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Predictive models were developed for stiffness and bending strength of southern pine 2x6, eight ft. lumber using nondestructive measurements of stresswave velocity, density and visual characteristics such as knots, slope of grain and rate of growth. To account for local areas of weakened material due to knots and slope of grain, a grid system was developed to quantify general knot size and location. Multiple regression models were created using these physical and visual measurements. Two sets of models were developed: one that removed influential samples with abnormal wavespeeds (greater than 18,000 ft./s) indicative of poor wood quality; and, models that included all samples. Static modulus of elasticity (MOEs) model performance was significantly better for those that removed influential samples compared to the all-sample models, with an R2 of 0.892 and 0.720, respectively. Modulus of rupture (MOR) model performance was slightly better with influential samples removed R2 of 0.714 and 0.690, respectively. The location of knots within a board significantly altered the mechanical properties, especially bending strength. The results indicate potential for greater specification of allowable stresses for different orientations during bending. A simulated grading study was conducted to assess the feasibility of the developed models. Thousands of samples were generated according to estimated variable distributions and graded according to the American Lumber Standards Committee Machine Graded Policy. Results suggest that these models may be feasible in an actual lumber grading scenario.

Understanding gene flow and population structure in wildlife populations helps managers to protect distinct genetic lineages and genetic variation in small, isolated populations at high risk of extinction. I assessed genetic diversity in Bachmans Sparrows (Peucaea aestivalis) to evaluate the role of natural barriers in shaping evolutionarily significant units as well as the effect of anthropogenically-caused habitat loss and fragmentation on population differentiation and diversity. Genetic diversity was assessed across the geographic range of Bachmans Sparrow by genotyping 226 individuals at 18 microsatellite loci and sequencing 48 individuals at nuclear and mitochondrial DNA genes. Multiple analyses consistently demonstrated high levels of gene flow, which appear to have maintained high levels of genetic variation and panmixia in populations throughout the species range. Based on these genetic data, separate management units/subspecies designations or artificial gene flow among populations in habitat fragments do not seem necessary. High vagility in Bachmans Sparrow may be an adaptation to colonize ephemeral, fire-mediated longleaf pine habitat, but in recent times, it also appears to have reduced inbreeding and loss of genetic diversity in habitat fragments.

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No description available.

Floodplain lakes in floodplains of large rivers undergoing intensive alterations are subject to hydrologic alteration. One example is in the Lower Mississippi Alluvial Valley (LMAV) and pivotal habitat for wildlife. Catahoula Lake has experienced hydrologic regime alterations over the past ~150 years that may be contribute to changes in the habitat with expansion of woody plants. A Diversion Channel was constructed in 1972 to provide the natural, annual de-watering of the lake to maintain its ecological integrity, but ecologic changes are still occurring. Our general goal is to understand the hydrologic regime of the lake, particularly the historical hydrologic regime of Catahoula Lake and to identify the contribution of the adjacent rivers Little, Atchafalaya, Red, Black, Ouachita, Tensas, and Mississippi rivers to the variability of Catahoula Lake prior to and after extensive hydrologic modifications in the LMAV. Historical lake level and neighboring rivers stage time series were used to estimate the hydrologic links between the lake and its surrounding rivers. Our analyses were done for three time periods: (1) immediately prior to the Diversion Channel construction, (2) post-Diversion Channel period, and (3) estimated condition in the late 1800s prior to incision of the Atchafalaya River. Results indicate that water levels on the lake are complexly related to the influxes of the Little River or the stage of the Black River stage at Jonesville, and the most consistent relationship is with the Atchafalaya River, which controls the lake level via a backwater effect at stage 7.3 m or higher. This backwater effect has been reduced from 207 to 120 days per year between 1880 and 2010. Compared to its condition prior to hydrologic alterations, results indicate modifications in the LMAV and the construction of the Diversion Channel have altered the lake regime. Our best estimates is that current lake levels are lower in the high-water spring, less variable in the dry period, and lack the extreme high water events of 100+ years ago.

Coastal wetland forest ecosystems rely on the intimate interactions of hydrology, salinity, and coastal forest vegetation. The boundary between marsh and forest is often where hummock-swale terrain exists. It remains unknown as to the degree to which trees may experience varied salinity level within hummocks provided with freshwater flux. This study examined the hydrological regime of the hummock-swale terrain that resulted in salinity variation and whether freshwater source exists for baldcypress. Natural tracers of stable isotopes of water and salinity were applied to understand the sources of water. To better examine the tracers used, we conducted several experiments to gain a clearer understanding of the variability in isotopic compositions in throughfall and by extracting water from wood and soil. The studies indicated that baldcypress are able to avoid saline flooding from hummocks. We found that the throughfall process does correspond with the canopy structure enough to strongly influence throughfall amount but only weakly influence isotopic composition. Also at microtopographic scale, salinity of the groundwater in hummocks remained chronically high and vertical solute exchange was little. The shallow subsurface of hummocks was a zone characterized by slow dilution and episodic salinization rather than slow salinization and episodic flushing. Rainfall and frequent inundation by generally low-salinity water flushed salts and maintained lower salinity in upper layers. Thus the baldcypress forest overall occupies a nonsaline site, but the episodic influxes followed by slow leaching occurs superimposed on a layer of salinity that lies presumably beneath the root zone for most of the growing season. In addition, the systematic errors were little considering the isotopic fractionation during water extraction from wood.

