Stages Of Decay Research Articles

Intraguild scavenging on carnivore carcasses is delayed enough to allow successful dispersal of maggots for pupation

AbstractVertebrate carcasses are a valuable resource for a wide range of organisms, although their consumption rates can vary greatly by the type of carcasses. Studies have indicated that mammalian carnivores rarely consume carnivore carcasses, particularly in the early stages of decay, and thus these carcasses may potentially serve as a reproductive resource for necrophagous arthropods such as blowflies. However, it is unknown whether delays in consumption by carnivores are sufficient for necrophagous arthropods to complete their life cycle in the carcasses. This study addressed this question by monitoring 69 raccoon carcasses using camera traps in Yakumo, southern Hokkaido, Japan, during the summer seasons of 2016–2019. The decay stages of the carcasses were categorized by carefully observing the videos captured by the camera traps, and the timing of maggot dispersion was estimated. The first visitation and first consumption of vertebrate scavengers were also modelled, and the proportion of carcasses visited or consumed by vertebrate scavengers prior to maggot dispersion was determined each year. The proportion of carcasses visited by vertebrate scavengers before maggot dispersal ranged between c. 50% in 2017 and c. 30% in other years. However, only c. 20% of carcasses in each year were consumed before maggot dispersal, and consumption was only partial. The first species to scavenge at carcasses were red foxes and raccoon dogs, with the exception of two carcasses that were first scavenged by large‐billed crows. These results suggest that while delayed visitation of carcasses may partly explain delayed consumption, active avoidance of phylogenetically related species may increase the chances of successful maggot dispersal. Our approach of using careful video observations and statistical modelling may apply to a wide range of habitats and could improve our understanding of the ecological consequences of the taboo against cannibalism.

New Finds and Ecology of the Rare Liverworts Scapania apiculata, Scapania carinthiaca, and Scapania scapanioides in Austria.

Scapania apiculata, Scapania carinthiaca, and Scapania scapanioides are rare deadwood-dwelling liverworts threatened across Europe. Scapania carinthiaca is thus listed in the Habitats Directive. However, their distribution data are scattered, and their ecologic demands are insufficiently studied. Here, we present new locations and data on the ecology of the species, which resulted from a targeted search in selected regions of Austria. We found ten new sites each for Scapania apiculata and Scapania scapanioides and twenty for Scapania carinthiaca. Reproduction was exclusively asexual. The macroclimates of all known locations in Austria did not differ significantly between the three species. It was consistently wet, with a mean annual precipitation of 1615.3 mm, a high evenness of rainfall, and a low desiccation risk. The mean temperature averaged 7.4 °C. The habitat was shaded dead wood of Picea abies, Abies alba, and Fagus sylvatica of all decay stages at a median distance of 2.5 m from streams or springy areas in semi-natural forests of montane and submontane regions. Thus, high deadwood volumes under a suitable climate are a prerequisite for the occurrences of the species. The number of locations of new finds has more than doubled in Austria and thus in Europe.

A composite approach to produce reference datasets for extratropical cyclone tracks: application to Mediterranean cyclones

