Decay Relationship Research Articles

Community of soil-inhabiting myxomycetes shares similar assembly mechanisms with fungi, and is affected by bacterial community in subtropical forests of China

Myxomycetes (Myxogastrea) are found in soil as myxamoebae and are a major component of the soil protist flora. Yet, our understanding of the drivers of myxamoebae community assembly lags far behind that of other protist groups. In this study we simultaneously investigate the spatial patterns of myxamoebae and their prey (bacteria and fungi communities) across eight subtropical forests in China, and aim to identify the ecological processes that determine the community assembly of myxamoebae. We found that all three microbial communities exhibited significant distance–decay relationships, with a higher degree of community concordance between myxamoebae and fungi than between myxamoebae and bacteria. The community turnover of both myxamoebae and fungi was primarily influenced by deterministic processes, whereas bacterial assembly was dominant by stochastic processes. Variation partitioning analysis showed that bacterial community structure explained the largest portion of the community turnover of myxamoebae, followed by spatial factors. Co-occurrence network analyses further revealed that myxamoebae had more potential interactions with bacteria than fungi, but did not target specific bacterial or fungal taxa. Overall, the significant effects of biotic and spatial factors on myxamoebae community assembly are critical to deciphering the distribution and function of these ecologically important microorganisms in soil environments.

Empirical decay relationship between ionic conductivity and porosity of garnet type inorganic solid-state electrolytes

Ionic conductivity is one of the crucial parameters for inorganic solid-state electrolytes. To explore the relationship between porosity and ionic conductivity, a series of Li6.4Ga0.2La3Zr2O12 garnet type solid-state electrolytes with different porosities were prepared via solid-state reaction. Based on the quantified data, an empirical decay relationship was summarized and discussed by means of mathematical model and dimensional analysis method. It suggests that open porosity causes ionic conductivity to decrease exponentially. The pre-exponential factor obeys the Arrhenius Law quite well with the activation energy of 0.23 eV, and the decay constant is averaged to be 2.62%. While the closed porosity causes ionic conductivity to decrease linearly. The slope and intercept of this linear pattern also obey the Arrhenius Law and the activation energies are 0.24 and 0.27 eV, respectively. Moreover, the total porosity is linearly dependent on the open porosity, and different sintering conditions will lead to different linear patterns with different slopes and intercepts.

Biogeography and environmental drivers of zooplankton communities in permafrost-affected lakes on the Qinghai-Tibet Plateau

Global warming is accelerating permafrost thaw, forming new thermokarst lakes and substantially influencing the old ones. However, the biological communities in thermokarst lakes on the Qinghai-Tibet Plateau (QTP) are rarely studied. Here, we assessed the biogeographical patterns of zooplankton communities in 44 thermokarst lakes across the QTP. Across all lakes, 17 Cladocera and 13 Copepoda species were identified, with most of the lakes dominated by Cladocera. Chydorus sphaericus and Cyclops vicinus were the most frequently detected species. Both cladoceran and copepod communities had very low species richness and density, which lacked a clear spatial pattern but positively associated to dissolved oxygen. In general, species richness was negatively influenced by seston particle quantity while the density was positively influenced by water nutrient concentrations. Cladoceran and copepod communities had a high β-diversity (0.89 and 0.91, respectively), which was dominated by species turnover. However, Cladocera had significantly lower β-diversity and turnover component than copepod communities. β-diversity of Cladocera and Copepoda showed a significant but weak distance decay relationship and also significantly correlated with longitude, latitude, mean annual temperature, as well as concentrations of seston particle carbon and nitrogen. In addition, their β-diversities differentially correlated to other environmental variables. Overall, the results suggested that the geographical barriers, climate, and some local environmental variables are key factors in shaping the biogeography of zooplankton community. Although a general biogeographic pattern of zooplankton across the QTP cannot be drawn from this limited dataset, this study provided the first large spatial scale investigation and analyses of zooplankton biogeography in thermokarst lakes on the QTP. Given the important roles of zooplankton in aquatic ecosystems, this study could provide insights for understanding the influences of future environmental changes on thermokarst lake ecosystems.

