Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Tiller dynamics of blue grama and western wheatgrass subjected to drought and grazing(Montana State University - Bozeman, College of Agriculture, 1996) Eneboe, Erik JasonItem Effects of spring clipping on bluebunch wheatgrass in summer(Montana State University - Bozeman, College of Agriculture, 2002) Brewer, Tracy KayItem Nutritional and developmental responses of three mountain bunchgrasses to summer cattle and winter elk grazing(Montana State University - Bozeman, College of Agriculture, 1985) Dragt, William JohnItem Restoring native species to crested wheatgrass dominated rangelands(Montana State University - Bozeman, College of Agriculture, 2004) Johnson, Janel Denice; Chairperson, Graduate Committee: Bok Sowell.In the 1980's, there were an estimated 7 to 12 million ha of crested wheatgrass (Agropyron cristatum (L.) Gaertn.) in North America. Dense stands of crested wheatgrass lack species diversity, which negatively affects populations of wild mammals, birds, and reptiles. There is new interest among land managers in replacing stands of crested wheatgrass with native species for wildlife habitat, using minimal disturbance techniques such as herbicide and no-till seeding. The objectives of this project were to (1) evaluate the effects of glyphosate on crested wheatgrass and other species and (2) test seedling establishment of native grass and forb seed mixes planted in glyphosate treated crested wheatgrass sod with a no-till drill. Field trials were conducted with two herbicide application treatments and five planting treatments in 2002 and 2003 at five sites in central and eastern Montana. Crested wheatgrass biomass and seedling biomass index were collected in 2002 and crested wheatgrass, seeded species, and non-target species biomass were collected in 2003. Results from the field trials indicate that applying glyphosate in the spring was effective at reducing the biomass of crested wheatgrass for two seasons and shifting the dominance in the stands toward native or weedy species, depending on the plant and seedbank composition. Application of glyphosate increased diversity at sites with low initial diversity but not at sites with high initial diversity. Seeding was generally not successful, due primarily to lack of moisture and nitrogen. Switchgrass (Panicum mrgatum L.) and slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners) were the most successful seeded species. Other native bunch grasses and forbs did not establish well. Because of the high cost of native seed and no-till drilling, this treatment is not recommended unless there is sufficient moisture and nutrients in the soil at the time of planting to support seedling growth.Item Fuel load and heat effects on Northern mixed prairie and four prominent rangeland graminoids(Montana State University - Bozeman, College of Agriculture, 2011) Haile, Kimberly Fay; Chairperson, Graduate Committee: Clayton B. Marlow.Plant mortality following fire has been a concern of many people and agencies. There is little information, relating to the direct effect fire has on grass mortality, biomass production, and tillers at the community and individual levels. The objectives of this research were to determine the survival, tiller numbers, and biomass response to fuel load and direct measures of heat of four prominent graminoid species at the individual and community levels. The community level consisted of 24 plots measuring 20 X 20 meters. The plots were burned in autumn 2008 and 2009. Regression analyses were used to assess relationships of fuel load, degree-seconds, duration of heat, and maximum temperature, with relative biomass and frequency of species and species groups. The results illustrated fuel load, degree seconds, and duration were good predictors of total biomass. Threadleaf sedge increased in biomass to pre-treatment measures. Threadleaf sedge and needle-and-thread biomass was negatively related to fuel load, degree-seconds, and duration of heat. Neither blue grama nor western wheatgrass changed in biomass. A burn cage was used to apply the burn treatments for the individual plant study using range of fuel loads 500-9000 kg X ha -¹. Relationships of fuel load with degree-seconds, heat duration, and maximum temperature were tested independently. Probabilities of plant mortality were estimated based on fuel load, duration of heat, maximum temperature, and degree-seconds. Of 120 plants of each species, only one western wheatgrass and one threadleaf sedge plant died following fire. Mortality occurred for 20 blue grama plants and 17 needle-and-thread plants. Degree-seconds, duration, maximum temperature, and fuel load were good predictors of mortality for blue grama and needle-and-thread. Neither duration of heat or maximum temperature explained changes in biomass or tillers for any species. Plant response was less in the field than the burn cage even at heavier fuel loads. This study found that as fuel load increased, degree-seconds, duration, and maximum temperature increased. Fuel load was the primary factor increasing degree-second, duration, and maximum temperature and provided an alternative way to predict plant mortality following fire. Understanding direct fire effects on plants will provide better management decisions following a fire.Item Effects of sugar beet pulp on cheatgrass and bluebunch wheatgrass growth under controlled conditions(Montana State University - Bozeman, College of Agriculture, 2011) Sloane, Charles Emanuel; Chairperson, Graduate Committee: Clayton B. Marlow.Cheatgrass (Bromus tectorum L.,) an invasive, annual grass species, degrades range and pasture lands by out competing and replacing preferred native grass species resulting in economic and ecological losses. Current control strategies are costly and ecological risky. Soil nitrogen depletion by promoting microbial nitrogen utilization by application of a carbohydrate energy source such as sucrose may decrease cheatgrass's competiveness and permit seedling establishment of preferred native species. Review of the literature reveals attempts at restoration of native grasses and elimination of cheatgrass by nitrogen depletion with sucrose applications have failed or at best achieved limited success. We believe one reason for failure is that soil microbes utilize applied simple carbohydrates such as sucrose too rapidly resulting in only short periods of nitrogen depletion, and that application of sugar beet pulp may promote a longer state of nitrogen depletion. We hypothesize the growth of nitrogen dependent invasive grasses will be inhibited by nitrogen deprivation produced by mulch application of coarse granulated sugar beet pulp, and that the inhibition of growth is not related to a passive mulch effect. In a four armed green house study, we compared cheatgrass and bluebunch wheatgrass growth after application of ground sugar beet pulp at rates of 0.0, 0.5, 1.0 2.0 and 4.0 tons per acre. As a control, granite chicken grit was similarly applied in equal volumes to rule out a passive mulch effect. At 35 days, there was a negative linear relationship between rate of sugar beet pulp application and cheatgrass growth (p <0.001) and BBW growth (p<0.002). The negative effect of sugar beet pulp on cheatgrass growth was twice the negative effect on blue bunch growth. Granite grit application did not decrease growth of either species. We conclude that sugar beet pulp application depresses cheatgrass growth and that the cause is not a passive mulch effect. Our data indicates that longer duration nitrogen deprivation may aid in promoting restoration of cheatgrass dominated acreages, and treatments such as sugar beet pulp application may permit native grass seedling emergence and establishment.