The effects of sower and bed density on bareroot loblolly pine seedling morphology and early height growth

Precision sowing is commonly used at forest tree nurseries in order to improve the growing space uniformity of seedlings in the beds. Temple-Inland Forest Products Corporation recently purchased a vacuum sower and requested a study be conducted comparing their new sower with a drill sower on the morphological characteristics of loblolly pine (Pinus taeda L.) at lifting. The study was conducted in 2000 and repeated in 2001. The seed were sown using the two sower types to achieve four densities of 161, 215, 269, and 323 seedlings/m2. Two half-sibling families were tested in 2000, and one halfsibling family was tested in 2001. For both studies, the experimental design was a randomized complete block with four replications. Cultural practices used to grow the seedlings were typical for the nursery. The seedlings were hand-lifted mid-winter for measurements of stem height, root-collar diameter, and oven-dry biomass. For the 2001 study, seedlings were handplanted 1 week after lifting in a clearcut near Etoile, TX. The mean morphology of the seedlings was similar when comparing the two sowers. hen averaged for all densities, more seedlings with small root-collar diameters (≤ 3 mm) were sampled in the 2000 study from the drill sower plots than from the vacuum sower plots. For the 2001 study, slightly more seedlings with small diameters were sampled from the vacuum sower plots. At typical operational densities of 215 and 269 seedlings/m2, the use of the vacuum sower resulted in more seedlings at lifting, fewer small-diameter seedlings, and more large-diameter seedlings (≥ 5 mm). As seedbed density was reduced, mean seedling root-collar diameter and oven-dry biomass increased. Seedlings grown in the nursery at 161 seedlings/m2 were taller after the first and second growing season following planting

Frost Heaving of Container Hardwood Seedlings Planted in an Abandoned Agriculitural Field in Sharkey County, Mississippi

The use of container hardwood seedlings is an alternative to bareroot planting stock. In January 1996, 1,485 container seedlings of Nuttall oak (Quercus nuttallii Palmer), willow oak (Q. phellos L.). overcup oak (Q. lyrata Walter), and water oak (Q. nigra L.) were planted in Sharkey clay on an abandoned agricultural field situated in the Lower Mississippi River Alluvial Valley. Beginning with the passage of a cold front on January 31, daily minimum temperatures dipped as low as 6 °F. For 5 days, dally high temperatures did not climb above 32 °F. This cold period caused 33.7 percent of all seedlings to frost heave and an overall survival of 0.5 percent. Our observations suggest that container seedlings should not be planted on shrink-swell clay soils until after the threat of hard freezing has passed. Seedling root morphology combined with soil conditions at the time of planting may have contributed to the frost heaving

Seedling Survival and Natural Regeneration For a Bottomland Hardwood Planting on Sites Differing in Site Preparation

In January 1998, three tracts in Hardin County, TX, were hand-planted with seven species of 1-0 bareroot bottomland hardwood seedlings. The tracts, managed by The Nature Conservancy of Texas, were previously 20-year-old pine plantations. The tracts are located within the floodplain of Village Creek. An objective for this conversion is the restoration of a bottomland hardwood wetland in order to meet Clean Water Act requirements. A pre-harvest plant inventory was conducted for each tract. The tracts were clearcut during the Winter and Spring of 1997. Following harvest, each tract was subjected to a different site preparation technique. One tract was burned. Another tract was treated with herbicide to control Chinese tallow. The third tract was sheared, piled, burned and ripped. Planted seedling survival was greatest (72 percent) on the tract that was sheared, piled, burned and ripped. Hardwood natural regeneration was proportionally higher on the tract prepared by burning only. However, this tract appeared to have a greater potential for hardwood root collar sprouting following harvest of the pine overstory. Chinese tallow was a large portion of all natural woody regeneratton on each tract

Assessing the Vegetative Diversity of an East Texas Golf Course using Principles of Landscape Ecology

The objectives of this study was to determine the vegetative diversity and the effects of the edge between fairways (introduced patches) and out-of-bounds areas (remnant patches) to determine if such management activities influence plant diversity. This study was conducted at the Pineywoods Country Club in the Pineywoods Region of East Texas near Nacogdoches, TX, USA by assessing the spatial distribution of these matrices and patches and their influence on edge effect composition and structure in the matrix; and, if species diversity and composition differed between these edges and interior of the matrices. Nested plots were placed along transects and canopy cover, percent cover, number of individuals by species, tree density, and percent cover of ground cover materials were analyzed using ordination. Dbh, shrub and herbaceous percent cover, and canopy cover were tested for normality utilizing a Shapiro-Wilk normality test, Wilcoxon-Mann-Whitney was used to analyze edge plots and interior plots, and @RISK goodness-of-fit measures were utilized to identify percent cover data distributions. Statistical differences (0.05 α level) between the edge and interior dbh and shrub datasets and a similarity between the edge and interior datasets of the overstory and herbaceous strata were found. Many of the interior shrub plots had a higher H’ (Shannon-Wiener index) and D (Simpson’s index) than the edge plots. Canopy cover was often over 70%, and herbaceous species abundance was often higher (1-11 species) than that of the shrub stratum (1-3 species). Beta diversity indicated that the remnant patches were diverse ( between 0.19-0.30) within all three strata. Natural and anthropogenic disturbances altered the structure and function of the remnant patches: tree density decreased in edge plots due to management. Canopy cover was high over edge plots; however, light was able to reach the ground at an angle across the fairway. Past and current management practices combined with disturbance events have caused the interior of the remnant patches to be disturbed to the degree that they were not representative of the Pineywoods eco-region. The exceptional drought in 2011 may have influenced these results. It was not determined whether the fairway patches within the forest matrix resulted in edge effects