Suspended particulates mediate bacterial community coalescence in different habitats of a large sediment-laden river

Many studies have reported the influence of dispersal processes on aquatic bacterial communities, but the role of community coalescence is still unknown in sediment-laden rivers. Here, we examined the assembly of distinctive bacterial communities (free-living [FL], particle-attached [PA], and surface-sediment [SS]) with differing habitat preferences across different regions of the Yellow River (China) in the spring and autumn of 2019. We demonstrated that in both seasons SS bacteria featured the highest diversity, followed by PA bacteria, and then FL bacteria. Nonetheless, both FL and PA groups showed remarkable seasonal variation in water samples, while the SS group in sediment samples showed significant spatial variation. Furthermore, species sorting and dispersal limitation respectively governed the biogeographic patterns (strong distance–decay relationships) of water and sediment bacterial communities. With respect to community coalescence, not only the same habitats (i.e., water–water, particle–particle, and sediment–sediment) but also similar habitats (i.e., water–particle) had higher proportions of overlapped amplicon sequence variants (ASVs) compared with different habitats (i.e., water–sediment and particle–sediment). Moreover, the proportions of overlapped ASVs between PA and SS groups were higher than those between FL and SS groups. Network analysis revealed that the SS group harbored the highest network complexity, followed by PA and FL groups. Most connectors in the networks were identified as FL–PA–SS ASVs irrespective of the river reaches sampled. These findings demonstrate the biogeographic patterns of distinctive bacterial communities driven by species sorting and dispersal limitation, and provide evidence for bacterial community coalescence in the Yellow River’s water and sediment. Bacteria attached to suspended particles may play a paramount role in the microbial ecology of different habitats in large sediment-laden rivers.

Contrasting elevational patterns and underlying drivers of stream bacteria and fungi at the regional scale on the Tibetan Plateau.

Elevational gradients are the focus of development and evaluation of general theories on biodiversity. However, elevational studies of microorganisms and the underlying mechanisms remain understudied, especially at regional scales. Here, we examined stream bacterial and fungal communities along an elevational gradient of 990-4600m with a geographic distance up to 500km in the southeastern Tibetan Plateau and further analyzed their elevational patterns and drivers of three biodiversity indicators, including species richness, ecological uniqueness, and community composition. Bacteria and fungi showed distinct elevational trends in species richness and consistently decreasing patterns in their ecological uniqueness. The distance-decay relationships were concordant for the two microbial groups, while fungi showed higher dissimilarity and a lower turnover rate. Interestingly, bacterial and fungal compositions substantially differed between the elevations below and above 3000m. Climate predictors, such as the mean annual temperature and precipitation seasonality, had greater effects than local environment drivers. Notably, fungal diversity was mainly influenced by climate, while bacterial diversity was explained by the shared contributions of climate and local factors. Collectively, these findings revealed the elevational patterns of stream microbial biodiversity across mountains on a large spatial scale and highlight their underlying response mechanisms to environmental predictors.

Biodiversity and Biogeography of Abundant and Rare Microbial Assemblages in the Western Subtropical Pacific Ocean.

The levels of chlorophyll a and nutrient concentrations in the surface waters of the western subtropical Pacific Ocean are among the lowest globally. In addition, our knowledge of basin-scale diversity and biogeography of microbial communities in this vast extremely oligotrophic environment is still rather limited. Here, high-throughput sequencing was used to examine the biodiversity and biogeography of abundant and rare microbial assemblages throughout the water column from the surface to a depth of 3,000 m across a horizontal distance of 1,100 km in the western Pacific Ocean. Microbial alpha diversity in the 200-m layer was higher than at other depths, with Gammaproteobacteria, Alphaproteobacteria, and Clostridia as the dominant classes in all samples. Distinctly vertical distributions within the microbial communities were revealed, with no difference horizontally. Some microbes exhibited depth stratification. For example, the relative abundances of Cyanobacteria and Alphaproteobacteria decreased with depth, while Nitrososphaeria, Actinobacteria, and Gammaproteobacteria increased with depth in the aphotic layers. Furthermore, we found that environmental (selective process) and spatial (neutral process) factors had different effects on abundant and rare taxa. Geographical distance showed little effect on the dispersal of all and abundant taxa, while statistically significant distance–decay relationships were observed among the rare taxa. Temperature and chlorophyll a were strongly associated with all, abundant, and rare taxa in the photic layers, while total inorganic nitrogen was recognized as the crucial factor in the aphotic layers. Variance partitioning analysis indicated that environmental selection played a relatively important role in shaping all and abundant taxa, while the variation in rare taxa explained by environmental and spatial processes was relatively low, as more than 70% of the variation remained unexplained. This study provides novel knowledge related to microbial community diversity in the western subtropical Pacific Ocean, and the analyzes biogeographical patterns among abundant and rare taxa.

