THE YIELD OF EUCALYPTUS REGNANS LOGS FOR LUMBER PRODUCTION WAS EVALUATED. CRACK WIDTH AND LENGTH AT EACH LOG END WERE MEASURED. TWO LOG-CUTTING PLANS WERE USED TO OBTAIN SAWN LUMBER. THE FIRST PLAN (PA) CONSIDERED LOGS WITH DIAMETERS VARYING FROM 28 TO 40 CM, AND IN THE SECOND PLAN (PB), THE LOG DIAMETERS RANGED FROM 42 TO 56 CM (PB). LUMBER YIELD WAS DETERMINED USING TWO LOG VOLUME METHODS: THE JAPANESE AGRICULTURAL STANDARDS (JAS) AND SMALIAN

THIS STUDY AIMED TO EVALUATE THE EFFECT OF WATER IMMERSION ON THE RELEASE OF GROWTH STRESSES IN 17-YEAR-OLD EUCALYPTUS NITENS LOGS. A TOTAL OF 18 OF 90 TREES EVALUATED IN THE FIELD WERE SELECTED. THE AVERAGE DIAMETER AT THE HEIGHT BREAST OF ALL THE TREES WAS 37 CM. THE FIRST SECTION OF THE TREE, FROM THE STUMP TO 2.44 M, WAS USED. THREE STRESS LEVELS (LOW, MEDIUM, AND HIGH) WERE ESTABLISHED. SIX LOGS WERE STUDIED FOR EACH LEVEL, WHICH WAS DIVIDED INTO TWO GROUPS: THREE FOR CONTROL AND THREE FOR WATER IMMERSION. PERIPHERAL LONGITUDINAL STRAINS ON STANDING TREES, FRESHLY FELLING, AND AFTER THE IMMERSION PROCESS WERE DETERMINED BY AN EXTENSOMETER. THE DEFLECTION OF THE SAWN TIMBER AND LOG-END SPLITTING BEFORE AND AFTER AIR-DRYING WERE EVALUATED. IN ADDITION, THE DISTRIBUTION OF GROWTH STRESSES WAS DETERMINED. THE RESULTS SHOWED THAT DEFLECTION, THE LOG-END SPLITTING INDEX, AND STRESS DISTRIBUTION WERE REDUCED IN THE THREE LEVELS. THE WATER IMMERSION METHOD ALLOWED A REDUCTION OF GROWTH STRESSES IN EUCALYPTUS NITENS LOGS.

THE USE OF EUCALYPTUS NITENS HAS DIVERSIFIED THE CHILEAN LUMBER INDUSTRY IN UNPRECEDENTED WAYS. HOWEVER, GROWTH-INDUCED STRAINS CAUSE SPLITTING AND WARPING. THE OBJECTIVE OF THIS INVESTIGATION WAS TO DETERMINE THE EFFECT OF THE HEAT TREATMENT APPLIED TO LOGS OF EUCALYPTUS NITENS ON THE REDUCTION OF GROWTH STRESSES AND IMPROVEMENT OF QUALITY IN SAWN WOOD. LOGS WERE EXTRACTED AT DIFFERENT HEIGHTS OF THE TREE FOR 15-YR AND 20-YR-OLD TRESS. THE SAWMILL PROCESS WAS ALLOWED TO OBTAIN RADIAL, MIXED, AND TANGENTIAL PLANE PIECES, AT TWO THICKNESSES (25 AND 50 MM). THE EVALUATION OF MC AND WARPING WAS ACCORDING TO CHILEAN NATIONAL STANDARDS. THE RESULTS OBTAINED IN THIS RESEARCH SUGGEST THAT BY APPLYING THE HEAT TREATMENT TO EUCALYPTUS NITENS LOGS, A SIGNIFICANT REDUCTION IN GROWTH STRAINS CAN BE ACHIEVED. HEAT TREATMENT ALSO INCREASED THE QUALITY OF THE PIECES IN TERMS OF BOW, CROOKING, AND TWISTING. THEREFORE, THERE ARE SUBSTANTIAL BENEFITS OF USING HEAT TREATMENTS TO REDUCE DEFECTS CAUSED BY GROWTH STRAINS AND THUS INCREASE THE QUALITY OF THE WOOD AND REDUCE ITS WARP.

