Various non-destructive evaluation (NDE) technologies increasingly used to assess log stiffness and support sorting, segregation and processing decisions. However, comprehensive comparative evaluations of various NDE tools across the wood value chain remain limited. Therefore, this study compared several NDE methods for estimating modulus of elasticity (MOE) in southern pine grown in Queensland, Australia, at three processing stages: standing trees pre-harvest, felled logs post-harvest, and boards produced from those logs. Standing trees measurement included ultrasound MOE assessment on increment cores (USMOE) and Director ST300 (ST300_MOE) and IML-Resi PD-400 resistance drilling (Resi_MOE). Felled log measurements were obtained using Beam Identification by Non-destructive Grading (BING_MOE) and the resonance acoustic tool Hitman HM200 (HM200_MOE). These measurements were then related to log MOE, log density, and the average MOE and modulus of rupture of boards cut from the same trees. Finally, log stiffness measurement tools were compared in terms of deployability, efficiency, and predictive power. NDE tools applied to standing trees pre-harvest generally exhibited lower predictive power in estimating log and board MOE than tools applied to felled logs. For log MOE, HM200_MOE showed the strongest relationship with BING_MOE ( R^2= 0.78) followed by USMOE ( R^2=0.67 ), ST300_MOE ( R^2=0.61 ), and Resi_MOE ( R^2=0.57 ). BING_MOE explained the highest variability in the average board MOE ( R^2=0.84 ), followed by USMOE ( R^2=0.71 ), HM200_MOE ( R^2=0.69 ), ST300_MOE ( R^2=0.64 ), and Resi_MOE ( R^2=0.43 ). These results highlight a clear trade-off between predictive performance and operational practicality. BING and HM200 provided better accuracy and precision, but unsuitable for standing tree assessment. Among the standing trees methods, USMOE provided best balance between precision and accuracy and potential field use but are slower and more expensive. ST300 and Resi were faster and more practical for pre-harvest sorting their lower predictive performance underscores the need for improved calibration or modelling. Overall, tool selection depends on the required balance between predictive performance, operational efficiency, sampling requirement and cost.

• Within-stem and between stem variation in log stiffness in 591 logs of 2.5 meters in length were assessed from 65 Pinus radiata D.Don trees, sampled across 13 plots of 5 individual trees, representing 7 forests in northern Tasmania, Australia. • Average log stiffness was significantly affected by stand age, stocking and basal area. • Within stems, a consistent pattern of increasing then decreasing modulus of elasticity and acoustic resonance was observed with highest stiffness values between 5 and 15 metres above ground. The general pattern was consistent among sites with between site variance predominantly in the y-intercept value. • Resi-predicted basic density was significantly correlated with log modulus of elasticity (MOE), with the strength of the relationship varying markedly among sampling points based on position within the stem. • Multiple regression and random forest models, based on traits extracted from the Resi trace, were found to better account for variance in log MOE, compared to Resi-predicted basic density alone. Random forest models were able to explain 56% of the variation at the individual tree level; this improved to 88% at the site level.

The IML PD series Resi instrument is widely used for wood quality assessment, valued for its speed, cost-effectiveness, and precision. Currently, it is not known to what degree needle diameters are an issue for quantifying wood density and stiffness. Additionally, some anecdotal evidence suggests that the battery might have an effect as well. To quantify the impact of needle diameter, twelve new Resi needles (3.08-3.30 mm) were tested using a single IML Resi PD 500 instrument on a southern pine (Pinus elliottii var. elliottii (Engelm) x Pinus caribaea var. hondurensis (S & eacute;n & eacute;clauze)) log with settings of 200 cm/min feed speed and 3500 rpm. Each needle was tested 44 times, along with five different batteries. The maximum difference in drilling resistance between needles was 2.3%, corresponding to a 15.4 kg/m(3) difference in predicted basic density. This occurred with extreme needle diameters (3.08 mm or 3.21-3.30 mm), while needles within the typical 3.11-3.20 mm range showed no significant difference. Feed resistance was highly sensitive to needle diameter changes, with an 11.5% difference translating to a 108.1 kg/m(3) density difference. Battery effects were minimal, causing only a 0.5% amplitude difference in drilling resistance.

