Treesearch

The southern pines (yellow or hard pines, Genus Pinus Sub-genus Pinus Section Pinus Subsection Australes) occupy an immense land-base in the southeastern region of the United States (Little and Critchfield, 1969). In addition, they are planted and managed for wood production on millions of hectares worldwide including China, Brazil, Argentina, and Australia. The taxonomic subsection Australes consists of 11 species, ranging from relatively minor to major in terms of land base occupied and management opportunities. For example Table-mountain pine (Pinus pungens) sporadically occupies higher...

To examine soil moisture stress, light, and genetic effects on individual needle parameters and investigate total needle contribution to productivity, individual and total needle parameter variation were quantified in 32-year-old black spruce from five crown positions from four full-sib families studied previously for drought tolerance and differential productivity on a dry and a wet site. The wet site had greater average needle length (NL), specific needle area (SNA), and needle N concentration (NN) than the dry site. Site differences in NN were most likely driven by soil moisture stress...

Worldwide, efforts to manage atmospheric CO2 are being explored both by reducing emissions and by sequestering more carbon (C). Stem biomass, C, and nitrogen (N) parameters were measured in plots of first-generation (F1), 32-year-old black spruce (Picea mariana (Mill.) B.S.P.) from four full-sib families studied previously for drought tolerance and differential productivity on both a dry and a wet site in central Ontario, Canada. The wet site had greater stem wood N and bark N concentrations than the dry site. Site differences in N were most likely driven by soil moisture stress impairing...

Fire has long been a keystone ecological process in Western forests. In ponderosa pine (Pinus ponderosa)/Douglas-fir (Pseudotsuga menziesii) forests of the Colorado Front Range, historical fires are believed to have been "mixed severity" in nature. That means that these fires are believed to have typically burned within a range of severities from low severity surface fire where few trees were killed to high severity crown fire where all trees died. As a result, these historical fires created and sustained a heterogeneous mosaic of forest conditions. These fires are also believed to have...

To investigate the potential for using purified CO2-precipitated Kraft lignin (PCO2KL) with phenol-formaldehyde (PF) for application as an adhesive in plywood production, two lignin replacement procedures were examined to assess lignin’s effect on bond quality. Methylolation and oxidation with hydrogen peroxide (H2O2) were carried out to try to increase lignin reactivity. The first procedure involved substitution of 30% of the PF resin solids in the adhesive mix with a solution of methylolated lignin with or without prior oxidation; the second replacement procedure involved direct condensat...

While economics dictate that soy-based wood adhesives be made with soy flour, much of the recent literature on soy-based wood adhesives has involved using soy protein isolate. The obvious assumption is that the additional carbohydrates in the flour but not in the isolate only serve as inert diluents. Our studies have shown that the isolate can provide 10 times the wet bond shear strength than the soy flour at near neutral pH. Various models to explain the difference in wood adhesive performance between soy flour and purified soy products were examined. Prior studies eliminated some...

A continuous process involving gasification, syngas cleaning, and Fischer–Tropsch (FT) synthesis was developed to efficiently produce synthetic aviation turbine fuels (SATFs). Oak-tree wood chips were first gasified to syngas over a commercial pilot plant downdraft gasifier. The raw wood syngas contains about 47% N2, 21% CO, 18% H2, 12% CO2, 2% CH4 and trace amounts of impurities. A purification reaction system was designed to remove the impurities in the syngas such as moisture, oxygen, sulfur, ammonia, and tar. The purified syngas meets the requirements for catalytic conversion to liquid...

ASTM G198, “Standard test method for determining the relative corrosion performance of driven fasteners in contact with treated wood,” was accepted by consensus and published in 2011. The method has two different exposure conditions for determining fastener corrosion performance in treated wood. The first method places the wood and embedded fasteners in a chamber at 95% relative humidity (RH), 32°C, for 120 days. The second method involves a cyclic fog, with 48 h of fog followed by 72 h of dry for 120 days. The corrosion rate of embedded metals is an extremely sensitive function of the...

Rice straw pellets are the main type of biomass solid fuel and have great potential as a bioenergy resource of the future in China. But it also showed important problems because of its high content of ashes and its low gross calorific value, reducing the possibility to be used in domestic heating. It was certified that mixing different types of biomass materials was helpful to improve the properties of pellets. To improve properties of rice straw pellets and investigate the effect of mixing bamboo and rice straw on the pellet properties, some properties of pellets, manufactured using...

Thawing permafrost represents a poorly understood feedback mechanism of climate change in the Arctic, but with a potential impact owing to stored carbon being mobilized1–5. We have quantified the long-term loss of carbon (C) from thawing permafrost in Northeast Greenland from 1996 to 2008 by combining repeated sediment sampling to assess changes in C stock and >12 years of CO2 production in incubated permafrost samples. Field observations show that the activelayer thickness has increased by >1 cm yr-1 but thawing has not resulted in a detectable decline in C stocks. Laboratory mineralizatio...