ResearchPad - wood https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Mycelial biomass estimation and metabolic quotient of <i>Lentinula edodes</i> using species-specific qPCR]]> https://www.researchpad.co/article/elastic_article_15715 Lentinula edodes, commonly known as shiitake, is an edible mushroom that is cultivated and consumed around the globe, especially in Asia. Monitoring mycelial growth inside a woody substrate is difficult, but it is essential for effective management of mushroom cultivation. Mycelial biomass also affects the rate of wood decomposition under natural conditions and must be known to determine the metabolic quotient, an important ecophysiological parameter of fungal growth. Therefore, developing a method to measure it inside a substrate would be very useful. In this study, as the first step in understanding species-specific rates of fungal decomposition of wood, we developed species-specific primers and qPCR procedures for L. edodes. We tested primer specificity using strains of L. edodes from Japan and Southeast Asia, as well as related species of fungi and plant species for cultivation of L. edodes, and generated a calibration curve for quantification of mycelial biomass in wood dust inoculated with L. edodes. The qPCR procedure we developed can specifically detect L. edodes and allowed us to quantify the increase in L. edodes biomass in wood dust substrate and calculate the metabolic quotient based on the mycelial biomass and respiration rate. Development of a species-specific method for biomass quantification will be useful for both estimation of mycelial biomass and determining the kinetics of fungal growth in decomposition processes.

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<![CDATA[Valuing and mapping cork and carbon across land use scenarios in a Portuguese montado landscape]]> https://www.researchpad.co/article/5c8accd7d5eed0c484990136

The ecosystem services approach can inform decision-making by accounting for both short- and long-term benefits from different land use options. Here we used the InVEST toolkit to quantify and map key ecosystem services at the largest publicly-owned agro-silvo-pastoral farmstead in Portugal–a site representative for the montado landscape. We analyzed how Provisioning (cork production) and Regulating & Maintenance (carbon storage and sequestration) services would be affected under three land use change scenarios, which were developed in collaboration with the forest manager of the study area: Cattle Intensification, Forest Improvement, and Residential Development. Results show that increasing cattle or residential development would deliver substantially lower levels of services. We find that extensive management, improvements to forest quality, and promotion of traditional livestock grazing would provide the highest levels of assessed ecosystem services, resulting in 13.5% more carbon storage (worth between $0.34-$7.79 million USD depending on carbon price) and 62.7% more cork production (total value of USD $3.5 million) than the current land use. However, a shift in economic incentives to make sustainable cork harvesting and traditional low-density grazing of smaller ruminants like sheep and goats profitable are likely needed to reward traditional land stewardship and help support this iconic Mediterranean landscape in the future.

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<![CDATA[Potential role of weather, soil and plant microbial communities in rapid decline of apple trees]]> https://www.researchpad.co/article/5c89776ed5eed0c4847d2c8c

An unusual decline and collapse of young established trees known as “rapid apple decline” (RAD) has become a major concern for apple growers, particularly in the northeastern United States. This decline is characterized by stunted growth, pale yellow to reddish leaves, and tree collapse within weeks after onset of symptoms. We studied declining apple trees to identify potential involvement of abiotic and biotic stresses. We used 16S and ITS to profile bacterial and fungal communities in the soil, rhizosphere, roots, and shoots and tested for the presence of six viruses in scions and rootstocks of symptomatic and asymptomatic trees. The viruses detected were not associated with RAD symptoms. Bacterial and fungal populations were highly variable in plant tissue, soil and rhizosphere samples, with bacteroidetes, firmicutes, proteobacteria, acidobacteria, and actinobacteria the predominant bacterial classes in various samples. ‘Alphaproteobacteria-rickettsiales’, a bacterial class usually reduced in water-limiting soils, had significantly low abundance in root samples of symptomatic trees. Basidiomycota and Ascomycota fungal classes were the most common fungal classes observed, but neither showed differential enrichment between symptomatic and asymptomatic trees. Analyzing weather data showed an extremely cold winter followed by drought in 2015–2016, which likely weakened the trees to make them more susceptible to varied stresses. In addition, similar physical and nutritional soil composition from symptomatic and asymptomatic trees rules out the role of nutritional stress in RAD. Necrotic lesions and wood decay symptoms dispersing from bark or vascular cambium towards the heartwood were observed primarily below the graft union of declining apple trees, suggesting that the rootstock is the originating point of RAD. We speculate that differences in abiotic factors such as moisture levels in declining roots in combination with extreme weather profiles might cause RAD but cannot clearly rule out the involvement of other factors.

