• Reducing Incidence of Plant-Caused Congenital Deformities in Livestock by Grazing Management

      Keeler, R. F. (Society for Range Management, 1978-09-01)
      Effective grazing management can reduce the incidence of plant-caused deformities in livestock. The degree of success to be expected is related to certain principles of teratology. The following factors are among those that play a role: animal genotype, nature of the teratogen, dose, and susceptible gestation period. Each plant teratogen exerts its effect by a specific mechanism, and yet widely divergent teratogens can produce similar effects. The developing conceptus is not nearly so well protected as once thought from hazardous chemical compounds in the maternal circulation. When offending teratogenic plants grow in a restricted habitat or are hazardous only at certain growth periods or when the susceptible gestation period is short, then considerable success can be expected toward reducing incidence of deformities and attendant financial loss by careful grazing management methods.
    • Acute Impact of Herbicide Strip Treatment on Mixed-Brush White-tailed Deer Habitat on the Northern Rio Grande Plain

      Tanner, G. W.; Inglis, J. M.; Blankenship, L. H. (Society for Range Management, 1978-09-01)
      White-tailed deer tended to evacuate a 1,800-ha, mixed-brush pasture during 5 months following aerial strip-spraying in May with 2,4,5-T + picloram (1:1) at 0.56 kg/ha and 1.12 kg/ha and in two widths (80% coverage). Deer were attracted to the pasture in above-normal numbers the following winter but their numbers returned to normal by 11 months posttreatment. Apparently, succulent woody plant regrowth provided an attractive food base which induced the posttreatment increase in numbers. Deer on the pasture did not rearrange their use to favor untreated brush as a response to treatment rate or width of treated strip. Woody plant canopy cover was significantly reduced on all treated strips but cover screen at deer height was unaffected. Evidence suggests that only the high rate of herbicide application resulted in significant reduction in the stature of brush. Density of live brush stems was reduced less than 20% by treatment.
    • Artemisia vulgaris L.: An Ornamental Plant for Disturbed Land Reclamation

      Schuman, G. E.; Howard, G. S. (Society for Range Management, 1978-09-01)
      Mugwort wormwood (Artemisia vulgaris L), an ornamental sage, shows promise in the reclamation of disturbed lands. Dryland plantings at several mine sites showed excellent survival and growth. Analysis of the plant material showed the average protein content was 31.5% and the average in vitro digestibility, 67%. The low volatile oil content, 0.03%, accounts for its palatability and digestibility as compared with other species of Artemisia.
    • Coevolution of Poisonous Plants and Large Herbivores on Rangelands

      Laycock, W. A. (Society for Range Management, 1978-09-01)
      Early literature generally described toxic plant substances as waste products. However, more recent publications in entomology, plant biochemistry, and other fields suggest that toxic secondary compounds in plants may be defense systems against insects and other herbivores. The pertinence of these discussions to range management is the subject of this paper. If plant poisons have evolved as defense mechanisms, various ways that they might function include: (1) extreme toxicity; (2) poisonous properties linked with palatability; and (3) aversive conditioning, i.e., animals "learn" that a plant will make them ill and avoid that plant. All could reduce consumption of poisonous plants by herbivores, thus making the plants more competitive in natural communities. If plant poisons are defense mechanisms, it would be logical to assume that coevolution has occurred in herbivores to prevent their being poisoned by plants. Some of the possible evolutionary adaptations in large herbivores include: (1) a generalized diet that reduces the probability of eating a toxic amount of any one species; (2) ability to detect and avoid poisonous plants; and (3) ability to detoxify plant poisons. All appear to operate, at least to a degree, in both domestic and wild herbivores. Ability to detect and to detoxify poisons varies among species and appears to be more prevalent in native animals that coevolved with the vegetation than in domestic animals. Native big-game animals are occasionally poisoned by plants but large losses usually occur in overpopulated or overgrazed areas where nonpoisonous species have been depleted.
    • Control of Black Grass Bugs (Labops hesperius Uhler) in Northern New Mexico

