Theses and Dissertations at Montana State University (MSU)
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Item Short-term changes in vegetation and soil in response to a bulldozed fireline in northern great plains grasslands(Montana State University - Bozeman, College of Agriculture, 2015) Tulganyam, Samdanjigmed; Chairperson, Graduate Committee: Craig Carr; Craig A. Carr was a co-author of the article, 'Short-term vegetation response to bulldozed fireline in northern great plains grasslands' submitted to the journal 'Northwest science' which is contained within this thesis.; Craig A. Carr was a co-author of the article, 'Short-term soil response to bulldozed fireline in northern great plains grasslands' submitted to the journal 'Northwest science' which is contained within this thesis.The objectives of this study was to quantify the ecological cost of bulldozed fireline in comparison to burned and unburned sites and draw a management implications for ranchers and land owners. Vegetation cover and abundance were determined with biomass clipping and line point intercept method as separate functional groups across the bladed, burned, and unburned sites in two locations, north central and south west Montana for two years. Study area encompassed idaho fescue and bluebunch wheatgrass dominated north facing slope in Redbluff and rough fescue and bluebunch dominated grassland in Havre. After quantifying vegetation responses, top soil horizon depth, bulk density, aggregate stability and runoff and sediment yield were determined to quantify soil response to bulldozed fireline. In general, burned site did not differ from unburned site particularly by the second year after the fire. In other words fire was not detrimental to the rangeland condition. Whereas bulldozed fireline altered primary ecological processes, particularly nutrient cycle and hydrologic functioning, by mechanically removing native plant species, creating exposed bare ground which was susceptible to soil erosion and invasion of competitive non-natives.Item Elk effects on sagebrush-grassland after fire on Yellowstone's Northern Range(Montana State University - Bozeman, College of Agriculture, 2001) Rens, Reyer JanItem A comparison of burned and unburned big sagebrush communities in southwest Montana(Montana State University - Bozeman, College of Agriculture, 1997) Walhof, Kendal ScottItem Patterns of gray rubber rabbitbrush occurrence in burned sagebrush-grasslands, Missouri River Breaks, Montana(Montana State University - Bozeman, College of Agriculture, 2012) Owings, Glenn Curtiss; Chairperson, Graduate Committee: Clayton B. Marlow.Sagebrush-grasslands represent a large portion of the plant communities within the arid plains of the western United States. Grasses, forbs, and shrubs exist as subdominants to sagebrush that vary in density according to disturbances such as fire, wind, and defoliation. Fire is an important modifier of succession in sagebrush-grasslands, and shrub response to fire may be altered by browsing. The fire response of gray rubber rabbitbrush (Chrysothamnus nauseosus (Pallas ex Pursh) Nesom & Baird ssp. nauseosus) has not been well documented. Furthermore, it is heavily browsed in central and northeastern Montana and is an important winter forage for ungulates. This study investigated how it responds to fire and browsing. Fifteen sites (9 burned and 6 adjacent non-burned) in the Missouri River Breaks, Montana were analyzed to investigate relationships between shrub density, time since fire, shrub age, and browsing level (n=15). Density was counted in one 625m ² macroplot per site. Gray rubber rabbitbrush age (seedling, juvenile, mature) was estimated using basal stem diameter. A qualitative browsing level was assigned based on growth form characteristics (low, moderate, high). Time since fire was not significantly correlated with differences in gray rubber rabbitbrush (P=0.701, R-sq=0.00%) or sagebrush (P=0.391, R-sq=0.00%) density as a percentage of the shrub community (n=9). As a percentage of the shrub community, big sagebrush density at a site was a good indicator of gray rubber rabbitbrush density (n=15, P<.001, R-sq=68.45). Rabbitbrush decreases within the shrub community as sagebrush dominance increases. Gray rubber rabbitbrush composed a higher percentage of the shrub community in burned than non-burned sites (n=6, P=0.005). Big sagebrush composed a higher percentage of the shrub community in non-burned sites than burned sites (n=6, P=0.001). The percentage of gray rubber rabbitbrush shrubs in the "high" browse class was not a statistically significant predictor of density as a proportion of the shrub community (n=13, P-value=0.161, R-sq=9.49%). Results indicate that gray rubber rabbitbrush responds to fire by increasing shortly after disturbance, falling out of the community at some threshold as sagebrush is re-established. Browsing did not affect the ability of gray rubber rabbitbrush to dominate for a period after fire.