The biogeographic pattern of microbial communities inhabiting terrestrial mud volcanoes across the Eurasian continent

Abstract. Terrestrial mud volcanoes (MVs) represent the surface expression of conduits tapping fluid and gas reservoirs in the deep subsurface. Such plumbing channels provide a direct, effective means to extract deep microbial communities fueled by geologically produced gases and fluids. The drivers accounting for the diversity and composition of these MV microbial communities, which are distributed over a wide geographic range, remain elusive. This study characterized the variation in microbial communities in 15 terrestrial MVs across a distance of ∼ 10 000 km on the Eurasian continent to test the validity of distance control and physiochemical factors in explaining biogeographic patterns. Our analyses yielded diverse community compositions with a total of 28 928 amplicon sequence variances (ASVs) taxonomically assigned to 73 phyla. While no true cosmopolitan member was found, ∼ 85 % of ASVs were confined within a single MV. Community variance between MVs appeared to be higher and more stochastically controlled than within MVs, generating a slope of the distance–decay relationship exceeding those for marine seeps and MVs as well as seawater columns. For comparison, physiochemical parameters explained 12 % of community variance, with the chloride concentration being the most influential factor. Overall, the apparent lack of fluid exchange renders terrestrial MVs a patchy habitat, with microbiomes diverging stochastically with distance and consisting of dispersal-limited colonists that are highly adapted to the local environmental context.

Environmental selection overturns the decay relationship of soil prokaryotic community over geographic distance across grassland biotas.

Though being fundamental to global diversity distribution, little is known about the geographic pattern of soil microorganisms across different biotas on a large scale. Here, we investigated soil prokaryotic communities from Chinese northern grasslands on a scale up to 4000 km in both alpine and temperate biotas. Prokaryotic similarities increased over geographic distance after tipping points of 1760-1920 km, generating a significant U-shape pattern. Such pattern was likely due to decreased disparities in environmental heterogeneity over geographic distance when across biotas, supported by three lines of evidences: (1) prokaryotic similarities still decreased with the environmental distance, (2) environmental selection dominated prokaryotic assembly, and (3) short-term environmental heterogeneity followed the U-shape pattern spatially, especially attributed to dissolved nutrients. In sum, these results demonstrate that environmental selection overwhelmed the geographic 'distance' effect when across biotas, overturning the previously well-accepted geographic pattern for microbes on a large scale.

Determination of the gamma emission intensities of 125Xe based on 125I radioactivity

The radionuclide 125Xe plays an important role in diagnosing deuterium-tritium (DT) fuel areal density in inertial confinement fusion (ICF). Accurate data for the gamma emission intensities of 125Xe are highly desired. In this paper, after the 125Xe and 125I samples were prepared, the activity of 125I was determined by the sum-peak method using a high resolution well-type HPGe (High Purity Germanium) detector, and the activity of 125Xe was obtained by the decay relationship between 125Xe and 125I. The full-energy peak efficiencies of gamma-rays of 125Xe were accurately calibrated using standard radioactive sources. As a result, the absolute emission intensities of 125Xe for 12 gamma-rays were determined experimentally for the first time.

Prevalence of antibiotic resistance genes in Pangasianodon hypophthalmus and Oreochromis niloticus aquaculture production systems in Bangladesh

Antibiotic resistance genes (ARGs) constitute emerging pollutants of significant public health concern. Antibiotics applied in aquaculture may stimulate the proliferation and dissemination of ARGs. This study investigated the prevalence and diversity of ARGs in Pangasianodon hypophthalmus (formerly Pangasius) and Oreochromis niloticus (formerly Tilapia) commercial aquaculture ponds from four economically important divisions (i.e. regions) of Bangladesh using a high-throughput qPCR ARG SmartChip and further aimed to explore effects of aquaculture pond management and water quality on the observed ARG prevalence patterns. A total of 160 ARGs and 10 mobile genetic elements (MGEs) were detected across all samples (n = 33), of which 76 ARGs and MGEs were shared between all regions. Multidrug resistance genes were the most frequently encountered ARGs, followed by ARGs conferring resistance to β-lactams, aminoglycosides, tetracyclines, and macrolide-lincosamide-streptogramin B (MLSB). Research ponds managed by the Bangladesh Agricultural University had the lowest abundance and diversity of ARGs, suggesting that proper management such as regular water quality monitoring, fortnightly water exchange and use of probiotics instead of antibiotics may mitigate the dissemination of antibiotic resistance from aquaculture ponds. The Adonis test (R2 = 0.35, p < 0.001) and distance decay relationships revealed that the ARGs composition displayed a significant biogeographical pattern (i.e., separation based on geographic origin). However, this effect could possibly be due to feed type as different feed types were used in different regions. In conclusion, our results indicate that there is a vast potential for improving aquaculture pond management practices in Bangladesh to mitigate the environmental dissemination of ARGs and their subsequent transmission to humans.

