Growth of Eucalyptus pellita and E. urophylla and effects on pasture production on the coastal lowlands of tropical northern Australia

Eucalyptus pellita F. Muell. and E. urophylla S. T. Blake are important timber species which have potential for wood production in plantation and agroforestry systems in humid northern Queensland. This study was established to examine two provenances of each species on a coastal lowland site, using randomised complete block design. Survival, height, diameter at breast height (DBH), bole length and tree form were measured at ages 12, 24 and 39 months. The height and biomass of the pasture underneath each provenance plot were also measured at 39 months. Significant differences occurred in most of the tree characteristics at 39 months. Differences in pasture growth, on the other hand, were not significant. Compared with the two E. pellita provenances, the provenances of E. urophylla had superior height and DBH growth but had worse form. Overall, however, both species had high survival, fast growth, satisfactory form, and minimal effects on pasture growth. Although all four taxa appear to be suitable for silvopastoral systems, further trials involving more provenances on a wider range of sites are recommended to establish the environmental and economic limits for the use of these species.     

Growth and form of provenances of Eucalyptus saligna at Wondo Genet,southern Ethiopia

A trial testing 10 provenances from across the natural range of Eucalyptus saligna and a local land race was established at Wondo Genet, southern Ethiopia. Eight years after planting, survival, tree height, diameter at breast height over bark, stem form, number of forks, height to the first fork, number of branches, branch diameter and branch angle were assessed. Volume per hectare was also calculated. Survival ranged between 36% (a provenance from 87 km north of Windsor, NSW) and 79% (Consuelo Tableland, Queensland), and differences were significant (P < 0.05). Among morphological characteristics, only the number of branches showed significant variation (P < 0.05), with the greatest number (12.4) being recorded for the Bulahdelah, NSW, provenance and the least (8.5) for the Clyde River, NSW, provenance. Major growth and morphological parameters (tree height, diameter, volume and stem form) did not differ significantly. The overall volume production (mean annual increment 26.4 m³ ha^?1) was well above the minimum acceptable growth observed on good sites elsewhere. Differences between provenances were small and mostly not significant, and no pattern of geographic variation was detected. Given the acceptable mean annual increment, those provenances represented by an adequate number of parent trees could be maintained for further selection and breeding, and to maintain genetic diversity of the species in Ethiopia.     

Estimation of forest stand diameter class using airborne lidar and field data

In this study, a method for estimating the stand diameter at breast height (DBH) classes in a South Korea forest using airborne lidar and field data was proposed. First, a digital surface model (DSM) and digital terrain model (DTM) were generated from the lidar data that have a point density of 4.3 points/m², then a tree canopy model (TCM) was created by subtracting the DTM from the DSM. The tree height and crown diameter were estimated from the rasterized TCM using local maximum points, minimum points and a circle fitting algorithm. Individual tree heights and crown diameters were converted into DBH using the allometric equations obtained from the field survey data. We calculated the proportion of the total number of individual trees belonging to each DBH class in each stand to determine the stand DBH class according to the standard guidelines. More than 60% of the stand DBH classes were correctly estimated by the proposed method, and their area occupied over 80% of the total forest area. The proposed method generated more accurate results compared to the digital forest type map provided by the government.     

Using tree hollow data to define large tree size for use in habitat assessment

Habitat assessments often require observers to estimate tree hollows in situ, which can be costly, destructive and prone to bias. An alternative is to count the number of trees above a specific size. The size at which a tree develops hollows differs substantially among tree species. To assist with setting standards for habitat assessment we defined a large tree as the size at which a species has a 50% probability of supporting a 2-cm diameter hollow. We estimated this size for 68 species using a meta-analysis based on 18 data sources. We found that large tree size ranged from 21 to 106 cm diameter at breast height (DBH). Each species was attributed to vegetation types (formations and classes) to explore variation in large tree sizes. Despite considerable variation within vegetation classes and formations, our results suggest that a large tree size of approximately 50 cm DBH may be appropriate for most vegetation types, with lower estimates in semi-arid vegetation (~30 cm) and higher estimates in wet sclerophyll forests (~80 cm). Our estimates provide empirical support for defining large trees at species vegetation class and formation levels within New South Wales, and highlights the need for more empirical data.     