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<![CDATA[Trait divergence and habitat specialization in tropical floodplain forests trees]]> https://www.researchpad.co/article/5c706768d5eed0c4847c6fcb

Habitat heterogeneity of tropical forests is thought to lead to specialization in plants and contribute to the high diversity of tree species in Amazonia. One prediction of habitat specialization is that species specialized for resource-rich habitats will have traits associated with high resource acquisition and fast growth while species specialized for resource-poor habitats will have traits associated with high resource conservation and persistence but slow growth. We tested this idea for seven genera and for twelve families from nutrient-rich white-water floodplain forest (várzea) and nutrient-poor black-water (igapó) floodplain forest. We measured 11 traits that are important for the carbon and nutrient balance of the trees, and compared trait variation between habitat types (white- and black-water forests), and the effect of habitat and genus/family on trait divergence. Functional traits of congeneric species differed between habitat types, where white-water forest species invested in resource acquisition and productive tissues, whereas black-water forest species invested in resource conservation and persistent tissues. Habitat specialization is leading to the differentiation of floodplain tree species of white-water and black-water forests, thus contributing to a high diversity of plant species in floodplain forests.

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<![CDATA[The wood decay fungus Cerrena unicolor adjusts its metabolism to grow on various types of wood and light conditions]]> https://www.researchpad.co/article/5c633975d5eed0c484ae67e0

Cerrena unicolor is a wood-degrading basidiomycete with ecological and biotechnological importance. Comprehensive Biolog-based analysis was performed to assess the metabolic capabilities and sensitivity to chemicals of C. unicolor FCL139 growing in various sawdust substrates and light conditions. The metabolic preferences of the fungus towards utilization of specific substrates were shown to be correlated with the sawdust medium applied for fungus growth and the light conditions. The highest catabolic activity of C. unicolor was observed after fungus precultivation on birch and ash sawdust media. The fungus growing in the dark showed the highest metabolic activity which was indicated by capacity to utilize a broad spectrum of compounds and the decomposition of 74/95 of the carbon sources. In all the culture light conditions, p-hydroxyphenylacetic acid was the most readily metabolized compound. The greatest tolerance to chemicals was also observed during C. unicolor growth in darkness. The fungus was the most sensitive to nitrogen compounds and antibiotics, but more resistant to chelators. Comparative analysis of C. unicolor and selected wood-decay fungi from different taxonomic and ecological groups revealed average catabolic activity of the fungus. However, C. unicolor showed outstanding capabilities to catabolize salicin and arbutin. The obtained picture of C. unicolor metabolism showed that the fungus abilities to decompose woody plant material are influenced by various environmental factors.

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<![CDATA[Developing tools for evaluating inoculation methods of biocontrol Streptomyces sp. strains into grapevine plants]]> https://www.researchpad.co/article/5c536bfcd5eed0c484a496c7

