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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.
21

Habitat Assessment and Subspecies Identification of Sandhill Cranes Wintering in Louisiana

McGowan, Joseph Michael 31 July 2003 (has links)
The two biggest flocks of Sandhill Cranes (Grus canadensis) wintering in Louisiana are located in Cheneyville and Holmwood, LA. Resident Sandhill Cranes were once located in Louisiana, but because of habitat loss and over harvest these residents were extirpated from Louisiana in the early 1900s. In the 1960s, migrating Sandhill Cranes had returned to LA and were wintering in Cheneyville. Observations and habitat characteristics were conducted on these two flocks in the winter of 2002 and 2003 because of the lack data on these flocks. The two flocks contained about 1,300 individuals with four other known flocks throughout Louisiana ranging from 16-400 individuals. There were an estimated 2,200 Sandhill Cranes wintering in Louisiana. Morphometric measurements for eight birds fell within the range of the Greater Sandhill Crane (G. c. tabida) subspecies. Middle toe imprint measurements in the winter of 2003 showed no difference in size of cranes in the two flocks during January and February, however there was a difference in middle toe size in December. One radio-marked bird was radio tracked to Cheneyville and Holmwood. Cranes selected roost sites in rice fields with water less than 20 cm deep. Cranes feeding in Cheneyville selected rice fields and corn fields, while the Holmwood birds used rice fields and pastures. Fecal analysis showed that nutsedge tubers (Cyperus spp.), rice (Oryza sativa), and corn (Zea maize) were the major foods consumed in Cheneyville, while the Holmwood birds used mostly nutsedge tubers and rice. Rice was found in feces earlier in the winter and nutsedge was found more frequently later in the winter.
22

Hybridization of Lepomid Sunfishes by Use of Cryopreservation

Whaley, C. Brian 04 September 2002 (has links)
The goal of this project was to integrate cryopreservation into the hybridization of sunfishes. The first objective was to evaluate the conditioning of sunfishes to spawn in cages in warmwater ponds. Bluegill and green sunfish were stocked in cages in ponds heated to 27 C by geothermal water. Fish in heated ponds did not spawn on artificial nests in cages. Fish were also brought into the laboratory for artificial spawning. There were 22 spawns yielding 47 ± 19% (mean ± SD) fertilization. The second objective was to develop methods for the refrigerated and frozen storage of sperm of bluegill Lepomis macrochirus and green sunfish Lepomis cyanellus. Sperm were stored in Hanks balanced salt solution prepared at 300 mOsmol/kg, and activated with solutions prepared at 80 mOsmol/kg. Sperm stored at 4 C maintained motility for as long as10 d, but the optimum use of sperm was on the day it is collected. Cryopreserved sperm should be thawed in a 40 C water bath for 7 s. The motility of cryopreserved sperm lasted for less than 1 min. Cryopreserved sperm of bluegill and green sunfish were able to fertilize green sunfish eggs. The third objective was to improve methods of cryopreservation of sperm of bluegill and coppernose bluegill Lepomis macrochirus purpurescens to produce hybrids with green sunfish. Sperm were exposed to five concentrations of five cryoprotectants and motility was estimated at 10 min intervals for 30 min. There were concentration-dependent effects on motility over time. One concentration of each cryoprotectant was used for cryopreservation. Sperm cryopreserved with methanol had the highest post-thaw motility while sperm cryopreserved with propylene glycol yielded the highest fertilization. Sperm of bluegill and coppernose bluegill were cryopreserved and used to fertilize eggs of the same green sunfish. There were no significant differences between the subspecies for motility before freezing (P = 0.4704), post-thaw motility (P = 0.5841), fertilizing ability (P = 0.1351) and hatch (P = 0.1133).
23

Impacts of Vertebrate Herbivores and Hurricane Georges on Densities of Belowground Plant Material on Shallow Mudflats in the Active Mississippi River Delta