Nine year results from a Eucalyptus camaldulensis Dehnh. provenance trial in the Wellington catchment of Western Australia

Data for 20 provenances of Eucalyptus camaldulensis from the southern half of Australia including 14 provenances of variety camaldulensis and 6 provenances of variety obtusa were assessed for growth and form in the south west of Western Australia. Mean annual volume increment at age nine years was greater in variety camaldulensis (3.3 m³ ha^?1 yr^?1) than for variety obtusa (1.9 m³ ha^?1 yr^?1). No significant differences in forking or branching were found between the two varieties. Lake Albacutya (variety camaldulensis) was the most productive provenance yielding 5.3 m³ ha^?1 yr^?1 but was only average for form. Laura (variety camaldulensis) was the best all round performer yielding the third highest volume production (4.2 m³ ha^?1 yr^?1) and ranking in the top quartile for forking, branching and straightness. Within variety camaldulensis a weak correlation was found between height and mean annual rainfall, provenances from lower rainfall areas being more likely to produce taller trees. A trend for smaller numbers of persistent branches with decreasing rainfall was observed for the species as a whole.     

Comparative early growth of Eucalyptus species of the subgenera Monocalyptus and Symphyomyrtus in intensively-managed plantations in southern Tasmania

Four eucalypt species. Eucalyptus delegatensis, E. globulus, E. nitens and E. regnons were established at each of four plantations situated between 60 m and 650 m asl in SE Tasmania. E. grandis and E. pauciflora were also established at the lower and upper two plantations respectively. Each plantation was managed intensively through the application of fertiliser and pest control. There were large differences in height and diameter growth between ages I and 5 years between subgenera, species and provenances. In general, E. globulus and E. nitens of subgenus Symphyomyrtus grew faster than E. delegatensis and E. regnans of subgenus Monocalyptus. Survival was also greater in Symphyomyrtus than Monocalyptus species except at the uppermost (650 m) site where snow and frost killed E. globulus. The faster diameter growth across all sites at age 5 years was from the Upper Toorongo provenance of E. nitens with mean diameters at breast height between 9.6 and 10.5 cm; the tallest species. 11.1 m was the Otways provenance of E. globulus at 240 m.

Annual increments of both Symphyomyrtus species compared favourably with those obtained under management for high yield elsewhere in Australia.     

Are there genetic differences in susceptibility of Eucalyptus nitens and E. regnans stems to defect and decay?

Levels of spread of wood discolouration and incipient decay associated with artificial stem wounds were studied in a provenance trial of Eucalyptus regnans and a progeny trial of E. nitens. Natural incidence of discolouration and numbers and sizes of kino veins were also examined in a provenance × fertiliser interaction trial in E. regnans.

No differences were found between provenances of E. regnans for degree of spread of discolouration despite significant differences in tree diameter. However, incidence and size of kino veins differed between provenances of E. regnans. For E. nitens the spread of discolouration was less than that in E. regnans, and there were no significant differences in discolouration amongst the 10 open-pollinated families, or associated with tree diameter. Heritability estimates for lateral and longitudinal spread in E. nitens were relatively low and had large errors attached due to the small number of families sampled.

Degree of lateral spread was correlated with tree diameter in E. regnans but not in E. nitens. Nitrogen fertiliser did not appear to influence defect levels in E. regnans. However, adding phosphorus fertiliser was associated with fewer and smaller kino veins in disc samples removed from the base of the green crown.     

Stem biomass estimation based on stem reconstruction from terrestrial laser scanning point clouds

Forest biomass is often difficult to quantify because field measurements are time consuming and require destructive sampling. This study explores the retrieval of stem biomass of individual trees by terrestrial laser scanning (TLS). Destructive sampling was done to collect biomass data from sample trees and used as a dependent variable in a regression analysis. Two biomass estimation models were investigated: one based on diameter at breast height (DBH) and another based on the sum of the stem section volume. Both the DBH and the stem section volume were determined from automatic reconstruction of the stem curves. Two tree species (Scots pine and Norway spruce) were considered together. The quality of the performance of the models was evaluated via a leave-one-out cross-validation strategy using accurate field measurements for 30 trees. The correlation coefficient (r) and root mean square errors (RMSEs) between the predicted and measured stem biomass were used as measures of goodness of model fitting. The model with DBH as the predictor produced an r-value of 0.93 and an RMSE of 21.5%. For the model using the reconstructed stem and correspondingly derived stem volume as the predictor, an r-value of 0.98 and an RMSE of 12.5% were achieved. The results indicated that TLS measurements are capable of assessing stem biomass with high automation and accuracy by reconstructing the stem from TLS point clouds.     