The endophytic Streptomyces sp. VV/E1, and rhizosphere Streptomyces sp. VV/R4 strains, isolated from grapevine plants were shown in a previous work to reduce the infection rate of fungal pathogens involved in young grapevine decline. In this study we cloned fragments from randomly amplified polymorphic DNA (RAPD), and developed two stably diagnostic sequence-characterized amplified region (SCAR) markers of 182 and 160 bp for the VV/E1 and VV/R4 strains, respectively. The SCAR markers were not found in another 50 actinobacterial strains isolated from grapevine plants. Quantitative real-time PCR protocols based on the amplification of these SCAR markers were used for the detection and quantification of both strains in plant material. These strains were applied on young potted plants using two methods: perforation of the rootstock followed by injection of the microorganisms or soaking the root system in a bacterial suspension. Both methods were combined with a booster treatment by direct addition of a bacterial suspension to the soil near the root system. Analysis of uprooted plants showed that those inoculated by injection exhibited the highest rate of colonization. In contrast, direct addition of either strain to the soil did not lead to reliable colonization. This study has developed molecular tools for analyzing different methods for inoculating grapevine plants with selected Streptomyces sp. strains which protect them from fungal infections that enter through their root system. These tools are of great applied interest since they could easily be established in nurseries to produce grafted grapevine plants that are protected against fungal pathogens. Finally, this methodology might also be applied to other vascular plants for their colonization with beneficial biological control agents.

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<![CDATA[Culturally modified trees or wasted timber: Different approaches to marked trees in Poland’s Białowieża Forest]]> https://www.researchpad.co/article/5c52182ed5eed0c4847976a4

Studies of past forest use traditions are crucial in both understanding the present state of the oldest European forests, and in guiding decisions on future forest conservation and management. Current management of Poland’s Białowieża Forest (BF), one of the best-preserved forests of the European lowlands, is heavily influenced by anecdotal knowledge on forest history. Therefore, it is important to gain knowledge of the forest’s past in order to answer questions about its historical administration, utilisation, and associated anthropogenic changes. Such understanding can then inform future management. This study, based on surveys in Belarussian and Russian archives and a preliminary field survey in ten forest compartments of Białowieża National Park, focuses on culturally-modified trees (CMTs), which in this case are by-products of different forms of traditional forest use. Information about the formation of the CMTs can then be used to provide insight into former forest usage. Two types of CMTs were discovered to be still present in the contemporary BF. One type found in two forms was of 1) pine trees scorched and chopped in the bottom part of the trunk and 2) pine trees with carved beehives. A second type based on written accounts, and therefore known to be present in the past (what we call a ‘ghost CMT’), was of 3) lime-trees with strips of bark peeled from the trunk. Written accounts cover the period of transition between the traditional forest management (BF as a Polish royal hunting ground, until the end of the eighteenth century) and modern, “scientific” forestry (in most European countries introduced in the second half of the nineteenth century). These accounts document that both types of CMTs and the traditional forest uses responsible for their creation were considered harmful to “rational forestry” by the nineteenth-century forest administration. Thus the practices which created CMTs were banned and the trees gradually removed from the forest. Indeed, these activities drew the attention of forest administrators for several decades, and in our view delayed the introduction of new, timber-oriented, forest management in the BF.

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<![CDATA[An integrated characterization of Picea abies industrial bark regarding chemical composition, thermal properties and polar extracts activity]]> https://www.researchpad.co/article/5c06f03cd5eed0c484c6d494