The greatest diversity of crayfishes, especially of rare Orconectes species, is found in the central Louisiana watersheds (Red River, Mermentau, Calcasieu, and Vermillion-Teche), and most species are widely distributed among the drainages. The purpose of this research was to lay groundwork for species distribution and metacommunity modelling for crayfishes in this region. To address this goal, two field studies were performed in the summers of 2013 and 2014, as well as an indoor laboratory study. Analyses of broadly distributed species indicated no significant correlations between species abundances and habitat variables nor any significant environmental gradients for those species. Within-drainage variability of habitat was substantial in this study and a large range of site conditions were sampled within any particular drainage, despite significant drainage differences. Subsequent analysis of drainage-restricted species indicated that drainage-scale modelling is suitable for endemic species such as Procambarus pentastylus and P. natchitochae. However, more restricted Orconectes maletae, O. blacki, and O. hathawayi could not be effectively modelled at the drainage scale, in part because they were not detected in the majority of samples. Examination of gear types and times of day indicated that catch per unit effort (CPUE) and average total length of crayfish was greater with electrofishers than with dipnets; however, no differences between time of day were detected for either CPUE or crayfish total length. Differences in estimates of sample diversity using different combinations of gears and times of day were detected when calculated on a per individual basis, but not on a per site basis. In intraspecific competition trials, body size and chelae width were found to be significant biological factors in determining the odds of dominance in O. blacki and P. pentastylus. Presence of predator cue (water conditioned by Micropterus salmoides) generally reduced frequencies of dominance interactions in both species and generally increased median shelter occupancy times for both species. This research provides much needed information on the distributions and ecology of central Louisiana crayfishes, and future studies will be needed to quantify genetic units, dispersal corridors, and interspecific interactions between other co-occurring species and to characterize the central Louisiana crayfish metacommunity.

Wading birds in southwestern Louisiana and southeastern Texas rely heavily on rice fields and crawfish ponds as foraging areas; however, little information exists on food availability throughout the annual crop cycle. The objectives of this study are: 1) Develop a classification for rice and crawfish fields based upon tillage, forage crop (for crawfish fields), water depths, vegetation density, vegetation height, and other visible parameters; 2) Quantify the distribution of rice and crawfish fields in various stages across the landscape through time; 3) Determine the effects of rice and crawfish field types and landscape characteristics on wading bird use; and, 4) Evaluate the relationships among field classification, habitat characteristics, and invertebrate densities (including crawfish) in selected field types through time. To address these objectives, I used stratified-random sampling to select 50 1.6 km long road transects in 7 parishes and 3 counties of the major rice/crawfish producing parishes/counties in southwestern Louisiana and southeastern Texas. From April 2013 April 2014 I conducted monthly surveys along the transects to assess rice/crawfish habitat conditions, as well as conduct waterbird surveys. From May 2013 until February 2014 I conducted quarterly macroinvertebrate and nekton sampling of selected fields in the region. The results of the study demonstrate the intra-annual variability in resources available to waterbirds and other wetland dependent wildlife throughout the coastal prairie region. Rice agriculture as a percentage of surveyed land use varied from 0-30%. Crawfish agriculture varied in a 12-month period from 0-15% of lands surveyed. Crop type, irrigation and tillage were the factors that contributed most to macroinvertebrate abundance and biomass. Waterbird use of fields was not randomly distributed. Irrigation, seeding method and tillage all seemed to contribute to waterbird use of fields surveyed in the region.

The thesis examines a panel of trade flows during 2009-2013, exploring the influence of regulatory quality on the pattern of forest products imports by India from 143 partner countries. The study applies a pooled regression model followed by Generalized Least Squared (GLS) technique and a more robust Feasible Generalized Least Squared (FGLS) method of estimation with regulatory quality, distance between the partner country and India, total forest area of partner country, GDP and population indicators to assess the impact of partner countrys regulatory quality and other trade-related factors on imports of forest products by India. The results support the notion that imports of forest products depend on regulatory quality, the distance between the trading countries, forest cover, the size of the economy and other factors considered in the model. The study also considers the impact of regional variability on forest products import by India. Quantitatively, the results suggest that a 1 percent improvement in regulatory quality of the partner country would yield a 6.10 percent increase in imports of forest products by India. A 1 percent increase in distance between India and the trading country yields a 0.60 percent decrease in total import volume, whereas a 1 percent increase in forest area of partner country and a 1 percent increase in GDP of partner country yields an increase in forest products imports to India by 0.24 percent and 0.75 percent, respectively. Thus, it confirms that while improvement in regulatory quality of partner countries contribute to improved imports, improvements in the GDP of partner country and increase in the total forest area are equally important in facilitating the growth of forest products imports by India. This improvement implies policy emphasis on the governance, economy and environment of the trading countries and, are important to support the furtherance of the volume of trade flows across countries.