Showing papers in "Iawa Journal in 1999"
TL;DR: Phenology and cambium growth are progressively uncoupled from climatic seasonality in brevideciduous and evergreen trees growing at microsites with large soil water reserves which buffer trees against seasonal drought and thus may prevent the formation of distinct annual rings.
Abstract: The seasonal time course of vegetative phenology and cambium growth is compared for tree species from Central America and Asia growing in tropical climates with a long, severe dry season. Although the inhibition of plant growth by water stress is weH established, responses to seasonal drought vary widely among such trees, and their annual development is not weH synchronized by climatic seasonality. In deciduous trees growing at microsites with low soil moisture storage, phenology and cambium growth are weH correlated with each other and with seasonal rainfall, and most trees have distinct annual rings. Phenology and cambium growth are progressively uncoupled from climatic seasonality in brevideciduous and evergreen trees growing at microsites with large soil water reserves which buffer trees against seasonal drought and thus may prevent the formation of distinct annual rings. There is some experimental evidence conceming the control of growth initiation in apical meristems and the cambium, but little is known about the mechanisms which arrest growth and deterrnine qualitative changes in organ development and cambium cell differentiation.
193 citations
TL;DR: Effective strategies include sampling useful temperate or subtropical species that extend naturally into the tropics that have promising anatomical features such as ring porosity and marginal parenchyma and sampling species in botanical families that have already provided examples useful for dendrochronology.
Abstract: This paper outlines efficient strategies for the development of long, climatically sensitive tree-ring chronologies in the tropics. Effective strategies include sampling useful temperate or subtropical species that extend naturally into the tropics; sampling species in botanical families that have already provided examples useful for dendrochronology (e. g., Pinaceae, Taxodiaceae, Verbenaceae); targeting deciduous species in seasonally dry forests; and sampling species described in the literature or found in xylaria that have promising anatomical features such as ring porosity and marginal parenchyma. Dendrochronology can also be used to test the annual nature of growth banding in tropical species. The cross-dating oflong ring-width time series between individual trees and between multiple sites in a region is strong evidence that the growth rings are indeed synchronized with the annual calendar. This can be confirmed if the ring-width data are also strongly correlated with long annual or seasonalized records of climate variability. Blind cross-dating tests to identify the cutting dates of known-age timbers can provide a final proof that a species produces reliable annual growth rings.
128 citations
TL;DR: Chambers et al. as mentioned in this paper reported a tree with a maximum radiocarbon dated age of about 1400 years for the long-living pioneer species Cariniana micrantha, in the light of dendrochronological age determinations from Africa and South America together with results of indirect age estimations from other sources.
Abstract: The recent report of ancient trees in the Amazon region (Chambers et al. 1998) with a maximum radiocarbon dated age of about 1400 years for the long-living pioneer species Cariniana micrantha is discussed in the light of dendrochronological age determinations from Africa and South America together with the results of indirect age estimations from other sources. There is a tendency in the literature to considerably overestimate the maximum ages of tropical trees. Age determination by the direct counting of annual rings and making estimations for hollow trees by measuring growth rates and diameters result in ages between 400 and 500 years for the largest trunk dimensions, e.g. in Cariniana legalis.
83 citations
TL;DR: Irrigation of 5-year-old trees led to the loss of typical ring porosity of teak wood; their first three growth rings were more or less diffuse-porous and this was attributed to uninterrupted cambial activity resulting in production of rather uniform-sized vessels.
Abstract: Growth periodicity was followed for two consecutive annual cycles to reveal the pattern of wood fonnation in plantation-grown teak at three different localities in India. Rainfall and age were the two important factors that influenced cambial activity. Cambial reactivation occurred during March-April in both years. The pre-monsoon showers broke the cambial donnancy at all three localities. Almost a month's interval was observed between bud break and initiation of radial growth . Irrespective of age and locality, a peak period of cambial activity occurred during June-July. Dormancy began during October-December, depending on the age of the trees and locality. Juvenile trees and those grown in relatively high rainfall areas had a prolonged cambial activity and retained foliage throughout the year. They produced wider rings with higher proportions of latewood. Irrigation of 5-year-old trees led to the loss of typical ring porosity of teak wood; their first three growth rings were more or less diffuse-porous. This is attributed to uninterrupted cambial activity resulting in production of rather uniform-sized vessels.
