf}, author = {Gibbens, Robert P. and R.P. McNeely and Kris Havstad and Reldon F. Beck and B. Nolen} } @article {50988, title = {Root systems of some Chihuahuan Desert plants}, journal = {Journal of Arid Environments}, volume = {49}, number = {2}, year = {2001}, month = {October 1, 2001}, pages = {221-263}, abstract = {Root systems of 11 shrub or shrub-like species, 11 grass species, 19 perennial forb species and 4 annual forb species were excavated on the Jornada Experimental Range in the northern Chihuahuan Desert in southern New Mexico, USA. Maximum radial horizontal spread of shrub root systems usually occurred above calcic and petrocalcic horizons at depths above 1 m. .With one exception, all shrub species roots were traced through calcic and petrocalcic horizons to depths down to 5 m. Upward growing roots reaching very shallow depths (\< 10 cm) were common for most shrub species. Thus, the shrubs can readily access soil water and nutrients from both surface and deep soil horizons. Grass root systems on sandy soils extended radially up to 1.4 m, perhaps an adaptation to capture more soil water from the frequent small rainfall events. Grass roots did not extend through calcic or petrocalcic horizons and none penetrated deeper than 1.6 m. Perennial forb root systems varied in depth of branching but often penetrated into o through calcic and petrocalcic horizons and, like shrubs, have an advantage over grasses during droughts. Root systems of the annual forbs, excavated at the end of a season of above average precipitation, reached depths of 0.5 to 1.2 m. At each of the 18 excavation sites the roots of all the plant life forms were highly intermingled in the upper soil horizons, indicating that competition for water and soil nutrients is intense. It is believed that the plasticity and architecture of the shrub root systems, enabling them to compete with the grasses for soil water in the upper soil horizons and also access soil water at depths beyond the reach of grass roots, has been a major reason for the increase of shrubs during the historical period in this arid environment.}, keywords = {Chihuahuan Desert, competition, forbs, grasses, Jornada, root systems, shrubs, soil resources}, doi = {10.1006/jare.2000.0784}, url = {/files/bibliography/01-023.pdf}, author = {Gibbens, Robert P. and J.M. Lenz} } @article {51332, title = {Structure and function of C3 and C4 Chihuahuan Desert plant communities: Standing crop and leaf area index}, journal = {Journal of Arid Environments}, volume = {34}, number = {1}, year = {1996}, month = {September 1, 199}, pages = {47-62}, abstract = {

During the past 150 years, native C3 shrubs have invaded and dominated extensive areas of former C4 grasslands in deserts of the south-western United States. This vegetation shift has caused large changes in several aspects of the structure and function of these plant communities. To examine structural changes, we measured the standing crop of green herbaceous plants and live shrubs, leaf area index (LAI), and canopy cover and shrub density in grass and shrub plant communities that exist on sandy and clay soils in the Chihuahuan Desert. Standing crop ranged from 800 to 1800 kg ha-1 for grass communities and from 2800 to 3500 kg ha-1 for shrub communities. The LAI in grass communities was typically 0{\textperiodcentered}1 to 0{\textperiodcentered}2 and in shrub communities was 0{\textperiodcentered}3 to 0{\textperiodcentered}4. Averaged over the 2 years, the greatest LAI was in the shrub community on a clay soil that also had a herbaceous understory. Shrub canopy cover varied from 17\% (Flourensia cernua, tarbush) to 33\% (Prosopis glandulosa, honey mesquite). On sandy soils, this vegetation shift has resulted in a replacement of herbaceous vegetation with shrubs and a large reduction in species diversity, while on clay soils, due to greater soil fertility and soil water availability, there was only a slight decrease in herbaceous vegetation and little change in species diversity. This vegetation shift of desert grasslands has dramatically changed plant community structure.

}, keywords = {Bouteloua eriopoda, desert grasslands, Flourensia cernua, Larrea tridentata, Pleuraphis mutica, prosopis glandulosa, shrub invasion}, url = {/files/bibliography/483.pdf}, author = {Gibbens, Robert P. and Hicks, R.A. and W.A. Dugas} } @article {51445, title = {Root systems of desert plants}, journal = {Sonorensis}, volume = {14}, number = {1}, year = {1994}, month = {1994}, pages = {4,5 \&19}, abstract = {

We are all familiar with the above-ground parts of desert plants. While we may admire and photograph the pretty flowers or unusual plant forms that we can readily see, we seldom think of a major portion of the plant, the root system, which is concealed within the soil. Roots are very important to a plane because they not only anchor the plant in place but also are the means by which the plant acquires water and nutrients (nitrogen, phosphorus, potassium and other elements essential to growth). In low rainfall desert environments, water is often the most limiting factor for plant growth, and root systems of desert plants are often shaped to maximize the uptake of this vital element. Quite often, the weight of the root system is equal to or greater than the weight of the above-ground portion of the plant. A knowledge of the morphology or form of root systems is very helpful in understanding the ecology and interactions of the diversity of plant species found in desert environments.

