Little information is available to help managers of cool-season dominated semiarid rangelands determine when to begin and end grazing in the spring and fall. Therefore, we evaluated the effects of clipping spring and fall growth on subsequent-year yield of needle-and-thread (Hesperostipa comata [Trin. & Rupr.] Barkworth) and threadleaf sedge (Carex filifolia Nutt.) (USDA-NRCS 2012) using a randomized complete block, split-plot experimental design with fall moisture regimes (ambient or supplemental water) applied to main plots and defoliation treatments applied to subplots. Two combinations of spring defoliation, one for each fall moisture regime, were composed of a factorial array of three spring clipping dates (early May, late May, mid-June) and three levels of defoliation (0%, 40%, 80%). A third combination of treatments was composed of the supplemental water regime and an array of a single spring clipping date (late May), a single fall clipping date (late September, after regrowth), and three levels of defoliation (0%, 40%, 80%) in the same year. Ambient fall moisture was low, leading to continued senescence of needle-and-thread and threadleaf sedge, whereas the application of 10 cm of supplemental water in mid-August stimulated fall growth. The study was replicated with two sets of main plots at four sites in consecutive years, 2002 and 2003. Yield data were collected in mid-June of the year following treatment. Subsequent-year yield of needle-and-thread was not affected by defoliation under average plant-year precipitation conditions (2003) (P > 0.05); however, it was reduced following heavy (80%) late spring (late May or June) defoliation during a drought year (2002) (P > 0.05). Subsequent-year yield of threadleaf sedge was not affected by defoliation in either year (P > 0.05). Because it is difficult to predict when drought will occur, avoiding heavy late-spring grazing in needle-and-thread dominated pastures in consecutive years would be prudent.

Abstract Root growth is important to the competitive ability of plants, and understanding how herbage defoliation affects root growth has implications for development of management strategies. Objectives were to determine the effects of defoliation intensity and frequency on root characteristics and herbage production of slender wheatgrass (Elymus trachycaulus [Link.] Shinners), Nebraska sedge (Carex nebrascensis C. Dewey), and “Steadfast” birdsfoot trefoil (Lotus corniculatus L.). Plants of each species were transplanted into containers that had been placed in the ground at wet meadow field sites the prior year. There were eight replications of a control and five defoliation treatments, which were combinations of different frequencies (two or five times) and intensities (light or heavy) and haying. Treatments were applied for a single growing season, and aboveground biomass was collected. Containers were extracted in October, and plant crowns, rhizomes, and roots were separated from the soil. Defoliation treatment did not affect total root weight, length, and surface area of Nebraska sedge or birdsfoot trefoil (P > 0.10). Slender wheatgrass total root weight was less when defoliated five times (4.46 g · container−1) than when defoliated twice (6.62 g · container−1) during the growing season. More frequent defoliation of slender wheatgrass also reduced length (20%) and surface area (21%) compared to less frequent defoliation. However, defoliation frequency did not affect aboveground biomass. Defoliation intensity did not affect aboveground production or root characteristics of the three species. Abundant soil moisture in meadows likely buffers negative effects of defoliation. For all species, two defoliation events (e.g., haying followed by grazing) does not appear to negatively affect root growth and herbage production.

Understanding the long-term effect of summer grazing date and fall stocking rate on herbage production is critical to extending the grazing season in the Nebraska Sandhills. A study was conducted from 1997 to 2002 at the Gudmundsen Sandhills Laboratory located near Whitman, Nebraska, to determine the herbage production response to summer grazing date and October stocking rate on two different sites. Site 1 was dominated by warm-season grasses and site 2 was dominated by cool-season graminoids. At each site, three 0.37-ha pastures were constructed in each of four blocks before application of summer grazing treatments. Pastures in each block were grazed at 0.5 animal-unit months (AUM) . ha(-1) in June or July, or were deferred from summer grazing. Following summer grazing treatments, October stocking rate treatments (no grazing or 1.0, 2.0, or 3.0 AUM . ha(-1)) were applied to subunits of each summer grazing date pasture during mid-October. Vegetation was sampled in each pasture in mid-June and mid-August and sorted by functional group to determine the effect of 5 yr of grazing treatments on herbage production and residual herbage. Herbage production was not affected by summer or October grazing treatments on the warm-season grass-dominated site. Increasing October stocking rate, however, reduced cool-season graminoid production and subsequent herbage production 25% by year 5 of the study. Residual herbage at both sites at the end of the October grazing periods explained as much as 16% to 34% of subsequent year's herbage production. Grazing managers in the Nebraska Sandhills can extend the grazing season by lightly stocking pastures in the summer to facilitate additional fall grazing. Heavy stocking in October over several years on cool-season-, but not warm-season-, dominated sites will reduce production of cool-season graminoids on these sites.

