THE THERMAL MODIFICATION OF WOOD IS A POTENTIAL ALTERNATIVE METHOD FOR IMPROVING WOOD DIMENSIONAL STABILITY AND INCREASING THE RESISTANCE OF WOOD TO DECAY. HOWEVER, DURING THERMAL MODIFICATION, MORPHOLOGICAL CHANGES OCCUR WITHIN THE MICROSTRUCTURE OF THE CELL, AND THESE CONFER DIFFERENT PROPERTIES TO THE WOOD. THIS STUDY INVESTIGATED THE EFFECTS OF THE THERMAL MODIFICATION PROCESS ON THE MICROSTRUCTURE OF RADIATA PINE JUVENILE WOOD. THEREFORE, ANATOMICAL MEASUREMENTS WERE PERFORMED VIA OPTICAL MICROSCOPY IN SELECTED EARLYWOOD AND LATEWOOD SAMPLES AFTER EACH TREATMENT, AND THE RESULTS WERE COMPARED TO UNTREATED WOOD SAMPLES. IN THIS STUDY, TWO TEMPERATURES (190 °C AND 210 °C) WERE CONSIDERED FOR THE THERMAL MODIFICATION PROCESS. THE RESULTS SHOWED THAT THE LEVEL OF TEMPERATURE OF MODIFICATION AFFECTED TO MICROSTRUCTURE OF CELL WALL. THE CELL WALL THICKNESS DECREASED AS TREATMENT TEMPERATURE INCREASED, WHEREAS THE AVERAGE LUMEN DIAMETER INCREASED SLIGHTLY AS TEMPERATURE INCREASED. THERMALLY MODIFIED RADIATA PINE SHOWED SIGNS OF DAMAGE (CRACKS, BROKEN CELLS AND DEFORMATIONS IN THE WOOD CELL WALL). THE PROPORTION OF DESTROYED AREA INCREASED AS TEMPERATURE INCREASED, AND SIGNIFICANT DIFFERENCES WERE EVIDENT FOR THE THERMAL TREATMENT AT 210 °C.

THIS PAPER STUDIES THE RELATIONSHIP BETWEEN APPARENT DENSITY AND SOME ANATOMICAL PROPERTIES OF EUCALYPTUS NITENS SUCH AS VESSEL FREQUENCY, VESSEL AREA, RING WIDTH, FIBER CELL WALL THICKNESSES, AND FIBER LENGTH. THE STUDY INVOLVED 29 TREES FROM 10 FAMILIES OF EUCALYPTUS NITENS CUT FROM A 17-YR-OLD PLANTATION IN SOUTHERN CHILE. THE PROPERTIES WERE DETERMINED ALONG THE RADIAL DIRECTION OF THE TREES BY USING X-RAY EQUIPMENT AND AT SELECTED POSITIONS THROUGH MICROSCOPE AND FIBER QUALITY ANALYZER EQUIPMENT. THE RESULTS SHOWED THAT THE ANATOMICAL PROPERTIES OF E. NITENS DID NOT CHANGE GRADUALLY FROM PITH TO BARK, BUT THEY WERE BETTER DESCRIBED BY DIVIDING THE TREE RADIUS INTO THREE DIFFERENT WOOD-ZONES REFERRED AS * CORRESPONDING AUTHOR ? SWST MEMBER INNER-, MIDDLE-, AND OUTER-WOOD. THE APPARENT DENSITY OF E. NITENS WAS DEPENDENT OF THE VESSEL AREA, CELL WALL AREA, RING WIDTH, AND LATEWOOD WIDTH. THE CORRELATION COEFFICIENT BETWEEN APPARENT DENSITY AND VESSELS AREA WAS NEGATIVE AND THE CORRELATION COEFFICIENT BETWEEN APPARENT DENSITY AND CELL WALL AREA, LATEWOOD RING WIDTH, AND TOTAL RING WIDTH WERE POSITIVE. THESE MEANS THAT E. NITENS WOOD WITH LOWER DENSITY TENDED TO HAVE HIGHER VESSEL AREA, AND LOWER FIBER CELL WALL AREA, RING WIDTH, AND LATEWOOD WIDTH.

THE OCCURRENCE OF INTERNAL CHECKS AND THEIR RELATIONSHIP WITH ANATOMICAL STRUCTURE AND BASIC DENSITY IN THREE CLONES OF EUCALYPTUS NITENS PLANTATION TREES GROWN IN THE EIGHTH REGION OF CHILE WERE STUDIED. TWO TREES PER CLONE WERE SAMPLED. THE NUMBER, RADIAL LOCATION, AND LENGTH OF INTERNAL CHECKS WERE DETERMINED IN SAMPLES OVEN-DRIED AT TEMPERATURES INCREASING FROM 50 TO 100?C. WOOD ANATOMICAL FEATURES INCLUDING VESSEL FREQUENCY AND DIAMETER AND ANNUAL GROWTH RING WIDTH WERE MEASURED BY IMAGE ANALYSIS. RESULTS SHOW THAT INTERNAL CHECKS WERE GREATER FOR CLONES WITH LOWER BASIC DENSITY. INTERNAL CHECK FREQUENCY DECREASED WITH HEIGHT IN THE TREE AND INCREASED FROM PITH TO BARK. A LOW WOOD BASIC DENSITY WAS RELATED TO GREATER RING WIDTH AND VESSEL FREQUENCY, WHICH CONTRIBUTED TO THE DEVELOPMENT OF INTERNAL CHECKS.