      Dickerson, G. W. (Society for Range Management, 1978-09-01)
      Insecticides applied to improved wheatgrass pastures in northern New Mexico in the springs of 1976 and 1977 were all shown to reduce population of black grass bugs significantly (P<.01). Herbage yields were decreased as much as 50% on untreated crested wheatgrass plots in 1976. Plots treated with trichlorofon produced significantly (P<.05) higher herbage yields than the untreated plots. Malathion at rates as low as 354 g/ha of active ingredient were effective in controlling this pest.
    • Physiologic Responses Of Livestock to Toxic Plants

      Bailey, E. M. (Society for Range Management, 1978-09-01)
      Information is presented to describe various disease syndromes in livestock resulting from the ingestion or exposure to toxic plants. Additional material is presented concerning diagnosis of plant-related animal diseases.
    • Germination of Goldenweed Seed

      Mayeux, H. S.; Scifres, C. J. (Society for Range Management, 1978-09-01)
      Large, well-filled seed of Drummond's goldenweed (Isocoma Drummondii (T. & G.) Greene) germinated in excess of 80% over a broad range of continuous temperatures (10 to 25° C). Germination of Drummond's and common goldenweed (Isocoma coronopifolia (Gray) Greene) seed was about 20% higher under alternating than constant temperature regimes, and 20 to 30% lower in absence of light. Germination and early seedling growth were reduced by -4 and -2 bars simulated moisture stress, respectively. Germination and early seedling vigor were relatively tolerant of extremes of pH, but NaCl concentrations of 5,000 ppm or higher reduced germination. Drummond's goldenweed seed viability decreased significantly after 200 days storage at room conditions, and no achenes of either species germinated after storage for 15 months. Seed collected from robust plants growing on deep, fertile soil had a higher percent germination than those of plants growing under less favorable conditions, although unimbibed achene weight did not differ. No seed dormancy mechanisms were observed. Initial seedling establishment apparently depends primarily on the occurrence of adequate rainfall in late winter and early spring.
    • Predicting Green Weight of Mesquite (Prosopis glandulosa Torr.)

      Whisenant, S. G.; Burzlaff, D. F. (Society for Range Management, 1978-09-01)
      Planning for commercial utilization of mesquite wood requires a procedure for estimating biomass in a given stand. A study of virgin mesquite trees at three range sites in each of seven counties of the Rolling Plains of Texas was initiated. Data revealed a highly significant linear relationship (r = .933) exists between stem area at 60 cm above ground and the green weight of the tree. The green weight of individual trees can be predicted from a random sample of 256 trees when a prediction equation (Y = .410X) is used. Y = green weight of the individual tree expressed in kilograms. X = stem area at a 60 cm height above ground level expressed as square centimeters.
    • Management Approaches to Reduce Livestock Losses from Poisonous Plants on Rangeland

      Krueger, W. C.; Sharp, L. A. (Society for Range Management, 1978-09-01)
      Early approaches to management for the purpose of reducing or minimizing animal losses due to plant toxins were those of avoiding the areas with poisonous plants or eradicating these plants where feasible. As knowledge and information accumulated through scientific investigations and, often, through experience gained by livestock producers, other techniques could be followed. With a growing understanding of what plants are poisonous and the nature of the toxins, along with the conditions under which toxins are elaborated in the plant, management strategies have been improved.
    • Measuring Fireweed Utilization

      Harshman, E. P.; Forsman, R. (Society for Range Management, 1978-09-01)
      Measurement of grazing use on forbs has not received as much attention as grasses. On the Willamette National Forest, forbs are major forage producers for the first 10 years after clearcutting and slash disposal. Studies on fireweed showed that a percent-height to percent-weight curve could be developed which was accurate and efficient to use. Utilization measurements, to be meaningful, however, must be correlated with resource use or protection.
    • Net Aerial Primary Production of an Andropogon-Paspalum Grassland Ecosystem