72 citations
TL;DR: In this article, a summary of 14C data from atmospheric sampling and measurements on wood from annual tree rings for the period 1945-1997 AD is presented and evaluated, and Radiocarbon data from tree rings are summarised and plotted against atmospheric records from similar latitudes.
Abstract: A summary of 14C data from atmospheric sampling and measurements on wood from annual tree rings for the period 1945-1997 AD is presented and evaluated. Atmospheric records are characterized by different distributions of bomb-test 14C between the Northem and Southem Hemispheres, latitude dependence, and seasonal fluctuations. Radiocarbon data from tree rings are summarised and plotted against atmospheric records from similar latitudes. In some cases, discrepancies are found. Possible reasons for this include: 1) the use of stored carbohydrate from the previous year, 2) different 14C levels in the air around subcanopy trees due to respiration of CO2, 3) regional and local effects of anthropogenic CO2 and 14C sources, 4) sampling of wood material too close to ring boundaries, and 5) insufficient pretreatment of tree ring sampies for dating. But in cases where trees were carefully selected and the sampies adequately pretreated, radiocarbon data from tree rings show excellent agreement with direct atmospheric sampling records.
61 citations
TL;DR: Five teak trees in northem Thailand were selected for the study of vessels in terms of dendroclimatology and all vessel parameters of the total ring and of the earlywood were negatively correlated with precipitation during the transitional period between the dry and the wet season.
Abstract: Five teak trees in northem Thailand were selected for the study of vessels in terms of dendroclimatology. The tree rings were divided into earlywood and latewood, and fourparameters (average vessel area, average vessel diameter, average conductive area, and vessel density) were measured by automatie image analysis technique to obtain 50-year (1947-1996) time series. Two questions were addressed: 1) How strongly are the vessel characteristics related to climate and 2) are these relationships different from those of ring widths? All vessel parameters of the total ring and of the earlywood were negatively correlated with precipitation during the transitional period between the dry and the wet season. The latewood vessel parameters, however, are negatively correlated with J une temperature. The climatic signals of the vessel parameters and of the tree-ring width are different from each other.
54 citations
TL;DR: In both the forests active cambial cell division and simultaneous differentiation of xylem and phloem started in June when the dormant shoot buds opened and ceased in October and November, respectively.
Abstract: Seasonal behaviour of vascular cambium in Tectona grandis L. f. growing in Moist Deciduous Forests (MDF) and Dry Deciduous Forests (DDF) of Gujarat State in Western India was studied for one annual cycle. In both the forests active cambial cell division and simultaneous differentiation of xylem and phloem started in June when the dormant shoot buds opened. In MDF cambial cell activity reached its peak in August-September and ceased in October; in DDF it ceased in November after reaching a peak in July-August. Maximum radial growth in trees of both forests occurred during the monsoon period. In both forests, phloem differentiation ceased before xylem differentiation. During dry months and the leafless periods the cambium remained dormant. Xylem mother cells next to the mature xylem in MDF underwent differentiation into xylem elements following the onset of periclinal divisions in March. In both forests, the seasonal anatomical changes associated with the cambium closely followed the phenology of the tree and local climatic conditions.
52 citations
TL;DR: Lower tensile and tear strengths of tracheids as well as some modifications of the mechanical properties of solid wood and paper can be expected from Norway spruces growing faster than 2.2 cm/year in circumference.
Abstract: Fourteen Norway spruces [Picea abies (L.) Karst.], randomly sampled as 7 fast-grown and 7 slow-grown trees, were used to test whether an increased tree growth rate in circumference affects the intra-ring and inter-ring trajectories of the microfibril angle in the S-2 layer of the tracheid wall. Those trajectories describe the fluctuations of the S-2 microfibril angle, respectively, from earlywood to latewood within rings and from pith to bark among rings. Using the cross-field pit apertures, intra-ring measures of microfibril angle were made at 11 equally-spaced sampling sites over each of 8 growth rings, following an 11 x 8 doubly repeated measures design with the tree as the 'subject' on which repeated measures were made. All the intra-ring trajectories of microfibril angle decreased linearly from earlywood to latewood, whereas the intra-ring trajectories showed significant year effects. Both types of trajectories are significantly affected by the growth rate after first thinning, as the fast-grown spruces showed a systematically larger microfibril angle and a mean microfibril angle of 29 degrees compared to 21 degrees for the slow-grown spruces. Thus, lower tensile and tear strengths of tracheids as well as some modifications of the mechanical properties of solid wood and paper can be expected from Norway spruces growing faster than 2.2 cm/year in circumference.
