Latewood Formation Research Articles

Genetic relationships between wood density components and cambial growth rhythm in young coastal Douglas-fir

To better understand the genetic control of wood formation in coastal Douglas-fir (Pseudotsugamenziesii var. menziesii (Mirb.) Franco), and to assess the potential impact of selecting for increased wood density on adaptation of trees, genetic relationships of wood density, and its components, with cambial growth rhythm traits were examined in a 15-year-old progeny test. Timing of diameter growth during the 1987 growing season was available from an earlier study, and wood formation traits were estimated by X-ray densitometry of increment core samples. Wood formation traits were under weak genetic control [Formula: see text]. Lengths of earlywood and latewood formation were mostly determined by the timing of latewood transition. Overall core density was negatively correlated with the dates of cambial growth initiation (rA = −0.41) and latewood transition (rA = −0.62), and positively correlated with the date of cambial growth cessation (rA = 0.40). As a result of these relationships, higher wood density was associated with a longer duration of cambial growth (rA = 0.67) and a slower rate of wood formation (rA = −0.37). All density components showed similar relationships with cambial phenology and wood formation traits. Selection for increased wood density is expected to cause only a slight extension of the cambial growth period, but it would also cause an earlier transition to latewood formation, negatively affecting growth rate.

Bud and cambial zone phenology of lateral branches from Douglas-fir (Pseudotsugamenziesii) seedlings

Bud and cambial zone phenologies of outdoor-grown, containerized seedlings of Pseudotsugamenziesii (Mirb.) Franco (Douglas-fir) were determined and compared. Morphological characteristics of the live primordial shoots were related to known stages of bud development, while cambial zone phenology was based on anatomical characteristics. Secondary growth in branches of P. menziesii seedlings was separated into six stages: (i) early wood formation; (ii) latewood formation; (iii) cessation of cambial cell division; (iv) dormancy; (v) cambial cell expansion; and (vi) resumption of cell division. Early wood formation by the cambial zone, and primary leaf initiation in the shoot tips occurred until July. During this time of maximal activity, differences in wall thickness and shape distinguished cambial cells from vascular cells in early differentiation stages. By late July, earlywood formation was changing to latewood formation and bud-scale initiation had begun. The transition to preformed leaf initiation in the buds occurred over a period of 1 month in August and September. Cambial cell division ceased in early September but tracheid differentiation continued until about the end of October. Preformed leaf initiation lasted until the buds became dormant in mid-November. The cambial zone was dormant from the end of November until the beginning of March, and in transverse section was characterized by a distinct boundary at the border of the xylem and regular, cigar-shaped cambial cells with thick radial walls. Resumption of cambial activity in the 1st week of April began with radial expansion, followed about 2 weeks later by cell division. Differentiation of earlywood tracheids and bud swelling began in early April. The majority of buds flushed in the 3rd week of April. Rays in the lateral shoots were composed of monoseriate files of radially elongated cells. Ray initials were not observed. Ultrastructural features indicated that the dictyosomes of the cambial cells were active during the winter period.

Lignin Distribution During Latewood Formation in Pinus Radiata D. Don

Lignin distribution during formation of latewood tracheids in Pinus radiata, was determined by quantitative interference microscopy, and by potassium permanganate staining combined with transmission electron microscopy. Lignin distribution varied among trees sampled on the same date in late winter. In one tree, latewood tracheids were fully lignified up to the growth ring boundary. However in most trees sampled, latewood was only partially lignified. The extent of lignification varied from tree to tree but in all cases, at least some lignin was present in the middle lamella and primary wall at the growth ring boundary. Latewood was ideal for examining the lignification process because of the large number of different stages present in a single specimen.

Early- and Latewood Formation in Pinus Densiflora Trees with Different Amounts of Crown

The seasonal process of early- and latewood formation at different stern heights was examined in 20-year-old Pinus densiflora trees having different crown proportions. The initiation of tracheid production did not appear to vary among trees or within sterns; however, the transition to latewood formation and cessation of tracheid production began earlier at the lower stern. This tendency was more obvious in trees with smaller crowns. The duration and rate of tracheid production in early- and latewood also differed among trees with different crown proportions and within sterns. It is suggested that the quantitative distribution of latewood along the trunk are attributable not only to the date of transition from earlywood to latewood, but also to the duration and rate of latewood tracheid production.