Semi-non-destructive drilling resistance instruments have been widely adopted for timber testing and forestry for wood quality assessments. The accuracy of a drilling resistance tool for predicting wood density may be affected by needle (drill) wear, and there is limited information regarding the wear behaviour of drill bits in wood resistance drilling. It is unknown when changes in needle sharpness and diameter become critical for quantifying wood density. To measure the effect of Resi needle wear, an IML Resi PD 500 was used to obtain cross-sectional traces of Southern Pine (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Sénéclauze)) average outerwood density: 519 kg/m³ and Spotted Gum (Corymbia citriodora subsp. variegata (F. Muell.)) average outerwood density: 779 kg/m³ logs. Southern Pine was tested with feed speeds of 200 cm/min at 3500 rpm and 100 cm/min at 5000 rpm. Spotted Gum was tested with a feed speed of 70 cm/min at 5000 rpm. A new needle was used for each setting. The effect of needle wear was tested after 0, 100, 200, 300, 400, 500, and 600 m of drilling depth. There was no effect on drilling resistance values up to 600 m of drilling length with feed speed 200 cm/min and 3500 rpm settings for Southern Pine. This would result in 2000 drilling measurements of 30 cm diameter trees. With alternative setting for Southern Pine with a setting of 100 cm/min feed speed and 5000 rpm, the increase in amplitudes was not significant until 300 m of drilling, after which, at 400 m, the amplitude increased by 2

The IML PD series Resi is an instrument designed to measure the drilling resistance of wood. Use of the IML PD series Resi instrument is rapidly becoming a routine method among Australian forest plantation growers for wood quality assessments. The major driver in the commercial uptake of the IML Resi is that it is fast, cheap, and sufficiently precise for commercial use, particularly when the data are processed through a user-friendly, web-based processor. This study examined whether the accuracy of wood density predictions was impacted by the use of different Resi tools and different operators, which has never been examined before. Seven Resi instruments were evaluated across six sites with two operators on plantation-grown Southern Pine (Pinus caribaea var. hondurensis (Sénéclauze) or hybrids between Pinus elliottii var. elliottii (Engelm) × P. caribaea var. hondurensis) trees. Two types of Resi instruments were used (IML Resi PD-400 and IML Resi PD-500), and all had been recently serviced or were new. The instruments were operated by experienced operators. Constant sampling conditions of feed speed 200 cm/min and 3500 RPM were used. The order of instrument use, and hence the order of operator assessment at each site, was randomized. The variance between Resi instruments was small. The measured mean basic density of 50 mm outerwood cores across all plots was 542 kg/m3, while Resi-predicted basic density varied among instruments between 535 and 547 kg/m3. One Resi instrument underpredicted basic density by 9 kg/m3 and another overpredicted by 5 kg/m3. The operator had no effect on the basic density prediction. Resi PD400 or PD500 instruments gave similar basic density predictions.

Cost-effective, non-destructive means of estimating wood properties of eucalypts grown in Guangxi, China, were evaluated using near infrared (NIR) spectroscopy and resistance drilling. For this evaluation, wood samples for NIR analysis and resistance drill measurements were collected from 581 trees, representing eight plantation Eucalyptus taxa across five sites. The near infra-red (NIR) spectra collected from the 581 wood samples were analysed using existing calibrations for kraft pulp yield, cellulose content, hot water extractives and Klason lignin. These spectra and calibrations were effective in predicting over 60% of the variance in total carbohydrates and over 80% of the extractives and lignin values from independent laboratory analysis of a subset of 100 samples. Resistance drilling combined with software developed for processing the drill data proved to be a quick, low cost and effective means of quantifying wood density (as amplitude of the drill torque), stem diameter and bark thickness.

