Different Decaying Wood Effects on Bacterial Diversity:Insights from Molecular Methods

Decaying wood is a novel key factor required for biodiversity and function of a forest,as it provides a good account of substrate and habitats for various organisms.Herein,the bacterial diversity in decaying wood of Betula platyphylla was discussed through high throughput sequencing.Our results showed that most of the obtained sequences belonged to the phyla Firmicutes,Proteobacteria,Bacteroidetes,Actinobacteria,Acidobacteria and Verrucomicrobia.Bacterial community compositions in samples with higher moisture content were obviously different than that with lower content,which could be reflected by richness estimators,diversity indices,and cluster and heatmap analysis.All three networks were non-random and possessed topological features of complex systems such as small-world and modularity features.However,these networks exhibited distinct topological features,indicating the potential ability of extensive cooperative and competitive interactions in the decayed wood microenvironments.Redundant analysis showed that most bacterial phyla were mainly distributed in highermoisture trunks.The obtained data will increase the knowledge of the complex bacterial diversity associated with dead wood,and lay a foundation for the bioconversion technology of plant cell walls using bacteria.

Scoping Antifungal Activities of Various Forms of Chitosan Oligomers and Their Potential Fixation in Wood

Chitosan oligomers （average Dp-4） are known for their antifungal activity and wood decay resistance. These oligomers are susceptible to moisture, and promote yeast growth upon air exposure after a sufficient length of time. Chitosan oligomers of three different states viz. completely dried, freshly prepared and highly viscous form, were prepared to compare their in-vitro antifungal activities against three brown-rot fungi, two sapstain and one mould fungus using agar nutrient medium. Additionally, a mixture of chitosan oligomers and boric acid was used for wood treatment. The nutrient medium bioassay results show that all states of chitosan oligomers inhibited the growth of tested basidiomycetes fungi, but not sapstain and mould fungi. Subsequently, wood decay results confirm antifungal activity of chitosan oligomers plus boron against basidiomycetes, but highlighted their leachability upon water exposure.

Behavior of Decayed Spruce (Picea abies) during Kraft Pulping

This study indicated that by applying an improved classification system to decayed large-diameter Norway spruce(Picea abies)wood,its use as raw material for kraft pulping without loss of pulp quality could be essentially increased.This is based on the fact that although the cooking yield of decayed spruce material which has been sorted according to these new recommendations is somewhat lower and Kappa number higher than those of sound wood material,the greatest part of the decayed stem(the outer part of the stem)contains long-fiber wood material which produces pulp of good quality.Therefore,large-diameter spruce logs can also be separately used,for example,in the manufacture of reinforcement pulp.

Improving tree health assessment accuracy at low temperatures:considering the effect of trunk ice content on electrical resistance and stress wave tomography

Accurate decay detection and health assessment of trees at low temperatures is an important issue for forest management and ecology in cold areas.Low temperature ice formation on tree health assessment is unknown.Because electric resistance tomography and stress wave tomography are two widely used methods for the detection of tree decay,this study investigated the effect of ice content on trunk electrical resistance and stress wave velocity to improve tree health assessment accuracy.Moisture content,trunk electrical resistance and stress wave velocity using time domain reflectometry were carried out on Larix gmelinii and Populus simonii.Ice content is based on moisture content data.The ice content of both species showed a trend of increasing and then decreasing.This was opposite with ambient temperatures.With the decrease of temperatures,daily average ice content increased,but the range narrowed gradually and both electrical resistance and stress wave velocity increased.Both increased rapidly near 0℃,mainly caused by ice formation(phase change and freezing of free water)in live trees.In addition,both are positively correlated with ice content.The results suggest that ice content should be considered for improving the accuracy of tree decay detection and health evaluation using electric resistance tomography and stress wave velocity methods under low temperatures.

Neofomitella guangxiensis and Sebipora aquosa newly recorded white rot polypores from India

As a part of the documentation of the polyporoid fungi of Kerala State,India,two interesting polypore specimens were collected.Morphological and molecular characterization revealed the identity of two species as Neofomitella guangxiensis and Sebipora aquosa,which were reported as new records to India.We present the taxonomy of the two species based on morphology and molecular phylogenetic data.

Linking molecular deadwood-inhabiting fungal diversity and community dynamics to ecosystem functions and processes in Central European forests

Fungi play vital roles in the decomposition of deadwood due to their secretion of various enzymes that break down plant cell-wall complexes.The compositions of woodinhabiting fungal(WIF)communities change over the course of the decomposition process as the remaining mass of wood decreases and both abiotic and biotic conditions of the wood significantly change.It is currently not resolved which substrate-related factors govern these changes in WIF communities and whether such changes influence the deadwood decomposition rate.Here we report a study on fungal richness and community structure in deadwood of Norway spruce and European beech in temperate forest ecosystems using 454 pyrosequencing.Our aims were to disentangle the factors that correspond to WIF community composition and to investigate the links between fungal richness,taxonomically-resolved fungal identity,and microbial-mediated ecosystem functions and processes by analyzing physico-chemical wood properties,lignin-modifying enzyme activities and wood decomposition rates.Unlike fungal richness,we found significant differences in community structure between deadwood of different tree species.The composition of WIF communities was related to the physico-chemical properties of the deadwood substrates.Decomposition rates and the activities of ligninmodifying enzymes were controlled by the succession of the fungal communities and competition scenarios rather than fungal OTU richness.Our results provide further insights into links between fungal community structure and microbialmediated ecosystem functions and processes.