Abstract. Many cyclone detection and tracking methods (CDTMs) have been developed in the past to study the climatology of extratropical cyclones. However, all CDTMs have different approaches in defining and tracking cyclone centers. This naturally leads to cyclone track climatologies with inconsistent physical characteristics. More than that, it is typical for CDTMs to produce a non-negligible number of tracks of weak atmospheric features, which do not correspond to large-scale or mesoscale vortices and can differ significantly between CDTMs. Lack of consensus in CDTM outputs and the inclusion of significant numbers of uncertain tracks therein have long prohibited the production of a commonly accepted reference dataset of extratropical cyclone tracks. Such a dataset could allow comparable results on the analysis of storm track climatologies and could also contribute to the evaluation and improvement of CDTMs. To cover this gap, we present a new methodological approach that combines overlapping tracks from different CDTMs and produces composite tracks that concentrate the agreement of more than one CDTM. In this study we apply this methodology to the outputs of 10 well-established CDTMs which were originally applied to ERA5 reanalysis in the 42-year period of 1979–2020. We tested the sensitivity of our results to the spatiotemporal criteria that identify overlapping cyclone tracks, and for benchmarking reasons, we produced five reference datasets of subjectively tracked cyclones. Results show that climatological numbers of composite tracks are substantially lower than the ones of individual CDTMs, while benchmarking scores remain high (i.e., counting the number of subjectively tracked cyclones captured by the composite tracks). Our results show that composite tracks tend to describe more intense and longer-lasting cyclones with more distinguished early, mature and decay stages than the cyclone tracks produced by individual CDTMs. Ranking the composite tracks according to their confidence level (defined by the number of contributing CDTMs), it is shown that the higher the confidence level, the more intense and long-lasting cyclones are produced. Given the advantage of our methodology in producing cyclone tracks with physically meaningful and distinctive life stages, we propose composite tracks as reference datasets for climatological research in the Mediterranean. The Supplement provides the composite Mediterranean tracks for all confidence levels, and in the conclusion we discuss their adequate use for scientific research and applications.

Wood decomposition, carbon, nitrogen, and pH values in logs of 8 tree species 14 and 15 years after a catastrophic windthrow in a mesic broad-leaved forest in the East European plain

There are limited studies of decomposition of coarse woody debris (CWD) in natural conditions of multi-species mesic broad-leaved forests. We investigated 49 lying logs of 7 angiosperm and 1 gymnosperm species 14 and 15 years after a mass windthrow in an old-growth broad-leaved forest. We observed high heterogeneity of logs in terms of decomposition stages: up to 4 stages in one transverse disk and up to 5 stages in longitudinal fragments of one log. Due to the high heterogeneity of logs, we investigated traits of wood samples rather than individual logs. Bulk density, carbon and nitrogen concentrations, and pH values were examined for 188 CWD samples of 8 species at 5 decomposition stages (from stage 1 least to stage 5 most decayed wood) and 24 control samples of live trees (3 replicates for each species; zero stage of decay). Changes of deadwood volume, carbon and nitrogen stocks over 14 and 15 years after the windthrow were estimated by re-surveying transects established in 2010. From the first to the fifth decay stage, the mean CWD density decreased for all species and averaged 54 ± 16 kg m−3 (SD) at the 5th stage of decay. Regarding decomposition rates, the tree species were arranged in descending rate from diffuse-porous (Populus tremula, Betula pendula, Tilia cordata, and Acer platanoides) to ring-porous (Ulmus glabra, Fraxinus excelsior, and Quercus robur) angiosperms and the coniferous Picea abies was after the diffuse-porous species series and before the ring-porous species. Carbon concentration ranged from 39 to 54 %, but did not change significantly during decomposition (mean value for all species in all decay stages was 45.8 ± 2.5 %). Nitrogen concentration (percentage of dry mass) increased with increasing decay stage and the mean value was 0.2 ± 0.1 % at the zero stage and 0.9 ± 0.5 % at the last decay stage. Despite the increase in N concentration, the mass N per volume decreased during decomposition for all samples considered together due to a significant decrease in wood density. The change in C/N values during deadwood decay reflected the transition of organic matter from the CWD to the SOM (soil organic matter) in forest ecosystems: the ratio C/N varied from 829 (Picea, zero stage) to 16 (Ulmus, last stage) with the mean values 286 ± 149 and 75 ± 45 at the zero and the last stages, respectively. We observed a quadratic trend in the variation of wood pH values by stages: pH mainly decreased from the initial values to the minimum in the middle stages of decay, and then increased in the advanced stages. The mean deadwood volume in the surveyed plots decreased 1.4-fold in the 14–15 years after the windthrow, but the mean stocks of carbon and nitrogen decreased 3 and 2-fold, respectively. Over time, the different decomposition rate of fallen logs leads to a decrease in the proportion of C and N stored in diffuse-porous species at the expense of an increase in this proportion in ring-porous species. This result is worth considering in a carbon management strategy: planting, maintaining stands, and retaining deadwood of ring-porous species, such as Quercus, Ulmus and Fraxinus, promote relatively long-term carbon storage.