The IML PD series Resi is a device used to assess the drilling resistance of wood. The IML PD series Resi instrument is being widely adopted for commercial wood quality assessment due to its speed, cost-effectiveness, and precision when combined with web-based trace processing. Collecting Resi data with fixed feed speed and RPM settings is challenging due to inherent basic density variations within and between tree species. Altering these settings affects the drilling resistance amplitude of the Resi data, impacting basic density predictions. This study introduces the concept of chip thickness to combine feed speed and RPM into a single parameter to minimise the effects of different sampling conditions on the basic density predictions. Regression models, with chip thickness as the regressor variable, account for 97% to 99% of variance in mean Resi outerwood amplitude across six species. The demonstrated adaptability of chip thickness for adjusting feed speed and RPM settings, along with species-specific functions correlating it with Resi amplitude, holds promise for standardizing amplitude values across diverse feed speeds and RPM settings. Optimal sampling conditions needed to predict basic density lie within the 30%–40% amplitude range. To drill a ~30 cm diameter tree, the recommended fastest settings were 200 cm/min and 3500 RPM for Southern Pine (Pinus elliottii var. elliottii (Engelm) × Pinus caribaea var. hondurensis (Sénéclauze)) and Radiata Pine (Pinus radiata (D. Don.)), 200 cm/min and 2500 RPM for Hoop Pine (Araucaria cunninghamii (Mudie)), 50 cm/min and 5000 RPM for Spotted Gum (Corymbia citriodora subsp. variegata (F. Muell.)), 200 cm/min and 4500 RPM for White Cypress (Callitris glaucophylla (Thompson & Johnson)), and 150 cm/min and 3500 RPM for Shining Gum (Eucalyptus nitens (H. Deane & Maiden) Maiden) based on the billets sampled.

Mature age Pinus radiata D. Don trees were sampled across nine sites in northern New South Wales, Australia, that were expected, based on site quality and inventory metrics, to exhibit significant variation in productivity and wood quality. Twenty trees per site were harvested and 13 mm diameter, pith-to-bark increment cores were extracted from three trees per site from eight of the nine sites for SilviScan analysis. Outerwood increment cores were collected from all trees for basic density measurement. The same trees were also sampled using an IML PD400 (Resi) instrument. Radial mean properties of wood basic density derived from Resi traces were found to correlate strongly with the mean density data derived from SilviScan analyses and from increment cores. The Resi-derived basic density of 10 mm radial segments was strongly correlated with SilviScan measures of basic density averaged at similar intervals.

Eucalypt plantations in Tasmania have been managed predominantly for fibre production, but there is also growing interest in the production of solid wood products. For solid wood production, stiffness and basic density are key wood properties as they define the suitability of the timber for particular products and ultimately value. To inform processing options available for targeting high value wood products there is a need to understand how wood properties vary within a tree and how thinning impacts wood quality to foster efficient processing. Three thinning trials of 20-22-year-old plantation grown Eucalyptus nitens were used to assess stiffness and basic density longitudinally from the base to 20 m height in the tree and radially at a fixed height of 2.5 m. Longitudinally and radially, wood properties varied more within the tree than the variation which arose as a result of thinning. Stiffness was lowest at the bottom of the tree irrespective of thinning treatment and the highest stiffness was located from 7.5 to 15 m height depending on thinning and site. Commercial thinning to 300 trees ha(-1) had no effect on stiffness in the bottom of the tree but resulted in lower stiffness in the upper logs. Trees in thinned stands had slightly lower basic density and that reduction was consistent within the tree and across sites. Thinning resulted in significant radial change in wood properties and the thinning effect was apparent soon after the thinning treatment. The results demonstrate that thinning has an adverse impact on wood properties, but not to a degree that hinders the benefits thinning brings to maximizing wood growth. However, the high variation in wood quality within the tree suggests that it would be valuable segregating logs within a tree to maximize solid wood product value.