}, url = {/files/bibliography/423.pdf}, author = {Gibbens, Robert P.} } @article {51566, title = {Creosotebush vegetation after 50 years of lagomorph exclusion}, journal = {Oecologia}, volume = {94}, year = {1993}, month = {1993}, pages = {210-217}, chapter = {210}, abstract = {

In 1939 an experiment was established on the Jornada Experimental Range to evaluate the effects of brush removal, rabbit exclusion, furrowing, and seeding in creosotebush. Sixteen plots (21.3 x 21.3 m) were established in four rows of four with a buffer zone of 7.6 m between plots. A barbed wire fence excluded cattle and poultry wire fencing excluded lagomorphs. The treatments were factorially applied at two levels, yielding a check plot, 4 single-factor plots, and 11 plots with varying degrees of interaction. In 1989 the plots were sampled for shrub canopy cover and grass basal area with randomly located, line-intercept transects. The noneffective furrowing and seedling treatments were excluded from analyses. Multivariate analysis of variance was conducted by plant groups (shrubs, subshrubs, and grasses) to determine the effect of shrub removal and lagomorph exclusion. Grass basal area was higher (P = 0.026) on cleared (4.8\%) than on noncleared plots (4.0\%). Grass basal area on lagomorph-excluded plots (4.3\%) was higher (P = 0.018) than on plots grazed by lagomorphs (3.7\%). Subshrub canopy cover was different (P = 0.029) on lagomorph-excluded and lagomorph-grazed plots with different species showing opposite responses. These results indicate that lagomorphs have a profound influence on the species composition of creosotebush vegetation.

}, keywords = {Black-tailed jackrabbit, Larrea tridentata, Parthenium incanum, Spike dropseed, Sporobulus contractus}, doi = {10.1007/BF00341319}, url = {/files/bibliography/404.pdf}, author = {Gibbens, Robert P. and Billheimer, D.D. and Kris Havstad and C.H. Herbel} } @article {51524, title = {Recent rates of mesquite establishment in the northern Chihuahuan Desert}, journal = {Journal of Range Management}, volume = {45}, year = {1992}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1992}, pages = {585-588}, abstract = {

Honey mesquite (Prosopis glandulosa Torr. var. glandulosa) populations continue to expand and become more dense, even on areas once "successfully" treated either with herbicides or by bulldozing in southern New Mexico.\  Areas treated from 1958-1964 for mesquite control on the USDA-ARS Jornada Experimental Range and the New Mexico State University College Ranch were sampled to determine mesquite density changes.\  On herbicide treated areas sampled in 1976 and again in 1988, mesquite densities increased 10\%\  to 128\% and had densities from 67 to 494 plants/ha.\  Two areas\ treated by either bulldozing or fenuron in 1959-60, and with original kills near 100\%, had an average density of 377 plants.ha by 1988, with an establishment rate of 13.5 plants/ha/year.\  On the College Ranch, mesquite densities increased 11\%, from 130 (1982) to 147 (1988) plants/ha.\  Only 19\% of a cohort of mesquite seedlings which germinated in 1989 were still alive in May 1990.\  Even though only a small percentage of the mesquite that germinated survived into the second year, this is enough to change former grasslands into mesquite-dominated rangelands.\ 

