27 research outputs found
Earlywood vessel features in Quercus faginea: relationship between ring width and wood density at two sites in Portugal
Wood anatomy holds relevant information for tree development and timber
quality (e.g., wood density), which is important for the sustainability of the
species. Quercus faginea Lam. (Portuguese or Lusitanian oak) is an autochthonous
Mediterranean oak species characterized by a shrinking natural distribution
area and use abandonment. We studied the variation of several wood
properties and their relationships with the aim of determining and possibly increasing
the wood economic value of this species. The anatomical features of
earlywood vessels (area, number, frequency and proportion) were investigated
in twenty Q. faginea trees sampled at two locations within the natural distribution
of the species in Portugal. Moreover, we analyzed the variation of vessel
features from pith to bark, the radial growth and the wood density to
search for patterns and relationships among the analyzed parameters. Mean
earlywood vessel area increased with cambial age up to 60-70 years and then
leveled off. An inverse pattern was found for the number of vessels per ring
beyond that age. Similar radial patterns of all vessel features were found at
both sites, and no significant differences in earlywood vessel area were found
between sites. The within-tree development of earlywood vessels was age-related,
though not influenced by growth. Earlywood vessel features explained
the variation of wood density, i.e., wood density of Q. faginea was strongly
negatively correlated with both mean vessel area and proportioninfo:eu-repo/semantics/publishedVersio
Chemical characterization and extractives composition of heartwood and sapwood from Quercus faginea
Research ArticleHeartwood and sapwood of Quercus faginea were evaluated in relation to summative chemical
composition and non-polar and polar extracts composition, including an assessment of
antioxidant properties (DPPH and FRAP). Twenty trees from two sites in Portugal were analysed.
Heartwood had approximately two times more solvent extractible compounds than
sapwood (on average 19.0% and 9.5%). The lipophilic extractible compounds were below
1%, and most of them were polar e.g. ethanol-soluble compounds corresponded to 65% of
total extractives in heartwood and 43% in sapwood. Lignin content was similar in sapwood
and heartwood (28.1% and 28.6% of extractive-free wood respectively) as well as the sugar
composition. Site did not influence the chemical composition. The lipophilic extractible compounds
from both sapwood and heartwood included mainly saturated fatty acids (23.0%
and 36.9% respectively) and aromatic compounds were also abundant in sapwood (22.9%).
The ethanol-water extractibles had a high content of phenolic substances (558.0 and 319.4
mg GAE/g extract, respectively of heartwood and sapwood). The polyphenolic composition
was similar in heartwood and sapwood with higher content of ellagitannins (168.9 and
153.5 mg tannic acid/g of extract in sapwood and heartwood respectively) and very low content
of condensed tannins. The antioxidant activity was very high with IC50 of 2.6 μg/ml and
3.3 μg/ml for sapwood and heartwood respectively, as compared to standard antioxidants
(IC50 of 3.8 μg/ml for Trolox). The ferric reducing ability was 2.8 and 2.0 mMol Trolox equivalents/
g extract of heartwood and sapwood respectively. The variability between trees was
low and no differences between the two sites were found. Q. faginea showed a very good
potential for cooperage and other applications for which a source of compounds with antioxidant
properties is desirableinfo:eu-repo/semantics/publishedVersio
An Integrated Similarity Analysis of Anatomical and Physical Wood Properties of Tropical Species from India, Mozambique, and East Timor
Tropical species are highly valued timber sources showing a large diversity of wood
characteristics. Since there are major concerns regarding the sustainability of these tropical species
in many tropical regions, knowledge of the variability in wood properties is therefore a valuable
tool to design targeted exploitation and to enlarge the wood resources base, namely by identifying
alternatives for CITES-listed species. In this study, 98 tropical wood species belonging to 73 genera
from India, Mozambique, and East Timor were investigated regarding wood anatomy and physical
properties. Numerical taxonomy, by means of cluster analysis and principal component analysis
grouped species with anatomical and physical similarities from different geographical origins. In
addition to wood density, ray and vessel characteristics as well as wood moisture and wood shrinkage
properties explained the main variability of these species. The contribution of wood color patterns
was highlighted as consistently separating the Mozambique woods. A distinct geographical pattern
was not observed, reinforcing that species from India, Mozambique, and East Timor show similar
anatomical and physical wood properties, which could be useful to increase timber trade diversity.
The multivariate analysis showed that species from Mozambique, such as Morus mesozygia, and
Millettia stuhlmannii and Swartzia madagascariensis, could be alternatives for the CITES-listed species
Cedrela odorata and Dalbergia melanoxylon, respectivelyinfo:eu-repo/semantics/publishedVersio
Estrutura e caracterização anatómica da madeira de carvalho português (Quercus faginea Lam.)
Apresenta-se um estudo sobre a madeira de carvalho-português (Quercus faginea Lam.), uma das mais
importantes espécies de carvalho autóctones do nosso território. Este trabalho está integrado num projecto de
investigação cujo principal objectivo é identificar novos usos de qualidade para a madeira de carvalho-português.
