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29081. 题目: Distribution and constraining factors of planktonic and benthic foraminifers in bottom sediments of the southern South China Sea
文章编号: N180625B1
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Jian Yin, Chunlian Liu, Jinpeng Zhang, Xiaoqiang Yang, Jie Wu, Wolfgang Oschmann, Franz T. Fürsich, Benduo Zhu, Huodai Zhang
更新时间: 2018-06-25
摘要: A total of 93 surface sediment samples were collected to analyze the environmental factors constraining the foraminiferal distribution pattern in the southern South China Sea (SCS). Species distributions and stable isotopic compositions were combined to reveal the controlling factors, such as depth, salinity, substrate, runoff, currents, and cold seep activities. Water depth is the dominant factor controlling both assemblage composition and δ18O of benthic foraminiferal tests. The 1000 m isobath separates the sites into two clusters (Cluster A and B), which are dominated by deep-water species and shallow-water species, respectively. The sites in the deep-water zone (Cluster A) are characterized by lower absolute abundances, species richness and Shannon Index values (a measure of diversity), and higher proportions of planktonic foraminifers compared with the sites in the shallow-water zone (Cluster B). Increasing proportions of agglutinated tests with depth and rapidly decreasing proportions of planktonic foraminifera in the Nansha Trough Basin provide evidence of calcium dissolution occurring at a depth corresponding with previous reports. Oxygen stable isotopes (δ18OB) of benthic foraminifera become more positive with depth only up to 1000 m and remain constant beyond. Differences in the proportion of agglutinated and porcelaneous tests in the shallow-water zone suggest that terrestrial runoff from nearby river systems (Mekong River and northern Borneo rivers) and seasonal surface currents (SCS Southern Cyclonic Gyre and SCS Southern Anticyclonic Gyre) jointly influence the distribution patterns of foraminifera in the study area. Enrichment of planktonic δ18O is a response to cold waters brought by the SCS southern cyclonic gyre during winter. An upwelling current (Winter Natuna Off-Shelf Current) containing higher amounts of organic matter/nutrients contributes to the depleted δ13C of planktonic foraminifera and to the abnormal abundance of foraminifera at the sites within its area of influence. The dominance of the foraminifer Melonis barleeanus at sites belonging to Subcluster A1 and the stable isotope compositions of benthic foraminifera (δ18O > 0, δ13C < 0) across the sites suggest the influence of active cold seeps in the southern SCS. This research highlights the complexity of environmental variables that interact to influence the foraminiferal assemblages and geochemistry in the southern South China Sea, which could serve as a model for paleoenvironmental and palaeoceanographic reconstructions.

29082. 题目: Eocene (Bartonian) benthic foraminifera and paleoenvironmental changes in the Western Tethys
文章编号: N180625B0
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: L. Rivero-Cuesta, E. Molina, L. Alegret
更新时间: 2018-06-25
摘要: The Eocene was a period of intense climate variability and the response of deep-sea biota is still poorly understood, especially across certain understudied intervals from the middle Eocene. We present new benthic foraminiferal data from a Bartonian marine sequence deposited in the western Tethys Ocean (Torre Cardela section, Spain), and determine the biotic and paleoenvironmental turnover. The assemblages indicate a middle to lower bathyal depth of deposition, and they contain allochthonous taxa (e.g. asterigerinids) that were transported from shallower settings. A Detrended Correspondence Analysis (DCA) performed on the total assemblage differentiates the autochthonous and allochthonous taxa, supporting the idea of different provenience. We suggest that the latter were likely transported downslope by currents. Quantitative analyses of the autochthonous assemblages show a strong dominance of calcareous infaunal taxa, mainly bolivinids, which point to a high flux of organic matter to the seafloor. Bolivinoides crenulata, the most common species, is associated with inputs of refractory organic matter and high-energy environments. Five intervals were differentiated based on changes in the relative abundance of taxa. Two intervals (B and D) show the highest percentages of allochthonous taxa and B. crenulata. We suggest that enhanced current activity not only transported allochthonous taxa, but also brought in refractory organic matter to the seafloor, which was consumed by opportunistic taxa during these two intervals. We conclude that benthic foraminiferal assemblages at Torre Cardela were strongly controlled by the amount and type of organic matter reaching the seafloor, which were in turn affected by sedimentary and, ultimately, by climatic factors.