      Britton, C. M.; Dodd, J. D.; Weichert, A. T. (Society for Range Management, 1978-09-01)
      Changes in net aerial primary production as influenced by selected environmental parameters were evaluated in a grassland ecosystem for the 1973 and 1974 growing seasons. Biomass weight was estimated for phenologically determined harvest intervals. Efficiency of converting solar energy to chemical energy was determined. Between years, precipitation was the dominant environmental parameter associated with production. The quantity was not as critical as the date and the resultant effect on available soil water. Increments of production followed a monomodal pattern similar to yearly trends in soil temperature and solar radiation. Deviations in production from this monomodal pattern were related to available soil water and soil water deficit. Total production during 1973 (ca. 400 g m-2) was approximately 100 g m-2 higher than in 1974. This difference was due primarily to lower available soil water during early spring and a 4-week longer summer dry period in 1974. Based on measurements of photosynthetically active radiation, energy values, and production, the growing season conversion efficiencies were 0.34% in 1973 and 0.23% in 1974. The highest conversion efficiencies for a harvest interval occurred each year during June: 0.87% in 1973 and 0.59% in 1974.
    • The Ecological Niches of Poisonous Plants in Range Communities

      Cronin, E. H.; Ogden, P.; Young, J. A.; Laycock, W. (Society for Range Management, 1978-09-01)
      So many diverse plant species are poisonous to domestic livestock that it seems highly improbable that a universal competitive advantage is common to all poisonous species. Plant poisons may have originated in mutations that were of no direct adaptive value. Once these secondary chemical products became established in the physiologic systems of plants, their interactions with insects and rodents that consumed the seeds, seedlings, or herbage of the plant may have given them adaptive value. Evolution of resistance to poisons of plants by the herbivores probably has led to the proliferation of species in genera that contain many poisonous species such as Astragalus. The study of such relationships should be given priority in range ecology to achieve effective management of the range resource. Some poisonous plant species have also evolved allelopathic defense mechanisms that enhance competitive advantages. The coevolution of poisonous plants, large herbivores, and rumen microfloras offers intriguing possibilities for study that may answer questions basic to the future success of range management.
    • The Economic Impact of Poisonous Plants on the Range Livestock Industry in the 17 Western States

      Nielsen, D. B. (Society for Range Management, 1978-09-01)
      Poisonous plants cause serious economic losses in many areas of the West. However, there is no systematic way of accounting for the magnitude of these losses. A significant proportion of the poisonous plant loss is reflected in annual death loss in livestock and in calf and lamb crop percentages. By concentrating one's effort on the effect of poisonous plants on these measures, one should be in a better position to make reasonable estimates of the economic costs of poisonous plants. Other losses from poisonous plants should be considered as data become available. Based on the assumptions outlined, the economic loss in the 17 western states is about $107 million annually. Poisonous plants have the potential on many ranches of causing financial ruin to the business. It has been shown that poisonous plants can be economically controlled and losses kept at manageable levels.
    • Tiller Development and Growth in Switchgrass

      Beaty, E. R.; Engel, J. L.; Powell, J. D. (Society for Range Management, 1978-09-01)
      Switchgrass accessions collected from throughout the Southeast were grown without harvesting for 8 years. Measurements were made on tiller generation, rate of clone spread, time of tiller initiation, and number of tillers per given area. Data collected show that tillers are true biennials, buds at the base of shoots growing as rhizomes the first year and growing as green leaf bearing shoots the second when an inflorescence is produced. Rate of clone spread is determined by rhizome length. Ecotypes with short rhizomes produce tight clones which are pushed above the soil line by roots. In some of these varieties, actively growing tillers will be found only at the edges of the clones, not within the central region. Accessions which have both short and long rhizomes tend to spread much faster and stands are more stable than accessions which produce only short rhizomes. Tiller density ranged from 12-30 per dm2 on sod forming ecotypes to 20-35 per dm2 on bunch types.
    • Herbaceous Vegetation Changes Following Applications of Tebuthiuron for Brush Control

