Welcome to the Rangeland Ecology & Management archives. The journal Rangeland Ecology & Management (RE&M; v58, 2005-present) is the successor to the Journal of Range Management (JRM; v. 1-57, 1948-2004.) The archives provide public access, in a "rolling window" agreement with the Society for Range Management, to both titles (JRM and RE&M), from v.1 up to five years from the present year.

The most recent years of RE&M are available through membership in the Society for Range Management (SRM). Membership in SRM is a means to access current information and dialogue on rangeland management.

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Print ISSN: 0022-409x

Online ISSN: 1550-7424


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Recent Submissions

  • Variability of crude protein in crested wheatgrass at defined stages of phenology

    Angell, R. F.; Miller, R. F.; Haferkamp, M. R. (Society for Range Management, 1990-05-01)
    Variability of crude protein concentration in crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult) is an important consideration in the development of grazing programs. Crude protein (CP) concentration in crested wheatgrass was monitored at specific stages of phenology for 5 years. During that time September through August precipitation varied from 68 to 142% of the 37-year mean. Vegetation was clipped once at 10 phenological stages beginning in April. At the last clipping date, in mid-August, regrowth accumulated after prior clippings was collected. Over the 5-year period, CP of vegetation clipped during mid vegetative growth in late April varied 35%, relatively, from 14.7% in 1983 to 9.5% during 1985. Even though 1984 crop year precipitation exceeded 1983 by 84 mm, maximum topgrowth biomass was 449 kg/ha lower in 1984. Also, CP percentage of vegetative growth in April was 1.8% lower in 1984 than in 1983. Regrowth CP was positively correlated (r=0.98) with June precipitation, and with the number of rain events in July (r=0.97). Plants clipped in the boot stage had greater forage CP in August than plants clipped prior to boot stage. However, regrowth biomass was affected by soil water availability and was highly variable. Crude protein in vegetative growth was marginal for growing steers in 1985. Although growing stock are often supplemented in late summer, these data are interpreted to show that spring supplementation may be needed some years.
  • Variability for seed size and yield in two tall dropseed populations

    Boe, A. (Society for Range Management, 1990-05-01)
    Tall dropseed [Sporobolus asper (Michx.) Kunth var. asper] is a drought-tolerant, perennial, warm-season grass that has potential for forage and soil conservation purposes. A prairie and an adjacent roadside population from northeastern South Dakota were evaluated for seed yield and size characteristics for 3 years (1985-1987) in a space-plant nursery at Brookings, S. Dak. The objective was to obtain information on between and within population variability and intraplant variability that would provide a basis for designing a breeding program to improve seed production and quality in this germplasm. The roadside population produced significantly (P<0.01) higher seed yields and larger mean 100-seed weight than the prairie population. Percent small seed (based on screen-separation of seed yields of individual plants into small, medium, and large seed size classes) decreased significantly (P<0.01) as seed yield increased, but the volume of small seed increased concurrently with seed yield. Percent large seed increased significantly (P<0.01) with increased seed yield and mean seed size. Highly significant (P<0.01) differences were found among years for seed yield and mean seed size, but all plants produced seeds of each size class each year. Inter- and intrapopulation genetic variability was indicated for yield of the large seed size class. Screen-separation of individual plant seed yields could be used to identify superior genotypes to be used in the development of a cultivrr that produces a high percentage of large seed.
  • The effect of manager risk attitudes on range improvement decisions

    Bernardo, D. J.; Engle, D. M. (Society for Range Management, 1990-05-01)
    Despite the availability of potentially profitable range improvement alternatives, private land ranch managers in the central U.S. are not readily adopting recommended range improvement practices. One explanation for this behavior is that managers may not be willing to accept the increased risk associated with implementing range improvement programs. The objectives of this study were to estimate the expected value and variability of net returns derived from several range improvement practices and use this information to assess the influence that manager risk attitudes have on the selection of range improvement practices. A stochastic range simulation model was used to provide estimates of the expected value and variability of income following the application of several range improvement practices in the Cross Timbers Region. Generalized stochastic dominance procedures were then used to rank these practices for managers characterized by alternative risk attitudes. Results of the analysis illustrate that optimal range improvement practices may be sensitive to manager risk attitudes. Managers willing to accept the possibility of low or negative incomes may prefer more intensive range improvement practices such as application of tebuthiuron for brush management followed by annual prescribed burning. In contrast, risk averse decision makers are inclined to implement lower cost range improvement practices or fail to utilize any range improvement practice.
  • Technical Notes: Classifying herbivore diets using hierarchical cluster analysis