The present work determines the chemical and thermal characteristics as well as the phytochemical and antioxidant potential of the polar extractives of the Picea abies bark from an industrial mill, their wood and bark components and also different bark fractions obtained by mechanical fractionation (fine B1, Φ<0.180 mm, medium B3, 0.450 < Φ<0.850 mm and coarse B6, 2 < Φ<10 mm). The aim is to increase the knowledge on the Picea abies bark to better determine possible uses other than burning for energy production and to test an initial size reduction process to achieve fractions with different characteristics. Compared to wood, bark presented similar lignin (27%), higher mineral (3.9% vs 0.4%) and extractives (20.3% vs 3.8%) and lower polysaccharides (48% vs 71%) contents. Regarding bark fractions the fines showed higher ash (6.3%), extractives (25%) and lignin (29%) than the coarse fraction (3.9%, 19% and 25% respectively). Polysaccharide contents increased with particle size of the bark fractions (38% vs 52% for B1 and B6) but showed the same relative composition. The phytochemical profile of ethanol and water extracts presented higher contents for bark than wood of total phenols (2x higher), flavonoids (3x higher) and tannins (4-10x higher) with an increasing tendency with particle size. Bark antioxidant activity was higher than that of wood for ferric-reducing antioxidant power (FRAP, 10 vs 6 mmolFe2+/gExt for the ethanol extract) and free radical scavenging activity (DPPH, 6 vs 18 mg/L IC50 for the ethanol extract) methods. The different bark fractions antioxidant activity was very similar. Bark thermal properties showed a much lower volatiles to fixed carbon ratio (V/FC) than wood (3.1 vs 5.2) although the same higher heating value (20.3 MJ/kg). The fractions were quite similar. Bark presented chemical features that point to their possible upgrade, whether by taking advantage of the high extractives with bioactive compounds or the production potential for hemicellulose-derived oligomers with possible use in nutraceutical and pharmaceutical industries.

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<![CDATA[Trunk surface agarwood-inducing technique with Rigidoporus vinctus: An efficient novel method for agarwood production]]> https://www.researchpad.co/article/5c032e01d5eed0c4844f8ad4

Only when Aquilaria spp. or Gyrinops spp. trees are wounded, due to insect attack, or microbial invasion, agarwood can be successfully induced. In the present study, a fungus which can induce agarwood formation efficiently was isolated and a suitable method for its application to induce agarwood formation was developed. Rigidoporus vinctus was isolated from the inner layers from infectious A. sinensis trees. When the fermentation liquid of fungi inoculated back to A. sinensis tree, agarwood was found to be induced. In addition, a novel method called trunk surface agarwood-inducing technique (Agar-Sit) was developed to produce agarwood with R. vinctus. The alcohol soluble extract content of the agarwood, up to 38.9%, far higher than the requirement (10%) in Chinese Pharmacopoeia and the six characteristic compounds of agarwood used as Chinese Medicinal Materials were all detected. Their relative percentages of the sesquiterpenes in the essential oil were 22.76%. This is the first report of the Agar-Sit and also the application of R. vinctus in agarwood induction. According to the results, when the combination of Agar-Sit and R. vinctus is used agarwood can be induced with high yield and good quality.

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<![CDATA[Characterization and Functional Analysis of 4-Coumarate:CoA Ligase Genes in Mul-berry]]> https://www.researchpad.co/article/5989d9fbab0ee8fa60b72164

A small, multigene family encodes 4-coumarate:CoA ligases (4CLs) that catalyze the ligation of CoA to hydroxycinnamic acids, a branch point directing metabolites to flavonoid or monolignol pathways. In this study, we characterized four 4CL genes from M. notabilis Genome Database, and cloned four Ma4CL genes from M. atropurpurea cv. Jialing No.40. A tissue-specific expression analysis indicated that Ma4CL3 was expressed at higher levels than the other genes, and that Ma4CL3 was strongly expressed in root bark, stem bark, and old leaves. Additionally, the expression pattern of Ma4CL3 was similar to the trend of the total flavonoid content throughout fruit development. A phylogenetic analysis suggested that Mn4CL1, Mn4CL2, and Mn4CL4 belong to class I 4CLs, and Mn4CL3 belongs to class II 4CLs. Ma4CL genes responded differently to a series of stresses. Ma4CL3 expression was higher than that of the other Ma4CL genes following wounding, salicylic acid, and ultraviolet treatments. An in vitro enzyme assay indicated that 4-coumarate acid was the best substrate among cinnamic acid, 4-coumarate acid, and caffeate acid, but no catalytic activity to sinapate acid and ferulate acid. The results of subcellular localization experiments showed that Ma4CL3 localized to the cytomembrane, where it activated transcription. We used different vectors and strategies to fuse Ma4CL3 with stilbene synthase (STS) to construct four Ma4CL-MaSTS co-expression systems to generate resveratrol. The results indicated that only a transcriptional fusion vector, pET-Ma4CL3-T-MaSTS, which utilized a T7 promoter and lac operator for the expression of MaSTS, could synthesize resveratrol.