29083. 题目: Nitrogen isotope and trace element composition characteristics of the Lower Cambrian Niutitang Formation shale in the upper -middle Yangtze region, South China
文章编号: N180625A9
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Min Li, Jianfa Chen, Tieguan Wang, Ningning Zhong, Shengbao Shi
更新时间: 2018-06-25
摘要: The Early Cambrian is a key interval in the global development of biological evolution, in which occurred many important environmental events and organic-rich sedimentary layers were deposited, which formed important hydrocarbon source rocks. The Lower Cambrian Niutitang Formation is one of the most important marine sedimentary layers in the Yangtze region, South China, and it records abundant important geological information that can be used for the reconstruction of the Lower Cambrian paleo-climates and paleo-environments. Nitrogen isotope compositions record and reflect variations in the original sedimentary environment and the redox conditions of marine ecosystems. Trace elements are also reliable indicators of sedimentary environments. In this study, we collected samples from the Lower Cambrian Niutitang Formation shale in the upper-middle Yangtze region of South China and measured the nitrogen isotope values of bulk sediments (δ15Nbulk), as well as their organic carbon isotope values (δ13Corg), total organic carbon (TOC) contents, total nitrogen (TN) contents and trace element concentrations. The δ15Nbulk values of the Niutitang shale range from 0.6‰ to 2.8‰, they show a certain positive excursion from bottom to top in the longitudinal direction, and they exhibit a significant correlation with the longitudinal variations in trace elements. These trace element characteristics suggest that the lower section of the Niutitang Formation existed in a strongly reduced sedimentary environment and was located in a hydrothermally active layer. During the deposition of the lower section of black shale, the nitrogen cycle was dominated by anaerobic nitrogen fixation; thus, its nitrogen isotope values are relatively lighter. In contrast, during the deposition of the upper section of the Niutitang Formation, the redox conditions of water column were unstable, the oxygen contents increased, and oxygenated reactions were intermittent or localized; thus producing relatively strong isotopic fractionation and causing the δ15Nbulk values in the upper section of black shale to exhibit a positive excursion. We conclude that the sedimentary environment is the key factor affecting nitrogen isotopes and that the redox conditions of the water column exhibit a significant correlation with the nitrogen isotope values.

29084. 题目: Oligo-Miocene lacustrine microbial and metazoan buildups from the Limagne Basin (French Massif Central)
文章编号: N180625A8
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Adeline Roche, Emmanuelle Vennin, Anthony Bouton, Nicolas Olivier, Aurélia Wattinne, Irina Bundeleva, Jean-Fran?ois Deconinck, Aurélien Virgone, Eric C. Gaucher, Pieter T. Visscher
更新时间: 2018-06-25
摘要: The Limagne Basin (French Massif Central) is an extensive continental lacustrine system accommodating microbial and metazoan buildups from Chattian to Aquitanian age. A description of these buildups and their associated biotic components in Grand Gandaillat and Crechy quarries provides insights into their spatio-temporal distribution patterns. Flats, cauliflowers, domes, cones and coalescent columnar morphologies have been identified with a main laminated mesofabric and laminated, columnar, filamentous and caddisfly-coated microfabrics. Two low-gradient margin models emerged based on the changes in the distribution, morphology and size of the microbial and metazoan-rich deposits through time: the first model applies to the Chattian deposits in the Grand Gandaillat quarry and the second to the Aquitanian deposits in the Crechy quarry. This study emphasizes the heterogeneity of marginal lacustrine carbonate-siliciclastic cycles. The lacustrine/palustrine cycles of the Limagne Basin record (i) lacustrine deposits composed of microbial and metazoan buildups and organic matter-rich marls indicating periods of high accommodation, and (ii) palustrine deposits composed of mudstone and clayey paleosoils, indicative of periods of low accommodation. The cycles differ with thin and symmetrical deposits that dominate the Chattian cycles whereas thicker and asymmetrical deposits mark the Aquitanian cycles. In addition, the Chattian buildups are exclusively microbial and only a few centimeters thick whereas the Aquitanian ones are multiple meters in height and are composed of both microbes and metazoans. Climatic, tectonism, volcanic and local parameters are involved in the deposition of buildups and their organization in each different cycle. Climate may control the long-term arid/humid sedimentary succession, tectonic may explain the difference in the deposit thickness between two cycles of different ages and localizations as well as the specific distribution of the buildups throughout the basin, volcanism may control the chemical lacustrine conditions and local physiography may impact the soil removal ability of the lake margin.

