High-quality Timber Research Articles

Geographical variation and genetic diversity of Parashorea chinensis germplasm resources.

Parashorea chinensis is a rare monodominant species in southwest China known for its production of high-quality timber, is facing decline due to its narrow distribution, human interference and habitat destruction. However, there are no reports on genetic diversity and geographical variation of phenotypic traits of P. chinensis. In this study, phenotypic characters and genetic diversity of 15 germplasms resources from five provenances in southwest China were investigated, and their relationships with geographical and environmental factors was discussed. Our results revealed a rich phenotypic diversity among the germplasms, with variation coefficients ranging from 3.63% to 45.49%. Among the studied germplasms, NP03 from Napo and ML02 from Mengla region exhibited superior phenotypic traits. Notably, NP03 also demonstrated the highest genetic diversity. Genetic differentiation analyses including genetic differentiation coefficient (0.6264) and gene flow (0.3736) illustrated that genetic variation was most prevalent among populations. Furthermore, redundancy analysis showed that temperature related factors (maximum air temperature, annual mean temperature and minimum air temperature) significantly affected phenotypic variation. Similarly, altitude, longitude, latitude, annual mean precipitation and the minimum air temperature significantly impacted the level of genetic diversity. The molecular variation of the natural population of P. chinensis followed a certain geographical pattern. Our finding indicated abundant phenotypic variation among P. chinensis germplasms. However, populations exhibited low levels of genetic diversity alongside high genetic differentiation, potentially contributing to the species' rarity. Based on our results, NP03 and ML02 germplasm could be used as the parents for breeding superior germplasm of P. chinensis. Overall, this study provides valuable insights into germplasm diversity and conservation, genetic improvement, and utilization of P. chinensis.

Tradeoffs between Stand Volume and Understory Vegetation Diversity in Quercus wutaishanica Forests under Climate Change

Natural forests play a crucial role in providing various ecosystem services, including timber production and biodiversity conservation. However, climate change and anthropogenic factors pose a severe threat to competing forest ecosystem services functions. Therefore, to optimize and sustainably utilize competing forest services, tradeoffs are often necessary. This study was conducted in Northwest China to explore tradeoffs aimed at improving the quality of Quercus wutaishanica Mayr natural forests under climate change conditions, focusing on stand volume, timber production, and understory vegetation diversity conservation. Data from 77 field surveys were used to construct a coupled model for stand growth, stand structure, and site conditions. Changes in understory vegetation species number (UVSN) with crown cover were quantified. These models and relationships can be used as tools to estimate tradeoffs. As stand density increased, single-tree volume decreased, whereas timber volume increased. UVSN increased and then decreased with increasing crown cover and was able to maintain a relative maximum at 0.5–0.65. Under the current climatic conditions, the optimum stand densities corresponding to 30, 40, 50, and 60 years were 1390, 1153, 1042, and 871 trees/ha, respectively, to maintain a high UVSN and adequate stand volume. When mean annual temperature rose, stand densities could be reduced to maintain high-quality timber. Although only two major services were considered, the tradeoffs presented in this study can inform future research to improve the quality of natural forests.

Conservation genomic study of Hopea hainanensis (Dipterocarpaceae), an endangered tree with extremely small populations on Hainan Island, China.