Novel Chemoresistive Sensor for Sensitive Detection of Pb2+ Ions Using an Interdigital Gold Electrode Fabricated with a Reduced Graphene Oxide-Based Ion-Imprinted Polymer.

This study presents novel chemoresistive reduced graphene oxide–ion-imprinted polymer (IIP–rGO)-based sensors for detection of lead (Pb2+) ions. The ion-imprinted polymer was synthesized by bulk polymerization and modified with a variable amount of rGO incorporated to form an IIP–rGO composite. The amount of rGO in the polymer matrix affected the sensor’s relative response, and 1:3 mass ratio produced excellent results, with a consistent trend as the concentration of Pb2+ ions increased in the solution. The decrease in relative resistance (ΔR/Ro) followed an exponential decay relationship between the ΔR/Ro response and the concentration of Pb2+ ions in aqueous solutions. After solving the exponential decay function, it is observed that the sensor has the upper limit of ΔR/Ro >1.7287 μg L–1, and the limit of detection of the sensor is 1.77 μg L–1. A nonimprinted polymer (NIP)-based sensor responded with a low relative resistance of the same magnitude although the concentration was varied. The response ratio of the IIP-based sensor to the NIP-based sensor (ΔR/Ro)IIP/(ΔR/Ro)NIP as a function of the concentration of Pb2+ ions in the solution shows that the response ratios recorded a maximum of around 22 at 50 μg L–1 and then decreased as the concentration increased, following an exponential decay function with the minimum ratio of 2.09 at 200 μg L–1 but never read 1. The sensor showed excellent selectivity against the bivalent cations Mn2+, Fe2+, Sn2+, and Ti2+. The sensor was capable of exhibiting 90% ΔR/Ro response repeatability in a consecutive test.

Dose-Dependent Blood-Feeding Activity and Ovarian Alterations to PM2.5 in Aedes aegypti.

Simple SummaryAedes aegypti (Ae. aegypti) is a mosquito that transmits arboviruses and responds to various biological and environmental stressors, including temperature, rainfall, and humidity. However, there is a lack of knowledge about fine particulate matter (PM2.5) effects on arbovirus vectors. We hypothesized that fine particulate matter (PM2.5) may affect Ae. aegypti blood-feeding rate and organs. We set up an environmental chamber that could adjust the concentration of PM2.5 and observed their blood-feeding activity. We observed a dose–response relationship between PM2.5 level and blood-feeding rate in adult female Ae. aegypti mosquitoes. In addition, histopathological study showed some changes in the ovaries. Vacuolated or vacuolar degeneration characterized by a formation of non-lipid small droplets in the cytoplasm was observed. This demonstrated the degenerative stage of the cells before developing hydropic degeneration or another advanced stage of cellular damage. The present study explored the effects of PM2.5 exposure on the blood-feeding rate and organ integrity in the major arboviral vector Ae. Aegypti, providing information on the potential but indirect operational impact of PM2.5 exposure on the survival and transmission capabilities of this major vector. Our findings may contribute towards the conceptualization and implementation of mosquito control measures with due consideration of the effects of ambient PM2.5 on their populations.High levels of fine particulate matter (PM2.5) air pollution are a concern for human health. Several studies have examined the effects of air pollution on human and animal health. However, there is a lack of knowledge about its effects on arbovirus vectors. Thus, we investigated whether PM2.5 concentration alters the blood-feeding activity of Ae. aegypti mosquitoes. We investigated the effect on the females’ propensity to blood feed at eight concentrations of PM2.5 ranging from 100 to 1000 μg/m3. Correlation analysis showed blood-feeding activity had a significant strong negative correlation with concentration of PM2.5 (rp = −0.85; p ≤ 0.00001). Exploratory linear and non-linear models showed an exponential decay relationship was the best fitting model (corrected Akaike’s information criterion, 193.0; Akaike’s weight, 0.766; adjusted R2, 0.780). Ultrastructural study demonstrated PM2.5 did not obstruct the respiratory system, but some fine particles were present on the antenna and abdominal body parts. Ovaries showed a dose–response relationship between PM2.5 level and vacuolated degeneration. In conclusion, the blood-feeding behavior of Ae. aegypti females may have an exponential decay relationship with PM2.5 level, and their ovaries may demonstrate dose-dependent degeneration. These findings may be important in understanding the vector’s biology and disease transmission in settings with high PM2.5 levels. These results are important to understand blood-feeding and feeding pattern of mosquitoes during PM2.5 pollution, which is important for disease transmission and vector control.

