Characteristic fragment ions from lignin and polysaccharides in ToF–SIMS

Different model compounds for lignin, hemicelluloses and pectins were studied by time-of-flight secondary-ion mass spectrometry (ToF–SIMS). Mass spectra of Klason lignin from normal and compression spruce wood, aspen wood and wheat straw were compared. Spectra of brominated spruce and aspen wood sections showed fragment ions attributed to brominated guaiacyl and syringyl units in lignin at m/z 215, 217, 229 and 231, and m/z 245, 247, 249 and 261, respectively. Spectra of mono-, oligo- and polysaccharides showed fragment ions at m/z 127 and 145 characteristic for hexose units, and ions at m/z 115 and 133 characteristic for pentose units. The same ions were detected in spectra of delignified spruce and aspen wood sections. Labelling of anionic groups by Sr²⁺ ions followed by ToF–SIMS analysis showed that pectins were present at specific locations on the surfaces of spruce and aspen wood sections still after delignification with hydrogen peroxide in acetic acid.     

Study on the effect of nano-silver impregnation on mechanical properties of heat-treated <Emphasis Type="Italic">Populus nigra</Emphasis>

The present study is aimed at investigating the effect of heat treatment of nano-silver-impregnated Populus nigra on weight loss, modulus of rupture (MOR), modulus of elasticity (MOE), and compression parallel to grain. Specimens were impregnated with 200 PPM water-based solution of nano-silver particles at 2.5 bar in a pressure vessel. For heat treatment, both nano-silver-impregnated and simple specimens were kept for 24 h at 45°C and then further for 24 h at 145°C and finally for 4 h at 185°C. MOR decreased from 529 to 461 kg/cm² in heat-treated specimens; MOE and compression parallel to grain were though improved. Also, comparison between heat-treated and nano-silver-impregnated heat-treated specimens showed that there was a decrease in MOR and MOE in nano-silver-impregnated heat-treated specimens. This shows that nano-silver impregnation facilitates transfer of heat in wood and it may increase the process of degradation and pyrolysis of wood structures in deeper parts of specimens.     

Comparative analysis of a wood: adhesive bondline

The wood–adhesive interface was analyzed using five methods with the objective of quantitatively assessing penetration of adhesive into the porous wood network. Methods included fluorescence microscopy, scanning electron microscopy, backscatter electron imaging, wavelength dispersive spectroscopy, and X-ray microtomography (XMT). Each method provided a visual inspection, and all of the analysis methods were applied to the same field of view. XMT was the primary technique of interest. Rubidium hydroxide was used in place of sodium hydroxide in the formulation of phenol–formaldehyde adhesive. Rubidium was found to increase the X-ray attenuation of the adhesive. However, rubidium migrated beyond the adhesive interphase during specimen preparation, thus reducing its effectiveness for image contrast enhancement. The wood species studied included red oak (Quercus rubra), Douglas-fir (Pseudotsuga menziesii), and hybrid poplar (Populus deltoides × Populus trichocarpa). All techniques used for this study were useful, but each presented some limitations for bondline analysis. Despite the problem with rubidium migration, XMT for this application was promising.     

Defining the poor by the rural communities of Burkina Faso: implications for the development of sustainable parkland management

Parklands are mixtures of trees and shrubs that farmers select for certain functions. In the Sahel, parklands are cultivated together with staple food crops, such as millet and sorghum. Parkland trees are sources of foods, including fruits, fats, oils, leafy vegetables, nuts and condiments that complement food crops in the local diet. Despite their socio-economic and ecological role, many studies have shown that the parklands are degrading very rapidly. Therefore, there is a need to undertake restoration actions that are based on a clear understanding of the livelihood context, such as the wealth status of the farmers, in which these agroecosystems are evolving. Thus, we conducted a wealth survey with rural communities in two different farming systems of Burkina Faso that are the cereal-based system in the “Plateau Central” and the cotton-based system in the “Boucle du Mouhoun”. A total of twelve villages were sampled, six villages for each system. The Participatory Analysis of Poverty and Livelihood Dynamics (PAPoLD) method was used by rural farmers to rank farmer households of their communities according to their wealth status. The results revealed that 70% of households in the Plateau Central and 56% in the “Boucle du Mouhoun” managed to escape poverty, and became wealthy. However, 2% of households of the villages in the Plateau Central and 6% in “Boucle du Mouhoun” fell into poverty in the same period whereas 9 and 12% remained poor in these zones, respectively. The main causes associated with households getting out of poverty are subsidies for cotton, external revenues from relatives working in towns and gardening activities. Death of spouse, illness, high number of people in the household and indebtedness are the main causes that lead into poverty. The implications of these findings in designing appropriate policies and management options for a sustainable management of agroforestry parklands under different land use systems were finally discussed.     