Hopea hainanensis Merrill & Chun is considered a keystone and indicator species in the tropical lowland rainforests of Hainan Island. Owing to its high-quality timber, H. hainanensis has been heavily exploited, leading to its classification as a first-class national protected plant in China and a plant species with extremely small populations (PSESPs). This study analyzed genome-wide single nucleotide polymorphisms obtained through restriction site-associated DNA sequencing from 78 adult trees across 10 H. hainanensis populations on Hainan Island. The nucleotide diversity of the sampled populations ranged from 0.00096 to 0.00138, which is lower than that observed in several other PSESPs and endangered tree species. Bayesian unsupervised clustering, principal component analysis, and neighbor-joining tree reconstruction identified three to five genetic clusters in H. hainanensis, most of which were geographically widespread and shared by multiple populations. Demographic history analysis based on pooled samples indicated that the decline in the H. hainanensis population began approximately 20,000 years ago, starting from an ancestral population size of approximately 10,000 individuals. The reduction in population size accelerated approximately 4,000 years ago and has continued to the present, resulting in a severely reduced population on Hainan Island. Intensified genetic drift in small and isolated H. hainanensis populations may contribute to moderate differentiation between some of them, as revealed by pairwise F st. In conclusion, our conservation genomic study confirms a severe population decline and an extremely low level of nucleotide variation in H. hainanensis on Hainan Island. These findings provide critical insights for the sustainable management and genetic restoration of H. hainanensis on Hainan Island.

Quantitative trait loci for bearing habit in a ‘Sparrow’ × ‘Schessler’ Juglans nigra mapping population

Eastern black walnut, Juglans nigra L., is an economically important tree species valued for its high-quality timber and edible nuts. A regional industry for the species’ nut and kernel products resides in Missouri, where over 9 million kg of hulled in-shell nuts are purchased in masting years. The crop is primarily based upon nuts harvested from wild trees, placing a ceiling on nut volume and quality (e.g. small nut size, dark pellicle color, and 10–14% kernel by weight). Orchards of named cultivars, like ‘Kwik Krop’ and ‘Sparrow’, supply up to 22,000 kg of nuts with a higher kernel percentage (> 26%) and improved quality. Such cultivars often represent chance wild or on-farm seedlings, clonally propagated since the late 1800’s by enthusiasts. Today, continued improvement of eastern black walnut as an orchard crop is limited by a long generation time, delayed expression of important traits, and space requirements – creating a strong need for marker-trait association studies that inform progeny selection. The first linkage map for J. nigra was recently created using the ‘Sparrow’ × ‘Schessler’ F1 population and loci for phenology traits discovered. The objective of this study is to utilize these genetic resources to detect quantitative trait loci (QTL) and report associated DNA markers for the spur-bearing habit, which promotes precocity and high yield. Using single-year data from the 11-year-old population, we observe that segregation for the spur-bearing habit appears to be recessive and multigenic. Three QTLs (p > 0.99) were identified on linkage group (LG) 8, LG11, and LG16 that explain 7.2%, 8.7%, and 10% of trait variation, respectively. Regions between flanking DNA markers were 3.16 cM, 4.32 cM, and 9.69 cM, respectively. This study is the first to examine the genetic control of bearing habit and yield in eastern black walnut and informs breeders’ approach for their future genetic improvement.

Produrre legname per l’edilizia aiutando la natura di montagna e l’economia nazionale

The use of timber in the construction sector plays two fundamental roles, both “downstream” and “upstream” of industrial wood processing. Downstream, the construction sector is responsible for 37% of global emissions, and the expansion of timber construction is rightly considered strategic as part of a decarbonization process, where the need to replace high-emission materials represents a competitive advantage for biomass products. It also enhances the quality of living spaces, as highlighted in the New European Bauhaus initiative. Upstream, the construction sector is privileged and therefore essential for providing an outlet for “Closer-to-Nature” forest management: without a market for high-quality timber from sustainably managed forests, the incentives for long-rotation seminatural forest management diminish. This second motivation is well recognised in the public procurement policies of many advanced countries and in those that promote the construction sector. These two roles are of fundamental importance but often neglected in Italian policies aimed at adding value to mountain forests.

