Early inflorescence and floral development in Cocos nucifera L. (Arecaceae: Arecoideae)

Palms are generally characterized by a large structure with a massive crown that creates difficulties in anatomical studies. The flowering behaviour of palm species may be a useful indicator of phylogenetic relationships and therefore evolutionary events. This paper presents a detailed histological study of reproductive development in coconut (Cocos nucifera L.), from initiation up to maturation of staminate and pistillate flowers. Reproductive development in coconut consists of a sequence of individual events that span more than two years. Floral morphogenesis is the longest event, taking about one year, while sex determination is a rapid process that occurs within one month. The inflorescence consists of different ultimate floral structural components. Pistillate flowers are borne in floral triads that are flanked by two functional staminate flowers. The staminate flowers are born in floral diads towards the base of the rachilla followed by solitary flowers in the middle to top of the rachilla. Three primary phases were identified in reproductive development, namely, transition of axillary bud into inflorescence bud, formation of floral buds, and sexualisation of individual flower buds. All developmental events with respect to stage or time of occurrence were determined.     

Testing the utility of Nothofagus pumilio for dating a snow avalanche in Tierra del Fuego, Argentina

In the subalpine forest zone, snow avalanches are potentially stand-devastating disturbances. Historical data regarding past avalanches in Argentina are scarce, but sufficiently old trees can show signs of past avalanche episodes that can be accurately dated using dendrochronological methods. Tree-ring analysis has not yet been used for dating avalanches in Tierra del Fuego, even though these disturbances are important to the dynamics of these southern forests. In this study, we evaluated the quality of Nothofagus pumilio for dating the avalanche that took place in the Martial Valley in 1976. Tree-ring data, complemented with vegetation analysis, was used to study the avalanche path. The dendrochronological study consisted of the analysis of wood samples taken from living trees located on the boundary between the undisturbed forest and the avalanche path. The vegetation analysis compared the forest structure within the avalanche path with the unaffected nearby forest. Wood scars and the abrupt increase in tree growth confirmed the occurrence of an avalanche event in 1976 in the Martial Valley of Tierra del Fuego, Argentina. The vegetation structure within the avalanche path was considerably different than that of the undisturbed forest. We found an important relationship between sapling abundance within the avalanche path and their distance from the undisturbed forest and their altitudinal position. The dendrochronological dating obtained in this research confirmed that the techniques and methodology used for N. pumilio in this study can be successfully applied for dating other avalanches that lack historical information.     

Dilute phosphoric acid-catalysed hydrolysis of municipal bio-waste wood shavings using autoclave parr reactor system

The visibility of using municipal bio-waste, wood shavings, as a potential feedstock for ethanol production was investigated. Dilute acid hydrolysis of wood shavings with H?PO? was undertaken in autoclave parr reactor. A combined severity factor (CSF) was used to integrate the effects of hydrolysis times, temperature and acid concentration into a single variable. Xylose concentration reached a maximum value of 17 g/100 g dry mass corresponding to a yield of 100% at the best identified conditions of 2.5 wt.% H?PO?, 175 °C and 10 min reaction time corresponding to a CSF of 1.9. However, for glucose, an average yield of 30% was obtained at 5 wt.% H?PO?, 200 °C and 10 min. Xylose production increased with increasing temperature and acid concentration, but its transformation to the degradation product furfural was also catalysed by those factors. The maximum furfural formed was 3 g/100 g dry mass, corresponding to the 24% yield.     

Performance of a mobile mechanical screen to improve the commercial quality of wood chips for energy

The study analyzed the performance of a mobile screening device for upgrading coarse wood chips to residential user standards, by removing oversize particles and fines. The machine was designed for transportation to forest landings, logistic terminals and plant chip yards. Average productivity was 1.9 oven-dry tons (odt) h⁻¹, corresponding to a screening cost of 28.5 € odt⁻¹. This figure was lower than the price increase obtained by upgrading industrial chips to residential user standards. Hence, screening offered a profit of 4.7 € odt⁻¹, or 16% of the original screening cost. The screening process was capable of upgrading chips from industrial to residential specifications, by reducing the incidence of oversize particles below the 1% critical threshold. Screening also allowed a substantial reduction in the content of fines. A similar effect was not verified for crushed wood, which failed to meet the specifications for residential fuel.     

Modeling of high-temperature treatment of wood using the reaction engineering approach (REA)

A simple and accurate model of high-temperature treatment of wood can assist in the process design and the evaluation of performance of equipment. The high-temperature treatment of wood is essentially a drying process under linearly-increased gas temperature up to final temperature of 220-230 °C which is a challenging process to model. This study is aimed to assess the applicability and accuracy of the reaction engineering approach (REA) to model the heat treatment of wood. In order to describe the process using the REA, the maximum activation energy (ΔE_v,b) is evaluated according to the corresponding external conditions during the heat treatment. Results indicate that the REA coupled with the heat balance describes both moisture content and temperature profiles during the heat treatment very well. A good agreement towards the experimental data is indicated. It has also been shown that the current model is highly comparable in accuracy with the complex models.     

