Wood Decay Research Articles

Lasiodiplodia theobromae causes rachis blight on coconut palms (Cocos nucifera L.) in Florida.

Lasiodiplodia, a genus in the family Botryosphaeriaceae, has a broad host range and causes dieback, root rot, fruit rot, leaf rot, and blights in many plant species across sub-tropical and tropical geographical areas (Alves et al., 2008). In palms, this fungal pathogen is known to cause fruit and heart rot, wood decay and leaf blight around the globe (Atallah et al., 2024; Santos et al., 2020). In field-grown coconut palms symptoms usually start on older fronds progressing to younger fronds. Symptoms including discoloration of internal tissue, profuse pathogen sporulation, fruiting body formation, and death of entire fronds, universally characterize rachis blight caused by Lasiodiplodia. In summer 2023, a disease incidence of 30% and severity ranging from 20% to 100% of the canopy was observed in Florida. Three diseased coconut palms were sampled from a five-acre plot and the symptomatic tissue (internal rachis discoloration) was excised at the margin of the advancing lesion, and surface sterilized (30s 75% EtOH, 1 min 3% sodium hypochlorite, 1 min rinse in sterile water). Six pieces were plated on one Potato Dextrose Agar (PDA, Difco) plate supplemented with three antibiotics, penicillin, streptomycin, and neomycin, each at 5mg/L (Gibco PSN), and a total of three PDA plates per sample were processed. Plates were incubated at 25°C under darkness and Lasiodiplodia-like colonies were consistently recovered from all 54 rachis pieces. Initially white in color, the fungal colony grew radially, turned gray, and eventually took on a darker shade, with an abundance of aerial mycelium and rare occurrence of conidiomata and conidia in older plates. Two morphologically similar isolates Las1A and Las1B were obtained from single spores and grown at 28°C in the dark for 7 days. DNA was extracted using the quick DNA extraction protocol (Liu et al., 2000) and regions from two fungal barcoding genes, nuclear ribosomal internal transcribed spacer (nrITS) and translation elongation factor 1-α (TEF1-α) were amplified using primers ITS1/ITS4 (White et al., 1990) and EF1-728F/EF1-986R (Carbone & Kohn, 1999), respectively, and sequenced. The ITS (PQ282128 and PQ282129) and TEF1-α sequences from both isolates (PQ278132 and PQ278133) were 100% identical to Lasiodiplodia theobromae isolate G112-8 (OR453211 and OR482955, respectively). One-year-old seedlings of coconut palm (Cocos nucifera L.) were used for pathogenicity tests. Agar plugs from margins of actively growing cultures of Las1A and Las1B were placed on cut end of petioles from fronds close to the spear leaf and covered with parafilm. The control palms were treated with distilled water. The onset of disease symptoms was observed about 14 days post inoculation. The inoculated petioles were soft, listless, lost turgidity, and could be easily bent without snapping about 1 month following inoculation. In contrast, the palm control seedlings that were inoculated with water remained turgid, healthy and alive. Fruiting body development was observed on inoculated petioles, the pathogen was reisolated, and examination of its colony and spore morphology as well as presence of paraphyses was used to verify its identity. This is the first report of Lasiodiplodia theobromae causing disease on Cocos nucifera in Florida. This pathogen is a potential threat to coconut palm production in Florida and further research on pathogen diversity, pathogenicity, and distribution is needed to develop options for disease management.

To epiphytotic process at bursaphelenchosis (Bursaphelenchus mucronatus) of common pine