(from visible to near infrared), we evaluated an image processing technique known as spectral angle mapping for mapping the invasive species distribution. A minimum noise fraction algorithm was used to remove the inherent noise and redundancy within the dataset during the classification. The classification algorithm applied on the AISA image revealed five categories of invasive species distribution including (1) saltcedar; (2) Russian olive; and a mix of (3) Canada and musk thistle, (4) Canada/musk thistle and reed canary grass, or (5) Canada/musk thistle, saltcedar, and reed canary grass. Validation procedures confirmed an overall map accuracy of 74%. Saltcedar and Russian olive classes showed producer and user accuracies of greater than 90%, whereas the mixed categories revealed accuracy values of between 35 and 74%. The immediate benefit of this research has been to provide information on the spatial distribution of invasive species to land managers for implementation of management programs. In addition, these data can be used to establish a baseline of the species distributions for future monitoring and control efforts. Nomenclature: Canada thistle, Cirsium arvense L. Scop.; musk thistle, Carduus nutans L.; reed canary grass, Phalaris arundinacea L.; Russian olive, Elaeagnus angustifolia L.; saltcedar, Tamarix sp. Lour.

Knowledge of how current-year grazing and drought stress affect subsequent-year herbage production is needed to enhance the management of semiarid Sandhills prairies. This study quantifies subsequent-year effects of defoliation and precipitation on prairie sandreed (Calamovilfa longijolia), a high-seral, warm-season tallgrass, and total graminoid herbage production in the Nebraska Sandhills. Mainplots (9.0 m2) received either ambient precipitation (noncovered) or precipitation was excluded during April-May, June-July, or August-September, resulting in 66% to 135% of the long-term average (434 mm) precipitation. All species in 1.0 m2 defoliated subplots were clipped in early July at the stubble height required for 30%, 60%, or 90%

Soil water is generally the most limiting factor for plant growth in and and semiarid rangeland ecosystems. Interactions between precipitation regimes and optimum air temperatures for growth of different species often have measurable effects on peak standing herbage and species composition. Simulating multiple precipitation regimes in a single year will enhance our ability to quantify plant-environment interactions. Evaluating the seasonal effects of variation in timing and quantity of precipitation will require controlled water applications with little or no runoff. A diversity of plot watering systems has been developed for different kinds of agronomic and rangeland research. However, most of these systems were designed to simulate heavy precipitation events and features of all previously described systems limit the number of plots and/or variation in site characteristics that can be included in rangeland field studies. Therefore, we developed the Passive Application Watering System (PAWS), which is composed of a graduated polyethylene application tank connected to a discharge system of polyvinyl chloride (PVC) and soaker hose subunits. It is portable and suitable for applying water over a wide range of slope, soil texture, and residual herbage conditions with little or no runoff. Application rates are controlled by the amount of hydrostatic pressure, which is determined by the head, the difference in height between the tank's water level, and the soaker hoses. Heads of 0.1 m and 2.0 m produce application rates of 5 mm . hr(-1) and 40 mm . hr(-1) which correspond to the permeability of clay loam and silt loam, respectively. Application rates increase about 1.8 mm . hr(-1) +/- 0.15 SE for each 10-cm increase in head. We have successfully used the PAWS in 3 research projects on range sites with sandy and loamy soil texture classes.

