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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Chemical Analysis of Extracts from Port-Orford Cedar Wood and Bark

Gao, Heng 03 July 2007 (has links)
This study investigated a Soxhlet extract procedure to separate chemical components in the wood and bark of Port-Orford cedar (POC) (Chamaecyparis lawsoniana). The bio-activities, antioxidant properties, and decay resistance were evaluated. The heartwood extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). Three vitro assays including (1) 1, 1-diphenyl-2-picrylhydrazyl hydrate (DPPH ) radical scavenging assay, (2) 2,2-azinobis ( 3-ethylbenzothiszoline-6-sulfonic acid) diammonium salt (ABTS) radical cation scavenging ability assay, and (3) metal chelating activity assay were carried out to evaluate the antioxidant activity. The total phenol content of the extracts was determined by the Folin-Ciocalteu method and expressed as Gallic Acid Equivalent (GAE). The results showed that the methanol extracts of the heartwood and the sapwood contained moderate radical scavenging activities, and the inner bark and outer bark extracts showed the most activities. The sapwood extracts demonstrated the strongest chelating metal capability. Among the four partitions of POC bark, the n-Butanol extracts (n-Bu) showed the highest inhibition effect on ABTS<sup>+</sup> and the highest amount of total phenolic content, followed by ethyl acetate extracts (EA), water soluble components (Wa) and n-hexane extracts (n-He) subtractions. The correlation suggested that phenolic compounds are likely to contribute to the radical scavenging activity of the methanol extracts. There were three major components found in hexane extracts from the heartwood of POC, which were τ-cadinol, azulene, and τmuurolol. Hexadecadinoic acid was found in ethyl acetate extracts. Both the n-hexane and ethyl acetate extracts of the heartwood of POC had excellent growth inhibitory effects on white- and brown-rot fungi. The n-hexane extracts showed a higher antifungal index in this assay system, which was significantly higher than the ethyl acetate extracts.
122

Quantifying the Edge Effects Associated with Predator Removal Blocks on the Nesting Success of Upland Ducks in North Dakota

Kuhn, Margaret Jean 12 June 2007 (has links)
Much evidence suggests that nest success is one of the key drivers of duck production. Accordingly, for the past thirty years, waterfowl managers have focused their efforts on increasing nest success. One way to increase nest success is through predator trapping. Previous studies have shown that predator trapping increases nest success on different sized trapped blocks. This study attempted to answer the question: does trapping affect nest success on areas directly adjacent to trapped block boundaries? I hypothesized that predator abundance outside trapped blocks would be reduced. I predicted that nest success would decline with distance from the boundary while predator abundance would increase with distance from the boundary. This study was conducted in the Drift Prairie section of the Prairie Pothole Region in northeast North Dakota during the summers of 2005 and 2006. A total of 3,231 nests were found inside of six trapped blocks and a total of 2,006 nests were found outside of five trapped blocks. Daily survival rates were estimated using Shaffers logistic-exposure model and then related to distance from the center (for inside) or distance from the edge (for outside) of a trapped block, trapped block, field within a trapped block, and all interactions. Model fit was assessed using Akaikes information criteria as adjusted for small sample size. The most important variables for explaining variation in daily survival rates of nests, both inside and outside trapped blocks, were year, and field within a trapped block. Distance appeared to have a negligible effect on daily survival rates for nests inside and outside trapped blocks. Mean daily survival rates were higher inside trapped blocks. Trapping, therefore, did not appear to increase daily survival rates outside trapped blocks. Predator scent-stations were used in 2006 to obtain an index of predator activity. Distance from a trapped block edge did not affect visitation rates for any individual predator species or for all species combined, both inside and outside trapped blocks. There were, however, significantly higher visitation rates inside versus outside trapped blocks for raccoons and for all species combined.
123

Effects of Aversive Conditioning on Behavior of Nuisance Louisiana Black Bears

Leigh, Jennifer 05 July 2007 (has links)
Consistent habitat loss and fragmentation are contributing factors to the rise of human-bear conflicts in south Louisiana. Complaints associated with nuisance activities of Louisiana black bears (Ursus americanus luteolus) experienced in this region have steadily increased since 2000, requiring intervention by state and federal agencies. As a threatened species, Louisiana black bears require non-lethal management referred to as aversive conditioning. We used rubber buckshot and dogs to test the effectiveness of management techniques used by the state to deter nuisance activity by black bears. Eleven bears, representing approximately 15% of the estimated population in this region, were captured in residential and industrial areas reporting nuisance activity. Bears were fitted with radio-transmitting collars and released within 2 km of the capture site. Each bear was randomly placed within 1 of 2 treatments; treatment 1 (n=5) used rubber buckshot and treatment 2 (n=6) used the rubber buckshot in combination with dogs. Bears were monitored using telemetry to estimate movements and interactions with anthropogenic resources. Bears, on average, remained within 2 km of capture sites 2 weeks following release. Ten bears (91%) returned to nuisance behavior within 5 months, regardless of treatment. Results suggest that aversive conditioning techniques used to deter bears from nuisance activity have limited short term effectiveness.
124