Synthesis and Characterization of a New Non-Linear Optical Material: (4-Chlorophenyl)(4-Hydroxypiperidin-1-yl) Methanone

A new organic and nonlinear optical material namely (4-chlorophenyl) (4-hydroxypiperidin-1-yl) methanone [HPCP] was synthesized from the mixture of 4-hydroxypiperidiene, triethylamine, and 4-chlorobenzoyl chloride by solution growth technique. The 3D structure of the title crystal has been derived using the X-ray diffraction (XRD) spectrum. The compound was crystallized in the orthorhombic crystal system with non-centrosymmetric space group Pca21. Optical properties of the as-grown compound have been elucidated through 1H-NMR, UV-Visible, FTIR, and PL spectral studies. The melting point, stages of mass decay, and thermal stability of the synthesized material were obtained by TG/DTA thermal analysis. Vickers microhardness test was performed to comprehend its mechanical strength. The second harmonic generation (SHG) efficiency was estimated by employing Q-switched high energy, Nd: YAG the laser source, and the SHG efficiency was found to be 1.73 times that of KDP, the reference crystal.

Fungal community dynamics in coarse woody debris across decay stage, tree species, and stand development stage in northern boreal forests

Fungi are primary agents of coarse woody debris (CWD) decay in boreal forests, playing an essential role in nutrient cycling and carbon storage. We compared fungal community assemblages using alpha and beta diversity metrics, and physical and chemical properties of CWD across three tree species (trembling aspen [ Populus tremuloides], black spruce [ Picea mariana], and jack pine [ Pinus banksiana]), five decay classes, and two stand development stages, differing in time since stand replacing disturbance in Ontario’s boreal forest region. We sampled 180 individual CWD logs from 6 independent stands, with 3 replicates per each species × decay class combination at each site. Using high-throughput sequencing of marker DNA, we found that fungal community structure significantly differed across tree species, decay stage, and stand age. Fungal diversity was highest in decay class 4 CWD. We found that Mn and K concentrations, total carbon, C/N ratio, N/P ratio, and moisture content were important predictors of fungal composition across CWD species and/or decay stage. This study suggests that forest management guidelines that consider both deadwood quantity and quality will support a broader range of fungal species and communities through post-disturbance stand development.

N6-adenosine (m6A) mRNA methylation is required for Tribolium castaneum development and reproduction

Gene expression is regulated at various levels, including post-transcriptional mRNA modifications, where m6A methylation is the most common modification of mRNA. The m6A methylation regulates multiple stages of mRNA processing, including splicing, export, decay, and translation. How m6A modification is involved in insect development is not well known. We used the red flour beetle, Tribolium castaneum, as a model insect to identify the role of m6A modification in insect development. RNA interference (RNAi)-mediated knockdown of genes coding for m6A writers (m6A methyltransferase complex, depositing m6A to mRNA) and readers (YTH-domain proteins, recognizing and executing the function of m6A) was conducted. Knockdown of most writers during the larval stage caused a failure of ecdysis during eclosion. The loss of m6A machinery sterilized both females and males by interfering with the functioning of reproductive systems. Females treated with dsMettl3, the main m6A methyltransferase, laid significantly fewer and reduced-size eggs than the control insects. In addition, the embryonic development in eggs laid by dsMettl3 injected females was terminated in the early stages. Knockdown studies also showed that the cytosol m6A reader, YTHDF, is likely responsible for executing the function of m6A modifications during insect development. These data suggest that m6A modifications are critical for T. castaneum development and reproduction.

Structural and functional microbial diversity in deadwood respond to decomposition dynamics.