The grazing season on upland Sandhills range traditionally begins in mid-May when the dominant warm-season grasses have initiated growth. Initiating grazing earlier would improve efficiency of use of cool-season plants and reduce the time period during which hay is fed. A 2-year study was conducted to determine nutrient and botanical composition of cattle diets when grazing upland Sandhills range during spring. Diets were collected from esophageally-fistulated cows on 10 April, I May, and 22 May each year. Concurrently, current-year, and residual herbage was clipped to determine pasture composition and calculate preference indices for the primary plant species and groups. Averaged across dates, needleandthread (Stipa comata Trin. & Rupr.), bluegrasses (Poa spp.), and sedges (Carex spp.) accounted for 19% of the total herbage and 68% of the current-year herbage yield. These species constituted an average of 74% of cow diets. Diet composition of sedges was less on 10 April than on 22 May (P < 0.05), whereas similar amounts of needleandthread and bluegrasses were present on all dates. Preference indices indicated strong selection for species with abundant current-year growth and avoidance of residual herbage. Crude protein content of diets was less on 10 April (10.7%) than on 1 May or 22 May (13.9%, P < 0.05), likely because of a greater amount of residual herbage present in 10 April diets. Overall quality of diets would meet requirements of average spring-calving cows; however, grazing management strategies would need to account for the limited availability of current-year growth during spring, particularly April, to ensure that cattle are meeting their nutrient needs.

Crop ScienceVolume 45, Issue 1 cropsci2005.0416 p. 416-417 Registrations Of Cultivars Registration of ‘NU-ARS AC2’ Crested Wheatgrass K.P. Vogel, Corresponding Author K.P. Vogel [email protected] USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937Corresponding author ([email protected])Search for more papers by this authorD. Tober, D. Tober USDA-NRCS, North Dakota State Office, 220 East Rosser Avenue, P.O. Box 1458, Bismarck, ND, 58502-1458Search for more papers by this authorP.E. Reece, P.E. Reece D.D. Baltensperger, Panhandle Research & Extension Center, Univ. of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939Search for more papers by this authorD.D. Baltsensperger, D.D. Baltsensperger USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937 USDA-NRCS, North Dakota State Office, 220 East Rosser Avenue, P.O. Box 1458, Bismarck, ND, 58502-1458 D.D. Baltensperger, Panhandle Research & Extension Center, Univ. of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939 High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899 KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State Univ., Hays, KS, 67601Search for more papers by this authorG. Schuman, G. Schuman High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899Search for more papers by this authorR.A. Nicholson, R.A. Nicholson KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State Univ., Hays, KS, 67601Search for more papers by this author K.P. Vogel, Corresponding Author K.P. Vogel [email protected] USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937Corresponding author ([email protected])Search for more papers by this authorD. Tober, D. Tober USDA-NRCS, North Dakota State Office, 220 East Rosser Avenue, P.O. Box 1458, Bismarck, ND, 58502-1458Search for more papers by this authorP.E. Reece, P.E. Reece D.D. Baltensperger, Panhandle Research & Extension Center, Univ. of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939Search for more papers by this authorD.D. Baltsensperger, D.D. Baltsensperger USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937 USDA-NRCS, North Dakota State Office, 220 East Rosser Avenue, P.O. Box 1458, Bismarck, ND, 58502-1458 D.D. Baltensperger, Panhandle Research & Extension Center, Univ. of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939 High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899 KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State Univ., Hays, KS, 67601Search for more papers by this authorG. Schuman, G. Schuman High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899Search for more papers by this authorR.A. Nicholson, R.A. Nicholson KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State Univ., Hays, KS, 67601Search for more papers by this author First published: 01 January 2005 https://doi.org/10.2135/cropsci2005.0416Citations: 5 Registration by CSSA. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References Bailey, Robert G. 1995. Description of the ecoregions of the United States. 2nd ed. rev. and expanded 1st ed. 1980). Misc. Publ. No. 1391 (rev). U.S. Forest Service, Washington, DC. Cathey, H.M. 1990. USDA plant hardiness zone map. USDA Misc. Pub. No. 1475. U.S. National Arboretum, Agricultural Research Service, U.S.D.A., Washington, DC. (1998 U.S. National Arboretum “Web Version” is available at www.usna.usda.gov/Hardzone/ushzmap.html, verified 20 September 2004). Munsell Color. 1977. Munsell color charts for plants tissues. 2nd ed. Munsell Color (Firm), Baltimore, MD. Citing Literature Volume45, Issue1January–February 2005Pages 416-417 ReferencesRelatedInformation