Assessment of the effectiveness of wood pole repair using FRP considering the impact of climate change on decay and hurricane risk

Electric power distribution systems are vulnerable to disruption due to severe weather events,especially hurricanes.Such vulnerability is expected to increase over time due to the impact of climate change on hurricanes and the decay of wood poles that support the distribution lines.This study investigates the effectiveness of using fiber-reinforced polymer(FRP)sleeve to reinforce wood poles subjected to decay and hurricane hazard to restore their lost strength and extend their effective service life.The potential impact of climate change on the pole decay rate and the intensity and frequency of hurricanes is also considered.The optimal FRP repair time based on the structural reliability of the poles is also determined.Three locations with varying climates are chosen to evaluate and compare the results:Miami,Charleston,and New York City.The results show that in all three locations,the application of the FRP sleeve can more than double the service life of the pole depending on the time of the repair.The results also show that climate change significantly increases the vulnerability of the pole.The probability of failure of the pole at the end of the 21st century under RCP8.5 emission scenario in Miami,Charleston,and New York City increase by about 30%,70%,and 73%,respectively,compared to a no climate change scenario.If climate change is only assumed to affect the decay of the pole,i.e.,no change in hurricane hazard intensity,the corresponding increases in failure probability are 5%,22%,and 20% in Miami,Charleston,and New York City,respectively.This implies that most of the impact of climate change on pole failure risk is due to the increase in hurricane intensity.The impact of climate change on decay is found to be comparatively small.It increases with time as variation in temperature and precipitation becomes more prominent towards the end of the 21st century.The optimization results show that the optimal FRP repair time depends on how the FRP affects the pole's decay rate.If the FRP can significantly slow down the wood decay rate,the optimal time of repair is at the beginning of the pole's life cycle.If the FRP has no impact on the wood decay rate,it is better to repair the pole after significant decay has occurred.

Quantitative Analysis on Measure Results by Resistograh for Wood Decay of Ancient Architecture

The air-dried density, bending strength (MOR) and compressive strength parallel to grain of different grades of rotten wood were measured with test specimens of 100-130 year-old larch (Larix sp.) collected in Wu Ying Dian, the Forbidden City. In addition, the MOR of specimens was measured by Resistograph and the correlations were analyzed between resistance value and mechanical properties of wood. The correlations are significant for quantitative evaluation of wood structural condition by Resistograph. The results showed that wood air-dried density, strength properties and resistance values decreased significantly with the increase of decay degree, and there were remarkable differences among various grades of wood. Based on the rotten degree, the attenuation rate is in the following order: MOR> compressive strength parallel to grain > air-dried wood density > resistance value, and the above 4 indexes were 32%, 53%, 73% and 74% of those of intact wood, respectively, when the degree of rotten wood reached grade 3. Significant positive correlation at 0.01 level was showed between the wave trough values and wood air-dried density, MOR, compressive strength parallel to grain. The correlations between the wave peak values and the average value and air-dried wood density, MOR reached 0.01 level, and the correlations between the wave peak values and the average value and compressive strength parallel to grain reached 0.05 level. Based on the correlation between resistance value and physico-mechanical properties of wood, the values could be analyzed quantitatively.

The world’s ten most feared fungi

An account is provided of the world’s ten most feared fungi.Within areas of interest,we have organized the entries in the order of concern.We put four human pathogens first as this is of concern to most people.This is followed by fungi producing mycotoxins that are highly harmful for humans;Aspergillus flavus,the main producer of aflatoxins,was used as an example.Problems due to indoor air fungi may also directly affect our health and we use Stachybotrys chartarum as an example.Not everyone collects and eats edible mushrooms.However,fatalities caused by mushroom intoxications often make news headlines and therefore we include one of the most poisonous of all mushrooms,Amanita phalloides,as an example.We then move on to the fungi that damage our dwellings causing serious anxiety by rotting our timber structures and flooring.Serpula lacrymans,which causes dry rot is an excellent example.The next example serves to represent all plant and forest pathogens.Here we chose Austropuccinia psidii as it is causing devastating effects in Australia and will probably do likewise in New Zealand.Finally,we chose an important amphibian pathogen which is causing serious declines in the numbers of frogs and other amphibians worldwide.Although we target the top ten most feared fungi,numerous others are causing serious concern to human health,plant production,forestry,other animals and our factories and dwellings.By highlighting ten feared fungi as an example,we aim to promote public awareness of the cost and importance of fungi.