Evaluating wood volume estimates derived from Quickbird imagery with GEOBIA for Pinus nigra trees in the Pentalofo forest,northern Greece

The objective of this research was to evaluate wood volume estimates of Pinus nigra trees in forest stands, which were derived utilizing Geographic Object-Based Image Analysis. Information on forest parameters such as wood volume and number of trees is useful for forest management facilitating forest sustainability. Most of the existing approaches used to estimate wood volume of forest trees require field measurements, which are laboursome. In this study, the collected field data were utilized only in order to investigate the results. Wood volume was estimated based on an individual tree crown approach and using monoscopic satellite images in combination with allometric data. The study area is the Pentalofo forest, which is located in Kozani prefecture in western Macedonia, Northern Greece. About 1 plot surface of 0.1143 ha was utilized. During the preprocessing, a pansharpened image was produced from two Quickbird satellite images (one multispectral image of 2.4 m spatial resolution and one panchromatic image of 0.6 m spatial resolution). Bands of this image were utilized single or in combination in order to delineate the tree crowns individually. The allometric equation served in order to calculate the tree Diameter at Breast Height (DBH) utilizing the detected tree crowns. The evaluation was conducted on three levels: (i) number of trees, (ii) DBH class distribution and (iii) wood volume. On the third level, the evaluation procedure was conducted twice; once using field height and once without. The difference between the results and the field data for the wood volume reached a maximum of approximately 30%. The total number of trees was exactly the same as counted in the field and the DBH distribution showed a tendency for the trees to move to a higher DBH class, resulting in an overestimation of the wood volume.     

Assessing the thermal adaptability of tree provenances: an example using Eucalyptus tereticornis

ABSTRACT

A 2017 paper intended to assist climate-change studies concluded that provenances of the widely distributed Eucalyptus tereticornis ‘are not differentiated in their thermal responses’ in terms of photosynthesis, respiration and growth. The aim here was to place this surprising result, based on a short-term (48-day) experiment with seedlings of just three provenances, into the broader context of several years’ growth of provenances of the same species. To do this, a re-analysis of results from trials of 14 provenances of E. tereticornis was undertaken. These were grown for 3.5 or 5.0 years at four contrasting sites in southern China spanning mean annual temperatures (MAT) from 15.0°C to 23.5°C. The analysis described here compares MATs at climate-of-origin with volume growth. It demonstrates an approach that could easily be applied to provenance studies of other commercially important species. It makes use of the ready access to distributional and climatic data provided by a modern biodiversity database, the Atlas of Living Australia. Some of the provenances showed a surprising level of adaptability to climates markedly different to those of their origin. At the warmest site in China, however, the growth of the provenances was significantly related to the MAT at their climate-of-origin. It is concluded that researchers considering the likely impacts of climate change on tree species may find it useful to examine results from commercial provenance trials as well as from glasshouse experiments with seedlings.     

Estimating plot-level tree structure in a deciduous forest by combining allometric equations,spatial wavelet analysis and airborne LiDAR

Object-oriented classification methods are increasingly used to derive plant-level structural information from high-resolution remotely sensed data from plant canopies. However, many automated, object-based classification approaches perform poorly in deciduous forests compared with coniferous forests. Here, we test the performance of the automated spatial wavelet analysis (SWA) algorithm for estimating plot-level canopy structure characteristics from a light detection and ranging (LiDAR) data set obtained from a northern mixed deciduous forest. Plot-level SWA-derived and co-located ground-based measurements of tree diameter at breast height (DBH) were linearly correlated when canopy cover was low (correlation coefficient (r)?=?0.80) or moderate (r?=?0.68), but were statistically unrelated when canopy cover was high. SWA-estimated crown diameters were not significantly correlated with allometrically based estimates of crown diameter. Our results show that, when combined with allometric equations, SWA can be useful for estimating deciduous forest structure information from LiDAR in forests with low to moderate (<175% projected canopy area/ground area) levels of canopy cover.     