Standard correlation approaches in dendroclimatology provide limited scope to elucidate differences between years in timing of growth initiation and cessation. In the Southern Hemisphere (SH), with relatively few long-term climate reconstructions, a clearer understanding of signals contained in ring width variation is of partic-ular importance. In this study, we monitored growth in detail at two sites (low and high altitude) in Lagarostrobos franklinii (Huon pine) for five growing seasons. In concert, local environmental data were recorded, and cambial samples taken on several occasions. Season duration in Huon pine at low altitude lasted about six months, generally starting in September/October and ending in April. At higher altitude, season duration did not exceed about four months and generally started during November, ending in March. The shortest season and smallest rings were linked to cooler conditions compared to other years. On the other hand, an earlier growth onset in the 2011 growing season was evidently brought on by unusually warm conditions in late winter. Growth onset was linked to a running mean temperature of about 8.5 degrees C and 6.5 degrees C at the lower and higher altitude sites, respectively. While effects of limiting water on growth cessation were not universally clear, our results suggest that limiting water (during hotter, drier summers) may reduce growth rates, and precipitate earlier growth cessation.

Producing wood of the right quality is an important part of forest management. In the same way that forest growth models are valuable decision support tools for producing desired yields, models that predict wood quality in standing trees should assist forest managers to make quality-influenced decisions. A challenge for wood quality (WQ) models is to predict the properties of potential products from standing trees, given multiple possible growing environments and silvicultural adjustments. While much research has been undertaken to model forest growth, much less work has focussed on producing wood quality models. As a result, many opportunities exist to expand our knowledge. There has been an increase in the availability and use of non-destructive methods for wood quality assessment in standing trees. In parallel, a range of new models have been proposed in the last two decades, predicting wood property variation, and as a result wood quality, using both fully empirical (statistical) and process-based (mechanistic) approaches. We review here models that predict wood quality in standing trees. Although other research is mentioned where applicable, the focus is on research done within the last 20 years. We propose a simple classification of WQ models, first into two broad groupings: fully empirical and process-based. Comprehensive, although not exhaustive, summaries of a wide range of published models in both categories are given. The question of scale is addressed with relevance to the range of possibilities which these different types of models present. We distinguish between empirical models which predict stand or tree-level wood quality and those which predict within-tree wood quality variability. In this latter group are branching models (variation up the stem) and models predicting pith-to-bark clear-wood wood property variability. In the case of process-based models, simulation of within-tree variability, and specifically, how that variability arose over time, is always necessary. We discuss how wood quality models are, or should increasingly be, part of decision support systems that aid forest managers and give some perspectives on ways to increase model impact for forest management for wood quality.

Background: Resin pockets and blemishes in pruned logs of radiata pine (Pinus radiata D.Don) can reduce the value of clear and moulding grades of lumber. External resin features (ERF) on the bark of the logs have proved an effective method of predicting the incidence of resin pockets in the lumber. Resin canals have been associated with resin blemishes in radiata pine, and could prove useful in improving the prediction of the grade recovery of lumber. Methods: Pruned butt logs of radiata pine trees from two forests in the North Island, New Zealand, were selected for low, moderate, and severe levels of external resin features (ERF) on the bark, and for low, average, and high resin canal diameter, frequency and brightness from breast height increment cores. The relationships were evaluated between these properties, and the lumber resin features and grade recovery of the logs. Results: The number of resin pockets, the blemish rating, and the percentage of boards with resin streaks and resinous heartwood increased, and the recovery of clears and moulding grade boards and the lumber value declined, with the severity of the ERF class of the logs. Multiple regression models gave good predictions of the grade recovery and loss of lumber value, using the log ERF class, volume, heartwood content, and number of Type 1 resin pockets on the ends of the logs, as independent variables. The resin canal properties did not improve the regression models. Resin blemishes were associated with Type 2 resin pockets, and were more frequent in the forest where false growth rings were present. This suggests the constitutive resin flow from resin canals, rather than the resin canal size and frequency, is more important in determining the incidence of resin blemishes. Conclusions: The prediction of the grade recovery of lumber using the ERFs of radiata pine logs, was supplemented by the log volume, heartwood content and number of Type 1 resin pockets on the ends of the logs. The environmental factors that drive the constitutive resin enrichment of resin canals, such as drought conditions that give rise to false growth rings, could be useful in improving the prediction of grade recovery for forest stands.