Old Age as Horror Vision or Comfort Zone in the Late Fiction of Contemporary British Novelists

Abstract Old people have always figured in literature, but the unprecedented and worldwide growth of longevity in the twentieth century has triggered new fictional approaches to the topic of aging. Thus, since the late 1980 s, an ever growing number of established British writers, reaching their own advanced years, have written on age from an insider’s perspective, creating old main characters and focusing on their mental and physical experiences. I have examined six of such novels, published between 1986 and 2019, trying to find out how the authors construct their heroes’ and heroines’ aging selves by imagining their attitudes to certain central issues like time, death, physical decay and human relationships. Of the classical formative categories (gender, class, ethnicity, etc.) gender has proved to be the most essential, especially when it comes to the perspectives on time. While the view of heroes created by male writers remains fixed on the past, often with nostalgia, sometimes with regret, the women authors’ heroines focus on their present situation with a view to the future, represented by children and grandchildren. Class turned out to be a second important category: the (uncontemplated) safe middle-class position of all protagonists appears as an indispensable precondition for the free choice of attitude to the challenges of aging.

Drivers of soil microbial community assembly during recovery from selective logging and clear‐cutting

Abstract Despite important progress in understanding the impacts of forest clearing and logging on above‐ground communities, how these disturbances affect soil microbial β‐diversity and the ecological processes driving microbial assemblages are poorly understood. Furthermore, whether and how the microbial shifts affect vegetation composition and diversity during recovery of post‐logged forests remain elusive. Using a spatial grid experiment design in a primary tropical forest intermixed with post‐logged patches naturally recovered for half century in Hainan Island, China, we characterized and explained the distance–decay relationships of soil microbial similarities in primary, selectively logged and clear‐cut forests. Selectively logged sites showed a lower spatial turnover rate of bacterial assemblages based on phylogenetic and taxonomic β‐diversity, but a higher spatial turnover rate of fungal assemblages based on phylogenetic β‐diversity, suggesting a higher level of phylogenetic variability in fungal composition. Clear‐cut sites showed lower spatial turnover for both bacterial and fungal assemblages based on the two β‐diversity, indicating community homogenization. Main drivers of microbial assemblages shifted from soil properties in primary forest to tree composition in selectively logged sites, whereas microbial–tree associations declined in clear‐cut sites, leading to stochastically organized microbial assemblages. Synthesis and applications. The increased fungal phylogenetic turnover with tree turnover following selective logging promotes unassisted recovery of plant diversity. In contrast, the decoupling of tree and microbial turnover following clear‐cutting suggests restoration approaches based on tree planting, and tree species that have strong associations with bulk soil microbial community should be considered. Our findings advance the understanding of spatial patterns, processes and drivers of soil microbial assemblages in parallel with tree community recovery during regeneration of post‐logged tropical forests, and highlight the importance of coupling assemblage patterns between tree and soil fungal communities for conserving tropical forest biodiversity.

Hydrologic similarity: Dimensionless runoff indices across scales in a semi-arid catchment

In this study, an assessment of similarity relationships across runoff measurements at various spatial scales was carried in a typical Sahelian landscape, under semi-arid climate in northern Burkina Faso (west African Sahel). The scales of observations considered are the plot scale (1 m2, 50 m2, 150 m2) and the sub-catchment scale (6.1 ha, 33.8 ha), with various soil surface conditions and slopes. These scales were monitored during six years (2010–2015) under natural rainfall. Based on monitoring data, a runoff potential index I1 and an effective runoff index I2 are developed, encapsulating the physical characteristics of the observation scale into dimensionless forms, hence reducing their sensitivity to the scale effects. These indices help in assessing hydrological similarity across measurement scales. Results showed that runoff decreases with the increase of the observation scale size. Besides, dimensionless indices vary following a logarithmic decay relationship with the scale size (R2 > 0.98). Such results highlight the non-linear nature of runoff processes and also promotes similarity analysis as a means to model hydrological processes through soil surface conditions and landscape descriptors.