Evaluation of Eucalyptus red gum species and provenances for inland humid subtropical regions of southern China

There is a long history of eucalypt planting in inland regions of southern China where humid summers and frequent winter frosts and extreme cold events are features of the climate. Although early eucalypt plantings suffered widespread failures, some species managed to survive with individual trees in some plantings growing to impressive sizes with diameter at breast height (DBH) exceeding 50 cm. One of the most productive and best adapted species in the plantings was Eucalyptus camaldulensis. Two species–provenance trials were established in southern and central Hunan province in 2006 primarily to explore the potential of E. camaldulensis and the related E. tereticornis, but also to provide comparisons with two other species with potential for the climate. The trials included 65 provenances representing six taxa from four species: E. camaldulensis, E. tereticornis, E. amplifolia and E. macarthurii. Three provenances represented improved seed sources from Africa, whilst the others were natural stand provenances. Eucalyptus amplifolia var. amplifolia demonstrated the best potential for growth and survival up to age 5 years. Eucalyptus macarthurii had the best cold tolerance, but relatively poor performance for growth and survival. Both E. tereticornis and E. camaldulensis demonstrated reasonable cold tolerance, but growth and survival of E. camaldulensis var. camaldulensis provenances from temperate to subtropical climatic areas with dry summers and winter-dominant rainfall (Köppen climate classification Csa) were markedly inferior than those of E. tereticornis ig. ‘tereticamal’ and E. tereticornis ssp. tereticornis sourced from tropical and subtropical environments with summer-dominant rainfall (Köppen climate classifications Aw and Am). Seedlots of E. camaldulensis, E. tereticornis and E. macarthurii from improvement programs in Zimbabwe and South Africa mostly proved inferior to or no better than the best natural stand provenances of the same species in the Hunan environment.     

Polynomial taper model for Queensland plantation hoop pine

A stem taper model, involving a high order polynomial developed using plantation hoop pine (Araucaria cunninghamii Ait. ex D. Don) trees grown in Queensland, is presented. The stem profile for each tree was initially modelled using functions of diameter under bark and height, as the dependent and independent variables respectively. Parameter estimates from these individual tree regressions were subsequently modelled, using total height and diameter at breast height under bark (DBHub) as the independent variables. Finally, total height and DBHub were modelled in terms of predominant height' and diameter at breast height over bark (DBHob).

The largest mean error in the estimates of stem diameter predicted using the final model, with predominant height and DBHob as the independent variables, was 0.12 cm. The overall mean relative error in the estimate of volume, based on coefficients modelled using predominant height and DBHob, was 0.20 per cent. Apart from its accuracy, the main advantages of the model include its simplicity and its ability to model the whole tree using a single function.     

LIST OF MEMBERS AND ASSOCIATES 1966

We irrigated 36 species and provenances of mainly Australian native trees with saline drainage water (EC 2 dS/m and boron 2.4 mg/L) in a trial sited at Loxton, in semi-arid south eastern Australia. Twelve months after planting, the survival rates amongst species were similar with a site mean of 96%. Three years after planting, the tallest trees were E. gomphocephala and the provenances/clones of E. occidentalis and E. camaldulensis, with heights ranging from 5.3 to 6.7 m; these trees also had the greatest girth with basal areas (measured at 0.3 m above ground level) ranging from 16 m²/ha to 24 m²/ha. The basal area and height of E. camaldulensis was highly variable ranging from 1 m²/ha and 2.1 m for the CML42 clone, to 16 m²/ha and 6.2 m for the Alcoa clone 20. Provenance also had a significant effect on the values of these parameters in E. occidentalis. In the third year, water use rates were determined for 12 of the better growing species. Over summer, the mean daily water use rates ranged from 49 L/tree for the Alcoa clone 20 of E. camaldulensis, to 12 L/tree for E. kondininensis. The Alcoa clone 20 of E. camaldulensis had the higher daily rate of water use per unit area of sapwood, 4.7 kL/m². The hourly rates of water use per unit area of sapwood rose with increasing vapour pressure deficit up to a value of about 17 hPa and then remained constant as VPD rose to 55 hPa. Variation amongst tree species in the relationships between hourly rates of water use per unit area of sapwood and VPD was highly significant.     