Abnormal Wood Formation in Pinus taeda

SYNOPSIS A preliminary anatomical study of abnormal wood formation in P. taeda is discussed. The abnormal wood is found in some trees growing on either level or sloping ground on a variety of soil types. The abnormal wood does not resemble compression wood found in P. taeda as it is found around the entire circumference of the trunk to a height of approximately three metres (although it can be found higher). It shows no early wood or late wood formation, no rudimentary S3 layer, less pitting and pronounced helical cavities. The formation of this abnormal wood seems to be induced by plant growth regulators as it can be found in an area of induced compression wood near a forming bud, where plant growth regulator levels would be higher.

Red spruce stands downwind from a coal-burning power generator: tree-ring analysis

Tree rings of red spruce (Picearubens Sarg.) in uneven-aged forest stands downwind of an SO2, source (a coal-burning power generator) were analyzed in terms of spatial and temporal trends for bole increments and elemental concentrations (Al, Ca, Mg, K, P, Mn, Zn, Fe, Ni, Cu, Cr) in xylem. Five-year core segments were pooled with respect to distance from emission source, time of wood formation, and tree age (young trees <35 years; old trees >35 years). Soil analysis was done for all stands (total of 28) by soil layer (forest floor, A and B horizons) for pH, exchangeable K, Ca, Mg, Al, and oxalate-extractable Al and Fe. Also analyzed was the snowpack at each stand at three sampling dates in February and March 1986. The snow data for pH, Ca, Mg, K, and SO4 were highly variable, with some of the variability presumably related to fallout of fly ash. The soil data were also variable, but revealed a gain of water-soluble and bicarbonate-extractable SO4, and a loss of exchangeable Mg with increasing proximity to the power generator. Magnesium levels in the wood of the red spruce trees showed a similar trend. Wood concentrations for Ca, Mg, Mn, and Zn were found to decrease with increasing stand age. In contrast, wood concentrations for P, K, Fe, Ni, Cu, and Cr were highest in the most recently formed xylem. Some of these variations were probably affected (i) by the affinity of the wood for each element during wood formation, and (ii) by removal through flow of xylem sap. Some of these trends may also reflect changed ion availabilities in the soil or may be due to air pollution. Trends for the age-related variations of mean bole increments in each of the uneven-aged stands were probably affected by within-stand competition, modified by selective logging, and by recurring outbreaks of spruce budworm (Choristoneurafumiferana Clem.). An enhanced rate of SO2 emission since about 1965 may also have had a negative effect on radial bole growth. The availability of soil water appeared to be a principal factor in relating a tree growth index to year by year climate variations. This tree growth index (developed for an even-aged stand of red spruce upwind from the power generator) was positively related to precipitation of the preceding year and to precipitation in July and August (time of latewood formation). The growth index was negatively related to prolonged periods of high temperatures during earlywood formation.

The radial distribution and metabolism of IAA-14C in Pinus echinata stems in relation to wood formation

Radial distribution of auxin in differentiating xylem tissues was studied in decapitated 8- to 14-year-old Pinus echinata stems to which indoleacetic acid (IAA-14C) in lanolin paste was applied during early and late growing season. Small segments of the treated stems were sectioned tangentially with a sliding microtome, the serial sections were collected, and the radioactivity of each section was measured. The results indicate that IAA is radially distributed in the differentiating tissues along a steep gradient from the cambial region to the differentiating xylem and that this distribution varies during the growing season in relation to the seasonal transition to latewood formation in intact trees.Forty-five to 60% of the radioactivity recovered in methanolic extracts of the differentiating xylem after a 2-day labeling period was in the form of IAA. After 7 days 10–15% of the radioactivity recovered was in the form of IAA. The radioactivity recovered separated into ether and aqueous fractions when the methanol extract was reduced, acidified, and partitioned with ether. Chromatography of aliquots of both fractions in several solvent systems revealed no individually significant metabolite of IAA. The aqueous fraction derivatives accumulated in the tissue, and later in the season the metabolism of IAA and the accumulation of the aqueous fraction apparently decreased. In experiments where excised differentiating xylem was incubated with a liquid medium containing IAA-14C, the conversion of radioactivity to the aqueous fraction was twofold greater in early season than in late season. The significance of the results is discussed with possible relation to the control of the seasonal transition to latewood formation in conifers.

ALTERNATIVES TO THE ASSESSMENT OF EARLYWOOD AND LATEWOOD IN DICOTYLEDONOUS TREES: A STUDY OF STRUCTURAL VARIATION IN GROWTH RINGS OF APPLE (MALUS PUMILA MILL.)