    McInnis, M. L.; Larson, L. L.; Vavra, M. (Society for Range Management, 1990-05-01)
    Hypotheses are frequently posed that require comparisons among diet samples. Hierarchical cluster analysis is suited to this task, but has received little attention in food habits research. By grouping samples so that similar diets are close together and dissimilar diets are spaced farther apart, hierarchical cluster analysis reveals patterns in data difficult to recognize in the matrix of similarity coefficients typical of most food habits studies. We provide an example of this type of analysis, and indicate its application to management of large herbivores.
  • Spring burning Japanese brome in a western wheatgrass community

    Whisenant, S. G.; Uresk, D. W. (Society for Range Management, 1990-05-01)
    Plots dominated by Japanese brome (Bromus japonicus) and western wheatgrass (Agropyron smithii) were burned in Badlands National Park, South Dakota, in April 1983 and/or 1984. Standing crop of all species and tiller densities of the 2 dominate species were determined for 4 years. Burning favored western wheatgrass and reduced Japanese brome tiller density and standing crop for at least 1 growing season. In years where no burning occurred, Japanese brome standing crop and tiller density were dependent on the presence of litter on the soil surface. Burning in April killed Japanese brome seedlings for 1 growing season and reduced subsequent generations by reducing surface litter accumulations, with the effect being greatest when autumn precipitation was below average. April burning reduced the standing crop of green needlegrass (Stipa viridula) for at least 3 growing seasons after burning but increased standing crop of buffalograss (Buchloe dactyloides) and sand dropseed (Sporobolus cryptandrus) for 3 to 4 years after burning. Threadleaf sedge (Carex filifolia) standing crop was not significantly affected by burning.
  • Soil chemical properties during succession from abandoned cropland to native range

    Dormaar, J. F.; Smoliak, S.; Willms, E. D. (Society for Range Management, 1990-05-01)
    Succession from abandoned cropland to native range provides the opportunity to study soil transformation in progress from a known date. The purpose of this study was to assess soil transformations under abandoned cropland reverting back to native range in the Brown and Black Chernozemic soil zones of southern Alberta, Canada. Total extractable organic acids and phenols were generally greater in abandoned cropland soils than In adjacent native range soils. Ammonium N increased with succession but nitrate N decreased. Percent identifiable N of hydrolyzable N decreased with time of recovery. Aliphatic carboxylic acids increased quantitatively with succession in the Black soils and decreased in the Brown Chemozemic soils. A change in quality of soil organic matter towards a more complex and stable form occurred with time. Regression analyses of the Brown Chemozemic soils abandoned in 1925, 1927, 1950, and 1975 are interpreted to show that response to years of the chemical characteristics studied was essentially linear. In order to form the type of organic matter that occurs in undisturbed Black and Brown Chernozemic soils, recovery of abandoned cropland may take at least 150 years in the former and 75 years in the latter under moderate grazing.
  • Sodium concentration in germination blotters

    Morgan, D. R.; Booth, D. T. (Society for Range Management, 1990-05-01)
    Walter filtrate from blue germination blotters was analyzed by atomic absorption spectrophotometry and found to contain 509 micrograms of Na+/g of blotter. Since this is a sufficient concentration to confound the results of some studies of seed germination and seedling growth, researchers need to be aware of this potential bias. The findings emphasize the necessity for documenting the quantity of cations present in medium used in germination and seedling growth evaluations.
  • Relationship between phosphorus intake and blood or fecal phosphorus in gestating cows