Age and growth reductions increase the proportion of dark heartwood in sugar maple at the northern limit of its range

Abstract The wood of sugar maple (Acer saccharum Marsh.) in the northernmost part of the species range often exhibits high proportions of discoloured wood at the centre of the stems, which is referred to as dark heartwood. This defect significantly decreases the wood market value of the species, which, in turn, challenges the implementation of state-of-the art silvicultural treatments. The causes of dark heartwood are associated with trauma and the colder climate of the northern regions. In this study, we investigate factors influencing the occurrence of dark heartwood in sugar maple’s northern populations, considering tree age, vigour, stem growth, and local climate. We also aimed to determine whether the proportion of dark heartwood is higher in northern stands compared to more southern ones. We collected samples from 302 sugar maple stems at 16 sites within two bioclimatic domains of Quebec, Canada, i.e. the balsam fir–yellow birch domain (representing the northern limit of the sugar maple range) and the sugar maple–yellow birch domain (representing a more southern location within the range). Our results indicate a positive relationship between dark heartwood proportions and stem age, as well as with the amplitude of the maximum growth reduction throughout the tree’s lifespan and the length of the longest suppression period. We also observed significantly higher dark heartwood proportion for a given tree age in northern stands. The results suggest that silvicultural systems aiming to release suppressed crop trees through group selection using a cut-to-length system could favour the development of high quality timber.

Population genomics analysis reveals footprints of selective breeding in a rapid-growth variety of Paulownia fortunei with apical dominance

Paulownia fortunei is an ecologically and economically valuable tree cultivated for its rapid growth and high-quality timber. To enhance Paulownia germplasm, we have developed the elite variety QingT with patented advantages in growth rate and apical dominance. To illuminate the genetic basis of QingT's superior traits, here we harness comparative population genomics to analyze genomic variation patterns between QingT and common Paulownia. We performed whole-genome re-sequencing of 30 QingT and 30 common samples, detecting 15.6 million SNPs and 2.6 million indels. Phylogeny and population structure analyses robustly partitioned common and QingT into distinct groups which indicate robust genome stabilization. QingT exhibited reduced heterozygosity and linkage disequilibrium decay compared to common Paulownia, reflecting high recombination, indicating hybridizing effects with common white-flowered string is the source of its patented advantages. Genome selection scans uncovered 25 regions of 169 genes with elevated nucleotide diversity, indicating selection sweeps among groups. Functional analysis of sweep genes revealed upregulation of ribosomal, biosynthesis, and growth pathways in QingT, implicating enhanced protein production and developmental processes in its rapid growth phenotype. This study's insights comprehensively chart genomic variation during Paulownia breeding, localizing candidate loci governing agronomic traits, and underpinnings of future molecular breeding efforts to boost productivity.

Induction and characterization of induced tetraploid, mixoploid and control diploid teak seedlings (Tectona grandis L.f.) from shoot cultures treated with oryzalin*

Teak, known for its high-quality timber and economic value, holds significant potential as the major component of an agroforestry system to combat climate change and support sustainable development goals. The challenge of slow teak growth can be addressed by introducing fast-growing teak varieties amenable to vegetative propagation. Furthermore, the improvement of teak through somatic cell genetics, such as inducing polyploidy, can result in more vigorous, faster-growing, and drought-tolerant trees. While a report exists on a tetraploid teak accession with enhanced less water tolerance, information on the induction and characterization of tetraploid teak is lacking. In this study, we report the induction of polyploid teak by immersing 1 – 1.5 cm nodal stem segments and shoot tips obtained from teak shoot cultures in a modified MS liquid medium containing 5 − 30 µM oryzalin for one week, followed by subculture for 6 passages. The resulting shoots were acclimatized and grown in the nursery for 10 months. Based on flow cytometry for ploidy analysis of pre-selected plants having morphologies typical of polyploid followed by chromosome counting, we identified two tetraploid plants from one accession and 18 mixoploid teak plants from four accessions. Chromosome counting analysis confirmed that a diploid plant had a chromosome number of 2n = 2x = 36, tetraploid plant had a chromosome number of 2n = 4x = 72, and mixoploid plant exhibited both chromosome number of 2n = 2x = 36 and 2n = 4x = 72 in root tip cells. Morphological characterization revealed that tetraploid and mixoploid teak plants displayed typical polyploid characteristics, such as larger, thicker, and greener leaves, increased root diameter, increased cell size in root tip region, and larger stomata size but with reduced density. The development of tetraploid teak holds the potential to provide faster-growing and more drought-tolerant varieties, facilitating breeding efforts, including the development of triploid varieties.