The purpose of the research is to study pine bursaphelenchosis foci identified in Vladimir Region and to describe the epiphytotic process at bursaphelenchosis of common pine Pinus sylvestris caused by the coniferous wood nematode Bursaphelenchus mucronatus Mamiya, Enda, 1979.Materials and methods. Research was conducted on the wilt of pine P. sylvestris L. in July 1998 in the Gus-Khrustalniy district of Vladimir Region. The symptoms of the lesion are similar to wilt caused by the nematode B. xylophilus. Selected large branches with yellow or red needles from 4 wilt centers. Rotten wood with bark beetle tracks was taken from windbroken trees. Externally uninfected trees were stripped of their bark and pieces of wood were cut. In the lab, the samples were pulverized, cut and placed in water. Nematodes were counted under binoculars. Nematodes were identified using methods generally accepted in phytohelminthology.Results and discussion. Foci of phytohelminthosis were found in pine plantations of Gus-Khrustalny District. The symptoms are similar to pine stem nematode infection, including yellow or red needles and tree death. B. mucronatus nematodes were found in small and large branches, trunks with bark beetle passages and in tree wood with alternating light and dark bluish layers. Capricorn beetles Monochamus spp. are vectors of the pathogen. B. mucronatus, phytopathogenic fungi, and symbiont bacteria contribute to pine death. Capricorn beetles lay eggs the larvae of which eat wood and complete the epiphytotic process. Transportation of contaminated materials facilitates the spread of bursaphelenchosis over long distances. Increasing air temperature increases the symptoms of bursaphelenchosis.

Soil amendments alter tree growth and wood decay after forest thinning

AbstractForest soil amendments are increasingly used in western US forests to dispose of unmerchantable woody residues, reduce wildfire risk, and improve soil properties. Our objective was to determine the effect of fertilizer and organic amendments on tree growth and organic matter decomposition after thinning. Treatments were a control, three single soil amendments (wood chips, fertilizer, and biochar), and one combined soil amendment (biochar + fertilizer), each applied after thinning a ponderosa pine (Pinus ponderosa Dougl. ex. Laws) stand. After 10 years, amendment treatments had no effect on tree diameter increment (p = 0.600), but the biochar + fertilizer and wood chip treatments significantly increased height growth (p = 0.006). To estimate belowground biological changes, we used wood stakes made from aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.) as an index of microbial activity. Stakes were placed: (1) on top of the litter/amendments, (2) at the interface between the litter/amendments and mineral soil, and (3) vertically inserted into the mineral soil, and stake mass loss was measured over 5 years. Stake mass loss of each species was least on the soil surface and increased with increasing depth. Aspen stakes generally had greater mass loss at all three soil locations in the fertilizer and biochar treatments. In contrast, pine stake mass loss was lower than aspen and less affected by fertilizer. Using thinned tree biomass to create amendments can improve forest productivity by enhancing soil conditions and mitigating wildfire. However, the impact of amendments on tree growth may take decades to be detectable.

Geographical variability in hygrothermal simulation results of historical building envelopes with interior insulation in Belgium

Thermal retrofits of existing buildings offer a great potential to reduce Europe’s energy use and CO2 emissions. The impact of these retrofitting strategies on the risk for degradation in building envelopes is assessed through hygrothermal simulations. Due to the lack of long term climate data, hygrothermal simulations are performed for a certain location, and the results are generalised over a large region. However, this generalisation may not be valid, since the hygrothermal performance of building envelopes is highly influenced by local climate conditions. Therefore, we assessed the geographical variability on degradation risks in building envelopes. This paper presents the results of 34560 hygrothermal simulations of solid masonry walls, with and without interior insulation, and including a range of other parameter variations, for 20 synoptic weather stations across Belgium. Generally, the risk for degradation is higher at locations with a higher elevation above sea level. For Belgium, the elevation correlates well with the mean temperature (invers correlation), and the annual precipitation and wind-driven rain load. For a known wall orientation, the impact of interior insulation on the risk for freeze-thaw damage is most determined by the elevation above sea level. Also the mould index in uninsulated walls correlates best with the elevation. On the contrary, the brick type is more important than the location when considering wood decay of embedded beam heads in retrofitted walls. To conclude, the risk for degradation cannot be generalised, especially over areas with complex variations in orographic and climatological conditions.

Molecular phylogeny and morphology of the genus Fuscoporia (Hymenochaetales, Basidiomycota) and reveal three new species of the F.ferrea group.