We investigated the changes in microbial community diversities and functions in natural downed wood at different decay stages in a natural oak forest in the Italian Alps, through metagenomics analysis and in vitro analysis. Alfa diversity of bacterial communities was affected by the decay stage and log characteristics, while beta diversity was mainly driven by log diameter. Fungal and archaeal beta diversities were affected by the size of the sampled wood (log diameter), although, fungi were prominently driven by wood decay stage. The analysis of genes targeting cell wall degradation revealed higher abundances of cellulose and pectin-degrading enzymes in bacteria, while in fungi the enzymes targeting cellulose and hemicellulose were more abundant. The decay class affected the abundance of single enzymes, revealing a shift in complex hydrocarbons degradation pathways along the decay process. Moreover, we found that the genes related to Coenzyme M biosynthesis to be the most abundant especially at early stages of wood decomposition while the overall methanogenesis did not seem to be influenced by the decay stage. Intra- and inter-kingdom interactions between bacteria and fungi revealed complex pattern of community structure in response to decay stage possibly reflecting both direct and indirect interactions.

Dead Wood Elements Composition in Different Tree Species and Stages of Decay in the Broad-Leaved Forests of the Kaluzhskie Zaseki Reserve

The content and mass concentration of eight chemical elements Al, Ca, Cu, K, Mg, Mn, P, and Zn were analysed in dead wood of eight tree species at five stages of decomposition. Wood samples were taken at the site of the mass windfall of 2006 in a multispecies broadleaved forest in the Kaluzhskie Zaseki nature reserve. Deadwood of seven deciduous trees species was studied: maple (Acer platanoides), birch (Betula pendula), common ash (Fraxinus excelsior), common aspen (Populus tremula), English oak (Quercus robur), linden (Tilia cordata), rough elm (Ulmus glabra), as well as one coniferous tree species – Norway spruce (Picea abies). A series of one-way analyses of variance was carried out to assess the influence of the species and the stage of deadwood decomposition (including the zero stage for control samples) on the density, content of elements and their mass concentration. Tree species most clearly differed in the content and mass concentration of Mn, Zn, Mg, Ca, and K: R2 varied from 50 to 23% for the content and from 53 to 19% for the mass concentration of elements of the indicated series. The leaders in the content of these elements were the following species: Mn – maple, birch, spruce, linden; Zn – birch and aspen; Mg – maple, elm; Ca – elm; K – linden, elm. The stages of wood decomposition turned out to be a significant factor of variation for the content of Mn, P, Cu, Zn and Ca: R2 varied from 22 to 16%. During the destruction of wood trunks, a significant increase in the content of these elements occurred. Maintenance of cycles of biophilic elements is more successfully implemented in the presence of deadwood of different species at different stages of decomposition.

Impact of Exposure Status on the Diversity and Successional Pattern of Cadaverous Arthropods on Slaughtered Juvenile Pig (Sus scrofa Linn.) Carcasses in Wukari, Nigeria

Knowledge of successional colonization of cadaver is important in medico-legal studies especially with regards to postmortem interval (PMI) estimation. Paucity of data especially as it relates to juveniles has limited the appropriate application of this knowledge for the benefit of man. To bridge this knowledge gap, juvenile human cadaver was modeled using 2 slaughtered juvenile pigs – Sus scrofa Linn. (≈ 10 kg mean weight) at the study site. One pig was exposed to sunlight while the other shaded under a tree. Both pigs were protected from scavengers and allowed through the decay stages and sampling for adult arthropods continued till the dry-remainstage of decomposition. Data collected were used to compute frequency of occurrence and relative abundance. Paleontological Statistical Tool (Past3) was used to compute diversity indices. Of the 2032 arthropods of 20 species, across 17 families retrieved, the exposed carcass attracted 44.1% comprising 16 species within 15 families while the shaded carcass attracted 14 species within 12 families. Over 50% species similarity on the contrasting carcasses was observed. Calliphoridae, Muscidae, Dermestidae, Histeridae and Formicidae made-up the dominant families sampled. While Musca domestica L. (Muscidae) and Anochetus sp. (Formicidae) wereexclusively dominant for the shaded carcass, Crematogaster sp. (Formicidae) was exclusively dominant for the exposed carcass. Both carcasses completed decomposition in 14 days but exhibited a shorter advanced-decay stage for the shaded carcass and shorter dry remain stage for the exposed carcass. We thus conclude that, there was little distinction in the diversity and succession pattern of the arthropods colonizing both carcasses (shaded and exposed).