Effect of site, silviculture and tree social status on internal checking variation in plantation-grown Eucalyptus nitens

ABSTRACT Internal checking is a wood-drying defect that affects many tree species, including eucalypts, and can adversely affect the recovery of high-quality timber. We studied the patterns of within- and between-tree variation in wood checking from three Eucalyptus nitens silvicultural trials and determined the predictability of wood checking from wood properties. We hypothesised that changed wind exposure and inter-tree competition due to thinning would increase wood checking. In total, 144 trees from two silvicultural treatments (thinned/unthinned) and three social status classes per site (dominant/subdominant/suppressed) were sampled. Regardless of site, social status and silvicultural treatment, longitudinal and radial variation within trees was the major source of variation in checking. Checking was concentrated longitudinally in bottom logs and radially in the middle of wedges, with a shift in checking towards the cambium in the thinned treatment. On average, dominant trees in the thinned treatment had higher levels of checking than dominant trees in unthinned treatments at all sites, but the opposite trend was found for suppressed trees. Wedge checking was poorly predicted using non-destructive traits assessed on standing trees. Our models accounted for at most 22% of the variation in wedge checking and the best predictors were the destructive measures of wedge collapse. With most checking occurring in lower logs, future studies should concentrate on reducing checking in bottom logs, which are typically pruned for clearwood products.

Terrestrial laser scanning vs. manual methods for assessing complex forest stand structure: a comparative analysis on plenter forests

In continuous cover forestry, plenter silviculture is regarded as an elaborated system for optimizing the sustainable production of high-quality timber maintaining a constant but heterogeneous canopy. Its complexity necessitates high silvicultural expertise and a detailed assessment of forest stand structural variables. Terrestrial laser scanning (TLS) can offer reliable techniques for long-term tree mapping, volume calculation, and stand variables assessment in complex forest structures. We conducted surveys using both automated TLS and conventional manual methods (CMM) on two plots with contrasting silvicultural regimes within the Black Forest, Germany. Variations in automated tree detection and stand variables were greater between different TLS surveys than with CMM. TLS detected an average of 523 tree stems per hectare, while CMM counted 516. Approximately 9.6% of trees identified with TLS were commission errors, with 6.5% of CMM trees being omitted using TLS. Basal area per hectare was slightly higher in TLS (38.9 m3) than in CMM (38.2 m3). However, CMM recorded a greater standing volume (492.7 m3) than TLS (440.5 m3). The discrepancy in stand volume between methods was primarily due to TLS underestimating tree height, especially for taller trees. DBH bias was minor at 1 cm between methods. Repeated TLS inventories successfully matched an average of 424 tree positions per hectare. While TLS adequately characterizes complex plenter forest structures, we propose enhancing this methodology with personal laser scanning to optimize crown coverage and efficiency and direct volume measurements for increased accuracy of wood volume estimations. Additionally, utilizing 3D point cloud data-derived metrics, such as structural complexity indices, can further enhance plenter forest management.

American beech outgrows sugar maple at the sapling stage regardless of partial harvest intensity in northern hardwood forests