THE AIM OF THIS RESEARCH WAS TO PROPOSE MODELS TO PREDICT THE DRYING RATE OF EUCALYPTUS NITENS WOOD. FOR THIS, TANGENTIAL PIECES WITH A THICKNESS OF 36 MM, A WIDTH OF 100 MM AND A LENGTH OF 1000 MM WERE USED, WHICH WERE SUBJECTED TO ISOTHERMAL DRYING IN A SEMI-INDUSTRIAL CONVECTIVE CHAMBER, CONTROLLING THE MASS AT REGULAR INTERVALS OF TIME. THE TESTS CONSIDERED TWO CONDITIONS; CONDITION 1 (DRY / WET BULB TEMPERATURE 40/35 ° C) AND CONDITION 2 (55/50 ° C), WITH AIR VELOCITY 2 (M / S). THE EUCALYPTUS NITENS SHOWED DECREASING DRYING PHASES, WHILE THE CRITICAL MOISTURE CONTENT CORRESPONDED TO THE INITIAL MOISTURE CONTENT. THE SATURATION POINT OF THE EXPERIMENTAL FIBERS VARIED WITH THE DRYING TEMPERATURE, WITH AN ERROR OF UP TO 6.3% WITH RESPECT TO THE THEORETICAL VALUE. THE DRYING RATE WAS SIGNIFICANTLY AFFECTED BY MOISTURE CONTENT AND DRY BULB TEMPERATURE. THE RESULTS SHOWED THAT THE SIMPLE AND MULTIPLE REGRESSION MODELS (P-VALUE:

THE SELECTION OF EUCALYPTUS NITENS (H. DEANE & MAIDEN) LOGS FOR HIGHER VALUE-ADDED PRODUCTS IS COMPLEX, DUE TO THE PRESENCE OF RADIAL AND LONGITUDINAL SPLITS AS A RESULT OF GROWTH STRESS, WHICH REDUCES THEIR UTILIZATION IN SOLID PRODUCTS. THE OBJECTIVE OF THIS RESEARCH WAS TO DETERMINE THE LIMITED TIME FOR THE UTILIZATION OF THE LOGS TO INCREASE THEIR USE IN HIGHER VALUE-ADDED PRODUCTS. FORTY TREES WITH TWO 4 M LOGS WERE USED. THE RADIUS (RT), RADIAL, AND END-SPLITTING ALONG THE LOG (RLONG) WERE MEASURED ON DAYS 0 AND 1 IN THE FOREST AND LATER ON DAYS 7, 14, 21, AND 28, AT THE UNIVERSIDAD DEL BI = O-BI = O, WHERE THEY REMAINED UNDER SPRINKLER IRRIGATION AND COVERED WITH POLYETHYLENE PLASTIC. THE RELATIVE SPLITTING INDEX (SI) WAS DETERMINED AS (RMAX/RT) PER LOG. THE RESULTS SHOWED THAT THERE WERE SIGNIFICANT DIFFERENCES IN THE MAXIMUM END SPLITTING INDICATOR (RMAX) WITH LOG HEIGHT AND STORAGE TIME. THE SI INDICATOR SHOWED SIGNIFICANT DIFFERENCES WITH STORAGE TIME, BEING A BETTER FIT THAN RMAX. THE LINEAR MODEL THAT SHOWED THE RELATIONSHIP BETWEEN THE EXTERNAL OPENINGS OF THE SPLITS AND THE LONGITUDINAL SPLIT HAD A COEFFICIENT OF DETERMINATION (R2) OF 0.77. IN CONCLUSION THE USE OF EUCALYPTUS NITENS WOOD IS CONDITIONED BY THE INITIAL QUALITY OF LOGS THAT ENTER THE MECHANICAL TRANSFORMATION PROCESS, STORAGE TIME OF FEWER THAN 7 D, USE THE SECOND LOG AND HAVE A DIAMETER GREATER THAN OR EQUAL TO 40 CM, WITH RADIAL SPLITS AT THE ENDS LESS THAN 75% (SI 5 # 75*RT %) OF THE RADIUS AND CONSIDER AN OVERSIZE OF AT LEAST 20 CM AT EACH END OF THE LOG.