Do multipurpose companion trees affect high value timber trees in a silvopastoral plantation system?

Establishment of native timber trees on deforested land may contribute to the livelihood of farmers, to improved ecosystem services and to increased greenhouse gas uptake. Here, we present a new silvopastoral planting design to assess species performance and interspecific competition or facilitation effects among native timber and multipurpose trees in Central America. Two timber species, Tabebuia rosea and Cedrela odorata, were established in three low-density planting regimes allowing combined tree and future livestock production: (1) solitary planting, (2) companion planting with Guazuma ulmifolia, and (3) companion planting with the nitrogen-fixing Gliricidia sepium. We quantified survival, growth and reforestation potential of the two timber species subjected to the different planting regimes for the first 2 years after establishment. Nitrogen concentration as well as stable nitrogen and carbon isotope composition (δ¹⁵N, δ¹³C) of leaves of the timber saplings were determined. T. rosea showed higher survival and better growth than C. odorata under varying environmental conditions (soil, concomitant vegetation). Performance of the timber saplings was unaffected by either companion species. Planting regimes had no effect on foliar nitrogen concentration and δ¹⁵N of the two timber species, although δ¹⁵N values indicated nitrogen fixation activity in G. sepium trees. Planting regimes affected foliar δ¹³C values in T. rosea. δ¹³C values were significantly higher in solitarily growing individuals, suggesting lower exposition to water stress conditions in saplings surrounded by companion species. As we found positively correlated growth traits among timber and multipurpose trees, a combined planting may benefit farmers by providing additional goods and services.     

Composted biosolids as a source of iron for hybrid poplars (<Emphasis Type="Italic">Populus</Emphasis> sp.) grown in northwest New Mexico

Composted sewage sludge (biosolids) supply plant available Fe and may represent a sustainable alternative to more costly chelated Fe fertilizers currently used to supplement nutrition in hybrid poplar test plots of elevated soil pH. To test the response of poplars, field plots were amended with composted biosolids at two agricultural rates: 22.75 and 44.5 Mg ha⁻¹. Iron EDDHA served as a fertilizer check and control plots received no amendment. The hybrid poplar OP-367 (Populus deltoides × P. nigra) was planted on a 3.6 m grid spacing. Significant amounts of P and Fe originating from the sewage treatment process were detected in soils 13 months after amending. Chlorosis evaluated with a SPAD-502 meter, showed that poplars amended with biosolids remained the least chlorotic and had greater tree growth when compared to Fe EDDHA and control plots during two growing seasons. Biosolids show promise as a cost effective alternative for the remediation of Fe chlorosis in hybrid poplar agroforestry plantations and present new opportunities in northwestern New Mexico for municipalities seeking solid waste land disposal options.     

Do pine plantations provide mycorrhizal inocula for seedlings establishment in grasslands from Patagonia,Argentina?

