Hans M. Williams

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.

Total Nonstructural Carbohydrate Trends in Deeproot Sedge (Cyperus entrerianus)

Abstract Native to temperate South America, deeproot sedge has naturalized throughout the southeastern United States. Often forming dense, homogenous stands, deeproot sedge has become widespread, invasive, and potentially harmful ecologically throughout the coastal prairie ecoregion of Texas. Possessing characteristics (rapid growth, generalized habitat requirements) of other weedy congeners (purple nutsedge and yellow nutsedge), its relatively recent expansion highlights the critical need to develop effective control techniques and strategies for this species throughout this endangered ecoregion. Research was performed to delineate total nonstructural carbohydrate (TNC) trends in deeproot sedge rhizomes for development of a phenologically based schedule for herbicide applications and mechanical treatments. Overall, TNC levels were greatest in May to August and lowest from October to January, regardless of study area. Apparently, deeproot sedge exerts little energy into seed production because TNC levels were continually replenished throughout the growing season. As such, foliar-herbicide application throughout the growing season should achieve total plant kill. Conversely, deeproot sedge rhizome TNC levels never fell below 30%, even during winter, which indicates that winter mechanical treatments or winter prescribed fires will not be effective because substantial rhizome reserves are present to support resprouting during the next growing season. Beyond a priori prevention, sequential herbicide applications combined with integrated, sequential, prescribed fire and herbicide treatments will be needed for long-term deeproot sedge control throughout its geographic range. Nomenclature: Deeproot sedge, Cyperus entrerianus Boeck; purple nutsedge, Cyperus rotundus L.; yellow nutsedge, Cyperus esculentus L.

Variation in Forest Canopy Composition of Riparian Networks from Headwaters to Large River Floodplains in the Southeast Coastal Plain, USA

Data on canopy trees (stems ≥ 15xa0cm DBH) in riparian wetlands, spanning from headwaters to large river floodplains, were used to test whether forest canopy composition differed among hydrogeomorphic (HGM) riverine subclasses and among physiographic sub-regions (Major Land Resource Areas; MLRA) within a given HGM subclass. Riverine stands (nu2009=u2009225) were sampled in four MLRA regions of the Southeastern U.S. Atlantic and Gulf Coastal Plain Physiographic Provinces. Composition data were analyzed using Non-metric Multidimensional Scaling and Multiple-Response Permutation Procedures to evaluate differences among HGM subclasses and MLRA regions. Analyses showed that canopy composition differed among three a priori subclasses related to Strahler stream order: headwater complex (along 1st-3rd order streams), mid-gradient floodplain (4th-6th order), and low-gradient floodplain (> 6th order). Further, composition also differed by MLRA region within each subclass. Thus, not only was species composition related to riverine hydrogeomorphology across a wide physiographic area, but differences in composition within HGM subclasses were also related to sub-region. These data could be useful in defining floristic reference standards when evaluating floodplain condition in southeastern USA Coastal Plain stream networks.

Seedbank Potential of Chinese Tallow Tree (Triadica sebifera) in a Texas Bottomland Hardwood Forest

ABSTRACT: n Chinese tallow tree (Triadica sebifera) is arguably one of the most deleterious exotic invasive plants in the southern United States, where it alters ecosystem structure and function, especially near the Gulf Coast. Chinese tallow continues to expand into riparian floodplain forests, which likely facilitate regional invasion by dispersing seeds during seasonal flooding and providing corridors of favorable habitat. We attempted to estimate existing Chinese tallow soil seedbank presence and density in a bottomland hardwood forest located at Old Sabine Bottom Wildlife Management Area (OSBWMA) in northeastern Texas, where heavy infestation has not occurred to date, though mature seed-bearing trees are present regionally. No Chinese tallow seeds were detected across the study area, despite the occurrence of mature, seed-bearing plants on adjacent properties. Based on this lack of detected seeds, combined with the lack of observed Chinese tallow plants at OSBWMA, it appears the species continues to occur at low densities within apparently suitable habitats in northeastern Texas, perhaps reflecting a lack of en masse water-mediated dispersal into the region due to its upstream location in relation to heavily infested areas further south.

Vegetative Community Development Over 30 Years within Pine Plantations on Reclaimed Mine Land in East

Reclamation of surface mines to plantation forests is a management option that reestablishes both economic and ecological functions after mining. This study investigated vegetative community characteristics (composition, richness, importance) over time in loblolly pine (Pinus taeda L.) plantations established over a thirty-year period on reclaimed lignite coal surface mine land in East Texas, United States. The open landscape of newly planted loblolly pine plantations on reclaimed mine land was amenable to shade-intolerant herbaceous and grass species but, when the canopy closed, favored woody species (trees, shrubs, vines) within two decades after stand establishment. Given that these plantations were established on sites generally described as dry to mesic uplands, species composition was generally congruent with East Texas ecology. Community composition, species richness and species importance were discussed, and loblolly pine growth data and vegetative community characteristics of unmined loblolly pine plantation sites in East Texas were compared to reclaimed sites. Surface mined lands reclaimed to plantation forests are ideal locations to conduct further research on how biodiversity and other ecosystems services can be improved while maintaining intended economic and ecological purposes.

Response of East Texas Mid-Rotation Loblolly Pine Plantations to Poultry Litter and Chemical Fertilizer Amendments

Improving site quality with fertilization is a common forestry practice. Where poultry production occurs, a common issue is the disposal of the poultry litter, which can cause nutrient overload on some soils. Forest plantations offer an alternative litter disposal site, while providing for possible tree growth increases similar to those found with chemical fertilizers. To test that hypothesis, 3 sites in east Texas, USA supporting loblolly pine (Pinus taeda) plantations were treated at poultry or chemical fertilizers at mid-rotation, and the growth responses recorded over a four-year period. Only one of the three sites showed any growth response in quadratic mean diameter growth attributed to poultry litter, and that was only after four years. No other response was found significant, suggesting that longer-term responses may occur than what this study captured. Poultry litter, if economically feasible, does appear to be an alternative to petro-chemical fertilizers on these sites.

Vegetative Community Development over 30 Years within Mixed Pine-Hardwood Mine Reclamation sites in east Texas

The practice of mine reclamation aims to balance the energy needs of society with proactive environmental restoration of degraded land, and long-term studies of vegetative community development on reclaimed mine land have been invaluable in developing effective reclamation practices. This study investigated vegetative community characteristics (composition, richness, species importance) over a 30-year time frame in planted mixed pine-hardwood areas on reclaimed surface coal mine land in East Texas, United States. Reclaimed sites were compared vegetatively to unmined reference forests. A chronological pattern was shown for reclaimed community development in both understory and overstory strata. Understory community development exhibited natural patterns, while the overstory community varied with different groups of planted species. The older reclaimed sites were most similar to unmined reference sites. Dissimilarities between mined and unmined communities were also apparent; for example, the woody vine community of reference sites was much more substantial in midstory and overstory strata as compared to reclaimed sites. Overall, this study provided baseline ecological information about these plant communities that may assist land managers and researchers in furthering their development of reclamation techniques and attainment of reclamation goals. Additional