Fuscoporia is a polypore genus of Hymenochaetaceae that causes wood decay, although some species in the genus have medicinal values. Phylogenetic analyses of concatenated ITS1-5.8S-ITS2-nLSU sequence data and morphological features identified three new species, F.eucalypticola, F.resupinata and F.subtropica from Australia, China and Malaysia, and these new species derived from the Fuscoporiaferrea group. These three species are illustrated and described. A key to resupinate species of Fuscoporia without mycelial setae in the world is provided.

Antifungal Activity and Identification of Active Compounds From Wood Tristaniopsis whiteana (Griff) Against Wood Rot Fungus

Antifungal Activity and Identification of Active Compounds From Wood Tristaniopsis whiteana (Griff) Against Wood Rot Fungus

Fungal degradation of complex organic carbon supports denitrification in saturated woodchip bioreactors

Woodchip bioreactor (WBR) is a promising technology for the removal of nitrate from agricultural drainage, although the performance of WBRs is dependent on the decomposition of lignocellulosic biomass and the carbon availability for microbial denitrification. Fungal species are more efficient than bacterial counterparts in driving wood decomposition; however, little is known about the fungal community structure and functions in saturated WBRs. In this study, we investigated the dynamics of the mycobiome in field-scale, constantly saturated WBRs located in Willmar, Minnesota, USA. Fungal community analysis suggested that wood-rotting fungi were abundant in WBRs, especially near their inlet locations where microbial denitrification was most active. Complex network structures of fungal hyphae associated with a decayed cavity on the woodchip surface was further evidenced by confocal and scanning electron microscopy. These results suggest that fungi play a major role in wood degradation in WBRs, thereby promoting denitrification activity.

Ecology of the larvae of xylophilic druid flies (Diptera, Clusiidae)

For the first time, the biotopic associations of xylophilic druid fly larvae (Diptera: Clusiidae) with decaying wood, habitat conditions in wood, and trophic associations have been described. The features of the formation of the clusiid community and its composition are considered. For the first time, detailed information is provided about the species of insects (Coleoptera, Diptera) co-occurring with the clusiids in rotten wood.

First record of Hygrophoropsis flavida (Hygrophoropsidaceae, Agaricomycetes) from Türkiye

Hygrophoropsis flavida is reported for the first time from southern Türkiye, based on morphological and multi-molecular phylogenetic analyses, including nucleotide sequences of the nuclear ribosomal internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) and large subunit (LSU) of the ribosomal RNA (rRNA) gene. In addition, the species was found on the rotten wood of relict endemic Liquidambar orientalis trees, which are presented here for the first time as a new substrate for this genus. A description of this species, based on macro- and micromorphological characteristics, is provided, along with colour photographs and line drawings.

Evaluation of the utilization of Ginkgo biloba leaf (GBL) extract as an eco-friendly wood preservative

Ginkgo biloba leaf (GBL) extract was evaluated as a wood preservative, considering its sustainable availability in forests and cities worldwide. Previous research has demonstrated the antibacterial and antifungal properties of GBL extracts. Based on this information, it was hypothesized that GBL extract could effectively combat wood decay. The wood preservation properties of GBL extracts were evaluated using the “Laboratory test method of natural decay resistance of wood” KS F 2213 (2018). Its performance was compared to that of ACQ-2, a commercial wood preservative. The GBL extract was tested against two common wood decay fungi, namely Fomitopsis palustris and Trametes versicolor. The results showed mass loss rates of 13.6% and 9.9% after culturing these fungi, respectively. Although the GBL extract did not surpass the performance of ACQ-2, it achieved a “resistant” grade according to KS F 2213 (2018). This indicates that GBL extract exhibits a significant wood preservation effect. Furthermore, the GBL extract retains the natural color of wood, which is an advantageous characteristic.