We investigated if Pinus ponderosa plantations in Patagonia are able to produce viable mycorrhizal inocula towards adjacent grasslands, which only harbor endomycorrhizal vegetation. We hypothesized that these inocula have the potential to contribute to the establishment of naturally disseminated seedlings. Also, we determined the main fungal taxa involved in this process. Seven plantations in the onset of their reproductive phase and located in the Patagonian native forest/steppe ecotone (Argentina) were selected. Soil samplings were obtained at nine points along a 450 m long, W-E transect established in each plantation. Soil bioassays were performed in a greenhouse, with P. ponderosa seedlings acting as hosts for mycorrhizal inocula present in soil samples, during 12 months. Mycorrhization percentage, morphotype richness and morphotype composition was determined through morphological evaluation. Viable ecto- and ectendomycorrhizal inocula were found disseminated outside plantations. The amount of mycorrhizal inoculum followed a decreasing function with distance to plantation edges. Mycorrhizal fungal genus Rhizopogon and “E-strain” mycorrhizal types appeared as pioneering taxa regarding seedlings colonization, being the most persistent and frequent symbionts found. Plantations, thus, facilitate the surrounding terrain for newcoming seedlings through the dispersion of mycorrhizal fungal inocula.     

Grouping of <Emphasis Type="Italic">Tectona grandis</Emphasis> (L.f.) clones using wood color and stiffness

Commercial Tectona grandis plantations using clones have attracted considerable interest for lumber production in tropical regions where small areas are frequent. However, studies on wood properties are limited. Therefore, the purpose of this study is to group clones with similar wood color characteristics using the CIELab system, and mechanical resistance by dynamic stiffness (Ed) in order to obtain different types of clones for different climate and edaphic conditions. It was found that lightness (L*), yellowness (b*), redness (a*), and Ed are similar to those found for other plantation trees. These wood characteristics are significantly influenced by clone and site. Variance due to clone and site went from 31 to 53% and from 2.95 to 24.22%, respectively. Another source of variance was distance from pith, with the exception of parameter b*, which was not affected. Finally, clones were grouped (using multivariate analysis) according to color and mechanical resistance. This analysis established 4 groups by color and 5 groups by Ed. Clone clustering will allow us to choose or use clones with similar wood properties according to site and environmental conditions increasing area production and wood quality uniformity.     

Exotic tree species displace indigenous ones on farms at intermediate altitudes around Mount Kenya

Agroforestry systems are potentially suitable for conservation of tree genetic resources. Farmers around Mt. Kenya usually integrate trees into their farm. Large parts of these trees seem to be of exotic origin, whereas indigenous species have priority for conservation. This study aimed at determining on-farm richness, composition and frequency of indigenous and exotic woody species around Mount Kenya to assess the suitability of farms for the conservation of indigenous tree species. 265 on-farm plots of 0.5 ha size each were selected in 18 different agro-ecological zones by using a stratified sampling scheme. All woody species within the plot were recorded with their local and scientific names. Total species richness was 424 (including 306 indigenous ones), mean richness per plot 16.5 species (including 8.8 indigenous ones). Eight out of the 10 most frequent species were exotic ones with Grevillea robusta from Australia ranking first (found on almost 76% of the surveyed farms). The proportion of indigenous species increased with increasing aridity and temperature. Dominance of exotic species was found at farms of humid mid- and highlands. Ordination analysis revealed that mostly exotic species contributed to separation of farms in the highlands and upper midlands, whereas indigenous species in the lower midlands and lowlands. As the frequencies of most indigenous trees were low, only parts of the surveyed farms can contribute to conservation of tree genetic resources, particularly the less intensively managed farms of the more arid lands. Farmers’ access to knowledge on valuable indigenous tree species and to quality seedlings of these trees need to be improved to increase indigenous species’ frequencies on farms and possibly to replace some of the exotic species in the future.     

Effects of gibberellin A<Subscript>4/7</Subscript>, 6-benzylaminopurine and chlormequat chloride on the number of male and female strobili and immature cones in Chinese pine (<Emphasis Type="Italic">Pinus tabuliformis</Emphasis>) with foliar sprays

Three kinds of plant growth regulators, gibberellinA 4/7 (GA 4/7 ), 6-benzylaminopurine (BA), and chlormequat chloride (CCC), were evaluated for their ability to promote strobilus and cone production in a Chinese pine (Pinus tabuliformis Carr.) clonal seed orchard. Treatments (0, 250, 500, or 1000 mg L -1 ) were applied during three periods (June- July, July-August and August-September) in 2005. Of the three plant growth regulators, GA 4/7 was the best for promoting flower and cone production. Trees sprayed...