    Sanson, D. W.; Walker, G. L.; Clanton, D. C.; Eskridge, K. M. (Society for Range Management, 1990-05-01)
    The relationship between fecal, serum or plasma phosphorus (P), and P intake was examined with 10, crossbred, 5-year-old, gestating cows (avg wt 475 kg) in an individual feeding study using 2 orthogonal 5 X 5 Latin squares. All cows received 9.07 kg of meadow grass hay which contained 7.4% crude protein (CP) with an in vitro dry matter digestibility (IVDMD) of 56%, and received .5 kg of 1 of 5 supplements which resulted in P intakes of 10.3, 12.4, 14.3, 16.1, or 18.4 g/day. Fecal and blood samples were collected for 5 days after a 14-day dietary adjustment period. Fecal grab samples were taken twice daily (hour 0800 and 2000). Blood samples were taken at 0800. Statistical analysis included analysis of variance and regression analysis. A linear response to P intake was observed for both plasma and serum P, however, with regression of P intake, the R2 for plasma P was .06 and for serum P was .10. Evaluation of morning and evening fecal P levels with regression resulted in different equations. The morning equation (Y = .055 + .212X) had a larger intercept and a smaller slope coefficient than the evening equation (Y = -.781+ .310X). Morning and evening R2 were .69 and .78, respectively. To examine the predictive ability of the P intake equations, a validation trial was conducted with 20 4-to-gyear-old cows individually fed (4/treatment). Daily P intakes were 10.0, 12.4, 15.3, 20.4, and 22.6 g. Management and sampling procedures were the same as used in the previous trial except blood samples were not collected. There was no difference (P>.05) in the equations established with regression from the morning and evening samples. The combined regression equation was (Y = .306 + .219X). This equation was not different (P>.05) from the equations established from either the morning or evening samples in the previous trial. These data indicate that fecal P is related to P intake; however, the extent that this relationship is influenced by the availability of dietary P may limit the usefulness of this association.
  • Regeneration of woody species following burning and grazing in Aspen Parkland

    Bailey, A. W.; Irving, B. D.; Fitzgerald, R. D. (Society for Range Management, 1990-05-01)
    The effect of short duration, heavy grazing by cattle was evaluated 3 and 6 years after burning and seeding of an aspen (Populus tremuloides Michx.) grove. Replicated paddocks of June grazed (early), August grazed (late), and ungrazed treatments were established. Regardless of treatment, density of all woody species was lower 6 years after burning than after 3 years. Early or late season grazing reduced the density of aspen and wild raspberry (Rubus strigosus Michx.). Late season grazing promoted a greater density of unpalatable western snowberry (Symphoricarpos occidentalis Hook.). Grazing reduced the height of aspen, preventing the development of a forest canopy. Herbage production averaged 1,700 kg ha-1, not differing between years 3 and 6: but the proportion of smooth brome (Bromus inermis Leyss.) increased while orchard grass (Dactylis glomerata C.) declined, Burning of aspen forest in Central Alberta followed by forage seeding and short duration, heavy grazing is an effective, economical range improvement tool.
  • Recurrent phenotypic selection for low grasshopper food preference in rangeland alfalfa

    Berdahl, J. D.; Hewitt, G. B.; Miller, R. H. (Society for Range Management, 1990-05-01)
    Grasshopper [Melanoplus spp. and Cannula Pellucida (Scudder)] feeding is an important factor that can prevent establishment and reduce yields of alfalfa [Medicago sativa subsp. X varia (Martyn) Arcang.] interseeded into semiarid rangelands of the northern Great Plains. Objectives of this study were to determine narrow-sense heritability estimates of grasshopper preference for an alfalfa population and to develop low-preference alfalfa germplasm adapted to rangeland use. The base population was derived from 5 cultivars and an experimental strain, all of M. sativa L. subsp. sativa X M. sativa subsp. falcata (L.) Arcang. parentage, that had been developed for rangeland use in the northern Great Plains. Except for cycle 4 which was conducted in a greenhouse, each cycle of recurrent phenotypic selection involved transferring replicated half-sib families of 6- to 8-week-old plants in flats to a field site with a heavy infestation of grasshoppers. Half-sib families were scored for defoliation when the entire population was at least 50% defoliated. Narrow-sense heritability estimates of defoliation under greenhouse conditions for 31 half-sib families and their respective parents ranged from 45 to 58%, depending on how defoliation from the multi-specks grasshopper populations was measured. Alfalfa populations produced from cycles 1, 3, and 5 of recurrent phenotypic selection were evaluated simultaneously under greenhouse conditions with a common grasshopper population and rated for defoliation on a scale from 1-5 where 1 = 0-20% and 5 = 81-100% defoliation. Mean defoliation decreased significantly (P<0.05) from 3.83 to 3.25 from cycle 1 to cycle 3, but the small decrease from 3.25 to 3.15 from cycle 3 to cycle 5 was not significant. The lack of progress from cycle 3 to cycle 5 was attributed to a major change in species composition of the grasshopper populations used in the selection process.
  • Power requirements of an imprinter and rangeland drill