Developing Sustainable Wood Preservatives: The Antifungal Efficiency of Afzelia quanzensis Welv. and Androstachys johnsonii Prain Sawdust Extracts from Mozambique

This study aimed to both develop and assess the antifungal efficacy of extractives derived from different sets of sawdust originating from two hardwood species, namely chanfuta (Afzelia quanzensis Welv.) and mecrusse (Androstachys johnsonnii Prain). These hardwood species possess inherent characteristics of high natural durability. The primary objective was to use these extractives to impregnate perishable wood species, enhancing their durability and augmenting their commercial value. Collected wood sawdust was initially sieved to remove residues and unwanted materials and conditioned until 12% moisture content. Subsequently, the sawdust was Soxhlet-extracted using a mixture of organic solvents, including acetone, ethanol, and toluene. After evaporating the solvents, the resulting extractives were used to prepare a preservative solution with ethanol and acetone. The extractive solutions from each wood species were mixed with malt extract agar and then diluted to various concentrations: 0.125 mg/mL, 0.25 mg/mL, 0.5 mg/mL, 1.25 mg/mL, 2.0 mg/mL, and 2.5 mg/mL. For each concentration, fungal plugs from the periphery of actively growing cultures were moved to the centre of Petri dishes and placed in controlled laboratory conditions for incubation. The antifungal efficacy was assessed against specific wood-decaying fungi, including brown rot fungi (Coniophora puteana, Postia placenta, Lentinus lapideus) and white rot (Trametes versicolor). The evaluation involved daily monitoring of the linear expansion along two perpendicular radii for each fungus expressed as a percentage of the empty Petri dish area. The results indicated that the chanfuta extractives inhibited the growth of brown rot fungi at a concentration of 0.25 mg/mL and white rot fungi at 2.0 mg/mL. Similarly, the mecrusse extractives inhibit brown rot at 0.5 mg/mL and white rot at 2.0 mg/mL. The fatty acids Oleic (C18:1) present in the chanfuta extractives solution and linoleic (C18:2) in mecrusse extractives contributed to restraining the fungal growth. These results suggest that sawdust extractives from both wood species exhibit promising potential for creating environmentally friendly wood preservatives, which, with effective treatments, could extend the lifespan of perishable wood species

Conception and Optimization of Extraction-Free Loop-Mediated Isothermal Amplification Detection of Dry Rot Fungus Serpula lacrymans.

The use of nucleic acid-based detection tools for microorganisms and fungi has become a gold standard. This is particularly the case for wood-decaying fungi like Serpula lacrymans, which are hard to discriminate based on macroscopic and microscopic observations. This dry rot is important to detect as it is particularly destructive in an infested building, which requires immediate action to prevent spreading and significant damage to structural elements. Through the development and optimization of loop-mediated isothermal amplification against S. lacrymans-specific rDNA internal transcribed spacer region, we demonstrate that it is possible to achieve rapid and specific amplification without nonspecific self-amplification in a similar range as real-time quantitative PCR without any necessary DNA isolation using a colorimetric detection assay. Through a combined set of self-amplification minimization along with hand-held sample homogenization, the LAMP assay was optimized to provide a femtogram-range assay capable of confirming identification in a real field sample either predominantly composed of S. lacrymans or containing the fungus while remaining negative when tested on different types of fungi found in basement-collected samples.

Spatial distribution of dark heartwood and wood rot in sugar maple at the northern edge of its range

The wood of sugar maple trees (Acer saccharum Marsh.) is generally perceived as containing more defects, such as dark heartwood and wood rot, at the northern limit of its range compared to southern locations; however, assessments of these internal defects have primarily relied on direct observation, limiting the scope of analysis. To enable large-scale assessments, models are needed to estimate the internal quality of individual trees based on external defects. Accordingly, this study aimed to investigate the relationships between external and internal defects within sugar maple stems. Then, large-scale estimates of the importance of such defects were produced to understand the effects of site conditions and climate. Increment cores were sampled from 1,108 trees across 108 plots. Results revealed that the probability of wood rot and the proportion of internal defects were associated with the presence of cracks and fungal fruiting bodies. Also, colder sites increased the probability of wood rot as well as the proportion of the stem affected by internal defects. Moreover, the western Balsam fir-Yellow birch subdomain had both the highest probability of wood rot and the greatest proportion of internal defects. Future studies should examine how this spatial distribution could evolve with climate change.