51 citations
TL;DR: Recently, the Mongolian tree-ring data has been used to provide evidence of unusual warming that is in agreement with large-scale reconstructed and recorded temperatures for the Northem Hemisphere and the Arctic.
Abstract: Recent tree-ring studies in Mongolia provide evidence of unusual warming that is in agreement with large-scale reconstructed and recorded temperatures for the Northem Hemisphere and the Arctic. The Mongolian proxy record for temperature extends back over 450 years and is an important addition to the global tree-ring database. Precipitation reconstructions based on tree rings reflect recent increases but show that the increases are within the long-term range of variations. There is evidence for quasi-solar periodicity in long-term reconstructed precipitation variation, also shown by previous studies. Mongolia has excellent sampling resources for future studies.
47 citations
TL;DR: The immunological markers were successfully applied to transgenic plants in which lignin synthesis pathways had been modified, to tissues from reaction wood, as well as to materials degraded by ligninolytic fungi.
Abstract: The main subunits of lignin could be visualized by transmission electron microscopy (TEM) with antibodies raised against synthetic lignin model polymers. Thus, immunological probes against p-hydroxyphenyl propane, guaiacyl and mixed guaiacyl-syringyl units allowed to specifically localize the qualitative distribution of lignins in plant cell tissues . Depending on the mode of preparation of the synthetic lignin antigens , the corresponding antibodies showed specificity for condensed or noncondensed interunits linkages . This specificity is illustrated with the different labellings provided by the antibodies when applied to various wood and nonwoody materials . The results c1early show the heterogeneity of lignification between tissues but also demonstrate the microheterogeneity of lignin deposition within a a single wood cell wall. Our immunological markers were successfully applied to transgenic plants in which lignin synthesis pathways had been modified, to tissues from reaction wood, as well as to materials degraded by ligninolytic fungi.
46 citations
TL;DR: A quantitative evaluation of the growth-climate relationships based on response function analysis on a monthly and seasonal scale indicates a similar pattern across several regions of the Western Himalaya.
Abstract: Tree-ring chronologies of Himalayan conifers (viz. Pinus, Picea, Abies, Cedrus, etc.) were compiled from more than 300 tree core sampIes from 11 different sites covering a wide area of the Western Himalaya. Distinct annual growth and little occurrence of double or missing rings are characteristic features of Himalayan conifers. Dating of individual sampIes was achieved for all sites except for a few from a high elevation glacier which exhibited patches of very narrow rings and a high frequency of resin canals. Moderately high values of common variance and signal-to-noise ratio indicate their usefulness for dendroclimatic studies. Significant improvement of statistical performance is observed for all sites after removing the auto-correlation structure in the series by auto-regressive modeling. A quantitative evaluation of the growth-climate relationships based on response function analysis on a monthly and seasonal scale indicates a similar pattern across several regions of the Western Himalaya. March-April-May (pre-monsoon) climate (temperature and precipitation) is an important limiting parameter for tree growth and can be successfully reconstructed for the past few centuries.
TL;DR: Teleconnections between the tree-ring chronologies of a sampling network have demonstrated a distinct dendroecological region in the catchment area of the Yarlung Tsangpo river, where tree growth is mainly limited by summer precipitation.
Abstract: Southem Tibet is influenced by the Asian summer monsoon which causes 70-80% of the annual precipitation to fall between June and August, showing a steep gradient from east to west. Teleconnections between the tree-ring chronologies of a sampling network have demonstrated a distinct dendroecological region in the catchment area of the Yarlung Tsangpo river, where tree growth is mainly limited by summer precipitation. Ring width at these sites is strongly correlated to late summer (August to October) precipitation of the year prior to growth, indicating that the trees bear a high potential for the reconstruction of the rainfall variability at the northwestem fringe of the monsoonal regime. Light rings and other wood anatomical features like intra-annual growth bands can be observed in the westernmost stands of Pinus densata. If these growth bands occur in the earlywood of the tree ring, they can be explained by cold events during spring; ifthey are located in the transition zone between earlywood and latewood, they are caused by dry conditions during May and especially June, which points to a delayed arrival of the moist monsoonal air masses in southem Tibet in the corresponding years.
