Effects of post oak Quercus Stellata and Smooth Brome Bromus Inermis Competition on Water Uptake and Root Partitioning of Eastern Redcedar Juniperus Virginiana

Water availability may alter species competitive interactions, resulting in different outcomes as plants compete for available water. Eastern redcedar Juniperus virginiana (hereafter ERC) will likely continue to encroach into new habitats, which will affect soil and water budgets. We designed a greenhouse experiment to investigate changes in water uptake and rooting depths of two-year old ERC saplings in the presence of an invasive grass (Bromus inermis) and a native tree (Quercus stellata). We measured soil moisture content over two growing seasons. When grown together, ERC took up water from the deeper layers (21–40 cm) whereas B. inermis used water from the top layers of the soil (0–20 cm). Similarly, when ERC grew with Q. stellata, ERC took up water from the deeper layers and Q. stellata used water mostly from the top layers. This root partitioning can allow the co-existence of ERC, grasses, and other trees, which can facilitate ERC encroachment into grasslands and woodlands. However, when the three species grew together, we found root overlap between the ERC and Q. stellata. This overlap can affect ERC establishment and encroachment in habitats where grasses and trees co-occur. A major factor that affected ERC performance was higher mortality in treatments with B. inermis than in the ERC-alone or with Q. stellata. This indicates that competition with grasses is a major factor affecting ERC sapling establishment.

Radial growth responses of post oak (Quercus stellata) to climate variability and management in southeastern Oklahoma, USA

We investigated radial growth of post oak (Quercus stellata) growing in a range of stand structures (forest to savanna) created in 1984 by different harvesting and thinning treatments followed by different prescribed fire intervals. We related ring width index (RWI) to monthly and seasonal climate variables and time since fire to assess impacts of climate variability and interactions with management on radial growth. RWI of all treatments was positively correlated to minimum daily temperature the previous September and precipitation late spring/early summer the current-year, and negatively correlated to maximum daily temperatures and drought index late spring/early summer. June weather was most strongly correlated in four of five treatments. While stand structure affected absolute diameter growth, RWI of savanna and forest stands responded similarly to climate variability, and low intensity prescribed fire did not influence RWI. On average, 100 mm reduction in June precipitation decreased RWI by 8%, 1oC increase in previous-year September daily minimum temperature increased RWI by 3.5%, and 1oC increase in June maximum daily temperature decreased RWI by 3.7%. Therefore, negative effects of drought and warmer spring/summer temperatures may be reduced by longer growing seasons under warmer climate scenarios. However, management did not appear to influence RWI.

Avian Responses to Post Oak Savanna Restoration in Eastern Texas

In response to the loss and degradation of oak savannas, associated wildlife populations have experienced long-term declines. For example, 70% of disturbance-dependent bird species in the United States have experienced declines with most of these species being associated with grasslands, oak savannas, and open forest communities. Few studies have documented the success of restoration in post oak savanna systems in regard to breeding bird assemblages. Our objective was to quantify avian abundance, density, species richness, and assemblage structure in restored post oak savannas at Gus Engeling Wildlife Management Area (GEWMA) in Eastern Texas. We conducted vegetation and avian transect surveys post-restoration (2016-2017) and compared our results to pre-restoration baseline surveys conducted in 2009. Restoration conducted in 2010 was partially successful, with vegetation changes that closely resemble historical characteristics. The avian assemblage also showed indications of successful restoration, with the appearance of obligate grassland species following restoration efforts. Specifically, pre-restoration, one dickcissel ( Spiza americana ) and no lark sparrows ( Chondestes grammacus ) were detected. By 2017, dickcissel density in the restored sites was similar to densities recorded on tallgrass prairie and other high-quality habitat in the southern portion of its range. Lark sparrows were also detected, but at low densities. We also observed the persistence and/or increase of several woodland and open woodland species over time. These patterns are likely attributed to the creation of a mosaic of suitable microhabitats preferred by these species such as the persistence of mottes as well as their increased edge-to-area ratios. Restoration sites that are larger in size and in closer proximity to other restored or remnant savannas should have a higher priority to increase their likelihood of recolonization by target species. Restoration efforts may still be successful in more isolated areas, such as GEWMA, but post-restoration monitoring should be conducted and reported to provide insights regarding site-specific restoration dynamics.