Fungi Associated with Olive Tree (cv. 'Nocellara del Belice') Decay in Trapani Province (Sicily, Italy).

Recently, in several locations in the province of Trapani (Sicily, Italy), olive growers have reported cases of decaying olive trees of cv. 'Nocellara del Belice', showing symptoms of defoliation, branch drying, xylem browning, and reduced production. Internal symptoms include white and brown wood rot, starting from the base of the trunk. These alterations have been observed in trees irrigated using a pipe system at the trunk with spray sprinklers. To identify the causal agents of decay, some trees were eradicated and dissected, and woody samples were processed to isolate and identify the associated fungal micro-organisms. The most common colonies were identified using morphological (macro- and microscopical observation) and molecular (PCR amplification of the rDNA-ITS region) analyses. Nine fungal taxa were identified, of which four were associated with this decay syndrome (Coriolopsis gallica, Fomitiporia mediterranea, Kirschsteiniothelia sp., and Pleurostoma richardsiae), three were considered ubiquitous and opportunistic fungi (Alternaria spp., Aspergillus amstelodami, and Trichoderma sp.), and the other two were mycelia sterilia. Artificial inoculation satisfied Koch's postulates, confirming the pathogenicity of the aforementioned fungi, even though the infections in the fields seem to be related to the irrigation system. This hypothesis would seem to be confirmed by the progression of decay over time in the trees subjected to the irrigation system described but not reported in olive groves differently managed. It is therefore considered appropriate to conduct further and more in-depth investigations aimed at studying the correlation between the irrigation system, presence of fungal agents, and manifestation of the syndrome. A further ongoing investigation is aimed at the use of biostimulants (Agrusaver, Savory Sun, VA LLC) on symptomatic trees, with the aim of both improving the vegetative performance of the host and limiting the symptoms detected in the field.

The internal decay of wood is driven by the interplay between foraging Magellanic woodpeckers and environmental conditions

Although woodpeckers are known to forage in decaying trees, their contribution to internal wood decay is not well known. In this sense, non-destructive techniques for structural wood degradation provide an opportunity to quantitatively assess the role of woodpeckers in tree decay. We used sonic tomography to test that the trunks of living trees pecked by Magellanic woodpeckers show pronounced decay, which accelerates under environmental conditions favorable to wood-decaying fungi. The internal decomposition of wood and its decay rate were measured over four years on 156 living southern beech (Nothofagus) trees belonging to four dominant species of southern temperate forests in northern Patagonia. Half of these live trees had woodpecker feeding holes, while the rest served as controls. The percentage of decayed wood, although not severely decayed, increased in sections with the presence of woodpecker holes, but was also influenced by temperatures and biophysical variables such as elevation and topography. The trunk sections with woodpecker holes and exposed to intensive foraging showed accelerated inter-annual decay. Woodpecker foraging activity interacted with vegetation characteristics, resulting in accelerated wood decay in forest sites with an open canopy and exposed to water stress. Thus, sonic tomography provided evidence of a close relationship between woodpeckers and internal wood decomposition, suggesting a positive feedback mechanism regulated by forest disturbance. The approach used here can be extended to gain insight into the influence of woodpeckers on tree decay and mortality in regions experiencing severe drought and forest degradation, such as northern Patagonia.

Development and Evaluation of Real-Time Quantitative PCR Assays for Detection of Phellinus noxius Causing Brown Root Rot Disease.