SummarySeveral indices describing the variation in wood structure within growth rings of dicotyledon trees were examined in apple (Malus pumila Mill.) scions grafted on to four rootstocks of different vigour. The cross‐sectional dimensions of 9600 fibres and 7200 vessel elements were measured in each rootstock and scion combination. Indices incorporating lumen width and wall thickness of fibres varied more or less linearly across growth rings, so that assessment of latewood could be made only by selecting some arbitrary limit, which may not be suitable for all rootstocks. The patterns of variation in vessel lumen area within growth rings varied markedly between rootstocks, and gave no clear indication of the point in the ring at which latewood formation might begin. A less extensive study of the distribution of tissues in the xylem at five positions across a growth ring showed that there tended to be a prominent reduction in the proportion of vessels, and an increase in the proportion of fibres between 10 and 30% of the distance across the ring. It was concluded that the concept of earlywood and latewood is not helpful to fundamental studies of wood structure and formation, and that in industry, measurement of relevant properties, such as the density of wood or fibres, may be made as easily as the determination of proportions of earlywood and latewood, however these wood zones be defined.

Differenze Morfologiche ed Anatomiche in Individui Maschili E Femminili diGinkyo BilobaL.

Abstract Anatomical and histological differences between ♀ and ♂ plants of GINKYO BILOBA L. — Morphological characters in several ♀ and ♂ specimens of Ginkyo have been checked, with the aim to put in evidence those which are sex-linked. Anatomical data from a previous research have been utilized. (Maugini 1965). The main results are here summarized. In the climate of Florence the female plants unfold their buds in the first ten days of April, the male ones in the middle of March, so that the males break their dormancy about one month before the females. From the buds opening, brachyblasts are formed both in males and females, and catkins and ovules appear. At the beginning of May, the ovules have considerably grown, and catkins are faded. In the meanwhile the leaves have completely grown up in both sexes. Between the end of September and the beginning of October, the seeds become gold-yellow and begin to be shed off. Dissemination may go on for a long while, and still be active when all the leaves are fallen. Buds are formed during summer, they are very little and sharp in the female, round and bigger in the male. In both sexes leaves turn yellow and begin to fall between the end of October and the beginning of November. Females are generally considered more precocious than males in shedding leaves, but this behaviour did not result constant in the plants under observations so that the « leaf-fall time » cannot be considered a sex-linked character. In shoots and stems of males and females, proceeds downwards tracheid deposition and differentiation, the highest activity being in the brachyblasts, where cambium works continuosly, and the lowest in the stem, where late wood formation can be found only in the male plants. Unevenness of cambial activity along the plant axis is particularly evident in the female, where late wood formation in the stem is rare. The rhythm of cambial activity along shoots and stems of males and females have been compared with that of the buds, with the following results: both in the female and male plants the young leaves start expanding about two months before cambium activity starts in the stem. The male plant is more precocious than the female, probably the slower vegetation rhythm of the female being related to the seed ripening process.

Radial fissures in the early wood of conifers

In certain conifers anatomical evidence suggests that young trees may become exposed to conditions conducive to collapse during late wood formation, causing partial collapse and radial cleavages in the early wood. Living ray cells are exposed to the cavity after cleavage. Different species show different responses conditioned by the anatomy and physiology of the ray parenchyma. The cavities fill with cellular tissue in radiata pine (Pinus radiata D. Don), with resin in Douglas fir (Pseudotsuga tarcifolia (Poir.) Britt.), and remain empty in white spruce (Picea glauoa (Moench) Voss). Evidence is presented to show that when a living protoplast is given free access to moist air, a powerful growth stimulus is applied to the cell. In radiata pine, ray parenchyma cells have primary walls only, and the response is a proliferation of these cells. In Douglas fir and white spruce, the ray parenchyma has secondary thickening and small ray tracheid pitting, precluding growth. The response is an increased metabolic rate, producing resin in Douglas fir (heartwood-forming species) and without solid end-products in white spruce (species with little contrast between sapwood and heartwood).