Talley, Scotland 12 November 2002 (has links)
Delta National Wildlife Refuge (DNWR) is located in the active Mississippi River Delta (MRD). Resource managers at DNWR are implementing a marsh creation program that consists of dredging crevasses (openings) in the natural or man-made levees of major distributaries to divert sediment rich waters in to open bays. The mudflats thus created are colonized by stands of delta duck-potato (Sagittaria platyphylla) and delta three-square (Schoenoplectus deltarum). These plant communities stabilize the mudflats and provide high quality habitat for wintering waterfowl and nutria. Two challenges for the maintenance of these plant communities is disturbance from tropical storms and intense winter grazing. Objectives for my study were to measure initial (fall) density of belowground biomass in tropical storm impact vs. non-impact years and quantify herbivore use of belowground biomass. My study was conducted in 1998-2000 following disturbance by Hurricane Georges in September 1998. Exclosures were used to prevent all grazing or limit grazing to nutria only in two treatments. The third treatment was unrestricted grazing. Twelve replicates were distributed over four crevasse/mudflat complexes. Soil cores were collected in November, January, and March to assess production and use of belowground biomass. A mixed model (PROC MIXED, SAS 1996) was used to analyze treatment effects. Production in November 1998 was less than in November 1999 in both communities. In March of 1999 and 2000, belowground biomass in no grazing treatments was different from open grazing and nutria only grazing treatments, but the open grazing and nutria only grazing treatments did not differ. Disturbance from Hurricane Georges did reduce belowground production in 1998 and winter grazing further depleted belowground biomass, but belowground production in 1999 was greater than 1998. The productivity of these plant communities was capable of sustaining heavy reduction in belowground biomass, yet return to high levels of productivity in the following year.
24

The Influence of Hydrilla Infestation and Drawdown on the Food Habits and Growth of Age-0 Largemouth Bass in the Atchafalaya River Basin, Louisiana

Mason, Torrance D. 12 November 2002 (has links)
I compared diets and growth rates of age-0 largemouth bass in the Atchafalaya River Basin (Basin), Louisiana, to determine how hydrilla Hydrilla verticillata densities and drawdown influence bass food habits and growth. To assess hydrilla density effects on diet, I compared food habits of age-0 bass collected in high, intermediate, and low hydrilla densities, as well as in Henderson Lake, a semi-isolated portion of the Basin subject to drawdowns in 2001 and 2002 to reduce hydrilla densities. I also compared diets of age-0 bass from sites sampled in 2001 and 2002 that were also sampled in the mid-1970s before hydrilla had colonized the Basin. Frequency of occurrence and percentage of the diet by weight composed of fish prey consistently decreased as hydrilla coverage increased. Bass switched to a more fish-dominated diet sooner in Lake Henderson after the 2001 drawdown, but the importance of fishes in the diet decreased quickly as hydrilla beds became re-established. Effects of the 2002 drawdown in Lake Henderson lasted much longer, and age-0 bass switched to a piscivorous diet sooner and maintained a more fish-dominated diet throughout the spring and summer relative to bass collected from hydrilla-infested areas of the Basin. Length frequencies and mean length in August revealed smaller bass in areas affected by high hydrilla densities, however, there was no evidence that drawdown resulted in a growth advantage for age-0 largemouth bass. Mean length and weight of age-0 largemouth bass was significantly lower in areas supporting high hydrilla densities compared to habitats with intermediate and low hydrilla abundance. Results indicate high hydrilla coverage has major effects on the diet of age-0 largemouth bass, and those effects are reflected in reduced growth of individuals inhabiting high-density hydrilla beds.
25

Fundamental Properties of Borate-Modified Oriented Strandboard Manufactured from Southern Wood Species

Lee, Sunyoung 15 January 2003 (has links)
In the United States, damages to buildings from termites and decay fungi cost billions of dollars annually. As a result, there is an urgent need for building construction that will withstand the ravages of these biological pathogens. Chemical modification of building products is one of the techniques for developing durable wood-based construction. This study was conducted to examine the effects of powder zinc borate (ZB) and calcium borate (CB) on resin gel time, strength, swelling, leaching, termite, decay, and mold resistance properties of oriented strandboard (OSB). It was found that gel time of phenol formaldehyde (PF) resin decreased with increased amount of ZB, indicating interaction between the borate and the resin. The reduced gel time was partially recovered by using polyethylene glycol (PEG) in combination with ZB. Although panel stiffness was not affected by borate up to a 3.5 percent boric acid equivalent (BAE) level, ZB and CB showed a negative effect on the bending and internal bond (IB) strength. Thickness swelling (TS) of treated panels after 24-hour water soaking increased with borate level. ZB-treated OSB displayed less TS than CB-treated OSB at an equivalent BAE level. CB with a larger particle size caused significant TS. However, the chemical with a smaller particle size helped bring TS to a stable and acceptable level. A certain portion of borate leached out from OSB samples under the water-soaking conditions. The leaching rate varied with wood species, borate types, and amount. The use of borate with a smaller particle size helped reduce the leaching rate. The relationship between assayed BAE and leaching time followed a decaying exponential function for ZB and a decaying power function for CB. Laboratory termite tests showed that wood weight loss decreased and termite mortality increased with the increased BAE level. At the1% BAE or above, there was little damage on wood samples. There were significant correlations among termite mortality, weight loss, and visual damage ratings. Both borate chemicals provided an excellent decay and mold resistance for OSB. The information on various properties of borate-modified OSB is of significant value for developing durable structural panels from southern wood species.
26