Brown root rot disease (BRRD) is a highly destructive tree disease. Early diagnosis of BRRD has been challenging because the first symptoms and signs are often observed after extensive tissue colonization. Existing molecular detection methods, all based on the internal transcribed spacer (ITS) region, were developed without testing against global Phellinus noxius isolates, other wood-decay fungi, or host plant tissues. This study aimed to develop SYBR Green real-time quantitative PCR (qPCR) assays for P. noxius. The primer pair Pn_ITS_F/Pn_ITS_R targets the ITS, and the primer pair Pn_NLR_F/Pn_NLR_R targets a P. noxius-unique group of homologous genes identified through a comparative genomics analysis. The homologous genes belong to the nucleotide-binding-oligomerization-domain-like receptor (NLR) superfamily. The new primer pairs and a previous primer pair G1F/G1R were optimized for qPCR conditions and tested for specificity using 61 global P. noxius isolates, 5 other Phellinus species, and 22 non-Phellinus wood-decay fungal species. Although all three primer pairs could detect as little as 100 fg (approximately 2.99 copies) of P. noxius genomic DNA, G1F/G1R had the highest specificity and Pn_NLR_F/Pn_NLR_R had the highest efficiency. To avoid false positives, the cutoff quantification cycle values were determined as 34 for G1F/G1R, 29 for Pn_ITS_F/Pn_ITS_R, and 32 for Pn_NLR_F/Pn_NLR_R. We further validated these qPCR assays using Ficus benjamina seedlings artificially inoculated with P. noxius, six tree species naturally infected by P. noxius, rhizosphere soil, and bulk soil. The newly developed qPCR assays provide sensitive detection and quantification of P. noxius, which is useful for long-term monitoring of BRRD status.

Artificial tree microhabitats: Wound depth and position affect saproxylic beetles attracted to freshly veteranised trees

Abstract Veteran and ancient trees are key structures sustaining biodiversity in wooded landscapes. Their value depends on tree‐related microhabitats (TreMs) such as hollows, cracks and other structures related to wounds and wood decay. Decline and loss of veteran trees results in the loss of TreMs thus threatening the biodiversity associated with them. Veteranisation, that is, interventions aimed at creating or accelerating formation of rare TreMs in live trees, are thus increasingly applied to bridge gaps in habitat continuity and sustain the biodiversity associated with veteran trees. Several studies investigated the use of artificially created TreMs by various organisms. No study has, however, investigated saproxylic beetles attracted to freshly veteranised trees, and how different veteranisation techniques affect attractivity of veteranised trees to saproxylic beetles. We veteranised 48 sessile oaks using two types of deep and two types of shallow cuts and trapped saproxylic beetles on the veteranised and control trees in the first season after the intervention. The sampling yielded 280 species (6171 individuals) of saproxylic beetles, including 64 that are threatened. Veteranised trees attracted more abundant and diverse communities than control trees. Community composition differed between shallow and deep cuts and between the two types of deep cuts. Freshly veteranised trees thus attract diverse and abundant communities of saproxylic beetles consisting mainly of species potentially exploiting the wounds. The high proportion of threatened species, often associated with old oaks, suggests that veteranised trees benefit even some threatened saproxylic biodiversity already during the first year after the veteranisation.

Ultra-Pressurized Deposition of Hydrophobic Chitosan Surface Coating on Wood for Fungal Resistance.

Fungi (Neolentinus lepideus, Nl, and Trametes versicolor, Tv) impart wood rot, leading to economic and environmental issues. To overcome this issue, toxic chemicals are commonly employed for wood preservation, impacting the environment and human health. Surface coatings based on antimicrobial chitosan (CS) of high molar mass (145 × 105 Da) were tested as wood preservation agents using an innovative strategy involving ultra-pressurizing CS solutions to deposit organic coatings on wood samples. Before coating deposition, the antifungal activity of CS in diluted acetic acid (AcOOH) solutions was evaluated against the rot fungi models Neolentinus lepideus (Nl) and Trametes versicolor (Tv). CS effectively inhibited fungal growth, particularly in solutions with concentrations equal to or higher than 0.125 mg/mL. Wood samples (Eucalyptus sp. and Pinus sp.) were then coated with CS under ultra-pressurization at 70 bar. The polymeric coating deposition on wood was confirmed through X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) images, and water contact angle measurements. Infrared spectroscopy (FTIR) spectra of the uncoated and coated samples suggested that CS does not penetrate the bulk of the wood samples due to its high molar mass but penetrates in the surface pores, leading to its impregnation in wood samples. Coated and uncoated wood samples were exposed to fungi (Tv and Nl) for 12 weeks. In vivo testing revealed that Tv and Nl fungi did not grow on wood samples coated with CS, whereas the fungi proliferated on uncoated samples. CS of high molar mass has film-forming properties, leading to a thin hydrophobic film on the wood surface (water contact angle of 118°). This effect is mainly attributed to the high molar mass of CS and the hydrogen bonding interactions established between CS chains and cellulose. This hydrophobic film prevents water interaction, resulting in a stable coating with insignificant leaching of CS after the stability test. The CS coating can offer a sustainable strategy to prevent wood degradation, overcoming the disadvantages of toxic chemicals often used as wood preservative agents.