EUCALYPTUS NITENS HAS A GREAT POTENTIAL FOR ITS USE IN HIGHER VALUE-ADDED PRODUCTS, MAINLY DUE TO ITS GROWTH RATE AND ADAPTABILITY TO DIFFERENT SOILS AND CLIMATES. HOWEVER, ITS USE IS STILL LIMITED, DUE TO LACK OF KNOWLEDGE OF ITS PHYSICAL PROPERTIES THROUGHOUT THE LOG. IN THIS SENSE, THE OBJECTIVE OF THE RESEARCH WAS TO MODEL THE PHYSICAL PROPERTIES AT DIFFERENT HEIGHTS AND AGE OF THE TREE. TO DO SO, 40 TREES OF 13 YEARS, 12 OF 15 YEARS AND 5 OF 20 YEARS WERE SELECTED, EVALUATING THEIR PHYSICAL PROPERTIES FROM THE BASE (0.3 M) TO THE USABLE FREE DIAMETER OF 8 CM. THE BASIC DENSITY AND MOISTURE CONTENT WERE DETERMINED BY STANDARD NCH176/2 OF. 86 AND NCH176/1 OF. 86, RESPECTIVELY. THE RESULTS SHOWED A BASIC DENSITY AT 13 YEARS OF 474 KG/M 3 , WITH A MOISTURE CONTENT OF 116%, AT 15 YEARS IT WAS 496 KG/M 3 AND 108% AND AT 20 YEARS IT WAS 521 KG/ M 3 AND 104% RESPECTIVELY. THERE WAS AN INCREASE OF 4.6% AND 9.7% IN THE BASIC DENSITY AT 15 AND 20 YEARS COMPARED TO 13 YEARS. THE MODEL DETECTED AN INVERSE RELATIONSHIP BETWEEN THE BASIC DENSITY AND MOISTURE CONTENT, BOTH PRESENTING A HIGH CORRELATION WITH THE HEIGHT AND AGE OF TREE. FINALLY, THE MODEL PREDICTED WITH HIGH LEVEL OF PRECISION THE PHYSICAL PROPERTIES IN EUCALYPTUS NITENS TREES. SO, IT CAN BE USED AS A TOOL TO SUPPORT DECISION-MAKING WHEN DEFINING THE USE OF LOGS ACCORDING TO THE TYPE OF PRODUCT TO OBTAIN.

THE OBJECTIVE OF THIS RESEARCH WAS TO DEVELOP REGRESSION MODELS, WITH THE PURPOSE OF ESTIMATING THE GROWTH STRESSES AND END SPLITTING, IN 12-YR-OLD EUCALYPTUS NITENS TREES LOCATED IN THE PROVINCE OF VALDIVIA, CHILE. A TOTAL OF 40 TREES WERE SAMPLES. THEIR LONGITUDINAL RESIDUAL STRAIN (LRS) WAS MEASURED USING THE CIRAD-FORÊT METHOD AND COMPARED WITH THE COUNCIL OF SCIENTIFIC AND INDUSTRIAL (CSIR) INDEX AND WITH A NEW INDEX PROPOSED IN THIS INVESTIGATION, CALLED THE SPLITTING INDEX. PHYSICAL AND DENDROMETRIC PROPERTIES OF EACH SELECTED TREE WERE MEASURED TO IDENTIFY POSSIBLE CORRELATIONS BETWEEN THESE VARIABLES. THESE PREDICTORS WERE ANALYZED STATISTICALLY, ALLOWING THE DEVELOPMENT OF REGRESSION MODELS, WHICH SHOWED A COEFFICIENT OF DETERMINATION (R2) OF 0.783 AND 0.770 TO PREDICT THE LRS AND CSIR INDEXES, RESPECTIVELY. FINALLY, A RELATIVELY ROBUST REGRESSION MODEL WAS DEVELOPED TO PREDICT END SPLITTING IN LOGS USING LRS AND PHYSICAL AND DENDROMETRIC PARAMETERS.

SIMULATION HAS BEEN WIDELY USED TO IMPROVE AND OPTIMIZE THE WOOD DRYING PROCESS. OF THESE, THE DIFFUSIVE MODELS ARE USED TO PREDICT THE SLOW-DRYING HARDWOOD AND LOW PERMEABILITY SPECIES, SO IT COULD BE SUITABLE TO SIMULATE THE DRYING PROCESS IN EUCALYPTUS NITENS SAWN-WOOD. THE AIM OF THIS RESEARCH, WAS TO SIMULATE THE MOISTURE GRADIENT AND DRYING CURVE, IN EUCALYPTUS NITENS TANGENTIAL SAWN-WOOD. TWO ISOTHERMAL DRYING CONDITIONS WERE EVALUATED (40/35 °C AND 55/50 °C) AT AIR VELOCITY OF 2 M/S, AND THE EXPERIMENTAL VALUES OF MOISTURE GRADIENT AND DRYING CURVE WERE OBTAINED, BEING COMPARED WITH VALUES PROVIDED BY THE NUMERICAL SOLUTION OF THE MODEL. THE RESULTS SHOWED A DIFFUSION COEFFICIENT BETWEEN 1.5-4.5×10-10 (M 2 /S), SHOWING AN INVERSE RELATIONSHIP WITH THE MOISTURE CONTENT AND A DIRECT RELATIONSHIP WITH THE DRYING TEMPERATURE. THE SIMULATION SHOWED A CORRECT ADJUSTMENT OF THE MOISTURE GRADIENT AND DRYING CURVE, INCREASING THE PRECISION IN THE LAST DRYING STAGES. THEREFORE, THE MODEL WAS CONSIDERED ADEQUATE AND LOW COMPUTATIONAL COST, TO PREDICT THE DRYING IN EUCALYPTUS NITENS SAWN-WOOD.