Browsing by Author "Racher, Brent J."
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Item Herbaceous production as influenced by juniper canopy cover in west Texas(Texas Tech University, 1998-12) Racher, Brent J.Juniper encroachment and subsequent density and canopy cover increases on rangeland reduce herbaceous production beneath and outside of the canopy area. Associated problems are decreased water yield, reduced carrying capacity, higher erosion, and difficult livestock handling. The objective of this study was to quantify and correlate aerial phytomass production with different levels of redberry juniper {Juniperus pinchotii Sudw.) canopy cover, density, and canopy volume in west Texas. The Texas Tech Experimental Ranch (Borden County, TX) study sites were on a deep hardland range site with Olton clay loam soils. The Pitchfork Ranch (Dickens County, TX) sites were on a mixedland range site with very fine sand soils. The Stone Ranch (Tom Green County, TX) sites were on a clay loam range site with Angelo clay loam soils. The Triangle Ranch (Foard and Hardeman Counties, TX) sites were on a deep hardland range site with Tilhnan clay loam soils. Juniper canopy cover was measured with both line transects and belt transects. Aerial phytomass yield and relative frequency of grass species were estimated by clipping 0.25-m quadrats. Dominant grass species differed among locations. Line intercept canopy cover of redberry juniper was more highly correlated with herbaceous yield than the canopy cover estimates obtained with belt transects. Yield was reduced an average of 1,000 kg/ha as juniper canopy cover increased from 0 to 35%. Regression analysis predicted a yield reduction 33.5% and 50% at 20% and 40% juniper canopy cover, respectively. Yield reductions at 20% juniper canopy cover were greater on the two deep hardland range sites compared to the clay loam and mixedland ranges sites, but at 40% canopy cover, yield reductions were about equal across range sites. The largest decreases m yield occurred as juniper canopy cover increased from 0 to 15%, contrary to prior beliefs.Item Prescription development for burning two volatile fuel types(Texas Tech University, 2003-05) Racher, Brent J.Prescribed burning is used to manipulate vegetation worldwide. However, the practice carries an inherent danger because fires can escape and/or harm people. These studies were initiated to evaluate fire behavior and firebrand spotting potential for two volatile fuel types in which prescribed burning is being used. The first fuel type was saltcedar. Saltcedar stands carried crown fires and exhibited erratic fire behavior if they had not been burned before. Saltcedar that had been burned recently carried a fire through the fine, surface fuels. Differences in fire behavior occurred when saltcedar were burned at different phenologic stages. Spotting potential of firebrands from saltcedar fires was found up to 152 m and 163 m downwind for areas that had and had not been burned recently, respectively. The second fuel type was juniper/oak communities in Texas. Historically, prescriptions for burning during the late winter/early spring have been used. Recently, burning at higher temperatures mostly during the summer is becoming popular in this region. Behavior of some these fires exhibited alarmingly high rates of spread. Surprisingly, firebrands for many fires in this fuel type often were absent. However, firebrands were collected 152 m downwind from headfires. The volatility and conditions under which both of these communities have been and are being burned require that fire managers monitor more information than we have in the past. Variables such as 10-hr timelag fuel moisture, live fuel moisture, and the ability of personnel to perform under strenuous conditions need to be considered. Additionally, for these fuel types, installation of blacklines downwind of the fire at least 152 m and up to 213 m wide is critical to minimize the spotting potential from prescribed fires.