Wood Liquefaction in the Presence of Phenol with a Weak Acid Catalyst and Its Potential for Novolac Type Wood Adhesives

Pan, Hui 23 July 2007 (has links)
Wood liquefaction was conducted using phenol as a reagent solvent with oxalic acid as a catalyst. A series of studies were done on liquefied wood, liquefied wood residues, novolac-type liquefied wood resins, and bio-composites fabricated from liquefied wood resin. The results of the liquefied wood residue characterization revealed that the liquefaction reactions conducted in different reaction vessels underwent different liquefaction mechanisms. The crystallinity indexes of the liquefied wood residues were higher than that of the original wood, indicating that the amorphous lignin was the most susceptible component in wood to the liquefaction reaction. Fe2+ and Fe3+ ions were found to have catalytic effects during liquefaction reaction. The cure kinetic study of two typical liquefied wood resins (LWR) showed that the activation energies of liquefied wood resin were higher than conventional phenolic resins and close to that of a lignin-phenol-formaldehyde resin from another study. It was found that LWR followed an autocatalytic cure mechanism. Two kinetic models were proposed for LWR based on the isothermal differential scanning calorimetry (DSC) methods. The flexural strengths of the composites were comparable to that of similar products reported by other researchers, indicating that the liquefied wood resin and liquefied wood residue from a weak-acid-catalyzed liquefaction could be successfully applied to molded bio-composite products as a substitute for conventional novolac resin.
125

Spatial Ecology, Habitat Selection, and Survival of Wild Turkey Gobblers in a Managed Bottomland Hardwood Forest

Grisham, Blake Anthony 23 October 2007 (has links)
Wild turkey (Meleagris gallopavo) males were captured and radio-tagged in a bottomland hardwood forest of south-central Louisiana. Turkeys were monitored year round from fixed telemetry stations on Sherburne Wildlife Management Area, Atchafalaya National Wildlife Refuge, and Bayou des Ourses to observe seasonal patterns of space use, habitat selection and survival from 2005-07. The largest seasonal home range was in fall/winter (966.41 ha; Oct 1-Feb 28). Spring home range (767.77 ha; Mar 1- May 31) size was lower than reported in previous studies and was a function of female availability. Season and age interacted to influence core area size (F<sub>5/63</sub> = 2.35, P = 0.051), but not home range size (F<sub>5/63</sub> = 1.49, P = 0.207). Males did not move about their home range differently before or during the breeding season (t<sub>20</sub> = 1.11, P = 0.282). Additionally, males did not display spatial shifts of core areas before and during the breeding season at the population level (t<sub>20</sub> = -0.92, P = 0.367). Upland forests and water-based forests were selected by adults and juveniles at all 3 spatial scales (habitat selection in home ranges vs. habitat availability across study area [1st order], habitat selection in core areas vs. habitat availability across home ranges [2nd order], and habitat availability across home ranges [3rd order]), whereas lowland forests were avoided at all 3 spatial scales. Habitat selection in spring was based on location of females. Water-based forests were essential to male habitat as they provide quality roosting and feeding sites. Survival was lowest in spring (0.43, SE = 0.09; Mar 1- May 31) due to the spring harvest. Fall/winter survival averaged 0.74 (SE = 0.05; Oct 1-Feb 28) and survival during summer averaged 0.74 (SE=0.06; Jun 1-Sept 30). Mean annual survival was 0.64 (SE = 0.06), among the highest ever reported for wild turkey males. The conservative harvest strategy on Sherburne was likely related to high survival rates for males
126

Habitat Use, Movements, and Survival of Radio-Marked Female Mallards in the Lower Mississippi Alluvial Valley