}, keywords = {arid rangelands, desert grasslands, prosopis glandulosa, seedling establishment, shrub invasion}, url = {/files/bibliography/385.pdf}, author = {Gibbens, Robert P. and Reldon F. Beck and R.P. McNeely and C.H. Herbel} } @conference {51525, title = {Root systems of some Chihuahuan Desert plants}, booktitle = {Annual Meeting, Society for Range Management}, year = {1992}, month = {1992}, pages = {43}, abstract = {Root systems of shrubs, grasses and forbs were excavated in plant communities occurring on relatively deep, fine sandy and day loam soils on the Jornada Experimental Range in southern New Mexico. Root systems of grasses extended to depths of about 1 in and did not penetrate far into the well developed calcic horizons. Perennial forb root systems extended to depths of 1.6 m and were well developed in calcic layers. Shrub root systems, including tarbush (Flourensiacernua DC), fourwing saltbush [Atriplex canescens (Pursh) Nutt.], wolfberry (Lycium berlandieri Dunal), and winterfat [Ceratoides lanata (Pursh) J.T.Howell], besides extending laterally 1 to 5 m, grew through the calcic horizons and extended to depths of 3 to >5 m. Roots of crucifixion thorn (Koeberlinia spinosa Zucc.) penetrated >S m but the unusual feature was large roots branching off at a depth of 3.5 m and growing vertically or obliquely upward before branching extensively between depths of .8 to .1 m. The extensive root systems of shrubs is one reason they have been so successful in this desert environment.}, keywords = {Chihuahuan Desert plants, descriptions, root systems}, author = {Gibbens, Robert P. and J.M. Lenz} } @article {51565, title = {Some effects of precipitation patterns on mesa dropseed phenology}, journal = {Journal of Range Management}, volume = {44}, number = {1}, year = {1991}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {January 1, 1991}, pages = {86-90}, abstract = {

Phenology of mesa dropseed [Sporobolus flexuosus (Thurb.) Rydb.] was studied from 1979 to 1987 on the Jornada Experimental Range in southern New Mexico. Growing season (March through November) precipitation ranged from 99 to 308 mm during the 8-year period. Foliage height and number of leaves were recorded weekly for individually marked culms on 20 plants. New culms usually appeared during the first week in March and green leaf tissue often persisted until the end of November. Correlation analyses of accumulated weekly height increments and accumulated weekly precipitation showed that growth was highly dependent upon rainfall (r = 0.81 to 0.97). Leaf formation was also correlated with rainfall (r = 0. 79 to 0.98). Even in relatively wet years there were 1 or 2 periods of no growth. In drier years, no growth periods totaled as much as 87 days. Periods of rapid growth occurred only after rainfall events \> 13 mm. The first exsertion of seed heads occurred as early as the last week of July and as late as the second week of October. The temporal plasticity of mesa dropseed phenology indicates that it is well adapted to the arid environment.

}, keywords = {arid zones, Chihuahuan Desert, grass growth, leaf development, rangeland, Sporobolus flexuosus}, doi = {10.2307/4002646 }, url = {/files/bibliography/367.pdf}, author = {Gibbens, Robert P.} } @conference {51613, title = {Recent rates of mesquite (Prosopis glandulosa Torr.) establishment in the northern Chihuahuan Desert}, booktitle = {43rd Annual Meeting, Society for Range Management}, year = {1990}, month = {1990}, pages = {191}, address = {Reno, NV}, author = {Gibbens, Robert P. and Reldon F. Beck and R.P. McNeely} } @conference {51659, title = {Phenology of native and introduced grasses in southern New Mexico}, booktitle = {42nd Annual Meeting, Society for Range Management}, year = {1989}, month = {1989}, pages = {61}, author = {Gibbens, Robert P.} } @article {51714, title = {Changes in grass basal area and forb densities over a 64-year period on grassland types of the Jornada Experimental Range}, journal = {Journal of Range Management}, volume = {41}, number = {3}, year = {1988}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {May 1, 1988}, pages = {186-192}, abstract = {

Between 1915 and 1932, permanent 1 X 1-m quadrats were established on grasslands of the Jornada Experimental Range in southern New Mexico. Quadrat records accumulated from 1915 to 1979 on grasslands dominated by black grama [Bouteloua eriopoda (Torr.) Torr.], poverty threeawn (Aristida divaricata Willd.), tobosa [Hiltuia mutica (Buckl.) Benth.], and burrograss (Scleropogon brevifolius Phil.) were used to examine changes in perennial grass basal area and forb densities. Quadrats originally dominated by black grama had large reductions in basal area during droughts, and basal area increased slowly following droughts. By 1979, black grama no longer occurred on 77\% of the quadrats. Quadrats originally dominated by poverty threeawn changed to a mesquite (Prosopis glandulosa Torr. var. glandulosa) type. Perennial grass basal area on quadrats dominated by tobosa and burrograss decreased during droughts, but recovery was relatively rapid. Antecedent precipitation was associated with only 10 to 38\% of the variation in perennial grass basal area. Perennial forb densities were low and fluctuated among years in all types. Annual forbs and grasses displayed large fluctuations in densities among years. The necessity of basing management of Chihuahuan Desert ranges on the perennial grass component is borne out by the low densities of palatable perennial forbs, and the extreme fluctuation and unpredictability in densities of annual forbs and grasses.