Analysis of an improved Nishihara creep model considering plastic strain accumulation

Rock-engineering structures, particularly subway excavation rock-engineering structures, are subjected to the long-term effects of external loading that may gradually damage and cause creep and severe plastic deformations or even progressive failure. The traditional Nishihara creep model cannot accurately describe the accelerated creep stage of rock with particularly obvious nonlinear characteristics. Based on this model, a damage variable that can consider the plastic strain accumulation is introduced in this study to replace the viscoplastic body in the traditional model with a damaged viscoplastic body and establish an improved Nishihara creep model. Using the superposition principle, the creep equations of the improved model in the one- and three-dimensional stress states are derived. The accuracy and rationality of the improved model are verified using uniaxial and conventional triaxial creep tests of mudstone and sandstone under different confining pressures. The improved model can not only accurately reflect the nonlinear characteristics of the creep curve in the decay and constant velocity stages but also describe the accelerated creep characteristics of mudstone and sandstone in a high-stress state. Its applicability and accuracy are superior to those of the traditional model. This study can provide a theoretical reference for subway tunnel excavation and stability analysis of deep roadway surrounding rocks.

Wood-Decay Fungi Fructifying in Mediterranean Deciduous Oak Forests: A Community Composition, Richness and Productivity Study

Deadwood is involved in several important ecological roles, being the fundamental habitat of wood-decay fungi. At the same time, this polyphyletic group of fungi is the principal agent of wood decomposition, regulating the carbon cycle and the food resource for many other organisms. It is known that the diversity and community composition of wood-decay fungi are related to the tree species, decay stage and size of the woody debris in which they are living. Nevertheless, there is a lack of information on Mediterranean Quercus cerris L. forests. In response, we explored how wood-decay fungi colonize different woody types and how the productivity, richness and community composition of these fungi is influenced by the decay stage and size of the deadwood. Our results indicate that the studied groups, i.e., Ascomycetes, Corticioids, Polyporoids and Heterobasidiomycetes responded differently to the woody debris classes. Moreover, we note the high importance of smaller and soft-decayed woody debris for community composition and richness, hosting a great number of species, in addition to the positive effect of the heterogeneity of the woody debris size for wood-decay fungi productivity.

Fine-scale cation dynamics and control by Rhodonia placenta and Pleurotus ostreatus during wood decay

Fungi are the primary decomposers of wood across the globe. They redistribute the vast pool of wood carbon to other parts of the carbon cycle using mechanisms that also have intriguing potential in bioconversion and biotechnology applications. To make a living in the relatively sparse microenvironment of wood, these filamentous fungi must import many of their needs, including cations. Understanding the timing of cation import can help us validate the functions of cations in wood decay and create a clearer understanding of these complex wood degradation mechanisms. In this study, we resolved cation timing dynamics across space for two fungi (brown rot fungus Rhodonia placenta and white rot fungus Pleurotus ostreatus) using a wood wafer system. We found some expected patterns of the cation dynamics for both fungi, and a clear role for iron at the early stages of brown rot decay. On the other hand, the lack of an increase in manganese during initial white rot decay was surprising. Unexpectedly, we also saw a spike in copper during early brown rot decay that demands more investigation as a potential player in the brown rot mechanism.