29085. 题目: Post-caldera evolution of Deception Island (Bransfield Strait, Antarctica) over Holocene timescales
文章编号: N180625A7
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: M.C. Muniz, R.M. Anjos, R.P. Cardoso, L.H. Rosa, R. Vieira, H. Marotta, K. Macario, A. Ayres Neto, J.P. Felizardo, C.D.N. Barboza, L.F. Rodrigues, E.Q. Alves
更新时间: 2018-06-25
摘要: The study of palaeoclimatic changes in fast warming regions can contribute to the understanding of the forcing mechanisms responsible for the global changes that are presently happening. Deception is an active volcanic island in the Bransfield basin that has a complex history strongly influenced by both magmatic and tectonic processes. However, without accurate information on the distribution of melt, depth of sediments and Holocene timescales of its volcanic eruptions, the models for the post-caldera evolution of Deception Island are poorly constrained. Although this region has undergone severe environmental changes due to recent eruptions, hindering the location of potential study areas of paleo-volcanic eruptions, it is still possible to reconstruct post-caldera evolution at a local scale. Employing analyses such as radiocarbon dating, stable carbon and nitrogen isotopic compositions and particle-size distributions in subsoil horizons, we have studied the coastal areas of Whalers Bay and between Wensleydale Beacon and Cross Hill to identify the major periods of alluvial sedimentation on Deception Island. Whalers Bay was influenced by a large amount of moving water generated by ice melting. The coastal location of both sampling sites contributes to preserve the sedimentation history in their soil profiles, despite the severe environmental changes due to recent eruptions. Our findings indicate that from approximately 13 to 5 cal kyr BP, the accumulation of organic matter was stable and the landforms were not altered. After that time, post-caldera eruptions occurred, melting the glacier and, consequently, flooding surficial soil layers with mud. These changes are consistent with old 14C ages for subsoil organic matter and, therefore, with the occurrence of intense cryogenic disturbance processes.

29086. 题目: Refining the Jurassic-Cretaceous boundary: Re-Os geochronology and depositional environment of Upper Jurassic shales from the Norwegian Sea
文章编号: N180625A6
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Gyana Ranjan Tripathy, Judith L. Hannah, Holly J. Stein
更新时间: 2018-06-25
摘要: Limited chronological information for Upper Jurassic rocks hampers precise age assignment of the Jurassic-Cretaceous (J/K) boundary. This study presents Re-Os geochronology, Rock-Eval pyrolysis and geochemical data for Upper Jurassic rocks in the Nordland VII area, offshore northern Norway. Four intervals of organic-rich shale were investigated, two from the Krill and one from the Alge Member of the Hekkingen Formation and one from the underlying M snykan Formation (drilled cores 6814/04/U-01 and 6814/04/U-02). Rock-Eval pyrolysis data indicate immature organic matter with mixed (Type II/III) oil-gas potential in these units. Among the four intervals, Re-Os isochroneity prevails only for the Hekkingen Formation samples; data from the shale interval in the otherwise sand-rich M snykan Formation, deposited in a shoreface-to-foreshore marine environment, are not isochronous. Non-isochroneity of the samples from relatively proximal setting is attributable to non-conservative elemental (desorption of Os from sediments to dissolved phase) and isotopic exchange of Os at this depositional site. The Re-Os isochron age for the Alge Member (153.2 ± 7.3 Ma (Model 3); MSWD = 29; n = 9) is consistent with its biostratigraphic Kimmeridgian age (152.1–157.3 Ma). A Re-Os isochron for the lower part of the Krill Member yields an age of 144.5 ± 1.4 Ma (Model 3; MSWD = 3.7; n = 10) with an initial 187Os/188Os ratio of 0.552 ± 0.007. Given the interval's lower Tithonian biostratigraphic age, the Re-Os age suggests that the J/K boundary must be a few Myr younger than its currently assigned age of ~145.0 Ma (2017/02 time scale; www.stratigraphy.org). A Re-Os model age for shales from the upper part of the Krill Member places an upper age limit for the J/K boundary at 142 (±2) Ma. Hence, the J/K boundary is between 142 Ma and 144.5 Ma. Fe and S concentrations for the Hekkingen Formation show strong correlation and the S/Fe slope (~1.19) mimics the stoichiometric S/Fe ratio for pyrite (~1.15). A Fe-S-TOC ternary diagram for these samples points to an iron-limiting, sulphidic depositional environment. Anoxic to sulphidic depositional conditions for the Hekkingen shales are also evident from relatively higher authigenic enrichment of Mo compared to U. Unlike the Hekkingen Formation, shales from the more sandy M snykan Formation have lower S/Fe ratios and lower enrichment factors for redox-sensitive elements, indicating relatively oxygenated marine conditions during deposition.