Oak trees are elemental carbon sinks in urban ecosystems: patterns and drivers

<p>Cities represent a significant source of atmospheric elemental carbon (EC), a minor constituent of particulate matter (PM) but a major climate-forcing agent and air pollutant. Urban trees scavenge PM and regulate material fluxes to the ground. As such, urban trees represent potentially important sinks—not only for PM but also for EC—in urban landscapes. Here we assess the magnitude and spatiotemporal drivers of EC removal by trees in urban atmospheres. We quantified foliar EC accumulation by, as well as throughfall EC flux under, the canopy of two oak species (<em>Quercus stellata</em>: post oak; <em>Quercus virginiana</em>: live oak), which are widespread across the southern United States. Sampling was conducted from March 2017 to March 2018 across the City of Denton, a city at the northern edge of the Dallas-Forth Worth metropolitan area in Texas. Over the year-long study period, we found that post oak tree canopies accumulated two times more EC (0.53 mg EC m<sup>-2</sup> leaf d<sup>-1</sup>) than live oak trees (0.22 mg EC m<sup>-2</sup> leaf d<sup>-1</sup>), with 95% of EC depositing to leaf surfaces as opposed to leaf waxes. Throughfall EC fluxes were also greater under post oak (0.15 mg EC m<sup>-2</sup> d<sup>-1</sup>) compared to live oak (0.12 mg EC m<sup>-2</sup> d<sup>-1</sup>) canopies, but these differences between post oak and live oak were far less pronounced than for foliar EC accumulation. These results suggest that considerable amounts of dry-deposited EC are retained in post oak canopies, reducing species differences in throughfall EC fluxes. Our findings also revealed strong, albeit, contrasting seasonal patterns for foliar EC accumulation and throughfall EC fluxes. For both tree species, EC accumulation on canopy surfaces increased, whereas throughfall EC fluxes decreased from spring to fall, providing additional evidence that EC retention on canopy surfaces results in decreased EC fluxes to the ground. In summary, our findings show that urban oak trees scavenge considerable amounts of EC from the atmosphere and that the magnitude of accumulation and delivery to soil vary by species and season. This research highlights the potential for urban trees and forests to contribute to climate and air quality mitigation.</p>

The Oliver Bolton Collection of Dart and Spear Points from Camp County, Texas, and Other Remarks

This article analyzes the Bolton Collection of 1384 lithic artifacts, including dart and spear points from the Paleoindian through the Woodland periods. The analysis places the points in the sequence used by Perttula. The points are compared with those from the middle Sabine River basin counties as well as the analysis of the Archaic points of the Cypress Creek drainage basin. In addition, the Archaic and Woodland population density of Camp County based on the proportional frequency of projectile points of known age is compared with that of the middle Sabine River basin counties and the Cypress Basin. Additional comparisons are made with archaeological sites in the Post Oak Savanna to the north and west and in the Blackland Prairie to the west.

Aboriginal Ceramic Wares from Sites in the Yegua Creek Drainage of the Brazos River Basin, East Central Texas

Sherds from aboriginally-made ceramic vessels have been recovered on sites dating after ca. 2000 years B.P. in the Yegua Creek drainage of the Brazos River basin in the Post Oak Savannah of Burleson, Lee, and Washington counties in east central Texas (Figure 1). These sherds are from several different wares, including sandy paste Goose Creek Plain sherds made by Mossy Grove peoples, ancestral Caddo tempered and decorated wares made in East Texas, bone-tempered sandy paste wares that may be representative of a local ceramic tradition, and bone-tempered sherds from Leon Plain vessels made by Central Texas Toyah phase peoples. None of the ceramic sherd assemblages from the 18 sites discussed herein are substantial, ranging only from 1-72 sherds per site (with an average of only 13.3 sherds per site), indicating that the use (much less their manufacture) of ceramic vessels by Post Oak Savannah aboriginal peoples was not of much significance in their way of life, but may signify interaction, trade, and exchange between them and other cultures, such as the Caddo, inland and coastal Mossy Grove, and Toyah phase peoples that relied on ceramic vessel manufacture and use as key parts of their subsistence pursuits. It is likely that the benefits of trade (ceramics being just one of the items that was being traded) between these different peoples was to help establish cooperative alliances, and reduce competition and violence in the region, and such alliances were established and maintained by aboriginal peoples over a long period of time in the region.

The William Farrar Site (41TT1) in the Sulphur River Basin,Titus County, Texas

The William Farrar site (41TT1) is an ancestral Caddo settlement and cemetery on an alluvial terrace of the Sulphur River (Figure 1) in the East Texas Post Oak Savannah, a few miles downstream from the W. A. Ford site (41TT2) (see Goldschmidt 1935; Perttula 2016). University of Texas (UT) archaeologists completed excavations at the site in August 1934, but they had known about the site since as early as 1932, when they purchased or had donated several Caddo vessels from a Henry William Martin and, in 1934, purchased a vessel from a John Bowman, who had previously dug at the site.