Sugar maple (Acer saccharum Marsh) is a key species in the northern hardwood forests of North America and management has historically focused on promoting its regeneration and yielding high-quality timber. A decrease in the abundance of sugar maple to the advantage of American beech (Fagus grandifolia Ehrh.) has been observed over the last decades. Together with the spread of beech bark disease, the understory dominance of American beech has often resulted in depleted, low vigour forest stands (i.e., with a low proportion of healthy trees). To favour regeneration and growth of sugar maple, increasing harvest intensity of partial treatments has been suggested, but the harvest intensity required remains unclear. In this study, we monitored the radial growth of saplings in 12 northern hardwood stands located in the Province of Quebec, Canada. These were commercially harvested with removal intensities ranging from 0% to 80% of the basal area. Using generalized additive mixed models, we investigated the effect of harvest intensity on the growth response of both species. Our results revealed that American beech saplings consistently had a much stronger radial growth response than sugar maple after harvest, regardless of treatment intensity. Consequently, modulating the intensity of partial harvests cannot singlehandedly favour the growth of sugar maple regeneration where American beech saplings dominate the understory. Additional silvicultural interventions are thus needed to control advance understory beech.

Effects of forest thinning on sap flow dynamics and transpiration in a Japanese cedar forest

Historically, forest thinning in Japan was conducted to obtain high-quality timber from plantations. Today, in contrast, thinning is also motivated by forest water balance and climate change considerations. It is in this context that the present study examines the effects of thinning on the ecophysiological responses of remaining trees, which are inadequately understood, especially in relation to changes in the magnitude and duration of transpiration. Sap flux densities were measured in both outer and inner sapwood to obtain stand-scale transpiration for two years in the pre-thinning state and three years post-thinning. The effects of thinning on transpiration were quantitatively evaluated based on canopy conductance models. The larger increases in outer sap flux density were found in the first year after the treatment, while those in inner sap flux density were detected in the second and third years. The remaining trees required a few of years to adjust to improved light conditions of the lower crown, resulting in a delayed response of inner sap flux density. As a result of this lag, transpiration was reduced to 71 % of the pre-thinning condition in the first year, but transpiration recovered to the pre-thinning levels in the second and third years due to compensating contributions from inner sap flow. In terms of more accurately chronicling the thinning effect, the distribution of sap flux density with respect to its radial pattern, is necessary. Such measurements are key to more comprehensively examining the ecophysiological response of forest plantations to thinning and, ultimately, its effect on the forest water balance.

Growth and quality of 16-year-old sessile oak (Quercus petraea (Matt.) Liebl.) planted in traditional and alternative row planting patterns

Abstract Traditional oak silviculture is costly due to high initial planting density required to obtain management goals of producing high quality timber. New methods therefore reduce the initial planting density and use a planting pattern that allows the inclusion of naturally regenerated trees of other species. The study presents the results of a 13-year experiment on the growth and quality of sessile oak planted in traditional and three alternative planting patterns. We hypothesized that increasing of initial spacing and use of natural regeneration to compensate for lower intra-specific competition does not deteriorate growth and quality parameters of oak. Breast height diameter, height, slenderness, height of the first live branch, diameter of the thickest branch, stem shape and potential future crop oak trees (PFCT) were measured and analysed. The local competition of admixture species was estimated on the basis of the relationship between the height of the oak and the height of admixture trees in its close proximity. The type of planting pattern had no significant effect on oak diameter, but oak height was greater in the traditional pattern than in alternative patterns. Height of the first live branch was the only qualitative trait that differed significantly between the compared planting patterns. The probability of an oak being selected as a PFCT was similar in traditional and alternative patterns, but PFCT absolute number was increasing with an increase of oak planting density. Analysis of competition of admixture species in alternative methods shows that it can reduce height, diameter and stability of oaks. On the other hand, the probability of trees being selected as a PFCT increases significantly with increasing interspecific competition. We conclude that, with controlled competition and at least moderate natural regeneration, the alternative planting patterns can produce oaks with similar growth and quality to those in the traditional pattern.