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 werecompared vegetatively to unmined reference forests. A chronological pattern wasshown for reclaimedcommunity developmentin both understory and overstorystrata. Understory community development exhibitednatural patterns, while theoverstory community varied with different groups of planted species. The olderreclaimed sites were most similar to unmined reference sites. Dissimilaritiesbetween mined and unmined communities were also apparent; for example, thewoody vine community of reference sites was much more substantial in midstoryand overstory strata as compared to reclaimed sites. Overall, this study providedbaseline ecological information about these plant communities that may assistland managers and researchers in furthering their development of reclamation techniques and attainment of reclamation goals

Initial establishment success of five forages in an east Texas loblolly pine (Pinus taeda) silvopasture

The establishment at the end of 1 year of five forages was evaluated in a loblolly pine (Pinus taeda L.) silvopasture system. The five forages were: ‘Pensacola” bahiagrass (Paspalum notatum Fluegge), “Texas Tough” bermudagrass (Cynodon dactylon L. Pers.), “Alamo” switchgrass (Panicum virgatum L.), “San Marcos” Eastern gamagrass (Tripsacum dactyloides L.), and a native mix containing 45% “Texas” little bluestem (Schizachyrium scoparium Michx Nash), 15% sand lovegrass (Eragrostis trichodes Nutt. L. Alph. Wood), 15% “Blackwell” switchgrass (Panicum virgatum L.), 10% “Lometa” indiangrass (Sorgastrum nutans L. Nash), 10% “Haskell” sideoats grama (Bouteloua curtipendula Michx Torr) and 5% “Earl” big bluestem (Andropgon gerardii Vitman) by weight. The silvopasture was in a 22 year old stand of loblolly pine in the Fairchild State Forest near Rusk, Texas. Five plots for each forage were sown in March 2008 and the density of each forage after one year calculated. Soil samples were taken to a depth of 10 cm from each corner of each plot using a push probe sampler and a composite sample created for chemical analyses Soil depth to B horizon or restrictive layer was determined using an 8 cm diameter hand bucket auger. In addition, light quality under the canopy was evaluated in August, October and January using a hand-held spectroradiometer: for light quality analysis, light was divided into blue, green, red, and far red bands. Irradiance (μmol photons m-2 s-1) for each band was divided by the total for all bands to create a proportion. Soil depth was positively correlated to plant density in the silvopasture. Bahiagrass and Eastern gamagrass were well established after one growing season. Compared to full sun, light intensity in the silvopasture was reduced by 29% in August, 51% in October, and 56% in January. Proportion and light intensity of the far red band decreased from August to January. Light quality was not affected by the canopy; but the intensity of light reflected or absorbed by the canopy decreased between August and January. Light readings may have been influenced by the decrease in solar angle from August to January. Light intensity was higher than the light compensation point, but lower than the light saturation point for several of the grasses; light in the silvopasture was lowest in January when warm season forages are generally dormant

Changes in understory vegetation of a ponderosa pine forest in northern Arizona 30 years after a Wildfire

Wildland fires can cause shifts in understory species composition and production. Many studies have examined short-term changes in understory vegetation following a wildfire; however, very few long term studies are available. The objective of this study was to examine changes in understory (herb and shrub) species composition and production since the 1972 Rattle Burn wildfire on the Coconino National Forest near Flagstaff, Arizona. Understory species composition and production were originally sampled in 1972, 1974, and 1980 and were re-sampled during July and August of 2002 and 2003 on 30 plots in each of four sites: high severity burn, low severity burn, unburned site prescribed burned in 1977, and an unburned site. Repeated measures analysis was used to test for the effects of fire and time on species production. The effects of fire and time on species composition as well as species production were tested using Multi-Response Permutation Procedures (MRPP). A lingering effect of the Rattle Burn wildfire on the understory plant production and composition was revealed. Burned sites may have greater understory production as compared to unburned sites up to 30 years after a wildfire. However, species composition on burned sites is altered. A significant relationship between tree density and understory species composition and production was found for 1972, but no relationship was found for overstory parameters and understory species production and composition for 2003

Evidence of Two Distinct Dynamic Critical Exponents in Connection with Vortex Physics

The dynamic critical exponent $z$ is determined from numerical simulations for the three-dimensional (3D) lattice Coulomb gas (LCG) and the 3D XY models with relaxational dynamics. It is suggested that the dynamics is characterized by two distinct dynamic critical indices $z_0$ and $z$ related to the divergence of the relaxation time $\tau$ by $\tau\propto \xi^{z_0}$ and $\tau\propto k^{-z}$, where $\xi$ is the correlation length and $k$ the wavevector. The values determined are $z_0\approx 1.5$ and $z\approx 1$ for the 3D LCG and $z_0\approx 1.5$ and $z\approx 2$ for the 3D XY model. It is argued that the nonlinear $IV$ exponent relates to $z_0$, whereas the usual Hohenberg-Halperin classification relates to $z$. Possible implications for the interpretation of experiments are pointed out. Comparisons with other existing results are discussed.Comment: to appear in PR