Asymmetric Impacts of El Niño Development and Decay Stages on the Hadley Circulation

AbstractThe impact of El Niño on the Hadley Circulation (HC) has been a topic of previous studies, but the results have been inconclusive. We study how El Niño affects the HC during different stages of its cycle. In development years, the HC anomaly shows an equatorial quasi‐symmetric pattern, while in decay years, it shows an asymmetric pattern. This resolves previous discrepancies among studies about El Niño's impacts on the HC. The differences in tropical sea surface temperature (SST) during different stages of El Niño cause differences in SST meridional gradients, which determine the location of convergence. This explains why the HC anomalies have different spatial structures during El Niño development and decay years. Our results show that the meridional distribution of SST during different El Niño stages has significantly distinct impacts on meridional circulation and clarify the differences in El Niño's effects on climate.

A novel strategy for accelerating degradation of proton exchange membranes in fuel cell

Conventional proton exchange membrane (PEM) durability testing takes thousands of hours, which is consuming and costly. The development of a suitable accelerated aging strategy for PEM is essential for its durability research. In this work, we proposed and verified electron beam as an accelerated decay method to investigate the degradation of PEM. This solution is hundreds of times faster than in-duty durability testing. The results showed that different equivalents of radiation have different effects on the attenuation of PEM, which corresponds to different stage of the duty decay of PEM. As the irradiation dose gradually increases, the open-circuit voltage of the corresponding cell gradually decreases and the amount of hydrogen seepage gradually increases, which is the same phenomenon as the duty degradation of the PEM. The Pearson correlation coefficient was adopted to correlate accelerated decay data with duty decay data, the results exhibited that the correlation coefficient is close to 1 (0.9169457), with a high degree of correlation. This indicates that the electron beam accelerated decay of PEM has a very high similarity to the duty decay. Therefore, this accelerated decay scheme has great promise for highly durable PEM studies.

Lime and odour: A preliminary investigation into the effect of hydrated lime on the volatiles emitted from human remains

The location of human remains is performed primarily through the aid of cadaver detection dogs, which rely on the malodour produced through decomposition of decaying bodies. Malefactors will attempt to conceal these putrefactive odours through chemical additions such as lime, which is also wrongly believed to accelerate decomposition and prevent the identification of the victim. Despite the frequency of lime in forensic applications, to date no research has been performed to determine its effect on the volatile organic compounds (VOCs) released during human decomposition. This research was therefore conducted to ascertain the effects of hydrated lime on the VOC profile of human remains. Two human donors were used in a field trial at the Australian Facility for Taphonomic Experimental Research (AFTER): one donor was covered with hydrated lime, and the other had no chemical additions acting as a control. VOC samples were collected over a period of 100 days and analysed using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). The volatile samples were accompanied by visual observations of how decomposition progressed. The results showed that lime application decreased the rate of decomposition and decreased total carrion insect activity. Lime increased the abundance of VOCs during the fresh and bloat stages of decay, however the abundance of compounds plateaued during active and advanced decomposition and were much lower than those detected from the control donor. Despite this suppression of VOCs, the study found that dimethyl disulfide and dimethyl trisulfide, key sulfur-containing compounds, were still produced in high quantities, and can thus still be used to locate chemically altered human remains. Knowledge of the effects of lime on human decomposition can inform the training of cadaver detection dogs, and ensure a greater chance at locating victims of crimes or mass disasters.

Multivariate mapping of ontogeny, taphonomy and phylogeny to reconstruct problematic fossil taxa.

Exceptionally preserved fossils of soft-bodied organisms provide unique evidence of evolutionary history, but they are often contentious; different approaches frequently produce radically different reconstructions of taxa and their affinities. Conflict arises due to difficulties in disentangling the three non-independent factors that underlie all morphological variation within and between fossils: ontogeny, taphonomy and phylogeny. Comparative data from extant organisms can be extremely powerful in this context, but is often difficult to apply given the multi-dimensionality of anatomical variation. Here, we present a multivariate ordination method using discrete morphological character data from modern taxa at different ontogenetic and taphonomic stages (semaphoront and 'semataphonts'). Analysing multiple axes of morphological variation simultaneously allows us to visualize character combinations that are likely to exist in fossil specimens at intersecting stages of growth and decay, and thus constrain interpretation of fossils. Application to early vertebrates finds variation in fossil specimens to be accounted for by all three axes: primarily decay in Mayomyzon, ontogeny in Priscomyzon and phylogeny in 'euphaneropoids' and Palaeospondylus. Our demonstration of empirical multi-factorial variation underscores the power of multivariate approaches to fossil interpretation, especially non-biomineralized taxa. As such, this conceptual approach provides a new method for resolving enigmatic taxa throughout the fossil record.

