Browsing by Subject "Juniper"
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Item Economic evaluation of redberry juniper control in the Texas rolling plains(Texas Tech University, 1996-05) Gerbolini, Alfonso JavierTexas rangelands are an important resource to the Texas economy because they constitute a large portion of the state's total territory. Texas' total surface area amounts to 69.1 million ha. with rangeland constituting 38.5 million ha., or 61% of the area (Texas Soil and Water Conservation Board, 1991). This area has the capacity to sustain livestock and wildlife. In 1994, Texas rangelands supported 5.8 million beef cows, which produced about 4.4 million feeder cattle (Texas Agricultural Statistics Service, 1994). According to the Natural Resource Conservation Service, bmsh infestation is a major problem on Texas rangelands (U.S. Dept. of Agric, 1964). The occurrence of bmsh reduces the capacity of these lands to support livestock and wildlife. As rangelands become infested with bmsh, carrying capacity decreases because forage production is decreased. "Worthless bmsh is slowly and surely suffocating the livestock industry in Texas and the Southwest by robbing ranches of their soil, water, and plant resources" (U.S. Dept. of Agric, 1964, p. 1). To individual ranchers, the presence of brush results in lost productivity and lower revenue. Texas had 35.8 million ha. of rangeland infested by woody plants in 1964, representing 82% of all rangelands (U.S. Dept. of Agric, 1964). In 1982 the five major bmsh species on Texas rangelands were mesquite (Prosopis glandulosa), pricklypear (Opuntia spp.), yucca (Yucca spp.), live oak (Quercus virginiana), and redberry juniper Juniperuspinchotii). By 1987 the major rangeland-invading bmsh species had altered slightly so that the five most common species were mesquite, pricklypear, black brush {Acacia rigidula), live oak, and redberry juniper (Texas Soil and Water Conservation Board, 1991) (Table 1.1).Item Economic feasibility and risk of using prescribed extreme fire as an invasive brush management tool in Texas(2009-05-15) Van Liew, Dustin BruceThis component of the Conservation Innovation Grants Summer Burning project evaluates the economic feasibility of using prescribed fire that exceeds the current Natural Resource Conservation Service (NRCS) technical standards as a rangeland restoration practice on privately owned land in Texas. This study has four objectives: (1) Evaluate the economic effectiveness of using prescribed extreme burns as a rangeland restoration tool compared to other rangeland restoration strategies. (2) Provide economic research results that will facilitate a review of the technical standards, specification, and potential policy changes by the NRCS with respect to the use of prescribed extreme burning. (3) Assess economic effects of extreme fire when used in combination with other treatment practices over a 20 year planning horizon. (4) Through modeling, forecasting, and simulation assess the risk associated with the use of extreme prescribed fire, with respect to weather (rainfall) conditions. The research covers four contiguous counties in each of three eco-regions in Texas: Rolling Plains, Edwards Plateau, and the South Texas Plains. Focus group meetings with landowners and NRCS/Extension personnel were held in each region to obtain preliminary information including common rangeland uses, most problematic invasive brush species, and the most commonly used treatment methods and associated costs. The primary invasive species in each region include: Rolling Plains ? Prickly Pear (Opuntia phaecantha); Edwards Plateau ? Redberry and Ashe Juniper (Juniperus ashei Buchh. And J. pinchotii Sudw., respectively); South Texas Plains ? Huisache (Acacia smallii Isely). Mesquite (Prosopis glandulsa Torr.) was identified as a common invasive brush species across all three regions. When extreme fire was compared to the most commonly used invasive brush treatments, assuming the treatment was instituted in year one, it was economically superior in all cases and feasible (Net Present Value > 0 and Benefit/Cost Ratio >1) in all but two cases. The inclusion of forecasted rainfall figures with the combination of using the most commonly used brush treatment with extreme fire proved to substantially reduce the risk of instituting the treatment regimes. The probability distribution of NPVs was significantly smaller when treatment practices were spread over ten years and parcels than when treatment was restricted to the first year and whole ranch.Item Fixed Bed Counter Current Gasification of Mesquite and Juniper Biomass Using Air-steam as Oxidizer(2012-11-27) Chen, Wei 1981-Thermal gasification of biomass is being considered as one of the most promising technologies for converting biomass into gaseous fuel. Here we present results of gasification, using an adiabatic bed gasifier with air, steam as gasification medium, of mesquite