    Wilkins, D. E.; Haferkamp, M. R.; Ganskopp, D. C. (Society for Range Management, 1990-05-01)
    Energy requirements for a land imprinter and rangeland drill, were determined on seedbeds with -6.5, 0.0, 5.0, and 8.5% slopes. The imprinter was tested empty (1.3 Mg/m), full (1.9 Mg/m), and half-full (1.67 Mg/m) of water. The rangeland drill was half width (1.5 m wide). Each implement was pulled over 4 replicated 23-m runs per slope. During each test run we recorded speed of travel and 10 drawbar force measurements, sensed with a load cell and integrated over 100 milliseconds. A procedure outlined by the American Society of Agricultural Engineers was used to estimate cost of use for a 3-m wide rangeland drill and imprinter 3/4 full of water. A 5-year implement age and 100 hours use per year were assumed. Operating costs for the land imprinter and rangeland drill were $56.92/ha and $40.27/ha, respectively, excluding grass seed.
  • Old World bluestem responses to nitrogen fertilization

    Berg, W. A. (Society for Range Management, 1990-05-01)
    Old World bluestem (Bothriochloa ischaemum L.) is being extensively seeded on marginal farmland in the Southern Plains. This field study was conducted in western Oklahoma to develop guidelines for efficient N fertilization of this perennial, warmseason grass established on soil depleted in plant-available N by 80 to 90 years of cultivation and erosion. Ammonium nitrate at 0, 35, 70, and 105 kg N ha-1 yr-1 was broadcast on Old World bluestem stands for 5 years on Woodward sandy loam (Typic Ustocrept) and for 3 years on Pratt loamy sand (Psammentic Haplustalf). Forage production averaged 800 kg ha-1 yr-1 without N fertilization. An average of 30 kg of forage was produced per kg N applied at rates of 35 and 70 kg N ha-1 yr-1. The 105 kg N ha-1 yr-1 treatment produced substantially more forage than the 70 kg N ha-1 yr-1 treatment only in years with above-average precipitation or favorable precipitation distribution. Partial die-out of Old World bluestem occurred one year; N fertilization increased die-out on Pratt loamy sand. Application of 70 kg N ha-1 in April was more effective in forage production and fertilizer N use in some years than split applications of 35 kg N ha-1 in April and June. Accumulation of N in forage over 5 years, plus residual N in stem bases, roots, and the surface 0.1 m of the Woodward sandy loam was 1,040 and 1,350 kg N ha-1 for the 0 N and 70 kg N ha-1 yr-1 treatments, respectively. The difference of these values, 310 kg N ha-1, suggests that most of the 350 kg N ha-1 applied over 5 years was accounted for; however, the standard error of difference between the means was large (50 kg N ha-1).
  • Nutritional characteristics of important desert grasses in Saudi Arabia

    Bokhari, U. G.; Alyaeesh, F.; Al-Noori, M. (Society for Range Management, 1990-05-01)
    A few representative dominant grasses were studied from various regions in Saudi Arabia to evaluate their nutritional and survival characteristics under the harsh growing environment of the Kingdom. Desert grasses are the main sources of nutrients for pastoral grazing animals. Analyses of representative samples indicated high protein and carbohydrate contents in various parts of the plants. However, these nutrients are available only for a short duration and are below sufficiency level for many milk and meat animals during much of the growing season.
  • Mefluidide effect on Caucasian bluestem leaves, stems, forage yield, and quality