Thinning of forestry plantations is a common silviculture practice to increase growth rates and to produce larger dimension logs. The wood properties, basic density and stiffness, are key indicators of the suitability of timber for particular purposes and ultimately determine timber value. The impact of thinning operations on wood properties is, therefore, of considerable interest to forest growers and timber producers. To date, studies examining the impact of thinning on wood properties have produced variable results and understanding the consistency of the effects of thinning treatments across various sites for important plantation species is limited. Two non-destructive assessment techniques, drilling resistance and acoustic wave velocity, were used to examine the impact of thinning on basic density and stiffness in 19–21-year-old plantation grown Eucalyptus nitens across three sites. Commercial thinning to 300 trees ha−1 decreased the stiffness of standing trees and this effect was consistent across the sites. Reduction in stiffness due to thinning ranged from 3.5% to 11.5%. There was no difference in wood properties between commercially and non-commercially thinned trees to 300 trees ha−1 and no difference in wood properties when thinned to 500 trees ha−1. Basic density was not affected by thinning. The site had significant effects on both basic density and stiffness, which were lowest at the highest precipitation and highest elevation site. The results indicate that wood properties are influenced both by silviculture and site environmental differences. This knowledge can be used for the better management of E. nitens resources for solid wood production.

Eucalyptus globulus is widely grown for pulpwood production in temperate regions of the world. However, there is increasing interest in using it for solid-wood products. We studied the genetic architecture of key pulpwood and solid-wood selection traits using two E. globulus progeny trials in a high rainfall area (wet) of Tasmania and a previously studied trial in a low rainfall area (dry). These trials were established using open-pollinated families from native trees sampled from 13 subraces. We assessed traits in common [diameter at breast height (DBH) and wood basic density (BD)], and specific to pulpwood [Kraft pulp yield (KPY)] and solid-wood [stem straightness and acoustic wave velocity (AWV)] breeding. Significant genetic variation was found for all traits. Strong GxE was detected for DBH across the wet and dry sites, but little for BD and KPY. At the wet sites we show a positive genetic correlation between DBH and KPY, but not between DBH and BD. Subrace and family within subrace correlations between KPY and BD were significant but in opposite directions. We confirm previous reports of significant positive genetic and phenotypic correlations between KPY and AWV. A positive genetic correlation between stem straightness and DBH was detected, and subraces with straighter stems tended to have higher KPY. In general, correlations between most solid-wood and pulpwood traits were favourable, suggesting that past selection for pulpwood traits had neutral or favourable effects on many key solid-wood traits. We conclude that breeding for solid-wood and pulpwood are relatively compatible.

Abstract Basic density is a fundamental wood property of pulp and sawn wood. An IML Resi PD 400 drilling resistance tool (IML System GmbH, Wiesloch, Germany) was used to evaluate the basic density of Eucalyptus nitens discs and the impact of needle friction on basic density prediction. To determine the accuracy of that prediction with the commonly used linear drill bit shaft friction correction and determine whether this correction is linear, 40 discs were drilled radially, then cut into segments which were measured for basic density. Drilling resistance had a strong relationship with basic density in the outer wood; it was weaker at the pith but this did not compromise prediction accuracy. When using a linear friction correction, the drilling resistance underpredicts basic density by 7.6% in the first 2–3 cm after stem entry, after which the prediction error ranged from 0.6–1.9%. The friction correction was found to be nonlinear, especially at the first few centimeters. To apply this friction correction, basic density values from the model should be added to predict basic density values until 2.9 cm from Resi entry point and after that subtracted to account for the drill bit shaft friction.