Interaction of Fire and Insects in the Restoration and Management of Longleaf Pine

Bauman, Tessa Annette 30 January 2003 (has links)
The interactions of insects and fire on the health and restoration of longleaf pines in Louisiana were investigated. Insects found to be economically and ecologically important were considered, primarily bark beetles and weevils. First, insect populations in an area of fire exclusion of the Palustris Experimental Forest within the Kisatchie National Forest were quantified using baited flight intercept and pitfall traps. The possible influence of temperature and precipitation on insect abundance also was studied. Insects were most abundant during March and April and with correlating temperatures from 10-20 °C. Precipitation was not found to have an effect on insect abundance. Second, the roles of fire and insects and tree health were examined. As an indicator of tree health, 24-hour resin production was sampled from trees in the study area. Insects responded differentially to prescribed fire by season and feeding guild. Dormant season burns attracted significantly more root feeding than bark feeding insects. Growing season burns attracted significantly fewer insects than dormant season burns. Last, a portable propane burner was utilized to conduct semi-controlled burning of trees, simulating dormant and growing season burns of long and short duration of low and high intensity, respectively. Trees subjected to non-traditional prescriptions (high intensity dormant season fires and low intensity growing season fires) produced significantly less resin than trees burned under traditional prescriptions (low intensity dormant season fires and high intensity growing season fires). Overall, my research indicated that longleaf pine should be managed with prescribed burning during the growing season for stand maintenance. Growing season burns minimize insect response and have been shown to mimic natural burning patterns and be more effective at reducing understory competition. Depending upon management objectives, managers should consider insect response and the effect of fire on tree health when developing prescriptions.
27

Fine-Scaled Movements and Habitat Use of Black Bears in South Central Louisiana

Hightower, Dwayne Allen 30 January 2003 (has links)
Animal movements are related to many parameters of interest such as the search for food and other life requisites. Several measures, including home range, have been used to quantify and describe animal movement. However, fine-scaled movements of mammals have received less attention even though they are more directly related to energy expended for locating resources and provide information on how a home range is used. I tracked radiotagged female black bears (Ursus americanus) from two geographically separate populations in the Atchafalaya River Basin in south central Louisiana: the Coastal population at the southern extent and the Inland population at the northern extent. During tracking sessions, 2 technicians and myself measured azimuths from telemetry stations to radio-collared bears and test transmitters at 5-minute intervals for an average of 5.1 hours. I used these data to estimate 39 travel paths for 15 individual bears tracked from 1 to 7 times. Randomization tests indicated that telemetry precision was sufficient to detect fine-scaled bear movements. Movement path turning angles, measured relative to the previous direction of travel, and net displacement of individuals through time indicated that bears concentrated their movements (net displacement <72m) approximately 50% of the time, suggesting that they were utilizing a concentrated or patchily distributed resource. I failed to detect any differences in measures of fractal dimension, a scaling relation providing an index of path tortuosity or wiggliness, among bears in different reproductive conditions, study areas, or seasons. Bear, hour relative to sunset, reproductive condition, and season influenced the fall movement rates of bears. The effects of reproductive condition and time of day were not consistent across bears, and the effect of time of day was not consistent across reproductive conditions. Movement extent, or area traversed during an average tracking session, was similar between study areas, but Coastal females used a larger percentage of their home range. These data suggest life requisites are more compactly distributed in the Coastal area. Despite the difference in the distribution of bear resources between Coastal and Inland suggested by these data, I failed to detect any habitat preferences or avoidance of anthropogenic features such as roads and agricultural fields in either study area using movement path location data.
28

Evaluation of Repeated Removal of Mammalian Predators on Waterfowl Nest Success and Density