A focus of grazing management courses is the cause–effect relationships between grazing livestock distribution and environmental and management variables. A learning module for the classroom was developed to enable students to actively study livestock distribution by analyzing recently collected data from an on-ranch situation. Data were collected at the University of Nebraska’s Barta Brothers Ranch in the Nebraska Sandhills. Six cows (Bos taurus) were fitted with global positioning system (GPS) collars and grazed freely with a herd of cow–calf pairs. Their locations were recorded at 5- or 10-minute intervals during two summer grazing periods in 2003. Following each grazing period, the collars were removed and the data were transferred to a personal computer. A geographic information system (GIS) software program (GRASS) was used for data processing and analyses. A standard digital elevation model of the ranch property was imported into GRASS as the base topographical map. Software tools were used to create animations and present analyzed data in tabular and graphical form. The learning module has two lessons. The first lesson presents the principles of grazing distribution and the second lesson enables the student to analyze the GPS locational data. In analyzing the GPS data, students have numerous options and select the pasture, date(s), hours of the day, and the independent variable (e.g., topographical position or livestock water location) to be included in the analyses. Students can develop hypotheses concerning the relationship between these independent variables and livestock distribution, and test them using the output from the module. Student evaluations indicate that the module is effective in engaging the students as learners and improving their ability to think critically.

Crop ScienceVolume 45, Issue 1 cropsci2005.0414 p. 414-415 Registrations Of Cultivars Registration of ‘Beefmaker’ Intermediate Wheatgrass K.P. Vogel, Corresponding Author K.P. Vogel kpv@unlserve.unl.edu USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937Corresponding author (kpv@unlserve.unl.edu)Search for more papers by this authorP.E. Reece, P.E. Reece D.D. Baltensperger, Panhandle Research & Extension Center, University of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939Search for more papers by this authorD.D. Baltsensperger, D.D. Baltsensperger USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937 D.D. Baltensperger, Panhandle Research & Extension Center, University of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939 High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899 KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State University, Hays, KS, 67601Search for more papers by this authorG. Schuman, G. Schuman High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899Search for more papers by this authorR.A. Nicholson, R.A. Nicholson KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State University, Hays, KS, 67601Search for more papers by this author K.P. Vogel, Corresponding Author K.P. Vogel kpv@unlserve.unl.edu USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937Corresponding author (kpv@unlserve.unl.edu)Search for more papers by this authorP.E. Reece, P.E. Reece D.D. Baltensperger, Panhandle Research & Extension Center, University of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939Search for more papers by this authorD.D. Baltsensperger, D.D. Baltsensperger USDA-ARS, 344 Keim Hall, P.O. Box 830937, Univ. of Nebraska, Lincoln, NE, 68583-0937 D.D. Baltensperger, Panhandle Research & Extension Center, University of Nebraska, 4502 Ave. I, Scottsbluff, NE, 69361-4939 High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899 KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State University, Hays, KS, 67601Search for more papers by this authorG. Schuman, G. Schuman High Plains Grasslands Research Station, USDA-ARS, 8408 Hildreth Road, Cheyenne, WY, 82009-8899Search for more papers by this authorR.A. Nicholson, R.A. Nicholson KSU Agricultural Research Center and Dep. Biological Sciences, Fort Hays State University, Hays, KS, 67601Search for more papers by this author First published: 01 January 2005 https://doi.org/10.2135/cropsci2005.0414Citations: 4 Registration by CSSA. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume45, Issue1January–February 2005Pages 414-415 RelatedInformation

