Browsing Journal of Range Management, Volume 49, Number 5 (September 1996) by Title
Now showing items 13-16 of 16
Selaginella densa reflectance: Relevance to rangeland remote sensingSelaginella densa Ryd. is a shallow-rooted spikemoss that grows on sparsely vegetated short and mid-grass prairie. It covers a proportion of bare soil which may rival that covered by grasses. Not a forage plant, it is treated in agronomic research as background to the edible plants. Even when it appears to the eye as dry and without active chlorophyll, its spectral reflectance resembles more closely that of forage plants than that of soil background. It is distinguishable from dense stands of chlorophyll-rich fortes and grasses using the normalized differential vegetation index, but S. densa in all cases resembles sparse grasses. Its presence must be considered when estimating range condition using remote sensing techniques.
Soil quality response of reestablished grasslands to mowing and burningPrescribed burning and mowing are management practices commonly used on grasslands even though there is limited knowledge of long-term effects on soil quality. The influences of mowing and burning on soil quality were determined on 2 reestablished tallgrass sites in eastern Nebraska dominated by silty clay loam soils. Burn treatments included seasonal (i.e., October, May, or July) prescribed burning at either 1-year or 4-year intervals. Mow treatments included seasonal mowing at 4-year intervals. Both burn and mow treatments have been imposed at Site 1 since fall 1981. Only the burn treatments have been applied at Site 2 since fall 1979. Soil quality measurement were made at both sites in summer 1994. Season of application of the mow and burn treatments and season X treatment interactions were not significant. Infiltration rates at Site 1 for the mow and annual burn treatments were slower than for the control, whereas infiltration rate was comparable for the year burn treatments and the control. Unlike Site 1, the 1-year and 4-year burn treatments at Site 2 had similar infiltration rates, and the burn treatments had slower infiltration rates than the control. Generally, soil bulk density, pH, electrical conductivity, total nitrogen content, and organic matter content were similar for all treatments. Results demonstrate that repeated burning or mowing treatments can detrimentally impact infiltration rates on silty clay loam sites; however, soil properties other than those measured would need to be studied to explain infiltration response.
Technical Note: Spring grazing preference of wheatgrass taxa by Rocky Mountain elkWe measured the grazing preference of 3 castrated male Rocky Mountain elk (Cervus elaphus nelsoni) for 2 crested (Agropyron desertorum [Fischer ex Link] Schultes), 5 thickspike (Elymus lanceolatus ssp. lanceolatus [Scribner &J.G. Smith] Gould), 3 Snake River (proposed name E. lanceolatus ssp. wawawaiensis), and 2 bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love) entries. Number of bites and visits were highly correlated in early May (r2=0.77) and late May (r2=0.83). 'Critana' and 'Elbee' thickspike and 'Hycrest' and 'Nordan' crested wheatgrasses can be recommended for seedings for elk spring grazing where these grasses are adapted.
Viewpoint: Concept design in range management scienceThis paper is an analysis of general principles involved in designing concepts for range science. It discusses the diversity of conceptuality in range science, from dimensional units to variables to simple models to more complex decision-aiding models. It examines how considerations of abstraction, confounding, and generalization allow development of multi-objective concepts needed in a range management science of many variable, interactions, and models. Examples related to each principle are provided. The paper discusses the importance of avoiding internal confounding within concepts and the necessity that such confounding be avoided in order to allow clear analyses. Ad hoc indices are characterized as inadequate substitutes for explicit models of more complex concepts such as preference and diet selection. Design efforts emphasizing multiple objectives will produce concepts of general use in range management science.