Seleccionaram-se e abateram-se 10 árvores, com idades entre 34 e 60 anos, no Nordeste Transmontano, e
recolheram-se rodelas a 1,30 m de altura. Estudou-se para cinco árvores a variação radial na árvore e entre
árvores das dimensões das fibras, raios e vasos.
A madeira apresenta porosidade em anel, normalmente com camadas de crescimento bem distintas e vasos
solitários orientados radialmente. O padrão de variação radial das fibras caracterizou-se por um aumento de
comprimento da medula para a periferia, variando em média de 995 a 1195 m, enquanto a espessura se manteve
relativamente constante. Os diâmetros dos vasos aumentaram da medula para a periferia, em média de 170 a 208 m. O parênquima radial inclui raios unisseriados, em média com 10 células em média, e raios multisseriados,
com máximos de 21 mm de comprimento e 0,8 mm de largura
Wood density and ring width in Quercus rotundifolia trees in southern Portugal
Quercus rotundifolia Lam., known as holm oak or evergreen oak, occurs naturally in the
western Mediterranean region, mainly as part of the agroforestry or agrosilvopastoral systems in
Portugal (“montado”) and Spain (“dehesa”), and is economically important for acorn production.
Less attention has been given to Q. rotundifolia wood, and its density variability is not known,
namely related to tree growth. The wood density of 20 Q. rotundifolia trees was measured along
the radial direction by X-ray densitometry and the factors responsible for ring width and wood
density variation within and between trees were investigated at two sites located within the main
species region in southern Portugal. Ring width was significantly different between sites, with an
average of 1.81 mm and 1.55 mm. Wood density was very high and averaged between 888 kg/m3
and 914 kg/m3 but not significantly different between sites. Ring width and wood density showed
a positive and significant correlation at both sites. Cambial age was the main source of variation for
ring width and wood density, while between-tree effects accounted for a considerable proportion
of wood density variation. The results are an important contribution for the species valorisation
aiming at high-value wood products, also adding knowledge on the species growth of interest for
tree selection and sustainable managementinfo:eu-repo/semantics/publishedVersio
Chemical composition of barks from Quercus faginea trees and characterization of their lipophilic and polar extracts
The bark from Quercus faginea mature trees from two sites was chemically characterized for the first time. The barks showed the
following composition: ash 14.6%, total extractives 13.2%, suberin 2.9% and lignin 28.2%. The polysaccharides were composed
mainly of glucose and xylose (50.3% and 35.1% of all monosaccharides respectively) with 4.8% of uronic acids. The suberin
composition was: ω-hydroxyacids 46.3% of total compounds, ɑ,ω-alkanoic diacids 22.3%, alkanoic acids 5.9%, alkanols 6.7% and
aromatics 6.9% (ferulic acid 4.0%). Polar extracts (ethanol-water) had a high phenolic content of 630.3 mg of gallic acid equivalents
(GAE)/g of extract, condensed tannins 220.7 mg of catechin equivalents (CE)/g extract, and flavonoids 207.7 mg CE/g of extract.
The antioxidant activity was very high corresponding to 1567 mg Trolox equivalents/g of extract, and an IC50 of 2.63 μg extract/ml.
The lipophilic extracts were constituted mainly by glycerol and its derivatives (12.3% of all compounds), alkanoic acids (27.8%),
sterols (11.5%) and triterpenes (17.8%). In view of an integrated valorization, Quercus faginea barks are interesting sources of
polar compounds including phenols and polyphenols with possible interesting bioactivities, while the sterols and triterpenes
contained in the lipophilic extracts are also valuable bioactive compounds or chemical intermediates for specific high-value market
niches, such as cosmetics, pharmaceuticals and biomedicineinfo:eu-repo/semantics/publishedVersio
Quercus rotundifolia bark as a source of polar extracts: structural and chemical characterization
Quercus rotundifolia bark was studied regarding anatomical, chemical, and antioxidant
properties from trees in two sites in southern Portugal and are here reported for the first time. The
general structure and anatomy of Q. rotundifolia bark showed a rhytidome with sequential undulated
and anastomosed periderms with a small proportion of cork, while the phloem included broad rays
with strong cell sclerification, groups of sclereids with embed large prismatic crystals, and abundant
druses in parenchyma cells. The mean chemical composition was 15.5% ash, 1.6% dichloromethane
extractives, 6.4% ethanol and 9.3% water extractives, 3.0% suberin, 30.5% total lignin, and 33.8%
carbohydrates. Carbohydrates included mainly glucose (50.7% of total monomers) and xylose
(23.8%), with uronic (3.0%) and acetic acids (1.0%). Suberin was mainly composed of !-hydroxyacids
(48.0% of all compounds) and ,!-diacids (19.5%). The main compounds found in the lipophilic
extracts were triterpenes (43.6%–56.2% of all compounds) and alkanoic acids (32.7%–41.7%). Phenolic
content was high especially in the ethanol extracts, ranging from 219.5–572.9 mg GAE/g extract and
comprising 162.5–247.5 CE/g extract of flavonoids and 41.2–294.1 CE/g extract of condensed tannins.
