Sustainable management and conservation of the extensive bottomland hardwood forest resource in the southeastern U.S. requires a good understanding of basic structural and competitive relationships within these forests. To gain an insight into these relationships, plot information from stands in Arkansas, Louisiana, and Mississippi were analyzed. The effects of individual tree attributes, distance-dependant, and distance-independent competition measures on 5-yr radial growth of red oak crop trees were examined. Selected species included cherrybark oak (Quercus pagoda Raf.), water oak (Q. nigra L.), and Nuttall oak (Q. nuttallii Palmer). Spatial continuity of tree variables was explored through geostatistical analysis. Finally, spatial distribution patterns of all species, the intraspecific pattern of cherrybark oak, water oak, and sweetgum (Liquidambar styraciflua L.), and the interspecific pattern of their pairs was examined with point pattern analysis. In the analysis of 5-yr radial growth, the crown class score (from Meadows et al. 2001) accounted for a large portion of tree diameter growth. However, average plot-level characteristics failed to account for a significant proportion of the variability in tree growth. The basal area of trees taller than the crop trees and located within 2.5 mean crown radii had the highest negative correlation with crop tree 5-yr radial growth. Red oaks were likely exerting the greatest competition. Crop tree radial growth was also positively associated with the basal area of other red oaks taller than the crop tree and located between 3 and 4 mean crown radii from the crop tree (the indirect neighbors). Geostatistical analysis demonstrated that spatial continuity of unsuppressed tree attributes extended to a distance equal to 4 times the mean crown radius, suggesting that when resources are nonlimiting, multiple trees may be able to coexist and grow well in close proximity. Spatial point pattern analysis indicated that when species were combined, they were frequently aggregated and sometimes overdispersed. Plots with larger trees were more likely to exhibit overdispersion suggesting a shift to this pattern as trees grow. Interspecific and intraspecific pattern analyses suggested that strong interspecific competition resulted in species segregation, while weaker intraspecific competition led to aggregations of conspecifics.

A continuing challenge for wood and wood-based composite building materials has been durability--the power of resisting agents or influences which tend to cause changes, decay, or dissolution; lastingness. In the case of wood-based products, this often requires a resistance to biological degradation and moisture related dimensional instability (particularly in particle and flake or strand boards). Borden Chemical Company has developed a new low molecular weight phenol formaldehyde additive, PD-112, to improve durability in composite wood products. This study investigated PD-112s contribution to durability in oriented strand board (OSB) through laboratory testing of treated southern pine strandboard panels versus untreated control panels. Tests examined mechanical properties, as well as resistance to degradation by water infiltration, mold, decay fungi and termite attack. PD-112 treatment significantly reduced moisture induced thickness swelling without adverse effects on strength properties. Modulus of rupture (MOR) and modulus of elasticity (MOE) increased somewhat, while internal bonding strength (IB) increased greatly with increasing PD-112 treatment. PD-112 imparted good termite resistance to pine strandboard. Treatments gave excellent resistance to decay by selected brown rot fungi, and moderate resistance to growth of selected mold fungi.

I examined nest attendance patterns for 132 Gadwall (Anas strepera) females breeding in the prairie pothole region located in Towner County, North Dakota from May to July 2000 - 2001. Overall, Gadwall had a daily incubation constancy of 76.5 ± 10.8%, and daily recess frequency of 2.2 ± 1.1 with each recess lasting 179.8 ± 133.8 minutes. Unlike other waterfowl species, Gadwall increased incubation constancy and decreased recess frequency as daily high temperature increased and showed no change in constancy with precipitation. Gadwall incubation constancy did not fit the body-size hypothesis, as Gadwall have a lower incubation constancy compared to species smaller in size. This may be because Gadwall have the latest peak clutch initiation of all dabbling ducks, providing the advantage of dense nesting cover and warmer ambient temperature compared to earlier nesting species. Of the 132 females, 19 (14%) delayed nocturnal incubation resulting in a significant difference in incubation constancy (P= 0.001) and recess frequency (P = 0.001) from those that did not delay nocturnal incubation. However, components of the incubation rhythms, after the onset of nocturnal incubation were similar for both groups.