Tree species richness increases spatial variation but not overall wood decomposition

Empirical evidence for the positive relationship between tree species richness and wood decomposition is weak, despite the greater numbers of decomposers in diverse stands. Tree species identity affects decomposition rates strongly by altering soil communities and micro-environments. It is therefore likely that tree species richness influences spatial variation rather than the mean rate of decomposition. We used a neighbourhood approach to test this hypothesis by quantifying decomposition rates and decomposer activities within deadwood, whilst measuring the surrounding micro-environments.Using the BEF-China experimental platform, we placed three fine branches from seven tree species across richness gradients for one and two years. As expected, plot species richness increased the spatial variation of wood decomposition of three species but decreased the mean rate of wood decomposition of two species. Neighbourhood trees altered wood decomposition in two ways. First, increasing amounts of leaf tannins reduced termite activities and the number of fungal fruitbodies. Second, higher species richness increased tree volumes and thus cooled the understory, which reduced the occurrence and feeding intensity of ectothermic termites. Neighbourhood species richness showed positive effects on decomposer activities (i.e. termite occurrence, fruitbody number and mycelium cover) after two years, probably by weakening resource limitation of deadwood biomass and increasing the stages of decay. Neighbourhood metrics had comparable (after 1 year) and even stronger effects (after 2 years) on decomposer activities than wood traits. Our study reveals that tree species richness promotes spatial variation in wood decomposition rates by enhancing environmental heterogeneity. Our results explain how young regenerating species-rich forests, where termites are the dominant decomposers, can maintain deadwood stocks and decomposer activities over relatively longer time spans.

High-Throughput DNA Metabarcoding of Stem Sections from Trees with Cavities Describes Fungal Communities Associated with Variable Wood Decay, Position on Stem and Tree Species

The presence of unculturable fungi, variability in timing and frequency of fungal fruiting, hyper-rich fungal communities, and genetic and environmental variability explains the difficulty in adopting ideal sampling schemes and fungal identification approaches in studies of fungal communities in wood at variable stages of decay. Here, we use intensive within-tree sampling of five standing trees with cavities paired with high-throughput DNA metabarcoding, to study fungal communities in decayed and healthy wood of trees from two Populus species in British Columbia, Canada. The amplification of over 3000 fungal DNA sequence variants shows the presence of a hyper-rich wood fungal community that not only varied depending on PCR primers, tree species, tree stem portion and wood decay stage. but also included a large number of taxa unassignable to any known sub-kingdom taxonomic order based on published DNA sequences. Our data show that the use of two different primer sets greatly increases the power of the metabarcoding analysis. By testing three alternative models of fungal community composition, we identify the model that best explains fungal community by considering the position on the stem and distance from the cavity. We suggest this model may be used to design optimal sampling schemes to describe fungal communities in trees experiencing discrete decay pockets or cavities.

Changes in soil hydraulic conductivity in sweet potato field with living mulch

AbstractLiving mulch (LM) is used in agricultural fields to suppress weeds, control diseases, and mitigate erosion. It also enhances soil nutrient supply at the root death and decay stage during the growing season. However, benefits of LM to soil hydraulic properties related to soil pore structure have not been elaborated here. We focus on temporal changes in soil hydraulic conductivity (K) in a field where sweet potato was grown with and without LM (barley, Hordeum vulgare L.). K was measured in the field using a mini‐disk infiltrometer at three different pressure heads. In the plots with LM, K decreased significantly in August and then increased in October compared to plots without LM (at –0.5 cm pressure head). Changes in soil pore structure due to root growth or death and decay may alter soil hydraulic conductivity.