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<![CDATA[Properties of biochar derived from wood and high-nutrient biomasses with the aim of agronomic and environmental benefits]]> https://www.researchpad.co/article/5989db5aab0ee8fa60bdf6f9

Biochar production and use are part of the modern agenda to recycle wastes, and to retain nutrients, pollutants, and heavy metals in the soil and to offset some greenhouse gas emissions. Biochars from wood (eucalyptus sawdust, pine bark), sugarcane bagasse, and substances rich in nutrients (coffee husk, chicken manure) produced at 350, 450 and 750°C were characterized to identify agronomic and environmental benefits, which may enhance soil quality. Biochars derived from wood and sugarcane have greater potential for improving C storage in tropical soils due to a higher aromatic character, high C concentration, low H/C ratio, and FTIR spectra features as compared to nutrient-rich biochars. The high ash content associated with alkaline chemical species such as KHCO3 and CaCO3, verified by XRD analysis, made chicken manure and coffee husk biochars potential liming agents for remediating acidic soils. High Ca and K contents in chicken manure and coffee husk biomass can significantly replace conventional sources of K (mostly imported in Brazil) and Ca, suggesting a high agronomic value for these biochars. High-ash biochars, such as chicken manure and coffee husk, produced at low-temperatures (350 and 450°C) exhibited high CEC values, which can be considered as a potential applicable material to increase nutrient retention in soil. Therefore, the agronomic value of the biochars in this study is predominantly regulated by the nutrient richness of the biomass, but an increase in pyrolysis temperature to 750°C can strongly decrease the adsorptive capacities of chicken manure and coffee husk biochars. A diagram of the agronomic potential and environmental benefits is presented, along with some guidelines to relate biochar properties with potential agronomic and environmental uses. Based on biochar properties, research needs are identified and directions for future trials are delineated.

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<![CDATA[Decomposing functional trait associations in a Chinese subtropical forest]]> https://www.researchpad.co/article/5989db53ab0ee8fa60bdc9b7

Functional traits, properties of organisms correlated with ecological performance, play a central role in plant community assembly and functioning. To some extents, functional traits vary in concert, reflecting fundamental ecological strategies. While “trait syndromes” characteristic of e.g. fast-growing, early-successional vs. competitive, late-successional species are recognized in principle, less is known about the environmental and genetic factors at the source of trait variation and covariation within plant communities. We studied the three leaf traits leaf half-life (LHL), leaf mass per area (LMA) and nitrogen concentration in green leaves (Ngreen) and the wood trait wood density (WD) in 294 individuals belonging to 45 tree or shrub species in a Chinese subtropical forest from September 2006 to January 2009. Using multilevel ANOVA and decomposition of sums of products, we estimated the amount of trait variation and covariation among species (mainly genetic causes), i.e. plant functional type (deciduous vs. evergreen species), growth form (tree vs. shrub species), family/genus/species differences, and within species (mainly environmental causes), i.e. individual and season. For single traits, the variation between functional types and among species within functional types was large, but only LMA and Ngreen varied significantly among families and thus showed phylogenetic signal. Trait variation among individuals within species was small, but large temporal variation due to seasonal effects was found within individuals. We did not find any trait variation related to soil conditions underneath the measured individuals. For pairs of traits, variation between functional types and among species within functional types was large, reflecting a strong evolutionary coordination of the traits, with LMA, LHL and WD being positively correlated among each other and negatively with Ngreen. This integration of traits was consistent with a putative stem-leaf economics spectrum ranging from deciduous species with thin, high-nitrogen leaves and low-density wood to evergreen species with thick, low-nitrogen leaves and dense wood and was not influenced by phylogenetic history. Trait coordination within species was weak, allowing individual trees to deviate from the interspecific trait coordination and thus respond flexibly to environmental heterogeneity. Our findings suggest that within a single woody plant community variation and covariation in functional traits allows a large number of species to co-exist and cover a broad spectrum of multivariate niche space, which in turn may increase total resource extraction by the community and community functioning.