Comparison of Diazotrophic Composition and Distribution in the South China Sea and the Western Pacific Ocean.

Simple SummaryDiazotrophs are important contributors of bioavailable nitrogen that is essential to maintaining biological productivity in marine ecosystems. In this study, surface water samples were analyzed to explore the spatial variation of the diazotrophic community in the upper seawater of the South China Sea (SCS) and the Western Pacific Ocean (WPO). The well-conserved gene nifH, which is considered an important marker gene, was used for analyzing the phylogeny, diversity, and abundance of diazotrophs in this study. Our results showed that Proteobacteria was the main diazotroph in the SCS, while Cyanobacteria accounted for the largest proportion in the diazotroph community in the WPO. In addition, high abundances of diazotrophs in the subequatorial WPO indicated the occurrence of diazotrophs blooming. Variation in the composition of diazotrophs was significantly correlated with temperature, dissolved inorganic nitrogen, dissolved inorganic phosphate, and spatial variables between these regions. Our results provide insights into the ecological success and biogeochemical importance of diazotrophic communities in changing environments.The variation of diazotrophs has been elusive in multiple SCS and WPO regions due to insufficient data. Therefore, the dynamics of diazotrophic composition and distribution were investigated in this study, based on high-throughput sequencing and quantitative PCR of the nifH gene. We found that Proteobacteria dominated the diazotrophic community in the river-impacted SCS and cyanobacteria and Proteobacteria were more abundant in the ocean-dominated SCS and WPO. The qPCR analysis showed that cyanobacterial Trichodesmium was abundant in the Pearl River plume and in the SCS basin influenced by the Kuroshio intrusion, and it also thrived in the subequatorial region of the WPO. Unicellular cyanobacteria UCYN-A were mainly detected in the river-impacted area, UCYN-B was abundant in the WPO, UCYN-C had a relatively high abundance in the ocean-dominated area, and a preponderance of γ-Proteobacteria γ-24774A11 was observed in the ocean-dominated SCS and pelagic WPO. Diazotrophic communities had significant distance–decay relationships, reflecting clear biogeographic patterns in the study area. The variations of diazotrophic community structure were well explained by dissolved inorganic nitrogen, dissolved inorganic phosphate by an eigenvector spatial variable PCNM1. These results provide further information to help determine the ecological mechanism of elusive diazotrophic communities in different ocean ecosystems.

Spatial patterns of microbial nitrogen-cycling gene abundances along a precipitation gradient in various temperate grasslands at a regional scale

Despite the importance of microorganisms in soil nitrogen (N) cycling, studies on spatial patterns of microbial N-cycling gene abundances in temperate grasslands are still lacking, whose productivity is limited by N. Here, we investigated N functional genes in soil microorganisms from 60 sites in temperate grasslands across 1661 km in Inner Mongolia, China. Abundances of all N functional genes and 16S rDNA tended to decrease from northeast to southwest, consistent with the changing tend of precipitation but contrary to that of temperature. Non-linear saturation curves dominated patterns for abundances of most N functional genes and 16S rDNA along precipitation as they increased with the rising precipitation when <288–343 mm, but remained stable after these breaking points. Interestingly, these breaking points were clearly related to certain soil types, e.g. nifH did not change with precipitation in Chernozems and Gleysols, but increased with it in other soil types. Non-linear saturation patterns were also observed for most N functional gene and 16S rDNA abundances with temperature and soil total organic carbon. In contrast, no consistent spatial pattern for ratios of N functional genes: 16S rDNA was observed, which varied greatly by different N functional genes. Moreover, decay relationships were discovered for the abundance-based matrix of N functional genes over geographic distance. From the temperate meadows to typical steppes and to temperate desert steppes, the influence of relatively long-term environmental variables increased, but that of short-term ones decreased. Overall, we revealed non-linear patterns of N functional gene abundances along precipitation with a clear relationship with soil type, and discovered that attributions of geographic distance, plant community, historical-contingency and contemporary-disturbance to N functional gene community similarity decay were ecosystem–dependent.