Tree breeders are increasingly using resistance drilling (RESI) for the non-destructive assessment of wood basic density, but its application to the measurement of stem diameter at breast height (DBH) and bark thickness is less reported. UsingEucalyptus globulusprogeny trials established with open-pollinated families from native trees representing 13 subraces, and adjusting bark thickness for its inherent phenotypic relationship with DBH, we: (1) quantified the genetic correlation between RESI and analogous traditional measurements of these traits; and (2) studied their genetic architecture and associations with subrace home-site climate. Significant variation was detected for all traditional and RESI-derived traits at the family and subrace level. High family and subrace-level correlations (>0.90) were found between RESI and traditional methods for all three traits. Bark thickness exhibited among the highest subrace differentiation (Q(ST)> 0.63) reported to date forE. globulus, signalling divergent selection. Increasing bark thickness was positively associated with home-site temperature annual range and seasonality. Although subrace differentiation for wood density (RESI and traditional measures) was less (Q(ST) = 0.18-0.21), a similar climate association was detected, and the subrace-level correlation with bark thickness was positive and significant (0.61-0.75). However, the non-significant correlations between bark thickness and wood density at the family level suggest that selective covariance rather than pleiotropy have caused the correlated patterns of subrace variation. Variation in bark thickness (adjusted) and wood density was independent of DBH at the family and subrace level. Given the importance of these traits, RESI provides a useful approach for non-destructive assessments for silvicultural, genetics and ecological studies of forest trees.

Radial variation of wood properties affects product recovery from veneer logs. In Eucalyptus nitens , the radial variation in wood density, microfibril angle and modulus of elasticity was described using non-linear models. The timing of radial change was trait-dependent, and the age at which thresholds for structural products were reached differed between sites. Eucalyptus nitens is widely planted in cool temperate regions of the world. While mainly grown for pulpwood, rotary-peeled veneer is becoming important. Threshold levels of wood stiffness are required for using this veneer for structural purposes. Stiffness is determined by wood density and microfibril angle, which improve with tree age. The nature of this radial variation affects the recovery of suitable veneer and profitability of the plantation resource. We model the radial variation of these veneer-critical wood properties and determine whether it varies with growing conditions. We used logs from three 20–22-year-old Tasmanian plantations. Radial variations in wood density, microfibril angle and modulus of elasticity (measuring stiffness) were assessed using SilviScan. Eight linear and non-linear models were examined using cambial age as the independent variable. The increases in wood density and modulus of elasticity with age were modelled by sigmoidal functions and the decrease in microfibril angle modelled by an asymptotic function. The timing of radial change was trait-dependent, and the mean ages at which thresholds for structural products were reached between sites. Radial variation varied among sites and will likely impact the recovery of structural grade veneer from plantations.

To maximize utilization of our forest resources, detailed knowledge of wood property variation and the impacts this has on end-product performance is required at multiple scales (within and among trees, regionally). As many wood properties are difficult and time-consuming to measure our knowledge regarding their variation is often inadequate as is our understanding of their responses to genetic and silvicultural manipulation. The emergence of many non-destructive evaluation (NDE) methodologies offers the potential to greatly enhance our understanding of the forest resource; however, it is critical to recognize that any technique has its limitations and it is important to select the appropriate technique for a given application. In this review, we will discuss the following technologies for assessing wood properties both in the field: acoustics, Pilodyn, Resistograph and Rigidimeter and the lab: computer tomography (CT) scanning, DiscBot, near infrared (NIR) spectroscopy, radial sample acoustics and SilviScan. We will discuss these techniques, explore their utilization, and list applications that best suit each methodology. As an end goal, NDE technologies will help researchers worldwide characterize wood properties, develop accurate models for prediction, and utilize field equipment that can validate the predictions. The continued advancement of NDE technologies will also allow researchers to better understand the impact on wood properties on product performance.

