Yield and crown structure characteristics in a red oak (Quercus rubra L.) stand: Case study

The paper provides the results of a detailed analysis of timber volume and several important crown variables of red oak (Quercus rubra L.) based on an experimental plot in eastern Hungary. At the age 32 years the crop trees belonged to different height classes. If the volume of the mean tree from height class I was considered as 100%, the volume of the mean tree of class II was 59%, and the mean tree of class III was only 36%. It appeared that there was a significant correlation between crown indices and yield. For this reason, diameter at breast height showed a positive linear correlation with crown diameter (R2= 0.6211). Additionally, there was also positive linear relationship between crown diameter and volume (R2= 0.6908). The variation of crown indices is height even within the same stand and indicates the importance of following a selective thinning operation method.

Loss in macronutrient pools in bilberry and lingonberry in mesic Scots pine forests after Northern red oak introduction

Forest transformation from coniferous monocultures to mixed stands is being promoted worldwide, including the introduction of fast-growing broadleaved tree species within native stands. Here, we studied how enrichment of temperate European Scots pine (Pinus sylvestris) forest by North-American northern red oak Quercus rubra impacted macronutrient concentrations in two long-lived and dominant components of the forest understory: bilberry Vaccinium myrtillus and lingonberry V. vitis-idaea. Study sites were located in forest complexes (central Poland) which occupy continuously reforested lands (hereafter ancient forests) as well as post-agricultural lands (recent forests), all suitable for mesic pine forests. Samples of bilberry and lingonberry leaves, stems, and fruits were collected in pine stands and in adjacent Scots pine-red oak stands, in both ancient and recent forests. Concentrations of macronutrients (C, N, P, K, Ca, S, and Mg) in aboveground biomass components were analysed using standardized chemical procedures. The study revealed intra- and interspecific (bilberry vs. lingonberry) differences in concentrations of all nutrients in leaves, stems, and fruits, except for invariable C concentrations. Macronutrient accumulations in plants were decreased by land-use discontinuity and favoured by enrichment of tree stands by Q. rubra. The estimated macronutrient pools were much higher for V. myrtillus than V. vitis-idaea in all forest types studied. They were lower in forests enriched with Q. rubra, both ancient (up to 25.5% for bilberry and 99.9% for lingonberry) and recent (46.9% and 99.9%, respectively), as well as in recent pine forest (46.6% and 81.1%, respectively) than in ancient pine forest. Higher K and S pools (39.3% and 6.5%, respectively) noted for bilberry in an ancient forest with Q. rubra were exceptions. Despite more effective accumulations of elements at the species level, macronutrient pools of Vaccinium myrtillus and V. vitis-idaea decreased significantly in the presence of introduced Q. rubra due to negative impacts of this broadleaved tree on bilberry and lingonberry cover and biomass. Therefore, the limitation of alien Q. rubra planting in sites of mesic pine forest with the abundant occurrence of V. myrtillus and/or V. vitis-idaea is recommended. Graphic abstract

Effects of Wildfire and the Presence of the Invasive Paulownia tomentosa on the Regeneration of Native Tree Species in North-Central Appalachia

A wildfire occurred in Shawnee State Forest located in southern Ohio that consumed 1215 hectares. Based on earlier forest inventories it was known that paulownia (Paulownia tomentosa), a non-native invasive tree species, occurred in the forest. The objective of this study was to determine if paulownia heavily colonized areas two years after the fire where the burn occurred, and if its presence had a negative impact on the regeneration (<137 cm height) of native species—red and white oaks (Quercus sp.), red maple (Acer rubrum), and yellow-poplar (Liriodendron tulipifera). Two years after the fire, paulownia had invaded the burned areas but not at significantly higher densities than occurred in the unburned areas. Fire significantly reduced the number of regenerating stems of white oak and red maple two years after the fire, whereas the number of regenerating stems of red oak increased slightly and that of yellow-poplar increased significantly. In areas where paulownia occurred that experienced wildfire, all species studied displayed a reduction in the number of regenerating stems compared to paulownia’s absence in the burn areas. Where paulownia occurred in areas not affected by the wildfire, all the native species studied displayed a reduction in the number of regenerating stems. The average heights of red oak, white oak, and red maple were significantly taller when growing in areas affected by the wildfire due to a more open canopy. However, there was no significant change in the average heights of yellow-poplar. The presence of paulownia in both the burned and unburned areas reduced the number of regenerating stems of the native species studied.

Woodsmoke particulates alter expression of antiviral host response genes in human nasal epithelial cells infected with SARS-CoV-2 in a sex-dependent manner

We have previously shown that exposure to particulate air pollution, both from natural and anthropogenic sources, alters gene expression in the airways and increases susceptibility to respiratory viral infection. Additionally, we have shown that woodsmoke particulates (WSP) affect responses to influenza in a sex-dependent manner. In the present study, we used human nasal epithelial cells (hNECs) from both sexes to investigate how particulate exposure could modulate gene expression in the context of SARS-CoV-2 infection. We used diesel exhaust particulate (DEP) as well as WSP derived from eucalyptus or red oak wood. HNECs were exposed to particulates at a concentration of 22 μg/cm2 for 2 h then immediately infected with SARS-CoV-2 at a MOI (multiplicity of infection) of 0.5. Exposure to particulates had no significant effects on viral load recovered from infected cells. Without particulate exposure, hNECs from both sexes displayed a robust upregulation of antiviral host response genes, though the response was greater in males. However, WSP exposure before infection dampened expression of genes related to the antiviral host response by 72 h post infection. Specifically, red oak WSP downregulated IFIT1, IFITM3, IFNB1, MX1, CCL3, CCL5, CXCL11, CXCL10, and DDX58, among others. After sex stratification of these results, we found that exposure to WSP prior to SARS-CoV-2 infection downregulated anti-viral gene expression in hNECs from females more so than males. These data indicate that WSP, specifically from red oak, alter virus-induced gene expression in a sex-dependent manner and potentially suppress antiviral host defense responses following SARS-CoV-2 infection.

Red Oak (Quercus rubra L.) Fruits as Potential Alternative for Cocoa Powder: Optimization of Roasting Conditions, Antioxidant, and Biological Properties

Cocoa powder is a basic ingredient in the manufacture of chocolate, one of the most appreciated sweet products in the world for its sensory and nutritional properties. Furthermore, it displays a central nervous system stimulant effect. This study aimed to investigate acorn-derived powder as an alternative to cocoa powder, in order to obtain a chocolate that does not contain stimulants of the nervous system. Both the chocolate technological process and acorns roasting process (180 °C/25 min, 200 °C/20 min and 220 °C/15 min) were optimized to obtain acorn powder with an organoleptic profile as close as possible to that of cocoa powder. The chocolate sensory evaluation was performed by means of the hedonic test. Furthermore, the aqueous extracts obtained from the resulting powder were evaluated for total polyphenol content, and in vitro antimicrobial and antiproliferative properties. The results point out a high content of phenolic compounds (500.78–524.01 mg GAE/100 g); protection against microbial contamination based on the ability to inhibit a Gram-positive bacterium (Bacillus cereus) was also noticed. The aqueous acorn extracts were also able to reduce the cell viability of HFL-1 (human fetal lung fibroblast) and DLD-1 (colorectal adenocarcinoma) lines. This study suggests red oak (Quercus rubra) fruits as a potential alternative to cocoa powder in the manufacture of chocolate.