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<![CDATA[Seasonal Succession of Fungi Associated with Ips typographus Beetles and Their Phoretic Mites in an Outbreak Region of Finland]]> https://www.researchpad.co/article/5989da72ab0ee8fa60b95474

The ophiostomatoid fungi (Microascales and Ophiostomatales, Ascomycota) are common associates of Ips typographus, and include tree pathogens and species responsible for blue-stain of timber. Fungal assemblages associated with I. typographus have varied considerably between studies but few investigations have attempted to explain this variation. For this reason, we assessed the overall cultivable fungal diversity associated with I. typographus in a storm-felled spruce forest in south-eastern Finland. Fungi were isolated from the individually collected beetles as well as their phoretic mites in spring, summer and autumn, including different life stages of the beetle (hibernation, dispersal flight and first generation). The internal transcribed spacer (ITS) gene region was used to identify the fungi. A total of 32 operational taxonomic units (OTUs) were found and these resided in four fungal phyla/subphyla (24 Ascomycota, 2 Basidiomycota, 5 Mucoromycotina, 1 Mortierellomycotina) in association with adult bark beetles. Ophiostomatoid species were the most commonly detected fungal associates. A generalized linear model analysis showed a clear association between fungal communities and season, indicating seasonal succession among I. typographus-associated fungi. The season of sampling appears to be an important factor that has resulted in inconsistencies between results in previous studies. Many of these fungi were also found on phoretic mites and their presence or absence could have influenced variation in patterns of association.

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<![CDATA[Sources of Information as Determinants of Product and Process Innovation]]> https://www.researchpad.co/article/5989da01ab0ee8fa60b7401e

In this paper we use a panel of manufacturing firms in Spain to examine the extent to which they use internal and external sources of information (customers, suppliers, competitors, consultants and universities) to generate product and process innovation. Our results show that, although internal sources are influential, external sources of information are key to achieve innovation performance. These results are in line with the open innovation literature because they show that firms that are opening up their innovation process and that use different information sources have a greater capacity to generate innovations. We also find that the importance of external sources of information varies depending on the type of innovation (product or process) considered. To generate process innovation, firms mainly rely on suppliers while, to generate product innovation, the main contribution is from customers. The potential simultaneity between product and process innovation is also taken into consideration. We find that the generation of both types of innovation is not independent.

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<![CDATA[Integrated Chronology, Flora and Faunas, and Paleoecology of the Alajuela Formation, Late Miocene of Panama]]> https://www.researchpad.co/article/5989db53ab0ee8fa60bdce60

The late Miocene was an important time to understand the geological, climatic, and biotic evolution of the ancient New World tropics and the context for the Great American Biotic Interchange (GABI). Despite this importance, upper Miocene deposits containing diverse faunas and floras and their associated geological context are rare in Central America. We present an integrated study of the geological and paleontological context and age of a new locality from Lago Alajuela in northern Panama (Caribbean side) containing late Miocene marine and terrestrial fossils (plants, invertebrates, and vertebrates) from the Alajuela Formation. These taxa indicate predominantly estuarine and shallow marine paleoenvironments, along with terrestrial influences based on the occurrence of land mammals. Sr-isotope ratio analyses of in situ scallop shells indicate an age for the Alajuela Formation of 9.77 ± 0.22 Ma, which also equates to a latest Clarendonian (Cl3) North American Land Mammal Age. Along with the roughly contemporaneous late Miocene Gatun and Lago Bayano faunas in Panama, we now have the opportunity to reconstruct the dynamics of the Central America seaway that existed before final closure coincident with formation of the Isthmus of Panama.