Ciclo di Accrescimento e Differenziazione Delle Gemme in Piante Perenni Nel Territorio di Bari

Summary Growth cycle and buds differentiation in perennial plants growing in Bari's area. — V. The evolution of the wood ring in Rhammus Alaternus L. from December 1946 to March 1949. In Rhamnus Alaternus L. the cambium awackens in March with the production of an early wood, characterized by large vessels and loose fibers. It keeps on dividing the following months, producing intermediary wood, whose vessels become narrower and narrower. In June the wood ring is almost complete and the cambial activity slows down. In July late wood is formed, with narrow tracheae and highly lignified fibers. From August to February cambial activity is very scarce and irregular, in the wood produced fibers being tangentially compressed. In a young branch of R. A. cambium becomes suddenly active in February, that is one month before than in the stem, it goes on during the month of March-June, with an evident diminution in the size of the wood elements. This diminution of size instead of being regular, shows some oscillations, expecially during the month of May. In Sept. the cambium starts again dividing, but rather poorly and irregularly, forming some vessels a little wider than the preceeding ones, so that an incomplete false ring is formed only in some points of the branch. As a rule the autumn wood is a typical late wood. This scarce and irregular cambial activity goes on also during Oct.-Dec. In January is more active and forms rather wide vessels in comparison with those formed in the preceeding month. This new formed wood however does not show the characteristics of the early wood of a new ring. Concluding, the characteristics of the cambial activity of A. R. are In the stem: 1) March: early wood. 2) March-June: intermediary wood. 3) July: late wood, resting period. 4) At the end of Autumn a scarce production of late wood is sometimes possible. In the young branch: 1) February: early wood. 2) March-June: intermediary wood, with positive and negative oscillations in the vessels width. 3) At the end of June the late wood is already differentiated. 4) July-August: resting period. 5) Spt.-Juan.: the cambium starts again dividing very scarcely and producing a transition wood between the two rings. This wood can be regarded neither as a true ring nor a false one, it represents rather the last phase of the late wood formation. 6) In the young branch of the female specimen the cambium starts dividing somewhat later than in the male one. 7) The wood ring width does not vary much in relation to the yearly amount of rainfall. The lack of relation between rainfall and ring width is particularly evident in 1948 (a rainy year). The, «Compleasance» of R. A. could show that this species is, in Puglia, in its own habitat. On the other hand it is rather peculiar that R. A. forms only one wood ring during one year, with production of early wood during the spring, and of late wood in the autumn, instead of producing a second autumn ring following a distint summer rest, as could be expected.

Leader, Needle, Cambial, and Root Growth of Certain Conifers and Their Interrelations

1. The seasonal course of leader elongation, needle elongation, and cambial growth of certain conifers, particularly red pine and white pine, was measured during the 1931 growing season near Keene, New Hampshire. 2. Leader elongation in red pine began in late April, reached its maximum by June 10, and ceased about the middle of August, a growing period of approximately 105 days. Ninety-six per cent of this growth was made during the 60 day period from May 15 to July 15. Older trees were slightly later in their seasonal course of leader elongation than were younger trees. Trees located on southwest slopes started growth earlier than those located on level areas. 3. Leader elongation in white pine started slightly later than in red pine but reached its maximum at the same time (June 10) and ceased growth at the same time. Ninety-six per cent of the growth occurred from May 15 to July 15. 4. Leader elongation in pitch pine followed a seasonal course similar to that of white pine. Ninety-seven per cent of this growth occurred from May 15 to July 15. 5. Leader elongation in white spruce started the middle of May, reached a maximum June 10, and ceased July 23, a growing period of about 70 days. 6. Leader elongation in balsam fir started late in May, reached a maximum June 23 (two weeks later than the other species), and ceased July 23, a growing period of about 65 days. 7. From June 13 to June 29, 60 per cent of the leader elongation of red pine occurred at night, 40 per cent during the day. A correlation of +0.744 ± 0.075 existed between night growth and minimum temperature. No significant correlation existed between day growth and temperature. 8. The needles located at the base of the leader in red, white, or pitch pine pass through their grand period of growth earlier than do those located higher up on the leader. Those at the tip began elongation about June 5. 9. Needle elongation in red pine began about May 15, reached a maximum late in June, and ceased in early September, a growing period of 110 days. Ninety-four per cent of the growth occurred during the 60 days from June 10 to August 10. 10. Needle elongation in pitch pine was similar to that of red pine; white pine was slightly more tardy in its development than red pine. 11. Needles of the pines investigated grow from a meristematic region at their base. They do not elongate after the first growing season. 12. Daily needle elongation in red pine showed a correlation of +0.627 ±0.08 with the mean temperature. 13. Cambial growth in red pine as measured by the MacDougal dendrograph began in early May, reached a first maximum June 2, decreased slightly and reached a second maximum July 9. Growth ceased in early October, a growing period of 150 days. There was no correlation between the meteorological conditions and the double maximum in the growth rate. The first maximum is probably associated with the development of spring wood and the second maximum with the development of summer wood. 14. Stevens reports that the roots of white pine begin to elongate the middle of April, reach a first maximum June 8, decrease, rise to a second maximum on October 4, and cease in early November, a growing period of about 205 days. 15. There is a certain interrelation between the activity of the different growing regions of the tree. In early June there is a great surge of growth in leader, roots, and cambium at approximately the same time. This spurt of growth is made possible by the great amount of readily available reserve foods stored in the tree. There is probably a causal relation between these different growth activities having to do with the absorption, transportation, and utilization of water. 16. After this first surge of growth the needles reach their maximum growth rate, followed by the second maximum of cambial growth. After nearly all growth is completed and the full complement of needles is functioning, the roots reach their second maximum rate of elongation. 17. It is suggested that there is an internal balance between the metabolic activities of the different growing regions of the plant which determines the time of maximum development of needles, cambium (late wood formation), and roots. After the reserve foods are exhausted this balance is necessitated by limited supplies of elaborated foods, water, and possibly mineral nutrients.