A Study on an Active Functional Group and Antimicrobial Properties From Rhizophora apiculata Extracts Used in Traditional Malay as Medicine

A mangrove plant known as Rhizophora apiculata is employed by Malay for treating skin diseases, diarrhea, vomiting, and nausea, as an antiseptic, for tanning, and also as fuelwood and fodder. Its large-scale use can be attributed to its high-quality timber, availability as well and the presence of a chemical named tannin that is employed for reinforcing fishing lines, nets, and ropes. The tannin content of R. apiculata's roots, bark, and leaves is regarded to be a natural inhibitor of fungal infections. This study is focused on determining the different kinds of functional groups, as well as individual phenolic compounds present in R. apiculata for identifying new bioactive compounds via decoding of the traditional values of Malay remedies. There is a high demand for such natural bioactive compounds, particularly in the healthcare and pharmaceutical markets. Alkaline fractional extracts were employed to design an analytical extraction method for R. apiculata. As per the HPLC results, there were three phenolic acids detected namely Caffeic acid, 4-Hydroxybenzoic acid, and Vanillic acid. Meanwhile, ten volatile compounds were identified by the GCTOF-MS. With regards to antibacterial activity, S. aureus, S. epidermidis, and E. coli were inhibited by R. apiculata leaf extract, while C. albicans and Fusarium sp. were inhibited by their antifungal activity.

Selection for Both Growth and Wood Properties in Chinese Fir Breeding Parents Based on a 6-Year Grafted Clone Test

With the growing demand for high-quality timber, selection processes for both growth and wood properties are needed for multi-trait breeding programs in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.). The present study examined the variation and correlation of growth (tree height, diameter at breast height, stem volume, crown-width) and wood properties (wood basic density, hygroscopicity, and heart-wood ratio) traits of 201 Chinese fir breeding parents, aiming to select better parents for future multi-trait improvement. The results showed that significant differences (p < 0.01) regarding growth and wood property traits were observed among clones in an individual site and in a two-site joint analysis. The repeatability of the tested traits varied from 0.22 to 0.87. Strong and positive (p < 0.01) correlations were detected among the four growth traits, while wood basic density had a significant negative correlation (p < 0.01 or 0.05) with the growth traits. A set of parent clones was shortlisted with substantial realized gains (ranging from 4.59% to 83.77%) in growth and wood traits. It was suggested that these selected parents could be used to improve the growth and wood quality of Chinese fir.

Simulating Sustainable Forest Management Practices Using Crown Attributes: Insights for Araucaria angustifolia Trees in Southern Brazil

Araucaria angustifolia (Bertol.) Kuntze, commonly known as Brazilian pine, is a significant tree species in the Brazilian flora that once covered an area of 200,000 km2 in the Southern region. During the 1970s, high-quality timber logs from this conifer became the primary export product of the country. However, the species is endangered due to uncontrolled exploitation and is subject to a harvesting ban. It is crucial, therefore, to explore sustainable cultivation methods for this species, which necessitates urgent research and scientific insights. In this study, we present a simulation of a management strategy for in situ conservation by manipulating growth space and crown size dynamics. Forest inventory data and mixed forest regression equations were employed to describe the horizontal dimensions of average and maximum potential crown growth, resulting in two management scenarios. The results presented in management diagrams show that both approaches required logging numerous trees to ensure adequate space for healthy tree growth and provide soil coverage and forest protection. Therefore, the absence of effective forest management initiatives for Araucaria forests may have further implications for the structure, production, conservation, and overall development. To address these challenges, we propose two hypotheses: firstly, that tree diameter depends on crown dimensions, which are in turn influenced by tree growth space, and, secondly, that crown dimensions serve as a reliable indicator of existing competition and can be utilized to simulate forest management practices. We urge that implementing sustainable forest management initiatives for Araucaria angustifolia at selected locations can contribute to expanding natural forest areas, mitigate deterioration caused by high competition, discourage illegal logging, and prevent overexploitation of their edible seeds, which hinders regeneration. Our results underscore the significant implications of the lack of forest management initiatives in rural properties, potentially resulting in irreversible deterioration. The exact consequences of this deterioration remain unclear, emphasizing the need for further studies to understand its eventual effects on the growth reaction of trees of different diameters, ages, and crown conditions after the liberation of their crowns.

Effect of Neem Extract on Fungus Inhibition in Toona ciliata M. Roem.