}, keywords = {arid rangeland, black grama, burrograss, poverty threeawn, tobosa}, doi = {10.2307/3899165 }, url = {/files/bibliography/329.pdf}, author = {Gibbens, Robert P. and Reldon F. Beck} } @conference {51715, title = {The effect of precipitation patterns on the phenology of Sprobolus flexuosus}, booktitle = {41st Annual Meeting, Society for Range Management}, year = {1988}, month = {1988}, pages = {209}, author = {Gibbens, Robert P.} } @article {51772, title = {Field-scale tebuthiuron application on brush-infested rangeland}, journal = {Weed Technology}, volume = {1}, year = {1987}, month = {1987}, pages = {323-327}, abstract = {

The objective of this study was to determine the effectiveness of tebuthiuron \ {N- [5-(1,1-dimethylethyl)-1, 3,4- thiadiazol- 2- yl) -N,N{\textquoteright} -dimethylurea} to treat brush-infested arid rangeland under field-scale conditions. A 130- ha tract in southern New Mexico dominated by creosotebush \ [Larrea tridentata (Sesse \& Moe. ex DC.) Coville $\#$3 LARTR] was treated with pelleted tebuthiuron at 0.4 kg ai/ha. After the fourth season following treatment, control of creosotebush, honey mesquite (Prosopis glandulosa Torr. $\#$ PRCJG), and tarbush (Flourensia cernua DC. $\#$ FLOCE) was 87, 48, and 100\%, respectively. Total shrub density was reduced from 4440 plants/ha to 570 plants/ha. Grass basal area increased from 1.1 to 3.4\%. The treatment did not affect forbs greatly. Total herbaceous above-ground biomass production in the fourth season after treatment was 860 kg/ha compared to 140 kg/ha on an adjacent untreated area. Perennial grass production was nearly 11- fold greater on the treated area than on the untreated area.

}, keywords = {arid rangeland, FLOCE, Flourensia cernua, grass cover, Larrea tridentata, LARTR, PRCJG, prosopis glandulosa}, doi = {10.1017/S0890037X00029833}, url = {/files/bibliography/314.pdf}, author = {Gibbens, Robert P. and C.H. Herbel and J.M. Lenz} } @conference {51770, title = {Increase in number of dominance-classes on a grassland in the northern Chihuahuan Desert}, booktitle = {40th Annual Meeting, Society for Range Management}, year = {1987}, month = {1987}, pages = {43}, author = {Gibbens, Robert P. and Reldon F. Beck} } @article {51771, title = {Increase in number of dominant plants and dominance-classes on a grassland in the northern Chihuahuan Desert}, journal = {Journal of Range Management}, volume = {40}, number = {2}, year = {1987}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {March 1, 1987}, pages = {136-139}, abstract = {

Between 1915 and 1932, 104 permanent 1x1-m quadrats were established on grasslands of the Jornada Experimental Range in southern New Mexico.\  Primary- and secondary-dominant species were determined from the first quadrat records and each quadrat was reevaluated in 1981 to determine current dominants.\  The first records showed that 13 species of perennial grasses occupied all primary- and secondary-dominant positions on all quadrats.\  In 1981, there were 12 perennial grass species as primary- or secondary-dominance.\  Six shrub species occurred as primary- or secondary-dominance on 47\% of the quadrat sites in 1981.\  Dominance-classes, i.e., single-species dominance or two-species dominant combinations, increased from 24 to 43.\  Thus, vegetation on this range has become more diverse and this diversity must be considered in grazing management.\ 

}, doi = {10.2307/3899205 }, url = {/files/bibliography/313.pdf}, author = {Gibbens, Robert P. and Reldon F. Beck} } @conference {51823, title = {Canopy and ground cover inside and outside of livestock exclosures on brush ranges in southern New Mexico with up to 50 years of protection}, booktitle = {39th Annual Meeting, Society for Range Management}, year = {1986}, month = {1986}, pages = {133}, keywords = {brush ranges, canopy, groundcover, inside, livestock exclosures, outside}, author = {Gibbens, Robert P. and Reldon F. Beck and T.L. Atwood} } @article {51822, title = {Some Impacts of 2, 4, 5-T on a mesquite duneland ecosystem in southern New Mexico: A synthesis}, journal = {Journal of Range Management}, volume = {39}, number = {4}, year = {1986}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {July 1, 1986}, pages = {320-326}, abstract = {