    White, L. M. (Society for Range Management, 1990-05-01)
    'Caucasian’ bluestem [Rothriochloa caucasis (Trin.) C.E. Hubb.] provides high quality forage during early summer but growth of floral stems causes a rapid decline in forage quality. In 1985 and 1986 mefluidide [N-(2,4-dimethyl-S-{[(trifluromethyl)sulfonyl] amino)-phenyl)acetamide, a growth regulator, was applied to Caucasian in late May, early June, aud mid June at 0.00, 0.28, 0.56, and 0.84 kg/ha to determine which combination of date and rate of application would effectively decrease number of floral stems and yet increase forage quality. Caucasian was grown on a Pratt fine sandy loam (Thermic Pasammentic Haplustalfs) soil 6 km north of Fort Supply, Okla. Plots (1.5 by 5 m) were replicated 4 times in a randomized complete block design with a factorial treatment arrangement. Forage was harvested above a 6-cm stubble height in late July. On the control plots, the in vitro dry matter digestibility (IVDMD) and crude protein of leaves was 6.5 and 2.0 percentage units higher than stems. Leaves accounted for 40% of the forage yield the first year and 64% the second year. Mefluidide was most effective if applied late May. Response surface analysis showed that mefluidide (0.56 kg/ha) application in late May decreased number of floral stems 35 to 509, forage yields 20 to 251, and leaf yields 7 to 25%. In 1985, mefluidide had no effect on IVDMD and crude protein of leaves, stems, and whole plants. In 1986, application of 0.56 kg/ha mefluidide in late May increased leaf, stem, and whole plant IVDMD by 1.2, 2.7, and 2.0 percentage units and crude protein by 0.5 to 1 percentage units. Mefluidide did not decrease number of floral stems enough nor increase leaf yield and forage quality enough to be economically used on Caucasian to improve livestock gain during late July.
  • Managing individual juniper and pinyon infestations with pelleted tebuthiuron or picloram

    Johnsen, T. N.; Dalen, R. S. (Society for Range Management, 1990-05-01)
    Junipers (Juniperus spp.) and pinyons (pinus edulis Engelm.) are reinfesting areas from which they have been removed and are encroaching into other areas. Controlling these trees while they are small would help maintain forage production and protect the soils. Individual trees can be controlled by applications of pelleted picloram (4amino-3,5,6-trichloro-2-pyridinecarboxylic acid) and tebuthiuron [N-[5-(1,l-dimethylethyl)-l,3,4thiadiazol-2-yl]N-N-dimethylurea), but little is known of the comparative effectiveness of these herbicides on junipers and pinyon. We compared pelleted picioram and tebuthiuron on individuai alligator juniper (J. deppeana Steud.), one-seed juniper [J. monosperma (Engelm.) Sarg.], Utah juniper [J. osteosperma (Torr.) Little], and pinyon. Pellets were applied at 0.7 and 1.4 g picloram acid equivalent (a.e.) or tehuthiuron active ingredient (a.i.)/m of tree height at 3 Arizona and 3 New Mexico locations. Utah juniper and pinyon trees up to 2 m tall were killed with 0.7 g picloram a.e. or tebuthiuron a.i./m of height. One-seed junipers up to 2-m tall were killed by 0.7 g tebuthiuron a.i./m of height, but were not by picloram. Neither herbicide killed alligator juniper consistently. Some understory grasses were damaged more by tebuthiuron than by picloram.
  • Macro and trace mineral content of selected south Texas deer forages

    Barnes, Thomas G.; Varner, Larry W.; Blankenship, Lytle H.; Fillinger, Thomas J.; Heineman, Sharon G. (Society for Range Management, 1990-05-01)
    White-tailed deer (Odocoileus virginianus) derive the majority of their dietary mineral intake from range forages which may be deficient in one or more essential minerals. We have described the macro and trace mineral concentration of 18 shrub, 26 forb, 7 grass, and 1 cactus species, known to occur in south Texas deer diets, collected from the Chaparral Wildlife Management Area in 1974 and 1975. Within each forage class, there were no seasonal differences in calcium (Ca), sodium (Na), potassium (K), or magnesium (Mg) concentrations. Phosphorus (P) concentrations in browse were higher (P less than or equal to 0.05) during the season (0.20%) than during other seasons (0.14-0.16%). Forb P concentrations were greatest during the spring and winter periods (0.26 and 0.29%, respectively), and P levels in grasses (0.24-0.14%) decreased as the forage matured and reached senescence. Shrubs contained less P and K (P less than or equal to 0.01) than either grasses or forbs; whereas, grasses contained lower concentrations of Ca and Mg (P less than or equal to 0.01) than shrubs or forbs. Sodium concentrations did not differ among forage classes. Forbs contained greater (P less than or equal to 0.01) levels of copper (Cu) and zinc (Zn) than grasses or browse, and browse contained less iron (Fe) (P less than or equal to 0.01) than forbs or grasses. Manganese concentrations did not differ among forage classes. There were differences in mineral concentrations among species within forage class. Results suggest concentrations of all minerals except P met or exceeded minimum domestic animal requirements. Managers should provide a diversity of plant species and encourage practices that promote forb growth to provide optimum and nutritional benefits for deer.
  • Effects of spring headfires and backfires on tall grass prairie