Variation in oil content and tree size between six geographically separate Santalum spicatum families,established near Narrogin,Western Australia

Six geographically separate sandalwood (Santalum spicatum) tree families were established together in a trial near Narrogin, Western Australia to compare oil content and tree size variation at ages 10 and 18 years. The trial site contained a total of 300 sandalwood trees with 41–55 trees from each family. All 300 sandalwood trees were measured for tree size: height, stem diameter and bole length. Wood core samples (heartwood + sapwood) were also taken at 300 mm above the ground from 71 to 72 separate trees, at ages 10 and 18 years. Each wood core sample was ground separately and then a sub-sample was analysed for oil concentration, and α- and β-santalol concentration within the oil.

The mean extractable oil concentrations within the sandalwood stems at 300 mm above the ground were significantly greater from the Borden and Dumbleyung families (1.1–1.6%) than the Ravensthorpe family (0.5–0.8%), at both ages 10 and 18 years. However, the oil quality (mean concentration of α- and β-santalol) was not significantly different between the six families at ages 10 or 18 years. Instead, oil quality was highly variable within each family.

Between sandalwood ages 10 and 18 years, the overall mean extractable oil concentration from the six different families increased significantly from 0.8 to 1.3%. During the same time period, mean α-santalol concentration increased significantly from 8.6 to 13.8%, and mean β-santalol concentration also increased significantly from 3.3 to 4.5%.

Mean tree height, stem diameter and bole length varied significantly between the six families at age 18 years. The Borden family appeared to be more tree-like in form, with a significantly longer bole length, than some of the other families which were more shrub-like in appearance.     

THE KNOTTY CORE OF EUCALYPTS

Investigations were carried out between 1939 and 1942 in South Australia to determine the amount and distribution of moisture within the trunks of Monterey pine trees (P. radiata Don) and to study the differences from tree to tree. Between 1946 and 1948, additional but less extensive investigations were conducted in the Australian Capital Territory.

Large variations occur within each tree. The vertical distribution of water shows several distinct trends: in some trees the moisture content decreases from the base to a minimum and then increases again towards the top, in others it increases progressively up the tree, while in other trees it decreases progressively with height. The heartwood is a dry region with a moisture content of approximately 45 per cent. The moisture content of the sapwood varies throughout the tree both vertically and laterally.

Big differences in moisture content occur from tree to tree. The wood of young trees is much moister than that of old trees and the moisture content of the trees of fast-growing stands is higher than that of trees of the same age growing on poorer sites. In some stands the wood of dominant trees is moister than that of the suppressed. Interesting seasonal changes occur in the moisture content of the trees, those studied at Mt. Burr containing more water in spring than in autumn.     

Converting diameter measurements of Pinus radiata taken at different breast heights

Two compatible conversion factors for converting diameter measurements taken at different breast heights were derived for Pinus radiata using taper data from more than 3000 trees. The two breast heights used for conversion were 1.3 and 1.4 m above ground, as defined in Australia and New Zealand, two major radiata-growing countries in the world. The conversion factors were estimated through three alternative statistical methods including simple least squares regression, seemingly unrelated regression and errors-in-variables models. The three sets of estimates were almost identical and had similar conversion accuracy, although the second method was slightly better. The conversion factors were more accurate than overbark taper equations used for the same purpose. The factor was 0.9916 for converting diameter measured at 1.3 to that at 1.4 m above ground, and the inverse of this value, 1.0084, was for the vice versa. When calculating tree and stand volume and biomass using equations with diameter at a different breast height as a predictor to that of the input data, the bias, either over or under estimation, could be between 1.67% and 2.00% without conversion. These conversion factors will facilitate the sharing of data among radiata growing countries with different definitions of breast height, but more importantly it will help correct the bias in stand volume and biomass estimation caused by the seemingly negligible difference in breast height when software for forest resource management and decision support developed in one country is applied in another. Such bias when accumulated over a large management area may not be financially insignificant for an astute forest management agency.     

