• A Growth Form Method for Describing Browse Condition

      Keigley, Richard B. (Society for Range Management, 1997-06-01)
    • Characterization of crown node elevation in Panicoid grasses

      Tischler, C. R.; Voigt, P. W. (Society for Range Management, 1993-09-01)
      In Panicoid grasses, elevation of the crown node above the soil surface caused by excessive subcoleoptile internode elongation is detrimental to seedling establishment. We describe a technique to screen grass seedlings for excessive crown node elevation. Seed of 11 perennial grass cultivars were germinated and grown in a plywood box 1.2 X 1.2 X 1.2 m at an irradiance of 1.5 micromole m-2 sec-1 at 30 degrees C. A subset of 8 grasses were grown similarly but at an irradiance of 0.75 micromole m-2 sec-1. Elevation of crown nodes above the growth media and shoot length (from crown node to leaf tip) were measured 7 days after planting. The crown nodes of 4 Eragrostis species were not elevated above the soil surface, while other species had mean crown node elevations of 1 cm or more. Relative ranking of crown node elevation was similar for a species within each light level, but response to change in light intensity was not consistent across species. Sideoats grama (Bouteloua curtipendula (Michx.) Torr.), blue grama (Bouteloua gracilis (H.B.K. Lag. ex Steud.)), and kleingrass (Panicum coloratum L.) exhibited significant crown node elevation in this system. Estimates of genetic variation based on comparison of apomictic and sexual grasses within this group suggest that substantial genetic variation exists for excessive subcoleoptile internode elongation and that progress by selection for lower crown node placement should be possible in most of the grasses studied. This system allows characterization of grasses for extent of crown node elevation and is being used in a recurrent selection protocol to select for lower crown node placement.
    • Grassland Resources and Development of Grassland Agriculture in Temperate China

      Tinachen, Zhu (Society for Range Management, 1988-06-01)
    • Growth dynamics of crowns of eastern red-cedar at 3 locations in Oklahoma

      Engle, D. M.; Kulbeth, J. D. (Society for Range Management, 1992-05-01)
      Eastern redcedar (Juniperus virginiana L.) trees from a location in western, central, and eastern Oklahoma were aged by tree ring analysis to assess the relationship of tree age to tree height and crown area. The relationship of tree age to crown size differed with location. Trees in the oldest age class, 28 to 29 years, ranged in height from 6.2 m on the western Oklahoma location to 8.3 m on the eastern Oklahoma location. The oldest trees at all locations were still actively growing. Height growth rate of the oldest class of trees averaged 0.5 to 0.6 m yr-1 on the western and eastern study locations, respectively. Eastern redcedar reached 2.0 m in height at about 8 years of age on the eastern Oklahoma location. Trees reached 2.0 m in height in 10 to 14 years at the other locations. This suggests that burning intervals should be more frequent on the eastern Oklahoma location than on the central and western Oklahoma locations. Crown area as a function of tree age was not as similar as tree height among the 3 locations. Not only did the relationship differ among locations, but it differed also between 2 central Oklahoma range sites. Crown area of 28-year-old trees ranged from only 15 m2 on the central Oklahoma Loamy Prairie to 40 m2 at the eastern Oklahoma location. These data suggest that the smaller crown area of trees at the central Oklahoma location may be a result of an influence other than environment, such as an introduction of plants of a different race with an inherent columnar growth habit. The reduction in forage production associated with eastern redcedar and the efficacy of prescribed burning for controlling eastern redcedar would change more rapidly as trees age on the eastern Oklahoma location than on the other locations.
    • Guayule: A Rangeland Source of Natural Rubber

      Foster, M. A.; Moore, Jaroy (Society for Range Management, 1987-06-01)
    • 'Hatch' Winterfat: A Quality Shrub for Ranges and Wildlands

      Stevens, Richard; Monsen, Stephen B. (Society for Range Management, 1988-06-01)
    • Sites, mowing, 2,4-D, and seasons affect bitter-brush twig morphology

      Kituku, V. M.; Powell, J.; Olson, R. A. (Society for Range Management, 1994-05-01)
      Effects of site factors, mowing, 2,4-D, and seasons on antelope bitterbrush (Purshia tridentata Pursh.) twig length, basal and tip diameters, and weight were evaluated in southcentral Wyoming. Linear regression coefficients for twig length regressed on basal diameter were greater on productive sites than on less productive sites, greater on mowed areas than on sprayed or untreated areas, and greater in late fall because of leaves than in late winter. Twig elongation continued after data collection in early November. Twig length was more variable and more sensitive to different environmental conditions than twig basal diameter, tip diameter, or weight. Twig length accounted for 80-86% of the variation in twig weight. Sites, shrub management practices, and seasons do affect bitterbrush twig morphology, but habitat managers can use twig length-diameter-weight relations in this vegetation type to estimate utilization if the sampling is stratified along environmental gradients.