Upland sites in the Nebraska Sandhills are dominated by warm-season grasses, although cool-season graminoids often produce from 10% to 40% of the herbage. The grazing season on uplands traditionally begins when warm-season grasses have initiated rapid growth, which coincides with declining nutrient density of cool-season plants. Earlier initiation of grazing would improve the efficiency of use of cool-season plants. A study was conducted in 2001 and 2002 to characterize the growth of cool-season species on upland range and to determine the use and herbage production in response to spring grazing date and stocking rate. Grazing dates were 10 April, 1 May, and 22 May, combined with stocking rates of 3, 6, and 9 AUD (animal unit days) (.) ha(-1). Needleandthread (Stipa comata Trin. & Rupr.) and sedges (Carex spp.) accounted for an average of 48% of the spring herbage yield. Amount of total current-year herbage ranged from 114 to 472 kg (.) ha(-1) over the grazing dates. Overall, paddock use of needleandthread and sedges averaged 11% and 4%, respectively. Use on 10 April averaged 61% of that observed on 1 and 22 May, likely because of short plant height (5 cm). Residual (prior-year) herbage probably was a substantial component of animal diets on 10 April. Increasing stocking rate resulted in greater herbage use (% weight removed) and percentage of plants grazed (P < 0.1). Total herbage yield in mid-june (1 1.30 kg (.) ha(-1)) and mid-August (1 350 kg (.) ha(-1)) was greatest when paddocks were grazed in April, and it declined by approximately 20% when grazed in May (P < 0.1). Overall, upland grazing strategies that include a grazing period in early May will result in greater utilization of cool-season species, but summer yield will be reduced. However, utilization of cool-season species in the spring would be advantageous, because they are being consumed at a time when their nutritive value and palatability are greater.

Thousands of forb species are distributed among the diverse rangelands of North America. However, little is known about livestock grazing effects on the demographics and potential demise of palatable forbs in grassland ecosystems. A study was designed to quantify the cumulative effects of summer grazing on the demographics of stiff sunflower (Helianthus rigidus [Cass.] Desf. spp. subrhomboides [Rydb.] Heiser), a highly palatable, late-seral, perennial forb. Pastures were grazed for 5-7 days in mid-June or mid-July during 1995-1997 at 16, 32, or 48 animal unit days (AUD) per hectare. All grazing treatments reduced the plant height of stiff sunflower. However, population densities were maintained throughout the study at light stocking rates (16 AUD ha-1). In contrast, a single year of heavy stocking (48 AUD ha-1) in June reduced spring stiff sunflower densities 55%. Densities declined about 30% after 1 year at moderate stocking rates (32 AUD ha-1) in either month or heavy stocking in July. After 3 years of short-duration grazing in June, moderate and heavy stocking rates eliminated some colonies and reduced mean pasture densities by about 90% compared with 40% and 70% reductions in moderately and heavily stocked July-grazed pastures, respectively. Reductions in spring densities corresponded to increases in premature senescence the previous year when more than 30% of the plants turned brown before mid-August. Critical levels of premature senescence were likely to occur when more than 60% of stiff sunflower plants within colonies were grazed. Light stocking rates are rare on privately owned Nebraska Sandhills rangeland (4.7 million ha); therefore, vigorous populations of stiff sunflower are most likely to occur in pastures used predominantly during the dormant season.

Interannual differences in yield and species composition of herbaceous vegetation on semiarid rangelands are common and often related to variations in precipitation regime. Interspecific interactions that occur after drought-induced population fluxes of western ragweed (Ambrosia psilostachya D.C.) were evaluated by removing western ragweed or associated species from 1-m2 quadrats at weekly intervals beginning in early May, June, or July 1991 or 1992 on high-seral sandhills prairie in Nebraska. The composite of peak standing crops for ragweed and each group of associated species was 77% greater during May-October 1991 (2 252 kg ha-1) compared with 1992 (1 275 kg ha-1) when April and May precipitation was 98 mm below average and a late frost occurred. Mean levels of western ragweed herbage up to 436 kg ha-1 had no effect on associated species in 1991 when above average precipitation occurred throughout the growing season. In contrast, when an unusually dry spring occurred in 1992, relatively small mean levels of ragweed (189 kg ha-1) reduced end-of-season standing herbage of rhizomatous C4 grasses on control plots by about 21% (137 kg ha-1) with little effect on other associated species, regardless of when treatments were initiated. Within a given year, western ragweed density was seasonally constant, similar among treatments, and independent of preceding-year species composition. Severe defoliation of western ragweed had little effect on subsequent-year populations, indicating an ability to maintain primordia for several years with limited plant growth. Because western ragweed is not a strong competitor in the presence of vigorous graminoids, deferring use of June- or July-grazed pasture until after July in the subsequent year can minimize increases in western ragweed.