Chodachek, Kristen Dawn 26 February 2003 (has links)
Low levels of nest success in the prairie pothole region are mainly attributed to changes in predator community and abundance. Removal of predators from large sites (≥ 4144 ha) has been an effective strategy for increasing nest success; however, trapping small sites (< 301 ha) is considered ineffective. I examined the effects of removing predators from 10, 259 ha sites in northeastern North Dakota during 2001-2002. Overall nest success for both years was greater on trapped sites (53.4%) than non-trapped sites (28.7%). Furthermore, daily survival rate was greater on removal sites, and was positively correlated with total predators removed. Differences in nest density were apparent between treatments with an increased nest density on trapped sites, however year had no effect. Pair densities did not differ between treatments, but a 2-fold increase for both trapped and non-trapped sites was found in spring 2002. Cost to produce one fledged duckling, combining all species ranged from $16-20. Overall, the results of this study indicate that repeated removal of predators on small sites is an effective strategy for increasing waterfowl production; however, feasibility will ultimately depend on the user group, budget limitations, landowner objectives, and public acceptance.
29

Wood Laminated Composite Poles

Piao, Cheng 21 March 2003 (has links)
Wood composite poles are new engineered products with polygonal shapes and bonded with synthetic resins. The poles have multiple advantages over the solid wood poles and are a promising solid pole substitute in power transmission, telecommunication, and cable TV services. The use of composite poles may reduce the cost both in materials and manipulation, and facilitate installation and treatment. It is necessary to evaluate the factors that affect their properties and construct theoretical and analytical models to analyze these properties. Experiments were conducted to investigate strip thickness and number of strips (NOS) effects on the flexural properties and shear stress of wood composite poles. Small-scale (diameter = 7.6 cm (3 in), length = 1.16 m (48 in)) and full size poles (diameter = 10.2 cm (4 in), length = 6 m (20 ft) were manufactured for this purpose. Four strip thickness levels and three number-of-strip levels for the small-scale poles, and three thickness levels and two number-of-strip levels for full-size poles were chosen as experimental variables. The lumber was cut into strips, which were bonded with synthetic resin in molds, and the resulting poles were evaluated in a cantilever test. Results show that the effects of strip thickness were negative on glue-line shear and positive on the shear at poles clamped ends. But thickness had little effects on maximum bending stress of the small-scale poles and Youngs modulus of both full- and small-scale poles. With the increase of NOS, Youngs modulus of poles was increased. NOS had little effects on the maximum bending stress and glue-line shear of small-scale poles. A theoretical analysis was carried out to study the deflection and stress of composite poles. Governing differential equations were derived from high-order differential equations based on the principle of minimum potential energy theorem. Transverse shear and body forces were included in the model. Investigations were also carried out to find glue-line effects on the stress and deflection of composite poles. An analytical solution is modeled with the finite element analysis using ANSYS. Both theoretical and analytical solutions were verified by the experimental data.
30

A Mid-Rotation Bottomland Red Oak Stand Three Years after Thinning and Fertilization

Michalek, Alexander J. 03 April 2003 (has links)
To determine the effects of intermediate silvicultural treatments on bottomland hardwoods, two types of thinning (crown thinning and low thinning) and one level of fertilizer (200 lb/ac N + 50 lb/ac P) were applied to a predominantly red oak stand in southeastern Texas. Treatments were applied in a 3 × 2 factorial arrangement as a randomized complete block design of 12 ac in size. Crop trees were selected prior to the treatments, and diameter at breast height measurements were taken pre-treatment and for three proceeding years to assess diameter growth response of all trees. Epicormic branching measurements were also taken for three years post-treatment to evaluate epicormic branching response of all crop trees to crown thinning, low thinning and fertilization. Furthermore, reproduction plots were established pre-treatment to evaluate reproduction height growth response to all intermediate treatments. First-year results showed no significant difference in current annual increment (CAI) of crop-tree diameter growth response; however, second-year results of CAI diameter growth showed that crop trees in thinned plots achieved significantly more growth than in unthinned plots. With third-year results of CAI diameter growth, crop trees in crow-thinned plots grew significantly better than in both low-thinned and unthinned plots, all regardless of fertilization. Epicormic branching was generally greater in crown-thinned and fertilized plots immediately following treatment, and reproduction height growth was generally greater in crown-thinned, and in some cases, fertilized plots.

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