The increasing human population and continuous demands of timber and its derived products like composite wood, has created a significant pressure on the demand for high quality timber from forests. This, ultimately has resulted in pressurising the natural forests and increase in the unvailibility of the production of high quality or durable timber from the forests. The one way to neutralize this pressure on the forests is to modify the other non durable wood species having undesirable properties like hygroscopicity, anisotropy, dimensional instability and biodegradability. Treatment with neem extracts as a biopreservative proves to be very efficient to protect the wood from bacterial or fungal rots. In the present study, wood specimens of Toona ciliata M. Roem. were treated with neem leaf and seed extracts for 72 hours in concentrations of 0.25, 0.5, 1, 1.5 and 2% (w/v), and analyzed for fungal growth and inhibition on dry weight basis using Polyporous rubidus. The fungal growth was maximum in untreated (control) samples whereas, minimum growth was observed in the neem leaf and seed extracts with 2.00% concentration. This method comes to be one of the most eco-friendly processes of wood preservation and helps in utilization of Toon wood in more effective and sustainable way. Also, the minimal release of harmful chemicals in the environment, helps to widen the industrial applications of Toona ciliata wood and make its acceptance to the society with ease.

Just Bad Quality or Just Good Quality? The Meaning of Macroscopic Growth Features of Timber in Ship-Archaeological Analyses

Abstract The particular macroscopic growth features of the timbers of Bremen-Cog, a late 14th-century cargo vessel, were the subject of a detailed analysis during the European Research Council (ERC) research project TIMBER at the University of Copenhagen. The unexpected depth of the results of this examination led to the feasibility study presented in this paper, which evaluates the meaning of macroscopic growth features in ship archaeological analyses. In the past, the perception of wood in ship-archaeological analyses often seems to be either ignored or strongly idealised causing macroscopic growth features to be missing in many cases as decisive analytical features. The idea of a shipwright, who personally chooses only the best material, was likely born out of an idealised image of the past and influenced by recent shipbuilding practices. Detailed advice on the choice of high-quality timber for shipbuilding only appeared during the 20th century, long after wood was superseded by steel for most vessels, and the competition for shipbuilding timber on the market had ceased. In some cases, this has produced a somewhat distorted interpretation of ships and shipbuilding. As a holistic approach to features of growth can provide information beyond timber quality, such as environmental influences and human impacts on this resource. In certain cases, such an approach can draw conclusions on economic and social circumstances. The information gathered from building timber can alter the interpretation of boats and ships. This paper discusses the demand for shipbuilding timber and its quality in northwest Europe, and aims to reflect on possible social, economic, or environmental reasons for the shipwright’s choices.

DNA Extraction from Heartwood and Quick Species Authentication Using Real-Time PCR: A Case Study of the Rosewood (<i>Pterocarpus Indicus</i>)

Illegal logging, felling and timber trade have continued to increase over the past two decades, leading to a decline in forest biodiversity and the extinction of some wood species. <i>Pterocarpus indicus</i> Willd., listed in the National Standards of the People’s Republic of China for Hongmu (GB/T 18107-2017), is widely used in production of high-end furniture, decorative flooring and musical instruments due to its high-quality timber. For molecular species identification, the quality and quantity of DNA extracted from wood samples should first be ensured. However, extracting DNA from dried, aged timber heartwood is difficult, as heartwood contains little fragmented DNA, along with lots of phenolic compounds known to impede sequence amplification. In order to protect <i>P. indicus</i> from over-exploitation and to achieve accurate species-level identification, we established a particular extraction method for obtaining amplifiable DNA from heartwood samples and the real-time PCR assay for species discrimination of <i>P. indicus</i> in this study. The quantity and quality of DNA extracted from dry heartwood samples using the modified CTAB method were 2.40-37.70 ng/μL and 1.55-2.12 demonstrated by OD_260/280, respectively. Primer set P9, targeting <i>P. indicus</i> specific microsatellite Pin2-20 sequence, was amplifiable in newly established real-time PCR. Through analysis, this real time PCR was shown to be specific and sensitive with a detection limit around 0.17 ng/μL. Hopefully, this study will contribute to heartwood DNA extraction and species identification of timber logs for forensic discrimination, law enforcement and natural resource conservation.