Multidimensional Exploration of Wood Extractives: A Review of Compositional Analysis, Decay Resistance, Light Stability, and Staining Applications

Extractives, which naturally evolve as fundamental defense mechanisms in wood against environmental stresses, hold an essential place in the field of wood conservation science. Despite their low content in woody substrates, extractives are chemically complex and can be extracted accurately by solvents with different polarities, covering key components such as aliphatic, terpenoid, and phenolic compounds. The application of solvent extraction allows for the effective recovery of these extracts from forestry waste, thereby creating new opportunities for their reuse in wood modification and enhancing the economic value and potential applications of forestry waste. In the wood industry, extractives not only act as efficient preservatives and photo-stabilizers, significantly improving the decay resistance and photodegradation resistance of wood, but also serve as ideal dyes for fast-growing wood due to their abundant natural colors, which lend the product a distinct aesthetic appeal. The aim of this paper is to provide a comprehensive review of the origin and distribution characteristics of wood extractives and to examine the impact of solvent selection on extraction efficiency. At the same time, the mechanism of extractives in enhancing wood decay resistance and slowing down photodegradation is deeply analyzed. In addition, specific examples are presented to illustrate their wide utilization in the wood industry. This is intended to provide references for research and practice in related fields.

Mapping pathogenic fungi in decayed Norway spruce stands: Insights from harvester positional data

Abstract Root and butt rot caused by pathogenic fungi in the genera Heterobasidion and Armillaria is a pressing issue in managed Norway spruce forests. The disease results in financial losses for the forest owners and reduces the volume of wood that can be used in long‐lived products. Pathogenic wood decay fungi spread either with the aid of airborne spores or via mycelial growth among neighbouring trees, the latter leading to clustering (tendency of decayed trees to be in close proximity relative to their neighbouring trees) of decay‐affected trees in forests. Understanding the spatial patterns of the decay‐affected trees at the forest stand level is vital for designing management strategies to address this problem. We examined decay clustering in 273 clear‐cut Norway spruce stands in Norway using harvester‐recorded data on spatial occurrence of decayed and healthy Norway spruce trees. We tested clustering using three global‐cluster tests that account for population density and distribution, evaluating clustering without identifying specific cluster locations. The proportions of clustered and non‐clustered stands differed depending on the statistical test used for clustering assessment, resulting in overall agreement of 32.8% for clustered and 36.9% for non‐clustered. Clustered stands exhibited a median cluster distance (maximum distance between the decay‐affected trees within a cluster) of 12 m (Inter‐Quantile Range, IQR, 6–20 m) and a median of 6 (IQR 3–16) nearest neighbour trees (number of decayed trees forming a cluster), estimates comparable with prior studies focused on assessment of trees infected by mycelial spread of the same fungal individual. The decay incidence in the clustered stands was 16.24%, while the non‐clustered stands had a butt‐rot incidence of 20.97%. In clustered stands the average number of trees per hectare was higher (693) than in non‐clustered stands (553). Synthesis and applications: Our study demonstrates that Norway spruce stands display a diverse range of spatial patterns of butt rotted trees. We found that higher densities of Norway spruce trees probably facilitate the vegetative spread of pathogenic wood decay fungi, leading to clustering of decay‐affected trees. To disrupt the spread of decay fungi between tree generations, precision planting of trees other than Norway spruce around infested stumps of prior generation trees has been recommended by earlier studies. We discussed the potential of using harvester‐derived geoposition data for butt‐rotted trees upon planning and execution of forest regeneration.