This study examined the effects of intrahabitat variability on marsh edge use by fishes and decapod crustaceans. The objectives were to (1) identify quantitative measures of habitat complexity that describe the structural design of marsh edge habitats, and (2) examine differences in nekton use between cut-bank and gently sloping marsh edge habitats. The study was conducted in Barataria Bay, Louisiana at 75, 10-m marsh edge study sites. Monthly seining was conducted in fall 2003 and spring 2004 and measures of habitat complexity were recorded at each sample location. Indices of tidal inundation and site exposure to wind and wave action were calculated. Results showed significantly greater complexity (i.e., irregularity, elevation, bank height, bank undercut, vegetation densities and percent vegetated cover) at cut-bank edges over gently sloping edges (P < 0.0001). Nekton diversity (fall: P = 0.0236, spring: P = 0.0297) and mean abundance of bay anchovy Anchoa mitchilli (fall: P = 0.0010) were also significantly greater at cut-bank edges over gently sloping edges. Lower mean elevation at gently sloping edges resulted in significantly greater levels of inundation over cut-bank edges (P < 0.0001), providing earlier and prolonged use of inner marsh habitats. Mean abundances of marsh residents that frequent the vegetated marsh surface (naked goby Gobiosoma bosc (fall: P = 0.0055), gulf killifish Fundulus grandis (fall: P = 0.0280), and grass shrimp Palaemonetes pugio (fall: P = 0.0017) were significantly greater at gently sloping edges over cut-bank edges. Several associations were observed between nekton community parameters and measures of habitat complexity, including strong positive correlations between species diversity (fall: P < 0.0001, spring: P < 0.0001), species richness (fall P = 0.0001, spring P = 0.0029), and exposure to wind and wave action. Differences in use between cut-bank and gently sloping edges and associations between nekton variables and measures of habitat complexity suggest that differences in habitat structure exist among marsh edge habitats and that these differences do influence habitat selection by nekton. This study highlights the need for methods that provide more explicit identification of EFH by determining relationships between productivity and the different habitats used by aquatic organisms.

The goal of this study was to develop several techniques that utilize the use of geothermal water that can contribute to increased profitability for commercial catfish producers. The primary objectives of this study were to: 1) determine the heating requirement using degree-days of channel catfish spawning 2) improve the efficiency of artificial spawning and, 3) evaluate the effectiveness of stocking outdoor ponds and pools with channel catfish fry. The heating requirement for channel catfish spawning was determined to be between 99 and 129 degree days at the peak of spawning. There was no difference in degree-day values between spawns collected from heated ponds, and those collected from ambient ponds. There was also no difference in the weight and fertilization percentages between the egg masses collected before and after the start of natural spawning. In artificial spawning, female-female and male-female pairs showed no differences in the volume of unfertilized eggs collected, spawning latency, and neurulation in trials conducted before and after the start of natural spawning. Spawning behavior and egg release proved to be the most accurate way to determine the optimum time to manually strip female broodstock. Survival of fry before the start of regular spawning was greater in pools then in 0.04-ha ponds but that there was no difference in the stocking of sacfry or swim-up fry before or after the start of regular spawning in ponds or pools. The size, growth rate and number of fingerlings harvested are all affected by the survival percentage of fry stocked. Lower survival results in fewer fingerlings that grow faster and larger. Survival was mostly affected by the date of stocking and the number of growing days the fingerlings remained in the ponds or pools. These results support the use of geothermally heated ponds to increase the productivity of commercial catfish producers by providing better control over spawning, increased opportunities for artificial spawning, production of improved seedstock (including hybrids), and lengthened growing period for channel catfish fry. Future research needs to focus on improving these techniques and develop methods for efficient use of geothermal water in commercial catfish production.