TL;DR: Both the intensity of sclerification of phloem parenchyma cells and the degree of ray dilatation increase with tree age, giving rise to a specific within-tree pattern of axial variation.
Abstract: The bark structure of Eucalyptus globulus Labill. grown in plantations in Central Portugal is described, based on specimens extracted at six height levels from ten 15-year-old trees. No significant variation of qualitative features between trees was observed. The non-collapsed phloem is characterised by multiseriate tangential rows of phloem parenchyma alternating with rows of phloem fibres, interspersed with large sieve tubes and their respective companion cells, and uniseriate rays . With the onset of sieve tube collapse (collapsed phloem ), some parenchyma cells expand and sclerify, the course of rays becomes irregular, and ray dilatation is initiated. The periderm is composed of a phellem of lignified cells with horseshoe thickening (phelloids), followed by a layer of cells with suberised tangential walls, and a phelloderm with a variable number of layers of thin-walled cells. Age-related secondary changes give rise to a specific within-tree pattern of axial variation. Both the intensity of sclerification of phloem parenchyma cells and the degree of ray dilatation increase with tree age.
TL;DR: The anatomical features of the plant, which does not seem to suffer from water stress though growing entirely during the Mediterranean summer drought, are compatible with its adaptive strategy and might be involved in a possible osmotic shifting of water in the xylem.
Abstract: Root and stern wood of the Mediterranean summergreen Capparis spinosa L. was studied. Wood anatomical features favour high hydraulic conductivity, which is necessary for maintaining the high midday stomatal conductance and rates of photosynthesis observed in this plant. Xylem conduits of both stern and root consist of wide and short vessel elements with simple perforation plates. Vessel grouping in the stern secures xylem safety against cavitations. The plant would be highly vulnerable to cavitations due to freezing conditions, although these are rare during the Mediterranean winter. Thus, the anatomical features of the plant, which does not seem to suffer from water stress though growing entirely during the Mediterranean summer drought, are compatible with its adaptive strategy. The significant amount of minerals found in the root vessels, and the abundant starch grains of the wood might be involved in a possible osmotic shifting of water in the xylem.
TL;DR: Tree-ring studies have been taken up in the tropical and Himalayan region in India to develop millennium-long c1imatic reconstructions.
Abstract: There are several reports which indicate that the c1imate over the Himalayan region is linked both with the monsoon variation on the Indian subcontinent and in the whole of South-East Asia as well as with the El-Nino/Southem Oscillation. To understand the behaviour ofthese c1imatic phenomena we need long-term high-resolution c1imatic records which are in generallacking in this part of the globe. Tree-ring studies have therefore been taken up in the tropical and Himalayan region in India to develop millennium-long c1imatic reconstructions.
TL;DR: Trends in the wall and lumen percentages of the various cell types suggest that some physical properties may vary more within the tree (or with growth rate) than is suggested by the limited variation in density that is found in rauli.
Abstract: Cell wall and lumen percentages were determined for vessels, fibres and rays from 10 trees of Nothofagus nervosa (rauli), and analysed in relation to ring number from the pith, ring width, and density. Increase in density across the juvenile wood was mainly associated with an increase in fibre wall %, which outbalanced a simultaneous increase in vessel lumen %. Decrease in density across the mature wood was associated with changes in both fibre wall and total lumen percentages. Though density varied only slightly with ring width, this was accompanied by appreciable changes in percentages of different cell types. These trends in the wall and lumen percentages of the various cell types suggest that some physical properties may vary more within the tree (or with growth rate) than is suggested by the limited variation in density that is found in rauli. There were significant between-tree variations in both density and cell types, indicating the possibility of selection for either at an early stage of tree growth.
TL;DR: Wood and bark histology data on stems of two species of Stegnospenna (Stegnospermataceae, or Phytolaccaceae s.l.) is presented, complementing previous accounts and it is believed that successive cambia and their origin in Stegnosperma are believed to represent the same anatomical phenomena as in other Phytolia s.