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<![CDATA[Multilocus sequence typing provides insights into the population structure and evolutionary potential of Brenneria goodwinii, associated with acute oak decline]]> https://www.researchpad.co/article/5989db5cab0ee8fa60be0217

Brenneria goodwinii is one of the most frequently isolated Gram-negative bacteria from native oak species, Quercus robur and Q. petraea, affected by acute oak decline (AOD) in the UK. We investigated the population biology of this bacterial species using a multilocus sequence analysis to determine the population structure and evolutionary potential. Seven partial housekeeping genes were used in the analyses. Amongst 44 bacterial strains from seven different locations, we identified 22 unique sequence types [STs]; only one ST was found at two separate locations. Phylogenetic and cluster-based analyses suggested that B. goodwinii STs form two main distinct groups; however, no geographical pattern of their distribution could be observed. Clonality and recombination tests demonstrated that the studied population is primarily clonal, however both mutation and recombination processes play a role in shaping the genetic structure and evolution of the population. Our study suggests that the B. goodwinii population on oak in the UK has an endemic form, with background recombination appearing to generate new alleles more frequently than mutation, despite the introduction of nucleotide substitutions being approximately twice less likely than mutation. The newly emerged STs subsequently undergo clonal expansion to become dominant genotypes within their specific geographical locations and even within the individual host oak trees.

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<![CDATA[Development of a Compatible Taper Function and Stand-Level Merchantable Volume Model for Chinese Fir Plantations]]> https://www.researchpad.co/article/5989dad4ab0ee8fa60bb77d2

Chinese fir (Cunninghamia lanceolata [Lamb.] Hook) is one of the most important plantation tree species in China with good timber quality and fast growth. It covers an area of 8.54 million hectare, which corresponds to 21% of the total plantation area and 32% of total plantation volume in China. With the increasing market demand, an accurate estimation and prediction of merchantable volume at tree- and stand-level is becoming important for plantation owners. Although there are many studies on the total tree volume estimation from allometric models, these allometric models cannot predict tree- and stand-level merchantable volume at any merchantable height, and the stand-level merchantable volume model was not seen yet in Chinese fir plantations. This study aimed to develop (1) a compatible taper function for tree-level merchantable volume estimation, and (2) a stand-level merchantable volume model for Chinese fir plantations. This “taper function system” consisted in a taper function, a merchantable volume equation and a total tree volume equation. 46 Chinese fir trees were felled to develop the taper function in Shitai County, Anhui province, China. A second-order continuous autoregressive error structure corrected the inherent serial autocorrelation of different observations in one tree. The taper function and volume equations were fitted simultaneously after autocorrelation correction. The compatible taper function fitted well to our data and had very good performances in diameter and total tree volume prediction. The stand-level merchantable volume equation based on the ratio approach was developed using basal area, dominant height, quadratic mean diameter and top diameter (ranging from 0 to 30 cm) as independent variables. At last, a total stand-level volume table using stand basal area and dominant height as variables was proposed for local forest managers to simplify the stand volume estimation.

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<![CDATA[Models for Predicting the Biomass of Cunninghamialanceolata Trees and Stands in Southeastern China]]> https://www.researchpad.co/article/5989db3fab0ee8fa60bd6427