The extracts revealed very good antioxidant properties with IC50 values of 4.4 g ethanol extract/mL
and 4.7 g water extract/mL. Similar anatomical, chemical, and antioxidant characteristics were
found in the bark from both sites. The high phenolic content and excellent antioxidant characteristics
of polar extracts showed holm oak barks to be a promising natural source of antioxidants with
possible use in industry and pharmaceutical/medical areasinfo:eu-repo/semantics/publishedVersio
Avaliação de algumas propriedades físicas da madeira de sobreiro (Quercus suber L.) tendo em vista o seu potencial impacto tecnológico
Congresso Florestal Nacional: A floresta e as gentes - Actas das ComunicaçõesApresenta-se um estudo de caracterização e variação de propriedades físicas da madeira da Quercus suber L. tendo em vista a sua potencial utilização para o fabrico de peças de madeira de qualidade elevada. Foram analisadas as seguintes propriedades da madeira de sobreiro e a sua variação para diferentes temperaturas e humidades relativas do ar: teor de humidade de equilíbrio, densidade e variação dimensional. O estudo foi feito na madeira de 5 árvores adultas já sujeitas a descortiçamento. As temperaturas estudadas tipificaram um ambiente interior não climatizado no inverno (15ºC), no verão (27ºC) e um ambiente climatizado (22ºC) e a variação de humidade relativa estudado foi de 10% a 80%.
Verificou-se uma variação da retracção volumétrica total entre 14,3–15,2 % e do coeficiente de retracção volumétrica entre 0,49–0,56%. A retracção linear radial e tangencial variou, respectivamente entre 3,5–3,7% e 9,1–9,8%. Para a anisotropia obtiveram-se valores entre 2,4–2,7. Os valores da densidade a 12% de humidade variaram entre 0,63–0,64 g/cm3 e a higroscopicidade obtida foi de 0,003. Observaram-se diferenças pouco significativas para a variação das dimensões, teor de água e densidade da madeira entre as 3 temperaturas utilizadas nos ensaios físicos.
A classificação tecnológica da madeira de sobreiro em relação às propriedades estudadas é a seguinte: madeira moderadamente pesada, medianamente nervosa, retráctil (com retractibilidade radial fraca e tangencial média), anisotropia alta, teor de saturação das fibras alto e higroscopicidade média
Variabilidade anatómica da teca (Tectona grandis) de Timor-Leste
A teca (Tectona grandis) é uma importante espécie indígena do sudeste asiático, produtora de madeira
nobre com excelente qualidade e grande procura no mercado mundial pela sua resistência, durabilidade e beleza.
Estas propriedades dependem, entre outras, da estrutura e variabilidade da madeira, na espécie, entre árvores e na
árvore consoante as condições ambientais. Não existem estudos publicados sobre a variabilidade anatómica da
madeira para a teca proveniente de Timor-Leste.
O estudo incidiu em três árvores, em amostras retiradas a três níveis de altura total e da medula para a periferia
da árvore. Realizaram-se observações à lupa e ao microscópio e foram determinados: n.º e área de vasos por anel
de crescimento, comprimento, largura e espessura da parede de fibras, utilizando um sistema de análise de
imagem.
Os resultados indicam que da base para o topo da árvore houve um aumento do número médio e um decréscimo
da área média de vasos por anel de crescimento, do comprimento e largura média das fibras. Radialmente, da
medula para a periferia, diminuiu o número e aumentou a área média de vasos por anel de crescimento, o
comprimento, a largura e a espessura da parede das fibras
Caracterização da composição química da madeira de Quercus faginea
Neste estudo fez-se a caracterização da composição química somativa (cinzas, extractivos, lenhinas e
polissacáridos) da madeira de cerne e de borne de Quercus faginea proveniente de um local do Nordeste
Transmontano (Macedo de Cavaleiros). Foram seleccionadas e abatidas 10 árvores de Quercus faginea e
retiradas amostras de discos a 1,30 m de altura da árvore. As árvores de Quercus faginea estudadas apresentaram
todas formação de cerne, com um contorno regular e cor castanha amarelada bem distinto do borne de cor
castanha mais clara. A área de cerne variou entre 15% e 64% da área total da secção transversal da madeira, e a
espessura de borne entre 1,5 e 4,9 cm. A madeira de Quercus faginea apresentou a seguinte composição
química: cinzas 0,8%, extractivos totais 14,5% e lenhina total 24,5%. Os polissacáridos são constituídos
principalmente por glucose e xilose (respectivamente em média 59,5% e 31,0% dos monómeros)