and juniper. From Thermo-gravimetric analyses the pre-exponential factor (B) and activation energy of fuels for pyrolysis were obtained using single reaction models (SRM) and parallel reaction model (PRM). The single reaction model including convention Arrhenius (SRM-CA) and maximum volatile release rate model (SRM-MVR). The parallel reaction model fits the experimental data very well, followed by MVR. The CA model the least accurate model. The activation energies obtained from PRM are around 161,000 kJ/kmol and 158,000 kJ/kmol for juniper and mesquite fuels, respectively. And, the activation energies obtained from MVR are around100,000 kJ/kmol and 85,000 kJ/kmol for juniper and mesquite fuels, respectively. The effects of equivalence ratio (ER), particle size, and moisture content on the temperature profile, gas composition, tar yield, and higher heating value (HHV) were investigated. For air gasification, when moisture increased from 6% to 12% and ER decreased from 4.2 to 2.7, the mole composition of the dry product gas for mesquite varied as follow: 18-30% CO, 2-5% H2, 1-1.5% CH4, 0.4-0.6% C2H6, 52-64% N2, and 10-12% CO2. The tar yield shows peak value (150 g/Nm^3) with change in moisture content between 6-24%. The tar collected from the gasification process included light tar and heavy tar. The main composition of the light tar was moisture. The chemical properties of heavy tar were determined. For air-steam gasification, H2 rich mixture gas was produced. The HHV of the mesquite gas increased first when S: F ratio increased from 0.15 to 0.3 and when the S: F ratio increased to 0.45, HHV of the gas decreased. Mesquite was blended with the Wyoming Powder River Basin (PRB) coal with ratio of 90:10 and 80:20 in order to increase the Tpeak and HHV. It was found that the Tpeak increased with the increase of PRB coal weight percentage (0% to 20%).Item Influence of goat breed and dietary experience on juniper intake and metabolism(Texas Tech University, 1995-08) Pritz, Robert K.The ultimate purpose of this research is to find ways to decrease the impact of juniper on rangelands and create a forage resource from a previously unusable species. It is unlikely that this line of research will lead to the eradication of juniper. Junipers can be an important species in providing cover and a source of emergency browse for livestock and many species of wildlife. However, options for its management are necessary to maintain healthy rangeland ecosystems.Item The effects of juniper removal on rainfall partitioning in the Edwards Aquifer region: large-scale rainfall simulation experiments(Texas A&M University, 2006-08-16) Taucer, Philip IsaiahTwo experimental rainfall simulation plots in the Edwards Aquifer region of Texas were established to measure the effects of brush clearing on surface and subsurface water movement pathways. Multi-stage rainfall simulations were carried out at a site with Juniperus ashei (ashe juniper) cover both before and after brush removal, with three replications of a particular rainfall event for each vegetation condition. Similar simulations were carried out on a plot with a longstanding grass cover. Both plots included trenches at their downhill ends for observation of shallow lateral subsurface flow. Canopy interception was found to represent a major water loss, with interception of 32.7 mm for an average 166 mm, 5.25 hr rainfall event. Brush clearing had little impact on surface runoff, with no overland flow occurring at the juniper plot for either vegetation condition, while 31.9 percent of applied rainfall moved as overland flow at the grass plot. This difference was attributed to differences in the structure and permeability of the epikarst. Brush removal caused significant (90 percent confidence level) reduction in shallow lateral subsurface flow into the trench after brush removal, with 56.7 percent of water reaching the surface entering the trench for the pre-cut condition and only 43.4 percent for the post-cut condition. However, subsurface water movement through other pathways increased from 31.0 to 54.1 percent after brush removal. This additional water, due to removal of canopy interception, could either move off-site through conduit and fracture flow or remain on site as storage in conduits, unconsolidated caliche/marl layers, or in soil pockets. Two tracer tests with fluorescent dyes were also conducted using simulated rainfall to assess discrete flow paths discharging into the trench at the downhill end of the juniper plot. Analysis of samples from sixteen outlet locations revealed that not all areas of the plot were connected hydraulically to the trench. Additionally, subsurface flow paths were found to have a high degree of interconnection, linking conduit flow outlets with multiple inlet locations on the plot surface. Conduits showed strong connection with an area surrounding juniper vegetation, with rapid water flow (up to 2.4 m/h) from this area.