A life cycle evaluation of wood pellet gasification for district heating in British Columbia

The replacement of natural gas combustion for district heating by wood waste and wood pellets gasification systems with or without emission control has been investigated by a streamlined LCA. While stack emissions from controlled gasification systems are lower than the applicable regulations, compared to the current base case, 12% and 133% increases are expected in the overall human health impacts for wood pellets and wood waste, respectively. With controlled gasification, external costs and GHG emission can be reduced by 35% and 82% on average, respectively. Between wood pellets and wood waste, wood pellets appear to be the better choice as it requires less primary energy and has a much lower impact on the local air quality.     

Assessing the relative bioavailability of copper to fungi degrading treated wood

Copper is ubiquitous as a biocide component in wood preservatives. Some fungi detoxify copper by immobilizing copper ions with oxalate, decreasing its physiological availability (bioavailability). Decreases in copper bioavailability may also occur during wood treatment. To date, however, copper retention in wood has been measured as overall weight-to-volume concentration without an estimate of its bioavailability and without assessment of its relative contribution to preservative efficacy. Here, we gauge the bioavailability of copper ions in treated wood by using oxalate to pre-treat wood prior to colonization by a moderately copper-tolerant fungus. Copper-treated wood was treated with a gradient of sodium oxalate concentrations, rinsed thoroughly, and exposed in soil-block jars to an isolate of Serpula himantioides. Wood treated with copper ethanolamine was extremely effective in preventing decay by S. himantioides, but toxicity could repeatedly be overcome above a threshold level of oxalate pretreatment. In agar plates, copper-treated wood stimulated oxalate production by S. himantioides, but levels were less than those needed (>10 mM) to overcome copper in soil-block jars. This capacity to overcome copper using an oxalate pretreatment was absent in commercially available samples treated with co-biocide(s). Results demonstrate a useful relative measure of copper bioavailability, with potential to be modified for specific quantification.     

Distribution, settlement, and growth of first-year individuals of the shipworm Teredo navalis L. (Bivalvia: Teredinidae) in the Port of Rotterdam area, the Netherlands

During the period 2004-2008 the distribution, settlement, and growth of first-year shipworms (Teredo navalis L., 1758) was studied by exposing fir and oak panels in the Port of Rotterdam area, which is situated in the Rhine-Meuse estuary in the Netherlands and covers the complete salinity gradient. Shipworms were found yearly in the western large polyhaline harbours. On only a few occasions were they were found in harbours that showed large seasonal and daily fluctuations in salinity. In 2006 the shipworm was found in fir panels 20 km upstream from the polyhaline harbours, demonstrating their ability to travel with the tidal currents over considerable distances and to settle once the abiotic conditions become favourable. Although the water temperatures allowed them to breed from April until November, infestations were not found before September, and from the size of the animals in the panels it was concluded that in the Port of Rotterdam area they spawned from August until the end of November. The settlement height was negatively correlated with the distance of the panels to the sea floor. In the first season after settlement they showed a substantial growth rate of 0.18 cm day⁻¹. The longest shipworm found measured 36.8 cm after 4-5 months of growth after settlement. Infestations and growth were lower in oak than in fir wood. In 2006 the maximum consumption of wood by individuals settled in the same year in panels at the bottom accounted for 12.4%. Shell size and body length of the animal after the first season of growth showed a significant positive logarithmic relation. In both 2006 and 2007 a similar relation between the average boring tube diameter and the length of the animals was found. Lower river discharges leading to salinisation of the eastern part of the Port of Rotterdam area create conditions favourable for the shipworm, with serious consequences for the piles upon which the quays are built.     

Comparative study on the delignification of Azadirachta indica (L) Del., wood by Chrysosporium asperatum and Trichoderma harzianum

Structural alterations induced in response to degradation by two white rot Basidiomycetes on the secondary xylem of Azadirachta indica (L) Del., was compared. In vitro decay test was employed to investigate the pattern of delignification of Azadirachta wood by Trichoderma harzianum and Chrysosporium asperatum. Wood samples inoculated with both the strains were analyzed for different periods viz. 30, 60, 90 and 120 days after fungal inoculation. Initially there was no appreciable percent weight loss of the wood blocks but later on (after 60 days) it increased rapidly and was found similar for both the strains (43-46% of wood mass). Samples inoculated with both the strains showed dual pattern of degradation i.e. selective delignification in the initial stage followed by simultaneous rot during advance stage of decay. Separation of the cells due to dissolution of middle lamella was the characteristic feature of both strains but in the advanced stage of decay, formation of erosion troughs were conspicuous in all the cell types. Other features such as cell wall thinning, rounded pit erosion, formation of erosion channels and bore holes were also observed frequently. Initially, fungal invasion started through the vessel lumen, followed by all the cell types of the xylem. From the vessels, mycelia entered into the adjacent rays and parenchyma cells through the pits. In advanced stage, degradation was so pronounced that rays were partially or even completely destroyed while many cells including vessels were either deformed or destroyed due to loss of rigidity of their walls. Structural alterations induced in response to C. asperatum and T. harzianum attack is described in details.