Soil moisture deficit is usually the major limiting factor for herbage production in the Sandhills of Nebraska. We examined inter-population and interspecific variability in stomatal characteristics and drought tolerance in sand bluestem (Andropogon hallii Vitman), little bluestem [Schizachyrium scoparium (Michx.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scribn.], and switchgrass (Panicum virgatum L.). Ramets were collected during the dormant season across an aridity gradient from east to west (ranging from 560 mm to 340 mm average annual precipitation) in the Sandhills of Nebraska. Plants were grown in individual pots under greenhouse conditions. Once plants were well established, stomatal characteristics were determined and stomatal conductance (gs) was measured through a dry-down period of no watering. Populations did not differ in stomatal characteristics across the gradient, except for stomatal density on the adaxial leaf surface of prairie sandreed and the abaxial leaf surface of sand bluestem. Leaves of switchgrass and prairie sandreed were amphistomatic (stomata on both leaf surfaces), whereas leaves of little bluestem and sand bluestem were hypostomatic (stomata on the lower leaf surface). In the absence of drought, gs was 17 to 31% higher in little bluestem than in other species. Differences among species in gs were found mainly when watered and disappeared as the dry-down progressed. There was a positive relationship between stomatal density and gs in all species except prairie sandreed. Prairie sandreed maintained 35% of the initial relative water content of its leaves after 17 d of dry-down, compared to 23% for sand bluestem, 14% for switchgrass, and 9% for little bluestem. Variation in stomatal traits within species did not explain ecotypic adaptation to sites with a range of precipitation in the Nebraska Sandhills. Key words: Stomatal characteristics, water stress, warm season grasses, Nebraska Sandhills

This paper discusses how economists utilize an inter-disciplinary workshop to teach marketing and management concepts to beef cattle producers and beef industry advisors. Range and animal scientists along with economists teach concepts in the classroom and then demonstrate these concepts with hands-on field activities in an 8-day Ranch Practicum, spread over an 8-month period.

Multiple generations of rhizome-connected tillers stabilize soils and produce measurable amounts of herbage on sandy rangeland throughout the world. However, little is known about the dynamics of rhizome development in these clonal plant species. Seasonal relationships between foliar characteristics and rhizomes of prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were examined on sands range sites at 30-day intervals from May through September 1989 and 1990 at the University of Nebraska, Panhandle Experimental Range near Scottsbluff. Quadrats were excavated each year from two, 5 x 5 Latin Square macroplots in each of 2 grazing histories, long-term rest or current-year deferment. Under dry conditions in 1989, a 65% reduction in the length of new rhizomes during July preceded a 64% reduction in live tillers in August. After which, rhizome length and live tiller density were unchanged and mean tiller weight increased during September. When average precipitation occurred in 1990, a 25% reduction in live tillers and concurrent increases in new rhizome length and mean tiller weight occurred during July. Rhizome bud densities increased throughout the growing season at different but predictable rates (R2 greater than or equal to 0.95) for grazing histories, regardless of precipitation. Length of new rhizomes was highly correlated (R2 = 0.91) with live herbage throughout the growing season. Measurable increases in total rhizome length did not occur until live herbage of prairie sandreed exceeded a threshold of about 50 g m(-2). Maximum increase in length of new rhizomes per unit of live herbage was about 10 cm g(-1) near 100 g m(-2). Given its dependence on vegetative reproduction and relatively high palatability to beef cattle, periodic or repeated years of full growing season deferment may be the only reliable method of obtaining measurable increases in prairie sandreed populations.