Growth Studies in Forest Trees. 2. Pinus strobus L.

1. The winter condition of the secondary cortex and cambium of white pine is similar to that of Pinus rigida. The marked differences which occur between the mature bark of white pine and pitch pine are occasioned by changes which take place in the outer cortex (periderm). 2. The cambium varies both in number of cell layers (2-10) and thickness in different parts of a tree. It is smallest in both these respects in the twigs and young branches, and increases gradually in dimensions from the apex downward, until that point is reached in the bole where the last annual ring is the thickest. Thereafter, the decrease in the diameter is not proportional to the falling off in the diameter of the last formed ring. 3. Phloem development continues until late in the autumn, much longer than xylem development. Sieve tubes in all stages formation occur between cambium and fully formed phloem. The seasonal growth of phloem exhibits little or no compression as late as October first. Subsequently contraction occurs, due to the extreme cold temperatures of winter. All the seasonal growth of phloem is crushed with the exception of the last 6 or 8 transitional tracheids. Compression is greater in the crown than below. 4. The processes of primary thickening and secondary thickening overlap, and both may be going on in closely neighboring spot sin the tree at the same time. 5. Growth in white pine is divisible into (a) growth without cell division and (b) growth with cell division. The first begins as early as March and the elements concerned (phloem) increase in radial diameter from 50 to over 100 per cent. The awakening of growth is due apparently to the rise of soil water with an accompanying increase in temperature. 6. Growth by cell division begins during the last half of April. At the start it is very rapid, and more elements are formed at the inside of the cambium than at the outside. The formation of new xylem elements follows, the same order as in pitch pine, that is, it begins first in the bole at some distance below the apical shoot and spreads upward and downward. As a result, growth at the base of a tree may begin several weeks later than in the crown. 7. The awakening and rapidity of growth is dependent on three factors, moisture, available food (reserve), and temperature. The first two are at an optimum in the spring; the amount of growth therefore is directly proportional to prevailing temperatures. 8. The intensity of growth is a variable factor which changes from day to day and even within a single day. Two periodic optimums of growth intensity occur, one during May and early June, the second in July and August. These vary from time to time at a given height in the tree and follow no definite law. 9. The amount of growth at a definite time and place in the tree is equal to the sum of the prevailing growth intensities by the time each was in force. It is very irregular at different heights in the tree, but the cambium tends to even up discrepancies as the season progresses. The irregularities of growth are manifested not only in the actual dimensions of the newly formed tissues, but also in the xylem elements. Wide discrepancies may occur in closely neighboring trees; in general, larger differences may be expected the greater the disparity in age. 10. Growth is first retarded in the upper portions of the tree; it may continue vigorously below for some weeks longer. 1. Xylem formation goes on very Sluggishly in all parts of the tree (the terminal leader excepted) until late September and early October, phloem development as long as temperature permits. 12. The total growth of white pine extends over a period of 5.5 months, growth by cell division between 4 and 5 months. 13. Late wood formation begins during the first half of August; it is associated with a decrease in growth intensity and begins first in the higher parts of the tree. 14. Elongation of new shoots and leaves is simultaneous and begins in early May; it manifests itself only after xylem formation has begun. Growth in length in the shoots ceases about July 1; needle growth may continue until August 15 or even later. 15. White pine has long roots and short roots. Only the first elongate to any extent and often are in symbiosis with mycorhiza. Growth in length begins during the last half of April, in some cases even earlier; no reliable data were obtained regarding its cessation. Secondary growth occurs during the first season and proceeds in the usual way.