Defensive behaviour of building envelopes in terms of mechanical and thermal responsiveness by incorporating PCMs in cement mortar layers

This paper presents a comprehensive approach to elucidate the mechanical and thermal aspects of coating layers integrated with organic-based PCMs. In that respect, three sets of cement mortars were studied experimentally to underline the significance of PCMs proportion. From a mechanical point of view, the strength of specimens cured at 20 °C resulted to be superior compared to 40 °C, with a more evident influence for cement mortars containing PCMs. Laboratory tests on specimens subjected to 50 wetting–drying cycles demonstrated an insignificant increase of the mass for coatings without PCMs and a slight increase for coatings containing PCMs. During this process, growth in strength for the base mix without PCMs and a loss in strength for mixtures with PCMs was exposed; an exponential decay relationship was noted between the compressive strength with the PCM proportion. Alongside this, a transient thermal analysis was carried out to assess the effect of PCMs on the dynamic thermal parameters of coating layers. A higher proportion of PCM ingredients leads to enhanced responsiveness since the heat wave penetrating the layer is smoothen and delayed. These issues can adequately address the defensive behaviour capacity of building components, without surpassing their carrying structural stability and mechanical properties.

Soil Fungal Community Structure in Boreal Pine Forests: From Southern to Subarctic Areas of Finland.

The boreal forest environment plays an important role in the global C cycle due to its high carbon storage capacity. However, relatively little is known about the forest fungal community at a regional scale in boreal forests. In the present study, we have re-analyzed the data from our previous studies and highlighted the core fungal community composition and potential functional groups in three forests dominated by Scots pine (Pinus sylvestris L.) in Finland, and identified the fungal generalists that appear across geographic locations despite differences in local conditions. The three forests represent subarctic, northern and southern boreal forest, and are all in an un-managed state without human interference or management. The subarctic and northern areas are subject to reindeer grazing. The results showed that the three locations formed distinct fungal community structures (P < 0.05). Compared to the two northern locations, the southern boreal forest harbored a greater abundance of Zygomycota, Lactarius, Mortierella Umbelopsis, and Tylospora, in which aspect there were no differences between the two northern forests. Cortinarius, Piloderma, and Suillus were the core fungal genera in the boreal Scots pine forest. Functionally, the southern boreal forest harbored a greater abundance of saprotroph, endophytes and fungal parasite-lichen, whereas a greater abundance of ectomycorrhizal fungi was observed in the northern boreal forests. Moreover, the pathotroph and wood saprotrophs were commonly present in these three regions. The three locations formed two distinct fungal community functional structures, by which the southern forest was clearly separated from the two northern forests, suggesting a distance–decay relationship via geographic location. This study provides useful information for better understanding the common fungal communities and functions in boreal forests in different geographical locations.

Geographical Distribution of Iron Redox Cycling Bacterial Community in Peatlands: Distinct Assemble Mechanism Across Environmental Gradient.

Microbial-mediated iron (Fe) oxidation and reduction greatly contribute to the biogeochemistry and mineralogy of ecosystems. However, knowledge regarding the composition and distribution patterns of iron redox cycling bacteria in peatlands remains limited. Here, using high-throughput sequencing, we compared biogeographic patterns and assemblies of the iron redox cycling bacterial community between soil and water samples obtained from different types of peatland across four regions in Northeast China. A total of 48 phylotypes were identified as potential iron redox bacteria, which had greater than 97% similarity with Fe(II)-oxidizing bacteria (FeOB) and Fe(III)-reducing bacteria (FeRB). Among them, Rhodoferax, Clostridium, Geothrix, Sideroxydans, Geobacter, Desulfovibrio, and Leptothrix could be used as bioindicators in peatlands for characterizing different hydrological conditions and nutrient demands. Across all samples, bacterial communities associated with iron redox cycling were mainly affected by pH, dissolved organic carbon (DOC), and Fe2+. Distance–decay relationship (DDR) analysis indicated that iron redox cycling bacterial communities in soil, but not in water, were highly correlated with geographic distance. Additionally, null model analysis revealed that stochastic processes substituted deterministic processes from minerotrophic fens to ombrotrophic bogs in soils, whereas deterministic processes were dominant in water. Overall, these observations suggest that bacteria involved in iron redox cycling are widespread in diverse habitats and exhibit distinct patterns of distribution and community assembly mechanisms between soil and water in peatlands.