• Dating Past Fires in Curlleaf Mountain-mahogany Communities

      Arno, S. F.; Wilson, A. E. (Society for Range Management, 1986-05-01)
      Fire history was investigated in 4 curlleaf mountain-mahogany (Cercocarpus ledifolius) communities containing scattered, old ponderosa pine (Pinus ponderosa). Dating cross- sections of fire scars from the pines, through counts of annual growth rings, allowed us to develop reasonably complete fire chronologies extending back to the 1700's. Mean fire intervals in these communities ranged from 13 to 22 years until the early 1900's, but lengthened considerably thereafter. Mountain-mahogany stems with well-developed basal scars (not necessarily caused by fire) were cross-sectioned and finely sanded to enhance the often obscure growth rings. Estimated dates of the mountain-mahogany scars were compared to the pine-derived fire history. This evaluation suggests that where conifers of sufficient age are absent, careful interpretation of mountain-mahogany scars can be used to estimate fire history.
    • Forage Yield and Quality of Warm- and Cool-Season Grasses

      White, L. M. (Society for Range Management, 1986-05-01)
      High quality forage is needed in the northern Great Plains during the summer when major growth of cool-season grasses has ceased and quality of standing forage is low. The objective of this study was to compare forage yield, nutritional quality, and water use of 2 warm-season grasses {P-15584 little bluestem [Schizachyrium scoparium (Michx.) Nash] and 'Pierre' sideoats grama [Bouteloua curtipendula (Michx.) Torr.]} and 2 cool-season grasses {'Nordan' crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.] and 'Mayak' Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski]} harvested from 1979 through 1982 at anthesis or when drought stopped further plant growth. Forage was harvested from established stands seeded in rows 53-cm apart growing on a silty range site (Typic Haploborolls) near Sidney, Mont. Plots were 8 by 23 m replicated 5 times in randomized complete blocks. Forage yield averaged 0.84, 0.98, 1.75, and 2.52 t/ha (S-mean=0.17); in vitro organic matter digestibility averaged 56.4, 67.3, 62.0, and 62.3% (S-mean=1.1)$, crude protein averaged 8.0, 10.3 8.6, and 12.8% (S-mean=0.4); phosphorus averaged 0.14, 0.16, 0.15, and 0.16% (S-mean=0.01) over a 4-year period for little bluestem, sideoats grama, crested wheatgrass, and Russian wildrye, respectively. Regression showed that in vitro organic matter digestibility and crude protein concentration were negatively correlated with forage yield. Forage yield and phosphorus concentration were positively correlated with evapotranspiration. The study showed that Russian wildrye would provide the highest quality forage during June and sideoats grama during July. Livestock need both cool- and warm-season forages to provide the highest forage quality.
    • Habitat Use by Federal Horses in the Northern Sagebrush Steppe

      Ganskopp, D.; Vavra, M. (Society for Range Management, 1986-05-01)
      Distribution patterns of feral horses (Equus caballus) relative to plant communities, herbaceous production, and perennial water sources were studied from April 1979 to March 1981 in Oregon's Owyhee Breaks. Repeated observations of radio-collared and easily identified horses allowed estimation of home range sizes and documentation of the plant communities utilized. A map of plant communities was constructed, and composition and herbaceous production of key communities sampled. Time-lapse cameras monitored the daylight watering patterns of horses. One hundred thirty-three horses were initially censused and identified on the study area with the total population subsequently increasing at an annual rate of 13%. Home ranges averaged 12 km2 with the minimum convex polygon procedure and 27 km2 with the 90% confidence ellipse method. No seasonal shifts in home ranges occurred, and no correlations were detected between home range size and number of horses per band, densities of perennial water sources, or levels of forage production within home ranges. Six distinct herds were identified on the area. Only one band of horses moved from one herd to another during the 2-year study. Animals in each herd made greatest use of the most prevalent plant community, with no community being universally preferred to over another. Watering activities were most intense during the first and last periods of daylight. Horses rapidly vacated the watering areas after drinking. A seasonal trend was observed in which horses remained slightly closer to perennial water sources during warm, dry summer months than during spring periods when additional seasonal sources were available. Seasonal differences were not statistically significant, however.
    • Heterogeneity of Data: Implications for a Variable Federal Grazing Fee

      Fowler, J. M.; Blake, M.; Torell, L. A. (Society for Range Management, 1986-05-01)
      Average grazing lease prices as tabulated in the 1985 federal grazing fee review and evaluation study were found to be significantly different between some pricing regions of the study. Comparing the federal study with a New Mexico state land grazing fee study indicated that lease prices were not homogeneous, even within pricing regions. This heterogeneity of data indicates that a variable federal grazing fee structure should be established if welfare of public land ranchers and collecting full market value of public land forage is important. Other factors, such as ease of fee administration and strong political support have been important considerations in setting the current single uniform fee. The current single-fee formula that sets one uniform grazing fee for all western states cannot be statistically defended. If grazing fees were significantly increased using the current single-fee formula, or any other single-fee formula, an inequitable distribution of impacts upon public land ranchers would arise; some would be subsidized while others would likely be damaged.
    • Douglas-Fir Encroachment into Mountain Grasslands in Southwestern Montana

      Arno, S. F.; Gruell, G. E. (Society for Range Management, 1986-05-01)
      A study of plant succession in relation to disturbance history was conducted in Douglas-fir [Pseudotsuga menziesii var. glauca (Beissn.) Franco] forest and fescue (Festuca L. spp.) grassland communities along the eastern slope of the Continental Divide in Montana. The objective was to obtain ecological information needed for assessing management alternatives aimed at enhancing big game habitat and livestock forage. Fire history was reconstructed through analysis of fire scars and age classes of trees. Sizes and ages were inventoried in sapling stage, pole stage, and mature forest stands. Results indicate that prior to 1890 fires occurring every few decades favored grassland and confined tree growth to rocky or topographically moist sites. Since 1890 fires have been rare as a result of livestock grazing (which removes fine fuels), fire suppression, and cessation of ignitions by Native Americans. Lack of fire allowed extensive areas of Douglas-fir "invasion" now of pole size to become established in former grasslands between 1890 and 1915. Widespread invasion of sapling size trees occurred between 1941 and 1955, when seed crops apparently coincided with unusually favorable moisture conditions. For management of these areas, we recommend use of prescribed fire in conjunction with timber harvesting to enhance declining forage productivity for big game and livestock.