Serendipitous Data Following a Severe Windstorm in an Old-Growth Pine Stand

Reliable dimensional data for old-growth pine-dominated forests in the Gulf Coastal Plain of Arkansas are hard to find, but sometimes unfortunate circumstances provide good opportunities to acquire this information. On July 11, 2013, a severe thunderstorm with high winds struck the Levi Wilcoxon Demonstration Forest (LWDF) near Hamburg, Arkansas. This storm uprooted or snapped dozens of large pines and hardwoods and provided an opportunity to more closely inspect these rare specimens. For instance, the largest tree killed in this event, a loblolly pine (Pinus taeda), was 105 cm in diameter at breast height, 39.3 m tall, and if the tree had been sound would have yielded 3,803 board feet (Doyle log rule) of lumber. Gross board foot volume yield was also estimated from two other recently toppled large pines, an 85-cm-DBH loblolly and an 86-cm-DBH shortleaf pine (Pinus echinata), which tallied 2,430 and 2,312 board feet Doyle, respectively. A number of the other wind thrown pines on the LWDF were sound enough to count their rings for a reasonable (± 2-5 years) estimate of their ages. The stump of the fallen national champion shortleaf pine had 168 rings, and counts from other pines toppled by this storm had from 68 to 198 rings. We also searched for a new champion shortleaf pine using a LiDAR canopy height model of the LWDF to narrow our search. This preliminary assessment produced a number of targets that exceeded 40 m in height; further field checking of the tallest of these trees found that these were loblolly pines up to about 44 m. We eventually found shortleaf pines between 37 and 41 m tall, with diameters of up to 85 cm, indicating that the LWDF could still contain the Arkansas state champion

Modeling Loblolly Pine Aboveground Live Biomass in a Mature Pine-hardwood Stand: A Cautionary Tale

Carbon sequestration in forests is a growing area of interest for researchers and land managers. Calculating the quantity of carbon stored in forest biomass seems to be a straightforward task, but it is highly dependent on the function(s) used to construct the stand. For instance, there are a number of possible equations to predict aboveground live biomass for loblolly pine (Pinus taeda) growing in southeastern Arkansas. Depending on stem diameter at breast height (DBH), biomass varied considerably between four different prediction systems for loblolly pine. According to the tested models, individual tree oven-dry biomass for a 50 cm DBH loblolly pine ranged between 1,085 kg and 1,491 kg. Beyond this point, departures between these models became increasingly pronounced, with one even projecting an irrational decline to negative biomass for trees \u3e 138.7 cm DBH, while the others varied between 12,447 and 15,204 kg. Although some deviation is not surprising given the inherent differences in model form and three of the models were extrapolations across much of this diameter range, the difference between the extremes was unexpected. Such disparities significantly impact stand-level (cumulative) predictions of biomass in forests dominated by large-diameter individuals, as demonstrated for an existing stand (Hyatt’s Woods) in Drew County, Arkansas. Differences between these models caused loblolly pine aboveground live-tree biomass estimations in Hyatt’s Woods to vary by almost 34,000 kg/ha

Quantifying Forest Ground Flora Biomass Using Proximal Sensing

Current focus on forest conservation and forest sustainability has increased the level of attention given to measures of ground flora in forest ecosystems. Traditionally, such data are collected via time- and resource-intensive methods of field identification, clipping, and weighing. With increased focus on community composition and structure measures of forest ground flora, the manner in which these data are collected must change. This project uses color and color infrared digital cameras to proximally sense forest ground flora and to develop regression models to predict green and dry biomass (g/m^) from the proximally sensed data. Traditional vegetative indices such as the Normalized Difference Vegetative Index (NDVI) and the Average Visible Reflectance Index (AVR) explained 35-45% of the variation in forest ground flora biomass. Adding individual color band variables, especially the red and near infrared bands, to the regression model allowed the model to explain 66% and 58% of the variation in green and dry biomass, respectively, present

Achieving environmentally sustainable growing media for soilless plant cultivation systems – a review