Freshwater ecosystems, particularly streams and rivers, have been the subject of prodigious research. Unfortunately, in comparison to neighboring regions, the Gulf of Mexico coastal plain has not received as much attention. Therefore, I collected data on the macroinvertebrates of these streams to begin the understanding of the relationships between community structure and environmental characteristics. In contrast to the hypothesized ancestral streams of these macroinvertebrates, coastal plain streams are commonly devoid of rocks leaving only woody debris as usable hard substrates and are typically lower in dissolved oxygen. I examined habitat selection by colonization of woody debris with large and small surface areas. Secondly, given a similar surface area, I examined colonization in different levels of dissolved oxygen. Concurrently, I conducted biota and habitat surveys in three streams over four periods from August 2002 until April 2004 to collect baseline data for future investigations. The survey data included macroinvertebrate collections, microbial population estimations, water chemistry, and habitat descriptions. Finally, over the same time period, I collected macroinvertebrate, microbial, water chemistry, and habitat data in a stream with a potentially strong biotic disturbance, feral swine (Sus scrofa). All data were examined with appropriate multivariate statistics. The in-stream experiment suggested similar colonization of both sizes of woody debris for 20 of 21 taxa examined. Some potential high and low dissolved oxygen specialization was detected in the experiment, however, many macroinvertebrates (37%) appeared to be dissolved oxygen generalists. Further, survey data suggested more than 50% of collected macroinvertebrates also may be generalists with regard to other abiotic factors, but did demonstrate some affinity for woody debris. The single stream biotic disturbance appeared to significantly alter the macroinvertebrate community with a potential shift in favor of collecting organisms against scraping organisms. Therefore, in contrast with other regions, I suggest that coastal plain macroinvertebrates are tolerant to many abiotic factors, but are intolerant of some biotic disturbances.

Lake Pontchartrain and the drainage basin have experienced environmental degradation because of human settlement, land use and climate changes. A thorough understanding of hydrologic trends and variability associated with the changes is critical for sustainable water resources management and ecosystem restoration in the region. This study examined freshwater inflow (1940-2002) and suspended solids loadings (1978-2001) from three upper Lake Pontchartrain watersheds that contribute to the lake estuary: the Amite, Tickfaw, and Tangipahoa river watersheds. The relationships of freshwater inflow and suspended solids loadings with climate variables and population growth were investigated. Using observed daily discharge, a spatially-distributed hydrologic model (SWAT) was evaluated, and the model then was employed to assess hydrologic responses of the coastal watersheds to potential climate change. The study showed an annual freshwater inflow of 5 km3 yr-1 and average suspended solids inputs of 210,360 tons yr-1 entering Lake Pontchartrain. More than 69% of annual water yield and 66% of suspended solids occurred from December to May and from January to April, respectively. Over 80% of the variation in annual freshwater inflow could be explained by annual precipitation. A significant increase in freshwater inflow was found in the Amite River watershed over the past sixty years, coinciding with both climatic variation and population growth. The hydrologic modeling showed a good agreement between the simulated and observed daily discharge, with a relatively high Nash-Sutcliffe model efficiency (> 0.811) and low mean error (< 5.6%). The simulation further indicated that, unlike upland watersheds, calibration of the surface and channel routing parameters in the SWAT model became most critical for lowland coastal watersheds with gentle relief. The climate change assessment showed a significant influence of precipitation on annual freshwater yield with an increase of 19.3%-40.1% in response to a 10%-20% increase in annual precipitation. Potential air temperature increase would have only a marginal effect on freshwater yield as shown by a 1.4%-2.9% decrease in the annual freshwater yield for a 1.6 oC-3.3 oC increase in temperature. Warming, however, may pose risks of drought during spring and summer in this humid subtropical region.