      Scifres, C. J.; Mutz, J. L. (Society for Range Management, 1978-09-01)
      Aerial applications of 2.24 kg/ha (active ingredient) of tebuthiuron pellets to mixed brush and whitebrush-dominated stands in South Texas significantly increased grass standing crops at 1, 2, and 3 years after treatment. Higher rates did not significantly increase grass standing crop over that resulting from 2.24 kg/ha; lower rates did not increase grass standing crop compared to that on untreated plots at two of three locations. The genus Chloris appears to be particularly tolerant of the herbicide, and by 2 to 3 years after application, the overall grazing value of the grass stand was improved where at least 2.24 kg/ha of tebuthiuron were applied. Forb production and diversity were decreased where 1 kg/ha or more of the herbicide was applied, and the detrimental effect on forbs increased with increasing application rate. Forb production was nearly eliminated for 2 years following application of 4.48 kg/ha of tebuthiuron but recovery of the population was evident after 3 years regardless of rate of application.
    • Global Desertification and Range Management: An Appraisal

      Van Voorthuizen, E. G. (Society for Range Management, 1978-09-01)
      Spreading or creeping deserts worldwide are causing concern. Recent publicity indicates that man's efforts in supplying technology and aide projects to stem the desertification process have not always been successful. Range management as a component of technology is put on the defensive. An appraisal of the role that range management plays in the arid and semiarid regions, with special emphasis on the Sahel, is needed.
    • Grazing Management Practices Affect Lifestock Losses from Poisonous Plants

      Merrill, L. B.; Schuster, J. L. (Society for Range Management, 1978-09-01)
      Moderate stocking with cattle, sheep, and goats in a 4-pasture deferred-rotation system or light continuous stocking with cattle, sheep, and goats prevented livestock poisoning by bitterweed (Hymenoxys odorata), shinoak (Quercus mohriana), liveoak (Q. virginiana), and sacahuista (Nolina texana) over a 20-year period. Heavy stocking rates generally increased the incidence of poisoning. Using combinations of livestock reduced incidence of bitterweed and sacahuista poisoning, but not oak poisoning. The findings are attributed to better range conditions and forage variety under continuous light stocking and moderate stocking with a 4-pasture deferred-rotation system than under continuous stocking at moderate and heavy rates.
    • High Rates of Nitrogen Change Composition of Shortgrass Rangeland in Southeastern Wyoming

      Rauzi, F. (Society for Range Management, 1978-09-01)
      High rates of nitrogen applied at one time or over a 4-year period markedly changed the botanical composition of shortgrass range. Blue grama and buffalograss cover declined and western wheatgrass increased. Total yields were significantly increased, largely because of the increase of annual forbs. Thus the only desirable change in the composition resulting from the high N application was the increase of western wheatgrass. Over the 5-year period, the NO3- N accumulated in the 12- to 24-inch soil depth, whereas the grass roots were concentrated in the top foot of soil. The high rates of N increased crude protein significantly, thereby enhancing the palatability of the forage. Forbs on the high N plots were searched out and readily grazed by the sheep. Crude protein content was higher in the forbs than in the grasses in the fall. This study shows that high N rates applied either at one time or in yearly applications are neither economical nor practical because of the shift in the composition to undersirable annual forbs and slow recovery by the perennial grasses. The 150-lb N/acre rate applied once might be considered more practical than the other rates used in this study. Over the 5-year period this N rate produced 1,705 lb more total herbage than the check or 11.4 lb of herbage/lb of N. Neither the yield nor the crude protein increase was large enough to justify nitrogen fertilization of this range as an economic practice.