    Bidwell, T. G.; Engle, D. M.; Claypool, P. L. (Society for Range Management, 1990-05-01)
    We compared responses of tallgrass prairie vegetation to late spring herdfires and backfires on a moderately stocked 2.4 AUM ha-1) shallow prairie range site 15 km southwest of Stillwater, Oklahoma. We replicated treatments 4 times in a randomized complete block design on 10 X 20-m plots oriented with the prevailing wind direction. Treatment factors included burning treatments (headfire, backfire, and unburned check) and treatment years (1986 and 1987). Herbage standing crop was clipped to ground level in tive 0.25-m2 quadrats per plot in June and August and separated into vegetation categories. Standing crop of tallgrasses in August was 21% (400 kg ha-1) greater on headfired than backfired plots. Forb standing crop in August was 26% (98 kg ha-1) greater on backfired plots than headfired plots. On tallgrass prairie managed for livestock, the area headfired should be maximized within the constraints of the bum prescription. Backfiring in late spring can be used to increase wildlife habitat on small areas.
  • Effects of domestic goats on deer wintering in Utah oakbrush

    Riggs, R. A.; Urness, P. J.; Gonzalez, K. A. (Society for Range Management, 1990-05-01)
    Dietary composition and quality, activity budgets, and foraging behavior of tame mule deer (Odocoileus hemionus hemionus) were monitored in winter to ascertain the effects of prior summer use of oakbrush communities by domestic goats (Capra hircus). Reduction of deciduous browse by goats resulted in increased use of Wyoming big sagebrush (Artemisia Nutt. subsp. wyomingensis Beetle and Young) by deer when snow cover precluded use of understory species. As a result, the diets of deer confined to goat-browsed pastures contained less fiber and tannins, and were more digestible than those of deer in control pastures. Digestible protein in diets did not differ. No goat-related effects were observed in the absence of snow because deer grazed the herbaceous understory which had not been substantially altered. Quantity of cured herbage was low, and deer did not effectively select for fall regrowth. Consequently, diet quality under snow-free conditions was not substantially different from that observed under snow-covered conditions. Snow reduced foraging efficiency; deer travelled faster, and exhibited lower bite and intake rates when feeding under snow-covered conditions than under snow-free conditions. Goat-induced vegetal differences were not reflected in activity budgets or foraging behavior, regardless of snow condition. We conclude that goats may be used to periodically manipulate composition of oakbrush winter range, thereby enhancing quality of deer diets under snow-covered winter conditions. However, enhancement of deer diets under snow-free winter conditions probably requires annual manipulation of the understory.
  • Effect of soil water, nitrogen, and growing degree-days on morphological development of crested and western wheatgrass

    Frank, A. B.; Ries, R. E. (Society for Range Management, 1990-05-01)
    Production of total forage dry matter is mainly a function of available soil water and soil nitrogen (N), whereas plant morphological development from spring greenup to anthesis is primarily controlled by air temperature. There is a lack of information on effects of soil water and soil N on plant morpholoical development. A study was conducted in a rain-out shelter at Mandan, North Dakota, over a 3-year period to determine the effect of 2 fertilizer N rates (11 and 110 kg N/ha) and 3 rates of applied water (50, 100, and 150% of long term April-November rainfall at Mandan, North Dakota) on morphological development of initial spring growth and fall regrowth of crested wheatgrass [Agropyron desertorum (Fisch.) Schult] and western wheatgrass [Pascopyrum smithii Rydb, (Love)]. Regression analysis of plant development stage with accumulated growing degree-days (GDD) was linear for both initial and regrowth forage. There were no differences in rate of plant development for the 3 rates of applied water or the 2 rates of N fertilizer. Initial growth forage of crested and western wheatgrass required 82 and 98 GDD to produce a leaf, respectively. Regrowth forage of crested wheatgrass required 372 and western wheatgrass 135 more GDD than initial growth to produce a leaf. These data confirm that plants develop primarily in response to air temperature and not added water or N, which enhances the utility of using the accumulation of GDD for predicting development of crested and western wheatgrass under different growing conditions. This information will be useful for predicting plant development of these species in growth models and for farmers and ranchers in predicting grazing readiness.

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