Characteristics of Compression Wood Tracheid of Loblolly Pine Induced by Artificial Inclination

Three-year-old seedlings of loblolly pine (Pinus taede L.) were selected as materials in this article. The seedlings were planted in spring and divided into five groups, then were artificially inclined at the angles of 0°, 15°, 30°, 45° and 60° from the vertical. The characteristics of compression wood tracheid were observed and recorded, and their variation patterns were analyzed. The following conclusions were drawn: 1) with the increase of the inclined angle, the wall thickness of tracheid increased and the outline of the tracheid became round, the intertracheidular spaces were obvious and increased gradually in all sections derived from the inclined seedlings. The typical characteristics of compression wood were obvious when the inclined angle was bigger than 30°; 2) with the increase of the inclined angle, the tracheid length decreased firstly and then fluctuated, the minimum value reached at 30°; the tracheid width decreased firstly and then increased, the minimum value reached at 45°; the double wall thickness increased firstly and then decreased, the maximum value reached at 45°. 3) In the seedlings studied, the critical angle of inclination was about 30° or 45° from the vertical.

Effect of the position in a stem on the length of tracheids in spruce (Picea abies [L.] Karst.) with the occurrence of reaction wood

The paper was aimed at the determination of variability of tracheid dimensions in spruce wood in relation to the position in a spruce stem. Significant changes in dimensions were found in early-wood and late-wood tracheids along the stem length and radius. There were statistically significant differences (variability along the radius) between particular annual rings. The height of 22 m showed statistically significant differences as compared with other heights (variability along the height). Differences between the length of early-wood and late-wood tracheids were not corroborated in zones CW, OW and SWL. Only in the SWP zone, statistically significant differences were found. Data sets (early-wood and late-wood tracheids) from the CW zone showed statistically significant differences as compared with other zones. On the basis of the results obtained, 3D models were created (for CW, OW, SWL and SWP zones; models for an early-wood and late-wood tracheid) describing changes in tracheid dimensions in spruce in relation to the position in a stem. In the models, the length of tracheids decreases with the height of a stem and on the other hand, with an increasing distance from the stem pith the length of tracheids increases. The importance of the paper consists in the enlargement of findings on the structure of spruce wood. In addition to this, the paper can contribute to the partial explanation of the different behaviour of physical and mechanical properties of wood in particular parts of the spruce stem.

Study of the Influence of Anatomical Characteristics on Dyeing Effects of Plantation Pinus sylvestnis var. mongolica litv. Veneer

This paper takes plantation pinus sylvestnis var. mongolica litv. as study object, determines main anatomical factors influencing wood dyeing effects by measuring the related indexes of wood anatomical structure and dyeing effects, making a multiple regression analysis of them and analyzing the correlation variation law between wood anatomical structure and dyeing effects. The results show that there is a high correlation between pinus sylvestnis var. mongolica litv. dyeing effects and wood anatomical factors and the multiple correlation coefficients between anatomical factors and various dyeing effect indexes are between 0.573 and 0.786. The main anatomical factors influencing pinus sylvestnis var.mongolica litv.dyeing effects are tracheid proportion, wood ray proportion, resin canal proportion and late wood tracheid length, etc.

Effects of the position in a stem on the variability of tracheids in spruce (Picea abies /L./ Karst.) with the occurrence of reaction wood

The paper is aimed at the field of the microscopic structure of wood dealing with the description of the most important anatomic element in softwood – tracheids in a stem with the occurrence of reaction wood. Significant changes of tracheids were found along the height and radius of a stem. There were statistically significant differences between particular annual rings (variability along the stem radius). The height of a stem was also statistically significant. On the basis of the results obtained 3D models were created (for zones compression wood, opposite wood and site wood; models for radial dimension an early-wood tracheid and late-wood tracheid) depicting changes in transverse dimensions of the spruce tracheid in relation to its position in a stem. Structure of ring with compression wood was studied too. It was observed that the ring with occurrence of compression wood has a following structure: early wood tracheids at the beginning of the growing season, transitional tracheids, compression tracheids and at the end of an annual ring typical late wood tracheids. The rings with compression wood show more tracheids as compared with annual rings from the opposite side.

MICROFIBRIL ANGLES IN THE ROOT WOOD OF PINUS RADIATA AND PINUS NIGRA

Microfibril angles of the S2 layer and tracheid lengths were measured in the root wood of Pinus nigra, and the root and stem wood of Pinus radiata. Within 10 mm (the first 2–3 growth rings) from the root centre, microfibril angles were large in the wood of both species, ranging from 25° to 40°. Beyond 10 mm (the fourth growth ring and beyond) from the root centre, microfibril angles were small. This pattern of microfibril angle change in root wood differs from those normally found in stems where angles are large until the 10–15th rings. Root wood tracheid length also showed a different pattern in radial direction from that normally observed in stem wood. Tracheids of Pinus radiata root wood were long in the first ring, decreasing to the third ring and then increased to the seventh ring. Beyond the seventh ring tracheid length was stable at around 3 to 3.5 mm. It was noted that microfibril angles were not influenced by tracheid length in root wood.