An early exploration of the use of the Microsoft Azure Kinect for estimation of urban tree Diameter at Breast Height

ABSTRACT

Forest and urban tree inventory measurements are increasingly adopting Remote Sensing (RS) techniques due to the accurate and rapid estimates available compared to conventional methods. The focus of this study is to assess the accuracy and potential application of the Microsoft Azure Kinect – a lightweight depth sensor – for outdoor measurement of tree stem Diameter at Breast Height (DBH). Individual urban trees (n = 51) were recorded from one viewing angle at a distance of 1 m to 5 m away using the various Field of View (FOV) settings on the depth sensor, from which resultant point clouds provided DBH estimates using a circle-fitting approach. The optimal capture method was observed at a distance of 2 m using the binned Near Field of View (NFOV) setting. Root Mean Square Error (RMSE) of DBH using this method was 8.43 cm; however, after removing trees with irregular or non-circular stems, this improved to 3.53 cm. Variations in ambient light were observed to have little effect on DBH estimates. The results of this study suggest when in an outdoor environment, the Azure Kinect should be used at a distance no greater than 3 m away, using the binned NFOV sensor setting, for DBH estimates.     

Processing sawn wood from thinned,unpruned 17-year-old Eucalyptus dunnii in southern China

Sixty logs of 17-year-old thinned, unpruned plantation-grown Eucalyptus dunnii representing 10 trees from each of 2 provenances were obtained from a field-trial in central Guangxi Province, China, and processed in a nearby sawmill to produce dried appearance-grade sawn wood suitable for manufacture of short-length flooring. This study’s objectives included determining: interrelationships between log end-splitting and growth stress measured on standing trees and important wood behaviour during processing; relationships between log external features and sawn product recovery; the potential for improvement in processing and/or product quality with the application of a steam reconditioning treatment; and differences in product value and processing characteristics between two provenances of E. dunnii.

Boards were air-dried and kiln-dried in two matched batches and one batch was subsequently given a steam reconditioning treatment. For prediction of processing characteristics, the measured displacement on standing tree stems associated with growth stress release was moderately useful for prediction of log end-splitting but not significant for any other characteristic tested, and log end-splitting was not a significant predictor of recovery or product value. Log diameter measures and sweep were the only significant predictors of recovery. Diameter was sufficiently large in some logs to meet D-grade requirements according to Australian (VicForests) log grading standards. The estimated mill door values of sawn product obtained per log cubic metre for D-grade and residual-grade logs (below VicForests sawlog specifications) were RMB 1045 and RMB 887, respectively (approximately AUD 190 and AUD 161, respectively). Steam reconditioning treatment significantly reduced cupping and increased width and thickness dimensions but the presence of severe non-drying-related defect limited the direct benefit of the treatment. There was no significant difference between provenances in product recovery, product value or log end-split severity.     

A form diagram to optimise pruning schedules for eucalypt clear-wood production

Branch pruning is necessary to produce high-value wood products from eucalypt plantations. Four requirements of an effective and efficient pruning regime for clear-wood production are to (a) restrict the pruned-stem diameter to a specified maximum, (b) ensure only green branches are pruned, (c) remove a proportion of the green crown that allows for continued competitiveness of the pruned trees and (d) minimise the number of pruning interventions. In this paper, we present a pruning decision support tool that diagrammatically combines results from growing stands and crown reduction trials. Elements depicting the pruning schedule, target maximum pruned diameter (PD_max), lower height of the green crown (GC_LH) and target retained proportion of the green crown (GC_RP) are overlaid onto a set of stem-taper curves. The form diagram was demonstrated using data from two adjacent commercial plantations of Eucalyptus pellita (‘Caravan Hill’ and ‘Fishtail’), established in the same planting season, for solid-wood production in northern Queensland, Australia. We fitted a cubic tree taper model that described 89% of the variation in stem diameter at a given height. PD_max was set at 12 cm and GC_RP was set at 50%. Pruned height was set at 6 m assuming two lifts.

Site differences in E. pellita growth, slenderness and green-crown height resulted in different optimum pruning schedules even on adjacent holdings. Within-stand heterogeneity in slenderness and green-crown height contributed further to the complexity of pruning scheduling. Our results suggest that it would have been necessary to complete the Fishtail site pruning program at the commencement of the second dry season after planting to ensure that the pruned height was always greater than GC_LH. On the other hand, the first pruning lift could be conducted at the Caravan Hill site at the same time that the second lift was being completed at Fishtail. Management options that increase the height growth in the first year, promote live crown retention and increase within-stand homogeneity will improve the effectiveness of fixed-lift pruning for eucalypt clear-wood production.