First Report of Twig Anthracnose of Acacia melanoxylon Caused by Colletotrichum siamense in China.

Acacia melanoxylon R. Br. native to Australia, is a high-quality timber tree with wide genetic and phenotypic diversity. In recent years, A. melanoxylon has been extensively cultivated in some provinces in southern China. In December 2019, anthracnose-like symptoms were observed on twigs of A. melanoxylon in China. In certain valleys in south China, the disease incidence on plants and shoots was 60-75% and 80-90%, respectively. The wither rate of disease branches was 30-40% in dry seasons from September to November. The appearance of symptoms occurred in a humid and warm valley. Symptoms were initially observed on the young branches as brown spindle shaped sunken spots. At later stages, the disease spots girdled the whole branch, which became wilted and its leaves turned reddish-brown. For pathogen isolation, diseased branches were sampled and 55 pieces (5× 5 mm) of these branches section were surface-sterilized in 75% ethanol for 30 seconds, followed by 0.5% NaClO for 5 min and then were rinsed three times in distilled water. After drying with sterilized filter paper, the surface-sterilized sections were transferred to potato dextrose agar medium (PDA) and incubated at 25 °C for 7 days in the dark. Three isolates were obtained as representatives for morphological characterization and were labeled as 1A912, 1B912, and 1C912. These specimens were deposited in the Guangdong Province Key Laboratory of Microbial Signals and Disease Control at the South China Agricultural University (China). Purified isolates were initially white, cottony and with dense aerial mycelium on PDA at 25 ℃, ten days later their colonies turned grayish white with orange conidial masses. Conidia were one-celled, hyaline, straight, cylindrical, with round obtuse ends, and measured 11.0 to16.3× 4.0 to 6.0 μm (n= 100), appressoria were 5.86 to 9.07 × 3.55 to 6.96 μm (n= 100). Morphological characteristics of selected isolates matched the Colletotrichum gloeosporioides species complex (Weir et al. 2012). For further identification, the internal transcribed spacer (ITS) region, and partial sequences of the actin (ACT), beta-tubulin (TUB2), and glycerol dehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified by PCR, and sequenced, using primer pairs ITS1/ ITS4 (White et al. 1990), Bt2a/ Bt2b (Donaldson and Glass 1995), ACT512F/ ACT783R, GDF1/ GDR1(Weir et al. 2012). The sequences were deposited in GenBank (ITS: MW228101-MW228103; TUB2: MW250346, MW320707, MW320708; ACT: MW250347, MW320703, MW320704; GAPDH: MW250348, MW320705, MW320706). The multilocus phylogenetic analysis distinguished the isolates 1A912, 1B912, and 1C912 as C. siamense. Pathogenicity of those three isolates of C. siamense was tested on healthy twigs of the one clone of A. melanoxylon. 27 young twigs of nine 1-year-old plants were inoculated with the mycelium of the 7 days-old isolates 1A912, 1B912, and 1C912(Each isolate infected three plants and each infected three young twigs) through an artificial wound. The same nine plants were inoculated with PDA medium alone (each infected three young twigs) as a negative control. Five days after inoculation, brown spindle spots similar to the field disease symptoms were observed on the twigs. No symptoms were observed on the control plants. The experiment was repeated twice. The fungus was successfully reisolated from the symptomatic plants, and had identical morphological and molecular characteristics to the initial isolates, fulfilling Koch´s postulates. To our knowledge, this is the first report of anthracnose caused by C. siamense on A. melanoxylon in China. Twig anthracnose can reduce the growth of A. melanoxylon. Further research on management options for this disease is required.