Average bark-to-bark resistance of the IML Resistograph PD400 (hereafter referred to as Resi') was found to provide strong linear correlations with the basic density of 12-mm-diameter increment cores taken from standing plantation eucalypt trees. Relationships between Resi values and approximately 2 000 cores (predominantly Eucalyptus globulus but some E. nitens) were examined across seven studies (representing samples from nine distinct sites) in Tasmania, Victoria and Western Australia. Custom-written software was developed to process the Resi traces to automatically perform a linear baseline correction of the trace, and extract: over-bark and under-bark diameterbark thicknessaverage resistance of the bark-to-bark (under-bark) traceaverage resistance of the outer 50mm on the entry and exit side of the traces.Baseline correction was needed to counter the variable effects among trees of needle drag across the diameter, largely a function of tree diameter and wood density.Individual traces were collected in less than 20s tree(-1). The sampling conditions of 150 cm min(-1) speed of forward movement (feed speed) and 3 500 revolutions per minute (rpm) were identified as optimal for the plantation eucalypts studied. The relationship between different feed speeds and rpm were linear and coefficients determined to allow average Resi resistance to be converted to a common set of sampling conditions. A simple linear regression was identified in each study to define a slope and intercept to convert the Resi values to basic density and determine the variance between them. Resi traces from different studies were not always collected using the same instrument and this is believed to explain most of the between-study variance in slope and intercept.Trace processing software was built into a web-based package that is available to make trace processing easy, with defined variables downloadable for use in routine plantation assessment. Users can change the default slope and intercept values to suit their individual instruments or species as required. Further work is required to fully define the effects of instrument, site and species on these relationships.The IML Resistograph PD400 was found to be an accurate and quick (40-70 trees hour(-1) person(-1)) infield tool for estimating diameter and wood density in standing trees. When combined with automated, web-based processing software the methodology is among the lowest cost options conceivable for wood density assessment of plantation eucalypts.

Background Stem radial growth in forests is not uniform. Rather, it is characterized by periods of relatively fast or slow growth, or sometimes no growth at all. These fluctuations are generally a function of varying environmental conditions (e.g. water availability) and, importantly, will also be associated with adjustments in properties in the wood formed. Stand level conditions and forest management, particularly thinning and stand density will, however, also have a major influence on patterns of growth variation. We explore how different thinning histories and/or stand densities influence these dynamics of tree growth in the important commercial plantation species Pinus radiata D. Don. Methods Daily stem size change was measured using electronic point dendrometers over two growing seasons on P. radiata trees at two sites, subjected to different thinning regimes. Timing, rates and periodicity of annual growth were calculated from these data. Results Greater overall cross-sectional growth in thinned plots was driven mainly by two dynamics. First, the cessation of seasonal growth occurred at least 3 weeks later in the stands in which thinning had taken place. There was no difference between thinned/unthinned stands, however, in the timing of growth onset. Second, within the longer season, trees in thinned plots had more growth days (as much as 20% more) than unthinned plots. The rates of growth on days when growth occurred were not different, however. In this context, it is notable that in trees in the unthinned plots experiencing the most severe competition there were strong “pulses” of growth following drought-breaking rainfall events. Unthinned plots at high stand densities also maintained a smaller (but consistent) zone of dividing cells throughout the season than thinned plots. Conclusions In Pinus radiata growing under conditions as in our study, conditions late in summer, particularly drought, have an important effect on the timing of cessation of growth. Early season temperature appears to have no effect in determining timing of annual growth. Limiting conditions during the season reduce growing duration, and thus total growth, more in unthinned stands than thinned stands. These findings are valuable in developing new generations of fine-scale growth and wood property models.