6th Lone Star Regional Native Plant Conference

https://scholarworks.sfasu.edu/sfa_gardens_lonestar/1003/thumbnail.jp

Spatial Distribution of Earthworms in an East Texas Forest Ecosystem

Earthworms were collected and identified in different ecological habitats of the Stephen F. Austin Experimental Forest (SFAEF) in the Piney Woods Ecoregion (PWE) of Texas. Earthworm spatial distribution data were collected over four distinct ecological habitats with a range of soil conditions and vegetative cover. A total of 128 sampling plots were surveyed in two different, broadly defined locations (mesic slope = 68 plots, dry-mesic upland = 60 plots). Using multivariate classification/ordination (TWINSPAN) and detrended correspondence analysis (DCA) of overstory vegetation data, these two locations were further divided into four distinct habitats: dry-mesic mixed upland, transitional zone, mesic slope and wet forested seeps. By using TWINSPAN and principal component analysis (PCA), it was found that earthworm species assemblages and understory vegetation corresponded to these discrete ecological habitats. ArcGIS10 was then used to create spatial distribution maps of earthworm species throughout these delineated ecological habitats in the SFAEF. Six earthworm species from the native North American genus Diplocardia were collected at SFAEF: D. caroliniana Eisen (1899), D. eiseni Michaelsen (1894), D. komareki Gates (1977); D. macdowelli Murchie (1963), D. mississippiensis Smith (1924) and D. ornata Gates (1943). Two earthworm species from the native North American genus Bimastos were collected: B. heimburgeri Smith 1928 and B. longicinctus Smith and Gittins 1915. The collection of B. longicinctus is a new state record for Texas. Amynthas corticis Kinberg (1867) specimens were collected, which represent a non-native genus from Southeast Asia. Ocnerodrilidae, a megadrile family first described by Beddard in 1891, were also collected likely representing non-native species originating from intertropical America and Africa (Christoffersen, 2008)

Understory vegetative Diversity of Post-Thinned pine Plantations Treated with Fertilizer, Fire and Herbicide in East Texas

This study assessed biodiversity in the understory of two pine plantations where different management tools (fertilizer, prescribed burning, and herbicide application) were utilized. During three growing seasons, species, percent cover, and number of individuals, and physical characteristics were recorded. Responses to treatment were examined based on comparison of species richness, evenness, diversity, and importance. Two years after treatment, fertilized plots showed a decline in species richness, evenness, and diversity. Prescribed burning and herbicide treatments increased species richness but decreased species evenness, resulting in no change in diversity index. Herbicide treatment reduced the importance of dominant shrubs and increased the importance of disturbance-adapted species

Understory Vegetative Diversity of Post-Thinned Pine Plantations Treated with Fertilizer, Fire and Herbicide in East Texas

This study assessed biodiversity in the understory of two pine plantations where different management tools (fertilizer, prescribed burning, and herbicide application) were utilized. During three growing seasons, species, percent cover, and number of individuals, and physical characteristics were recorded. Responses to treatment were examined based on comparison of species richness, evenness, diversity, and importance. Two years after treatment, fertilized plots showed a decline in species richness, evenness, and diversity. Prescribed burning and herbicide treatments increased species richness but decreased species evenness, resulting in no change in diversity index. Herbicide treatment reduced the importance of dominant shrubs and increased the importance of disturbance-adapted species

An ecological classification system for the central hardwoods region: The Hoosier National Forest

This study, a multifactor ecological classification system, was developed for the Brown County Hills and Crawford Upland Subsections of the Hoosier National Forest in Southern Indiana. Ecological classifications use the interrelationships between components of ecosystems including vegetation, soils, and physiography as the basis for classifying sites across the landscape. Data for ground flora, saplings, and canopy trees species from selected stands older than 80 years were summarized and subjected to TWINSPAN classification and DECORANA ordination. Physiographic and soil measurements were regressed on ground flora DECORANA scores. Strong relationships were observed between DECORANA scores and slope aspect, soil A-horizon depth, slope position, and soil pH. The vegetation of the Hoosier National Forest is believed to be related to a moisture and nutrient gradient which is influenced by these factors. The landscape was divided into ecological land units on the basis of these relationships. Twelve ecological units for the Brown County Hills subsection, and fifteen units for the Crawford Upland subsection were described. These units ranged from floodplains along large streams to mesic sites on northerly slopes to dry forest on southwesterly slopes. Identification of the vegetation component of the units was aided by ecological species groups, groups of species which tend to occur together across the landscape in response to similar environmental factors. Seven ecological species groups for the Brown County hills and eight groups for the Crawford Upland were identified. Comparison of overstory and understory trees indicated that marked successional trends were evident on many of the 80-120 year-old sample sites. However, these trends varied among ecological units. Significant oak-hickory regeneration occurred on many of the dry ecological units while sugar maple was replacing overstory oak-hickory on moderately dry and mesic units. This classification system can serve both as a framework for future research and as a system on which ecologically sound forest management can be based. It will aid researchers, naturalists and forest land managers as they deal with complex forest resource issues

Denaturing Gradient Gel Electrophoresis as a Tool To Determine Batch Similarity of Probiotic Cultures of Porcine Cecal Bacteria▿

A continuous-flow porcine cecal bacterial culture has been used experimentally as treatment against enterotoxigenic Escherichia coli in weanling pigs. Periodically, the cultures must be started from frozen stock. Our results indicate that denaturing gradient gel electrophoresis can be applied as an indirect indication of culture similarity for each new batch generated from frozen stock

Under pressure : the relationship between cranial shape and burrowing force in caecilians (Gymnophiona)

Caecilians are elongate, limbless and annulated amphibians that, with the exception of one aquatic family, all have an at least partly fossorial lifestyle. It has been suggested that caecilian evolution resulted in sturdy and compact skulls with fused bones and tight sutures, as an adaptation to their head-first burrowing habits. However, although their cranial osteology is well described, relationships between form and function remain poorly understood. In the present study, we explored the relationship between cranial shape and in vivo burrowing forces. Using micro-computed tomography (mu CT) data, we performed 3D geometric morphometrics to explore whether cranial and mandibular shapes reflected patterns that might be associated with maximal push forces. The results highlight important differences in maximal push forces, with the aquatic Typhlonectes producing a lower force for a given size compared with other species. Despite substantial differences in head morphology across species, no relationship between overall skull shape and push force could be detected. Although a strong phylogenetic signal may partly obscure the results, our conclusions confirm previous studies using biomechanical models and suggest that differences in the degree of fossoriality do not appear to be driving the evolution of head shape