Davis, Bruce Edward 02 November 2007 (has links)
Mallard (Anas platyrhynhcos) populations in the Lower Mississippi Alluvial Valley (LMAV) historically averaged 1.6 million and represented the largest concentrations of wintering mallards in North America. Effective management of this wintering population requires current information on use of habitats, movements, and survival of female mallards. I used radio-telemetry techniques to assess these parameters during winters 2004-2005 and 2005-2006. Radio-marked female mallards used forested wetland habitats extensively during diurnal and nocturnal sampling periods. Proportional use of habitats varied inconsistently among time periods defined by hunting seasons and winters. Proportional use of forested wetlands ranged from 0.464 to 0.816 and from 0.280 to 0.764 during diurnal and nocturnal sampling periods, respectively. Movement distances (± SE) between diurnal and nocturnal locations averaged 2524 ± 150.1 meters and varied inconsistently by date among habitat types. The product-limit survival rate of radio-marked female mallards was 0.542 for the 140 day tracking season. Interval survival rates varied among time periods defined by hunting seasons and ranged from 0.721 to 0.981. Cause-specific mortality rates (± SE) for the tracking period were 0.177 ± 0.041 and 0.342 ± 0.119 for hunting and non-hunting sources of mortality, respectively. Continued restoration and establishment of forested wetland habitats should benefit wintering mallards in the LMAV. Finally, waterfowl managers may want to consider management actions to improve survival of female mallards in the LMAV.
127

The Ecology of Blacktail Redhorse Moxostoma poecilurum in West Fork Thompson Creek, Louisiana

Bahm, Jesse Adam 15 November 2007 (has links)
This study was designed to examine home range sizes and habitat use of blacktail redhorse Moxostoma poecilurum in West Fork Thompson Creek, Louisiana. Blacktail redhorse are a common non-game species found in Louisiana and other southeastern states. Adult blacktail redhorse (N=40; 187-273 mm total length) were implanted with radio transmitters and tracked twice weekly from February to September 2006 and from February to July 2007. To assess blacktail redhorse diet I analyzed 32 stomachs from fish collected by backpack electrofishing. I also conducted mark-recapture surveys of fish sampled monthly from May 2006 until July 2007. To assess homing ability in blacktail redhorse, I radio-tagged 10 individuals in 2007 and relocated them downstream (0.8 or 1.6 km) from their capture location. Results showed that implanted fish exhibited extremely high mortality or expulsion rates with 70% of all implanted transmitters being lost, even though retention rates in the laboratory were very high. On numerous occasions, I directly and indirectly observed avian and mammalian predators foraging in the study area, which likely explains high transmitter loss. Individual 95% linear home range sizes varied from 25 to 3,900 meters, with several fish having multiple home ranges, while others remained in the same pool throughout the study. Blacktail redhorse were observed foraging throughout the diel period, and their diet was primarily composed of chironomid (55%) and heptageniid larvae (17%). Similar to other redhorse species, blacktail redhorse were benthic feeders and foraging behaviors appear very similar to that of black redhorse Moxostoma duquesnei. Few marked individuals were recaptured (6 of 130) as indicated by mark-recapture sampling. The homing study showed only one individual moved back to its capture location. Small sample sizes and short study times limited both the mark-recapture and homing studies. Overall, blacktail redhorse exhibited a preference for pools with clay boulders, complex habitat, and undercut banks. The high levels of predation observed throughout this study and its impact on blacktail redhorse abundance suggest that local predation pressures structure this portion of the population and may be a driving force in structuring the entire headwater stream fish community in this area.
128

Environmental Factors Affecting the Distribution of Native and Invasive Aquatic Plants in the Atchafalaya River Basin, Louisiana, U.S.A.

Walley, Rachel Cathleen 13 November 2007 (has links)
Over the last century, the aquatic macrophyte community of the Atchafalaya River Basin (ARB) has become increasingly dominated by invasive species. I used digital photography and GIS software to determine ARB macrophyte community composition by measuring percent cover of each plant species within five 0.25-m2 quadrats sampled from 108 sites in 2005 and 103 sites in 2006. Macrophyte community data and measurements of soil and water physicochemistry at each site were used to investigate environmental associations of the macrophytes inhabiting bayou, lake, excavated canal, and swamp habitats. Analyses indicated substantial differences in physicochemical conditions among habitats, but none of the 20 macrophyte species collected during the study exhibited consistent preferences for specific habitat types. Percent coverage of invasive plants was greater than native plants across all habitat types in both years, with invasive plant richness increasing in 2006 with the arrival of giant salvinia (Salvinia molesta). Common salvinia (Salvinia minima) appeared to have the greatest impact on the native plants, exhibiting inverse abundance relationships with six of fourteen species (43%). Comparisons of slopes from areal coverage â dry weight regressions based on macrophytes that were photographed, collected, and dried from quadrats sampled at 26 sites in 2006 suggested that invasive species accumulated more biomass per unit area than ecologically similar native taxa. In both years, terrestrial plants were observed in association with floating mats of other macrophyte species, apparently taking advantage of the mats as âterrestrialâ substrate. Submerged plants exhibited few significant differences in abundance among the four habitats, although they did tend to occur where floating plants were not abundant. There were few physicochemical differences among vegetated and non-vegetated sites for native or invasive plants, although pH was lower at vegetated sites (versus non-vegetated) for both native (2005) and invasive (2005 and 2006) plants. Canonical discriminate function analysis revealed substantial changes in plant community composition and physicochemistry between the two years at approximately 25% of the study locations. These changes highlight the dynamic nature of the littoral zone and the multiplicity of deterministic and stochastic factors that likely affect the composition of the resident macrophyte community in the ARB.
129