Using existing equations to estimate the biomass of a single tree or a forest stand still involves large uncertainties. In this study, we developed individual-tree biomass models for Chinese Fir (Cunninghamia lanceolata.) stands in Fujian Province, southeast China, by using 74 previously established models that have been most commonly used to estimate tree biomass. We selected the best fit models and modified them. The results showed that the published model ln(B(Biomass)) = a + b * ln(D) + c * (ln(H))2 + d * (ln(H))3 + e * ln(WD) had the best fit for estimating the tree biomass of Chinese Fir stands. Furthermore, we observed that variables D(diameter at breast height), H (height), and WD(wood density)were significantly correlated with the total tree biomass estimation model. As a result, a natural logarithm structure gave the best estimates for the tree biomass structure. Finally, when a multi-step improvement on tree biomass model was performed, the tree biomass model with Tree volume(TV), WD and biomass wood density conversion factor (BECF),achieved the highest simulation accuracy, expressed as ln(TB) = −0.0703 + 0.9780 * ln(TV) + 0.0213 * ln(WD) + 1.0166 * ln(BECF). Therefore, when TV, WD and BECF were combined with tree biomass volume coefficient bi for Chinese Fir, the stand biomass (SB)model included both volume(SV) and coefficient bi variables of the stand as follows: bi = Exp(−0.0703+0.9780*ln(TV)+0.0213 * ln(WD)+1.0166*ln(BECF)). The stand biomass model is SB = SV/TV * bi.

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<![CDATA[Structure and dynamics of the gut bacterial microbiota of the bark beetle, Dendroctonus rhizophagus (Curculionidae: Scolytinae) across their life stages]]> https://www.researchpad.co/article/5989db51ab0ee8fa60bdc4d3

Bark beetles play an important role as agents of natural renovation and regeneration in coniferous forests. Several studies have documented the metabolic capacity of bacteria associated with the gut, body surface, and oral secretions of these insects; however, little is known about how the bacterial community structure changes during the life cycle of the beetles. This study represents the first comprehensive analysis of the bacterial community of the gut of the bark beetle D. rhizophagus during the insect’s life cycle using 454 pyrosequencing. A total of 4 bacterial phyla, 7 classes, 15 families and 23 genera were identified. The α-diversity was low, as demonstrated in previous studies. The dominant bacterial taxa belonged to the Enterobacteriaceae and Pseudomonadaceae families. This low α-diversity can be attributed to the presence of defensive chemical compounds in conifers or due to different morpho-physiological factors in the gut of these insects acting as strong selective factors. Members of the genera Rahnella, Serratia, Pseudomonas and Propionibacterium were found at all life stages, and the first three genera, particularly Rahnella, were predominant suggesting the presence of a core microbiome in the gut. Significant differences in β-diversity were observed, mainly due to bacterial taxa present at low frequencies and only in certain life stages. The predictive functional profiling indicated metabolic pathways related to metabolism of amino acids and carbohydrates, and membrane transport as the most significant in the community. These differences in the community structure might be due to several selective factors, such as gut compartmentalization, physicochemical conditions, and microbial interactions.

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<![CDATA[Climate-Driven Synchronized Growth of Alpine Trees in the Southeast Tibetan Plateau]]> https://www.researchpad.co/article/5989da34ab0ee8fa60b858aa

Knowledge about the spatiotemporal tree growth variability and its associations with climate provides key insights into forest dynamics under future scenarios of climate change. We synthesized 17 tree-ring width chronologies from four tree species at the high-elevation sites in the southeast Tibetan Plateau (SETP) to study the regional tree growth variability and climate-growth relationships. Despite of diverse habitats and different physiological characteristics of these species, these tree-ring chronologies shared a significant common variance in SETP. An unprecedented increase in the shared variance is found along the latter half of the 20th century, coinciding with the enhancement of the frequency of extreme rings among chronologies. It is found that minimum winter temperature tends to be the dominant climate for trees in this region. The site-specific responses in cold (1965–1980) and warm (1990–2005) intervals by means of Fuzzy Cmeans (FCM) clustering reveal that the remarkable enhancement of growth synchrony among trees mainly occur in warm conditions. This is different from previous findings indicating that increased consistence among temperature sensitive tree rings in cold periods. This may be related to the reduced temperature sensitivity of regional tree growth as winter minimum temperature is lower than a certain threshold, which is in agreement with the “principle of ecological amplitude”. In addition, it is worth noting that precipitation in June have started to restrain the tree growth since the beginning of the 1980s, which is possibly an important contributor for synchronized growth among trees in SETP.

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