Two aerial applications of 2,4,5-T [(2,4,5-trichlorophenoxy) acetic acid] were applied to 3,634 ha of mesquite (Prosopis glandulosa Torr. var. glandulosa) dunelands in southern New Mexico. Herbicide residuals; herbaceous plant production; soil microorganisms; insect, small mammal, and bird populations; cattle weights; travel; time budgets; and diets were studied on the treated area and an adjacent, untreated area. Stem kill of mesquite ranged from 17 to 66\%. Herbicide residuals in soils and plant tissue on the treated area dissipated within a single season. Herbaceous plant production was measured for 5 years on a small area sprayed in 3 consecutive years and on untreated rangeland. Production was greater on the sprayed than on the unsprayed area for the first 3 years and was about the same on both areas for the next 2 years. Microbial populations were not numerically different between treatments but dehydrogenase activity and C02 evolution were greater in dunal than interdunal soils. Numbers of tenebrionid beetles (Coleoptera: Tenebrionidae) did not differ between treatments. More mesquite leaf tiers (Tetralopha euphemella) were found on the sprayed area than on the untreated area. Population statistics for small mammals were similar on both treatments. More bird species were found on untreated than on sprayed areas. Cattle weights, travel, and time budgets did not differ between treatments and there were only minor differences between treatments in cattle diet quality. The sprayed area supported over twice as many A UM{\textquoteright}s of grazing as the untreated area in the first 3 post treatment years. In the second post-treatment year, cattle liveweight produced was 2.9 and 1.5 kg/ha on the sprayed and untreated areas, respectively. Overall, the 2,4,5-T treatment caused relatively minor perturbations in measured ecosystem components.

}, url = {/files/bibliography/291.pdf}, author = {Gibbens, Robert P. and C.H. Herbel and Morton, H.L. and W. C. Lindemann and J. Ryder-White and D. Richman and E.W. Huddleston and W.H. Conley and C.A. Davis and J.A. Reitzel and D.M. Anderson and A. Guiao} } @proceedings {51944, title = {Grass and forb production on sprayed and nonsprayed mesquite (Prosopis glandulosa Torr.) dunes and interdunes in south-central New Mexico}, year = {1983}, month = {1983}, pages = {437-440}, address = {Lexington, KY}, abstract = {Production of grasses and forbs was measured for 4 years beginning in 1976 and following aerial application of 2,4,5-T to 3,634 ha of mesquite (Prosopis glandulosa Torr.) dunelands on the Jornada Experimental Range in south-central New Mexico. Plant production was also measured on a 3,318-ha control area. The mesquite dunelands arc representative of large areas in the southwestern USA where mesquite has invaded former desert grasslands. Objectives of the study were to determine forage increases attributable to reduced mesquite competition and to evaluate the relationships between production and precipitation. Both sprayed and control areas were grazed by cattle. Temporary exclosures were used to exclude cattle from three sampling sites on the sprayed and control areas each year. The sampling sites were all on sandy ranges with relatively deep soils (>50 cm to caliche layer). A dune-centered sampling system permitted the determination of differences in production on dune and interdune areas. The mesquite dunes, occupying 28\% of the land surface, produced more annual forbs and fewer perennial grasses than the interdune areas. Stem kill of mesquite averaged 56\% at sampling sites on the sprayed area. End-of-season harvests were used to compare treatments.}, keywords = {dunelands, forbs, grasses, mesquite, New Mexico, nonsprayed, Prosopis glandulosa Torr., sprayed}, url = {/files/bibliography/230.pdf}, author = {Gibbens, Robert P.} } @conference {51945, title = {Grassland forb production during a five-year period on sprayed and nonsprayed mesquite dunelands in Southern New Mexico}, booktitle = {36th Annual Meeting, Society for Range Management}, year = {1983}, month = {1983}, pages = {No. 9}, keywords = {dunelands, forb production, grassland, mesquite, nonsprayed, sprayed}, author = {Gibbens, Robert P.} } @proceedings {51942, title = {The Jornada Experimental Range Biosphere Reserve}, year = {1983}, month = {1983}, pages = {45-47}, publisher = {USDA Forest Service General Technical Report WO-36}, address = {Rio Rico, AZ}, abstract = {

The 78,106ha Jornada Experimental Range is a research facility and operational cattle ranch in the northern Chihuahuan Desert. Continuous research programs since 1915 have provided much information on how to manage arid rangelands best. Current research, building on the past, is aimed at increasing products of direct benefit to man while preserving the integrity of basic ecosystems.