Abstract: Wood and bark histology data on stems of two species of Stegnospenna (Stegnospermataceae, or Phytolaccaceae s.l.) is presented, complementing previous accounts . Wood of Stegnosperma is relatively primitive within Caryophyllales because of presence of tracheids , diffuse parenchyma, and both multiseriate and uniseriate rays . The solitary nature of vessels is held to be correlated with tracheid presence , as in other groups of dicotyledons with vessels solitary or nearly so. Bark anatomy is newly reported for the genus . The method of section used permits analysis of divisions in cells with primary walls. Radial rows of parenchyma ('secondary cortex') develop in the inner cortex and are perpetuated by tangential divisions collectively termed a diffuse lateral meristem here. Successive cambia form within the radial rows of parenchyma. Despite diverse terminology and interpretations in literature on plants with successive cambia, the successive cambia and their origin in Stegnosperma are believed to represent the same anatomical phenomena as in other Phytolaccaceae s.l.
TL;DR: The wood anatomy of 31 species (23 genera) of Mimosoideae and Caesalpinioideae growing in the Sudanian savannas of West Africa was examined and types were grouped into 18 types according to wood anatomical structure.
Abstract: Leguminosae constitute an important proportion of the charcoal sampIes recovered at archaeological sites in the West African savannas. Identification of these fragments to a level below family or subfamily was problematic, because a comparative survey was missing. Therefore, the wood anatomy of 31 species (23 genera) of Mimosoideae and Caesalpinioideae growing in the Sudanian savannas of West Africa was examined. The species were grouped into 18 types according to wood anatomical structure. The types represent single species or genera (fourteen types), two genera (three types) or three genera (one type) . The following features are regarded as suitable for a reliable delimitation and identification . Heterocellular rays and storied structure allow for a first differentiation. Enlarged, non-bordered vessel-ray pitting , nonvestured vessel-pits, silica, axial canals, septate fibres and crystals in non-eharnbered ray cells are additional features characterizing few or single types. Types without these features are delimited less easily. Parenchyma distribution and ray width are, due to variability, not as reliable , but remain necessary features for identification. Types characterized by these features only may not always be recognized correctly. Quantitative features of the vessels are not regarded as helpful for the differentiation within the set of examined species. A table (Table 1) summarizes the results for easy reference.
TL;DR: An examination was made of the fine structure of bordered pit membranes in the radial walls between tracheids in the outer sapwood of Abies sachalinensis to improve understanding of the so-called extended torus, the minute holes in the torus and the imperforate zone near the periphery of the pit membranes.
Abstract: An examination was made of the fine structure of bordered pit membranes in the radial walls between tracheids in the outer sapwood of Abies sachalinensis to improve our understanding of the so-called extended torus, the minute holes in the torus and the imperforate zone near the periphery of the pit membranes, Field-emission scanning electron microscopy revealed that a so-called extended torus was present in many bordered pit membranes. We examined the frequency occurrence of and variations in the extended torus within a single annual ring. The frequency tended to increase from the earlywood to the latewood within a single annual ring. In the tori of many bordered pit membranes, we detected minute holes, and the number and location of such minute holes in a single torus varied among individual pit membranes. The appearance of each minute hole also varied. An imperforate zone was observed near the periphery of the pit membrane. In this imperforate zone, we found amorphous materials, and fine fibrils were visible that were an extension of the fibrillar meshwork of the margo.
TL;DR: In this article, the internal stress development in rattan canes (Calamus merrillii Becc) was investigated following the procedures used in trees, and it was found that longitudinal compressive stresses existed at the periphery while longitudinal tensile stresses at the core.
Abstract: Internal stress development was investigated in rattan canes (Calamus merrillii Becc.) following the procedures used in trees. Measurements showed that longitudinal compressive stresses existed at the periphery while longitudinal tensile stresses existed at the core. Such stresses originated from the fibers. Fiber MFA was observed to be beyond 20" and the lignin content was above 30%. Considering its similarities to compression wood tracheids, it was assumed that the rattan fibers generated longitudinal compressive stress. The amount of stress varied from base to top and from periphery to core because of the variation in the proportion of fibers along these points. This is why the longitudinal compressive stress that was generated at the base was higher than at the top and high longitudinal compressive stress was developed at the periphery. As a response to this high peripheral stress, longitudinal tensile stress was induced at the core.
TL;DR: During a study of fascicle abscission in Pinus taeda L., tyloses were observed to occlude tracheids of both proximal and distal abscissions scars.