Survival, Habitat Use, and Movements of Female Mallards Wintering in Southwestern Louisiana

Link, Paul Thomas 14 November 2007 (has links)
Little information is available concerning survival, habitat use, and movements of mallards (Anas platyrhychos) wintering on the Gulf Coast Chenier Plain (GCCP). Quantitative data on these parameters would be useful in making effective management decisions by GCCP waterfowl managers. Accordingly, I radio-marked 135 female mallards during winters 2004-2005 and 2005-2006 in southwestern Louisiana. My estimated survival rate for both winters combined was 0.68 ± 0.06 and did not differ by female age. Hazard ratios indicated that radio-marked females were 21-24 times more likely to die during hunted time periods than during non-hunted time periods. Estimated hunting and non-hunting mortality rates were 0.279 ± 0.062 (± SE) and 0.067 ± 0.029 (± SE), respectively, and did not differ between winters. Estimated product limit survival rates were 0.81 ± 0.05 (± SE) and 0.54 ± 0.09 (± SE) for HIGH and LOW condition birds, respectively. I found that diurnal use of areas closed to hunting was greater during hunted time periods in winter 2005-2006 than in winter 2004-2005. Nocturnally, use of areas closed to hunting was greater during SHUNT than during POST, and immatures used CLOSED lands more so than did adults. Diurnally, use of MARSH was 3.3 times greater than that of other habitats during both winters. Use of RICE and IDLE appeared to be related to availability of these habitats within the core study area. RICE acreage and use was greater in winter 2004-2005 than in winter 2005-2006, whereas IDLE acreage and use was greater in winter 2005-2006 than in winter 2004-2005. Female mallards used freshwater marsh habitats extensively; brackish or salt marsh was used much less frequently. Diel movements of female mallards generally were short (mean ± SE = 5.0 ± 0.2 km) and mean flight distances of individual females (n = 141) ranged from 3-15 km. My results suggest that mallards wintering in this area would benefit from programs and activities that target freshwater marsh for restoration and management. Management activities that increase mallard foraging habitats on areas closed to hunting may decrease hunting mortality rates and possibly increase female body condition.
130

Non-Industrial Private Forest Landowners and US Home Center Retailers Attitudes and Perceptions of Forest Certification

Perera, Polwattage Kushil 07 March 2008 (has links)
The concept of forest certification, a relatively recent development in forestry, is based on the use of market-based incentives to encourage sustainable forest management practices. Since the majority of forests in US South are privately owned, certifying forests owned by non-industrial private forest (NIPF) landowners is an important issue. From the demand perspective of certification, pressure from non-governmental environmental organizations and consumer awareness has prompted major wood products retailers to state preferences for certified wood products. In the US, wood product demand in the retail home centers sector is second only to the home building industry. In addition, home center retailers have been shown to be a primary driver of forest and wood products certification. In order to ascertain NIPF landowner and leading home center retailer perceptions of forest certification, two mail surveys were conducted. We surveyed 1,200 randomly selected NIPF landowners each in Louisiana and Mississippi, and the top 500 home retail centers in the United States. Results of the landowner survey indicate that a significant proportion of respondents believe certification could benefit NIPF landowners. Results suggest that many of the negative or neutral attitudes NIPFs hold towards certification are partially due to a lack of information and knowledge on the subject. Many respondents are skeptical of the publics willingness to support certification. However, they believe that certification can contribute to improving the forestry profession and forest management. It was also evident that the cost of certification will continue to be a main certification issue with over three-quarters of respondents being unwilling to pay anything for certification. Results from the home center study frame certification-related issues from the perspective of wood products retailers looking for the best way to market their products. Only a few leading wood products retailer respondents are currently participating in certification. Product quality, fair prices and supply issues are regarded as main concerns rather than safeguarding against environmental retaliation in order to be successful. Results indicate that, in general, price premiums for certified products are rare. However, niche markets exist that offer higher prices for certified products. Forest Stewardship Council (FSC) and Sustainable Forest Initiative (SFI) certification schemes are most preferred and accepted by retailer respondents. None of the respondent companies experienced any unexpected costs due to certification.

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