Five superior clones of Eucalyptus camaldulensis from in vitro propagation or tissue culture at the Sra Keaw plantation site in the eastern part of Thailand were selected for examining radial variations of anatomical characteristics and specific gravity. The age of the clones was 5 years at harvest. A 9-year-old tree grown from seed in the same site was also investigated. Results were as follows: 1) Mean specific gravity showed significantly different values among the 5 clones and the seedling. 2) Vessel density rapidly decreased in the first 2–4 cm from the pith in the clones and in 5 cm from the pith in the seedling. 3) Fiber lengths of the clones slowly increased from the pith outwards, while that of the seedling rapidly increased. 4) Each clone and the seedling had a different specific gravity and anatomical characteristics. 5) Clones had a narrower juvenile wood zone than the seedling due to the older cambial age of the clones.
In order to analyze the variation in wood properties within and between trees of an underutilized tree species, we sampled six Oregon white oak (Quercus garryana Dougl.) trees from an 80-year old mixed stand of Q. garryana and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in the Coast Range of Western Oregon, USA. Fibre length, earlywood vessel diameter, tissue proportions, and specific gravity were measured on samples across the diameter at two heights. Trees had a slight lean (2-12°), so we sampled separately both radii of a diametric strip that ran from the lower to upper side of lean.
Natural-grown and young (5.5 year old) plantation-grown trees were sampled for two Central American hardwood species: Hyeronima alchorneoides and Vochysia guatemalensis in the Atlantic lowlands of Costa Rica. Increment cores extracted at a height of 1.3 m from trees were divided into 1cm segments from pith to bark. Basic specific gravity was calculated for each segment. Using the same cores, fibre length was measured from macerations for five natural and plantation-grown trees of each species. Number of vessels/mm2 and vessel tangential diameter were measured from segment cross sections for five natural-grown trees of each species.
The specific gravity of 220 woody species, half of them from a tropical rainforest, half from a tropical deciduous forest was measured. The two groups were compared using a Student t-test. The results show highly significant differences in specific gravity between the species from the two areas: woods from the dry deciduous forest tend to be much heavier than those from the rainforest.
A technique is described that refines the standard sugar flotation procedure used to isolate nematodes from their surroundings. By centrifuging nematodes in a number of increasing specific gravity solutions and plotting the fraction floating, the cumulative probability distribution of the population’s specific gravity is generated. By assuming normality, the population mean, μ, and standard deviation, σ, are found by a nonlinear least squares procedure. These density parameters along with their error covariance matrix may be used as a taxonomic physical character. A chi-squared test is derived for comparing populations. Mean and standard deviation pairs (μ, σ) were found for the specific gravities of the adult stage of the plant parasites Pratylenchus agilis (1.068, 0.017), P. scribneri (1.073, 0.028), P. penetrans (1.058, 0.008) and the bacterial-feeder Caenorhabditis elegans (1.091, 0.016). La technique exposée affine le procédure standard par flottation au sucre utilisée pour séparer les nématodes de leur milieu. La centrifugation des nématodes dans une série de solutions de densités spécifiques et la mise en diagramme de la valeur de la fraction surnageante permettent de connaître le répartition de la probabilité cumulée de la densité spécifique de la population en cause. La normalité étant supposée, la moyenne de la population, μ, et la déviation standard, σ, sont calculées par la méthode des moindres carrés non linéaires. Ces paramètres relatifs à la densité ainsi que leur matrice de co-variance d’erreur peuvent être utilisés en taxinomie comme caractère physique. Un test chi2 en est dérivé pour comparer les populations entre elles. Des données en paires — moyenne (μ) et écart-type (σ) — ont été définies pour les densités des adultes des espèces phytoparasites Pratylenchus agilis (1,068; 0,017), P. scribneri (1,073; 0,028), P. penetrans (1,058; 0,008), ainsi que pour l’espèce bactérivore Caenorhabditis elegans (1,091; 0,016).
We studied wood anatomy and specific gravity in a total of 18 trees of Ocotea curucutuensis, a recently described species, lacking wood anatomical information. Nine sample trees were obtained in each of two areas, Pico do Itapeva (PI) and Núcleo Curucutu (NC), both in the state of São Paulo, Brazil. These areas have marked differences in precipitation, altitude, and temperature. Anatomical differences between the two populations appeared related to tree size, and possibly indirectly to climate. Higher wood specific gravity related with the smaller diameter in NC trees is hypothesized to contribute to mechanical support of the epiphyte-laden trees and to resistance against the prevailing strong winds.
Increases in wood specific gravity (SG) with distance from pith are associated with the growth strategies of trees and their environments. In the present study, radial gradients in SG were analysed for 20 species from nutrient-rich whitewater floodplains (várzea), including seven pioneer species, and for 15 species from nutrient-poor blackwater floodplains (igapó) in Central Amazonia. Average SG increased from pith to bark by 12% in the species from igapó, compared to 16% in the nonpioneers and 35% in the pioneers from várzea. The increases lie in the range of tropical dry forests. SG variation follows the growth strategies of the trees. The main trend in nutrient-rich várzea is fast growth, with low SG wood initially and higher increases in SG. In nutrientpoor igapó, the tendency is relatively constant, slow growth and low SG changes throughout tree life.
Wood specific gravity (SG) was analysed from wood cores of 180 individuals belonging to 58 common upper canopy tree species of late successional white water (várzea) forests in the Mamirauá Sustainable Development Reserve, Central Amazon Basin. We tested for a SG gradient of trees along the flood gradient. Mean SG in the low várzea was 0.62 g cm-3, in the high várzea 0.57 g cm-3. SG tended to increase with height and duration of flooding. In the two species that occurred in both forest types (Hevea spruceana, Tabebuia barbata) SG was significantly lower in the high várzea trees. Therefore, height and duration of flooding seem to be important factors influencing growth and wood properties in várzea trees. In addition, SG variation depended on the core section and to a lesser extent on tree diameter and height. Compared to trees in Amazonian upland ecosystems, SG of the várzea trees was lower than SG in Central and Eastern Amazonian terra firme, but was within the same range reported for Western Amazonian terra firme.
The raw material quality of Eucalyptus globulus during the first year was assessed in an experimental plantation established under four management strategies (control, fertiliser, irrigation and fertiliser/irrigation). The variation of bark content, moisture content, specific gravity and fibre length along the stem for 6-months and II-months-old trees is presented. Bark content decreases with tree diameter and was lowest for the irrigated and fertilised trees. Wood moisture was negatively correlated with specific gravity. No correlation was found between specific gravity and growth rate and fibre length was generally independent of management strategy.
The variation of specific gravity, ring width, tracheid length and tracheid crosssectional dimensions was studied among the remote natural forests of Cupressus sempervirens var. horizontalis Gord. of the Greek islands Crete, Rhodes and Samos.