Abstract: During a study of fascicle abscission in Pinus taeda L., tyloses were observed to occlude tracheids of both proximal and distal abscission scars. The tyloses represent the protrusion of ray parenchyma cells into tracheid lumens. Multiple tyloses often arise from a given parenchyma cell and can enter multiple tracheids. Tyloses occur as part of an abscission process that also includes the presence of Type II cells (programmed to enlarge during abscission in the presence of ethylene) and rupture of tracheids-features common to abscission in angiosperms.
TL;DR: Tree-ring sampies of different conifer species in various ecological settings from subtropical to temperate regions of the Eastern Himalayan region have been evaluated and reveal that temperature is a determinant factor for the growth of trees at high elevations.
Abstract: Tree-ring sampies of different conifer species in various ecological settings from subtropical to temperate regions of the Eastern Himalayan region have been evaluated for their potential for dendroc1imatic reconstructions. Most of these tree species have cross-datable growth rings except Taxus baccata and Tsuga dumosa where series of micro-rings and lack of variation in these suppressed zones make cross-dating difficult. Tree-ring chronologies have been established from Abies densa and Larix griffithiana, the only deciduous conifer species in the Himalayas. Tree growth-climate relationships reveal that temperature is a determinant factor for the growth of trees at high elevations. Abies densa in the western part of Arunachal Pradesh shows a negative response to the July-September temperature whereas Larix griffithiana shows a positive response to the May temperature.
TL;DR: Wood anatomy and lateral meristem activity of Barbeuia are distinctive enough to support segregation of the genus from Phytolaccaceae s.l., and are traditionally considered primitive features.
Abstract: Liquid-preserved material of mature sterns of Barbeuia madagascariensis Steud. permiUed analysis of meristematic activities. The species has successive cambia, each producing secondary xylem and phloem; outside of these vascular strands is a nondiffuse lateral meristem, probably functionally a single cell in thickness, which produces radial files of secondary cortex to the outside and conjunctive tissue and vascular cambia to the inside. The secondary xylem of Barbeuia has dimorphism in vessel diameter, reminiscent of vessel dimorphism in other lianas, such as Agdestis. Diffuse parenchyma and tracheids, found in Barbeuia, also occur in Stegnosperma and Agdestis but not other Phytolaccaceae s.l., and are traditionally considered primitive features. Wood anatomy and lateral meristem activity of Barbeuia are distinctive enough to support segregation of the genus from Phytolaccaceae s. s.
TL;DR: The wood fibres retain their living protoplast in eleven species of five genera of the Combretaceae while those of Anogeissus and Terminalia are trees while that of Calycopteris, Combretum and Quisqualis are large scandent shrubs.
Abstract: The wood fibres retain their living protoplast in eleven species of five genera of the Combretaceae. Among the species studied, those of Anogeissus and Terminalia are trees while those of Calycopteris, Combretum and Quisqualis are large scandent shrubs. Living fibres with oval to oblong or fusiform shaped nuclei were found among all the species but their occurrence is more persistent in trees than in scandent species. The fibres are septate, thick-walled with narrow lumen and possess slitlike simple pits. In Combretum ovalifolium prismatic crystals frequently co-occur with the nucleus in the same compartment of the fibres. The possible significance of living fibres is discussed.
TL;DR: TEM investigation of the torus-bearing pit membranes in tracheids of Botrychium dissectum wood has revealed a coating that covers the pit membrane and torus, and sometimes lines the lumen-side of the tracheary wall, which appears to be ethylene mediated.
Abstract: TEM investigation of the torus-bearing pit membranes in tracheids of Botrychium dissectum wood has revealed in some specimens a coating that covers the pit membrane and torus, and sometimes lines the lumen-side of the tracheary wall. Such coatings have been associated with wound response in dicot woods, but have not previously been reported in the wood of Botrychium. In response to wounding, rhizome sampIes incubated on water-saturated filter paper produced the coating material within 4 days. Rhizome sampIes that were incubated with an ethylene inhibitor for a maximum incubation time of 20 days did not develop the wound-response coating. Therefore, based on experimental evidence the wound response appeared to be ethylene mediated. Field sampIes which were artificially grazed by removing the leaf/spike complex exhibited a displaced wound-response coating in the rhizome. Histochemical studies indicate that the coating material has both pectin and phenolic components.