Soilless cultivation is recognized globally for its ability to support efficient and intensive plant production. While production systems vary, most utilize a porous substrate or growing medium for plant provision of water and nutrients. Until relatively recently, the main drivers for the selection of the component materials in growing media were largely based on performance and economic considerations. However, increasing concern over the environmental impacts of some commonly used materials, has led researchers to identify and assess more environmentally sound alternatives. There has been an understandable focus on renewable materials from agricultural, industrial and municipal waste streams; while many of these show promise at an experimental level, few have been taken up on a significant scale. To ensure continued growth and sustainable development of soilless cultivation, it is vital that effective and environmentally sustainable materials for growing media are identified. Here we describe the factors influencing material selection, and review the most commonly used organic materials in relation to these. We summarise some of the renewable, primary and waste stream materials that have been investigated to date, highlighting the benefits and challenges associated with their uptake. In response to the need for researchers to better identify promising new materials, we present an evidence-based argument for a more consistent approach to characterising growing media and for a clearer understanding of the practical and economic realities of modern soilless cultivation systems

Environmental Analysis of the Caddo River and its Tributaries: Comparison of Water Quality During 1992 with 1974-75

Environmental data related to water quality of the Caddo River and its tributaries were collected from March - October, 1992, and compared with data from August, 1974 - May, 1975. Bacterial, chemical and physical parameters were investigated at six river locations and thirteen tributary sites. Ammonia, nitrates, soluble phosphorus, turbidity and fecal coliform were significantly lower, and sodium and potassium were significantly higher in 1992 than during the previous study. Bacterial loading exceeded EPA criteria at some locations during both studies

The sphere-in-contact model of carbon materials

A sphere-in-contact model is presented that is used to build physical models of carbon materials such as graphite, graphene, carbon nanotubes and fullerene. Unlike other molecular models, these models have correct scale and proportions because the carbon atoms are represented by their atomic radius, in contrast to the more commonly used space-fill models, where carbon atoms are represented by their van der Waals radii. Based on a survey taken among 65 undergraduate chemistry students and 28 PhD/postdoctoral students with a background in molecular modeling, we found misconceptions arising from incorrect visualization of the size and location of the electron density located in carbon materials. Based on analysis of the survey and on a conceptual basis we show that the sphere-in-contact model provides an improved molecular representation of the electron density of carbon materials compared to other molecular models commonly used in science textbooks (i.e., wire-frame, ball-and-stick, space-fill). We therefore suggest that its use in chemistry textbooks along with the ball-and-stick model would significantly enhance the visualization of molecular structures according to their electron density

Collaboration and contestation in further and higher education partnerships in England: a Bourdieusian field analysis

Internationally, ‘College for All’ policies are creating new forms of vocational higher education (HE), and shifting relationships between HE and further education (FE) institutions. In this paper, we consider the way in which this is being implemented in England, drawing on a detailed qualitative case study of a regional HE–FE partnership to widen participation. We focus on the complex mix of collaboration and contestation that arose within it, and how these affected socially differentiated groups of students following high- and low-status routes through its provision. We outline Bourdieu’s concept of ‘field’ as a framework for our analysis and interpretation, including its theoretical ambiguities regarding the definition and scale of fields. Through hermeneutic dialogue between data and theory, we tentatively suggest that such partnerships represent bridges between HE and FE. These bridges are strong between higher-status institutions, but highly contested between lower-status institutions competing closely for distinction. We conclude that the trajectories and outcomes for socially disadvantaged students require attention and collective action to address the inequalities they face, and that our theoretical approach may have wider international relevance beyond the English case

Square lattice site percolation at increasing ranges of neighbor interactions

We report site percolation thresholds for square lattice with neighbor interactions at various increasing ranges. Using Monte Carlo techniques we found that nearest neighbors (N$^2$), next nearest neighbors (N$^3$), next next nearest neighbors (N$^4$) and fifth nearest neighbors (N$^6$) yield the same $p_c=0.592...$. At odds, fourth nearest neighbors (N$^5$) give $p_c=0.298...$. These results are given an explanation in terms of symmetry arguments. We then consider combinations of various ranges of interactions with (N$^2$+N$^3$), (N$^2$+N$^4$), (N$^2$+N$^3$+N$^4$) and (N$^2$+N$^5$). The calculated associated thresholds are respectively $p_c=0.407..., 0.337..., 0.288..., 0.234...$. The existing Galam--Mauger universal formula for percolation thresholds does not reproduce the data showing dimension and coordination number are not sufficient to build a universal law which extends to complex lattices.Comment: 4 pages, revtex