Louisiana black bears (Ursus americanus luteolus) exist in 3 isolated populations in Louisiana and are listed as a threatened subspecies under the United States endangered species act. In order to establish a population of black bears in central Louisiana and to promote connectivity among existing populations 11 adult females and 28 cubs were reintroduced to suitable habitat on Lake Ophelia National Wildlife Refuge. We captured and monitored females in the Tensas River Basin (TRB) in northeast Louisiana for use in these reintroduction efforts and to study their ecology. Specifically, I studied the food habits, space use, habitat selection, and denning behavior of female bears in the TRB and reintroduced populations. Within the TRB bears exist in 2 subpopulations (Tensas and Deltic) which inhabit highly variable landscapes. Bears on Tensas inhabit a large (>300 km²) contiguous block of bottomland hardwood forest, whereas bears on Deltic inhabit small (<7 km²) forest fragments surrounded by a matrix of agricultural fields. Bears in the TRB ate an omnivorous diet dominated by plant foods that shifted to exploit seasonally available foods. Important food items included: herbaceous vegetation, soft mast, corn, acorns, and beetles. Spring home ranges and core areas on Tensas differed between females with and without cubs. Ranges of females on Tensas were larger than those on Deltic, and ranges of reintroduced females were larger than both TRB subpopulations. Habitat selection patterns also differed as females on Tensas selected swamps and regenerating forests at most spatial scales and during most seasons, whereas Deltic females selected upland and lowland forests. Lake Ophelia females selected upland and lowland forests when establishing home ranges, but did not exhibit non-random habitat use within home ranges. In the TRB, parturient females used tree dens more frequently than ground dens, whereas non-parturient used tree and ground dens with similar frequency. Tensas den sites were closer than expected to swamps, water, and regenerating forests, whereas Deltic den sites were closer than expected to upland and lowland forests. I discuss the results in relation to fragmentation, forest management practices, and conservation.

Increasingly, attention is being paid to the role coarse woody debris (CWD) plays in forest ecosystems. CWD has been shown to provide valuable wildlife habitat, support food webs and contribute to nutrient storage and cycling, and mediate hydrological and geomorphic process. Timber management may be altering CWD dynamics by replacing aging stands with younger, more vigorous ones. The specific objectives of this study were 1) to quantify differences in coarse woody debris characteristics among bottomland hardwood forest stands with different management histories, and 2) to determine how differences in tree species composition and forest structure in bottomland hardwood forests influence coarse woody debris characteristics. Transects were established in ten forest stands with different management histories. Line intercept sampling was conducted to evaluate CWD characteristics, and point-centered-quarter sampling was used to compare characteristics in live vegetation. Large standard deviations were associated with most parameters measured, but results suggested that stands that have not been recently managed support more characteristics associated with structurally mature forest than stands that have been recently harvested. In particular, the Bayou Cocodrie NWR old growth natural area expressed characteristics such as relatively large volumes of CWD, a relatively high frequency of large diameter logs, snags, and trees, and a more stratified canopy and established mid-story. More research is needed to better understand the inherent variability in CWD and live vegetation characteristics among bottomland hardwood forests before explicit correlations between forest management and CWD dynamics can be inferred.

Louisiana is the leading state in number of river otters used in reintroduction programs in other states and in the production of pelts. However, habitat loss and degradation have prompted concern about the status of otter populations. This dissertation undertakes a spatial and temporal analysis of river otter harvest activity and examines environmental factors related to monitoring mercury levels in streams in Louisiana. Harvest data for 1957-2004 were analyzed to identify spatial and temporal trends in otter harvest activity. Changes have occurred in the last 20 years in the spatial dynamics of otter harvest in Louisiana, these include an increasing proportion of harvested otters coming from upland parishes in more recent years, and an increase in the proportion of trappers catching otters in that region. Spatial analysis indicated that this shift in harvesting activity has been gradual rather than abrupt. An explanation for this shift could be a greater interest of upland trappers in catching otters because of increasing otter pelt price and a decline in pelt price for other furbearer species. Analyses indicated that a management plan based on spatial control of harvest could be an option in Louisiana, with rice fields and protected areas playing an important role in the management/conservation plan. Temporal analysis suggested that the number of otters harvested 1 and 5 years ago has an impact on number of otters harvested at present time. An autoregressive model was developed to describe this association and to forecast number of otter pelts to be harvested 1 year in the future. The structure identified in the harvest data was used to develop a model to describe the dynamics of the otter populations. The simulation using 4-year and 8-year periods offered a reasonable approximation to the estimated cyclic dynamics of otter population in Louisiana. Mercury levels in otters were compared to levels in fish collected in different streams in Louisiana. Mercury levels in otters were higher than in fish. Otter samples also identified streams where mercury level in water may require further analysis. These results suggested that a mercury monitoring program based on river otters could be feasible in Louisiana.