TL;DR: In Ephedra campylopoda, a woody climber of the Ephedraceae (Gnetales), the secondary xylem of the upper and lower sides of horizontal stems has the same structure, but cambial activity in the lower side is greater, suggesting that the flexibility of the stems does not change.
Abstract: In Ephedra campylopoda, a woody climber of the Ephedraceae (Gnetales), the secondary xylem of the upper and lower sides of horizontal stems has the same structure. However, cambial activity in the lower side is greater, producing 1.5 times more xylem and 1.25 times more growth rings in thin stems and 1.8 times more xylem in thick stems. Gelatinous fibres are not formed in the upper side or elsewhere in the xylem. I suggest that this difference in cambial activity does not change the flexibility of the stems, an important adaptation for a climber.
TL;DR: The wood of E. venusta Schott is described, completing generic coverage of the wood anatomy of the tribe Swartzieae as defined by Cowan (1981), and is very similar to three closely related genera of SwartzIEae, Zollernia, Harleyodendron and Lecointea.
Abstract: The genus Exostyles consists of two to three species from Brazil. This paper describes the wood of E. venusta Schott, completing generic coverage of the wood anatomy of the tribe Swartzieae as defined by Cowan (1981). Small twigs from herbarium sheets of E. glabra and E. amazonica (labelled E. venusta) were also examined. Exostyles wood anatomy is compared with that of the other genera in the tribes Swartzieae (Gasson 1996) and Sophoreae (Gasson 1994; Fujii et al. 1994), and is very similar to three closely related genera of Swartzieae, Zollernia, Harleyodendron and Lecointea.
TL;DR: Karyokinesis was observed in severa1 wood fibers before the initiation of septum formation, while lignification was in progress after the completion of the S3 layer deposition, which suggests that the septation starts in parallel with the progress of lignifications after the deposition of theS3 layer.
Abstract: Septate wood fibers were abundant in the following parts of growth rings of Kalopanax pictus Nakai: 1) around the vessels, 2) in the vicinity of ray cells, 3) in terminal regions of the growth rings. Septum formation in wood fibers progressed from the initial region (pore zone) towards the terminal region within a current growth ring with progressing 1ignification of the wood fiber walls. Many septate wood fibers at the end of the growth ring had radially continuous septa. Karyokinesis was observed in severa1 wood fibers before the initiation of septum formation, while lignification was in progress after the completion of the S3 layer deposition. This suggests that the septation starts in parallel with the progress of lignification after the deposition of the S3 layer.
TL;DR: Perforated ray cells in the stem wood of Saracha quitensis (Solanaceae) are reported, generally larger than other ray cells, with simple perforations, as in vessel elements, located in both radial and tangential walls.
Abstract: This work reports perforated ray cells in the stem wood of Saracha quitensis (Solanaceae), In this species the perforated ray cells were found either isolated or together in groups of 2 to 4, localised mainly on the ends of multi seriate rays, though they may also be observed in the ray body. They are generally larger than other ray cells, with simple perforations, as in vessel elements, located in both radial and tangential walls.
TL;DR: It is concluded that the technique reduces the logistical problems of sampling separate trees to represent different ages from different sites; it controls within-site genetic and environmental variation and it is suitable to determine variation of pulping properties with age and site.
Abstract: A study was undertaken to determine the effects of rotation age and site altitude on the quality of unbleached kraft pulp made from Pinus elliottii and P. patula grown in the Usutu Forest, Swaziland. Stands well beyond the current rotation age of 18 years were selected at site altitudes of 850, 1200 and 1450 metres. From each tree felled, sample discs were removed to represent the tree as it was at 11, 18 and 25 years of age. This was done by counting back the appropriate number of growth rings for the required age at each sampling point up the stem and paring them off the disc. Wood density, alpha-cellulose, lignin and ethanol-benzene-soluble extractives were measured in the wood and tear and tensile indices on the pulp. The patterns of variation with age were as expected from previous work where whole trees were sampled for each age class except for the ethanol-benzene solubles which showed a decrease with age for the dissected tree. It is concluded that the technique reduces the logistical problems of sampling separate trees to represent different ages from different sites; it controls within-site genetic and environmental variation and it is suitable to determine variation of pulping properties with age and site.