}, url = {/files/bibliography/231.pdf}, author = {Gibbens, Robert P.} } @article {51943, title = {Soil movement in mesquite dunelands and former grasslands of southern New Mexico from 1933 to 1980}, journal = {Journal of Range Management}, volume = {36}, number = {2}, year = {1983}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {March 1, 1983}, pages = {145-148}, abstract = {

Soil levels were marked on grid and transect stakes in mesquite duneland and grassland areas at 3 sites on the Jornada Experimental Range in 1933 and 1935. Soil levels on one set of transect stakes were remeasured in 1950 and 1955. Remeasurement of soil levels at both transect and grid stakes in 1980 revealed that extensive soil movement had occurred during the intervening years. On a 259-ha site containing large mesquite dunes in 1935, maximum deposition and deflation was 86.9 and 64.6 cm, respectively, in 1980. There was a net gain of 1.9 cm in soil depth over the entire area. On a 259-ha site only partially occupied by mesquite dunes in 1933, there was a net loss of 4.6 cm in soil depth and mesquite dunes had completely occupied the site by 1980. On a transect established across a mesquite duneland-grassland ecotone in 1935, there was a net loss in soil depth of 3.4 cm. Mesquite dunes had completely occupied the former grassland and dune intercept increased from 34.9 m in 1935 to 149.6 m in 1980. Gross erosion rates on wind deflated areas were equivalent to 69 tonnes ha-1 yr-1 on the area of large mesquite dunes. On the area partially occupied by mesquite in 1935 the gross erosion rate was 52 tonnes ha-1 yr-1. At the ecotone transect gross erosion rates were 45, 101, and 40 tonnes ha-1 yr-1 for 1935-50, 1950-55, and 1955-80 periods, respectively.

}, url = {/files/bibliography/232.pdf}, author = {Gibbens, Robert P. and J.M. Tromble and J.T. Hennessy and Manual Cardenas} } @article {52033, title = {The binary search for accuracy in plant symbols}, journal = {Journal of Range Management}, volume = {34}, number = {3}, year = {1981}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {May 1, 1981}, pages = {239}, abstract = {

The transfer of data from field sheets to computer files always involves the risk of errors being made in plant symbols or other identifying codes. If a master list of symbols or codes is incorporated into the software programs used for data entry on CRT computer terminals the risk of making errors can be substantially reduced. This is done by utilizing the highly time efficient binary search to compare each entered symbol or code with the master list. Detection of errors before the data are transferred to computer files saves much time which would otherwise be spent in retrieving and correcting files.

}, url = {/files/bibliography/195.pdf}, author = {Gibbens, Robert P. and Bilan, T.N.} } @proceedings {52032, title = {Grass and forb production on sprayed and nonsprayed mesquite (Prosopis glandulosa Torr.) dunelands in south-central New Mexico}, year = {1981}, month = {1981}, pages = {222}, address = {Lexington, KY}, abstract = {

Production of grasses and forbs was measured for 4 years beginning in 1976 and following aerial application of 2,4,5-T to 3,634 ha of mesquite (Prosopis glandulosa Torr.) dunelands on the Jornada Experimental Range in south-central New Mexico. Plant production was also measured on a 3,318-ha control area. The mesquite dunelands arc representative of large areas in the southwestern USA where mesquite has invaded former desert grasslands. Objectives of the study were to determine forage increases attributable to reduced mesquite competition and to evaluate the relationships between production and precipitation. Both sprayed and control areas were grazed by cattle. Temporary exclosures were used to exclude cattle from three sampling sites on the sprayed and control areas each year. The sampling sites were all on sandy ranges with relatively deep soils (\>50 cm to caliche layer). A dune-centered sampling system permitted the determination of differences in production on dune and interdune areas. The mesquite dunes, occupying 28\% of the land surface, produced more annual forbs and fewer perennial grasses than the interdune areas. Stem kill of mesquite averaged 56\% at sampling sites on the sprayed area. End-of-season harvests were used to compare treatments.

}, keywords = {dunelands, forbs, grasses, mesquite, New Mexico, nonsprayed, Prosopis glandulosa Torr., sprayed}, url = {/files/bibliography/194.pdf}, author = {Gibbens, Robert P.} }