29087. 题目: Stepwise oxygenation of early Cambrian ocean controls early metazoan diversification
文章编号: N180625A5
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Xiangkuan Zhao, Xinqiang Wang, Xiaoying Shi, Dongjie Tang, Qing Shi
更新时间: 2018-06-25
摘要: The Ediacaran–Cambrian transition is a critical period in Earth history, during which both marine environment and life experienced drastic changes. It was suggested that pervasive oxygenation and associated chemical changes in the ocean have potentially triggered the rapid diversification of early Cambrian metazoans. The timing and process of ocean oxygenation, however, have not been well constrained. In this paper, an integrated study was conducted on the lower Cambrian Niutitang (NTT) Formation in Siduping area, western Hunan, which was paleogeographically located at shelf margin–upper slope setting of the Yangtze Platform. Using ICP-MS, Element Analyzer, FESEM, EDS and XRD techniques, the abundance of RSEs (redox sensitive elements), patterns of RSEs distribution, pyrite morphology, TOC (total organic carbon), TS (total sulfur), SPY (pyrite sulfur) as well as N and P contents were investigated systematically. The results show that during the NTT deposition, bottom seawater in the study area experienced a complicated evolution, with a dynamic alternation of three ferruginous and three euxinic intervals, and suboxic–oxic conditions occurring only in the latest Cambrian Stage 3. Comparison with relevant sections reported previously from other facies belts within the Yangtze Platform shows that the seawater oxygenation was a progressive process expanding from shallow to deep-water areas in time. Shallow-water platform area became oxygenated in the late Cambrian Stage 2, shelf margin area in the late Cambrian Stage 3, and the deep-water basin remained ferruginous until the latest Cambrian Stage 3, when it became euxinic. Sediment Mo/TOC, U/TOC ratios increased from bottom to top in the section, coupled with elevated Mn, N and P secular trends, likely indicating an overall enhancement of seawater oxygenation. The spatial-temporal distribution and increased paleoecologic complexity of major fossil groups on the Yangtze Platform over time coincide with the seawater oxygenation process, likely implying that increased ocean oxygenation and declining euxinic seawaters have driven the rapid diversification of early Cambrian metazoans.

29088. 题目: Organic contamination as a driver of structural changes of hydroid's assemblages of the coral reefs near to Havana Harbour, Cuba
文章编号: N180625A4
期刊: Marine Pollution Bulletin
作者: Susel Castellanos-Iglesias, Ana Caroline Cabral, César C. Martins, Maikon Di Domenico, R.M. Rocha, Maria Angélica Haddad
更新时间: 2018-06-25
摘要: Hydroid assemblage's responses to organic contamination were evaluated using sedimentary sterols as explanatory variables. At seven coral reef sites in the Havana west coast, hydroids were collected along three 10 m × 1 m, 10 m deep transects. Five sterols were analysed, i.e., coprostanol, an indicator of faecal contamination, and cholestanol, cholesterol, stigmasterol and brassicasterol, indicators of biogenic organic matter inputs. The sampling sites were classified by level of contamination. A total of 65 species comprised the hydroid assemblages. Hydroids community abundance and richness decreased in the contaminated sites. Coprostanol had the highest relative importance for these variables and also for Plumularia floridana and Clytia gracilis abundances. Obelia dichotoma and Halecium bermudense were relatively abundant in the contaminated sites. The results indicate that faecal contamination negatively affected the hydroid assemblages, highlighting the importance of integrated biological and chemical indicators to evaluate the environmental conditions of the Havana coral reef.

29089. 题目: Ants alter molecular characteristics of soil organic carbon determined by pyrolysis-chromatography/mass spectrometry
文章编号: N180625A3
期刊: Applied Soil Ecology
作者: Zhongsheng Zhang, Zhuo Wei, Jim Jian Wang, Ran Xiao, Yili Meng, Haitao Wu, Xianguo Lyu
更新时间: 2018-06-25
摘要: Colonization by ecosystem engineers, such as ants, have important but occasionally unnoticed roles in regulating soil carbon cycles. However, little information is available pertaining to ant effects on changing molecular features of soil organic matter. In this study, we characterized total soil organic carbon (SOC), total nitrogen, water extractable organic carbon (WEOC) as well as molecular characteristics of humic acids (HAs) of ant mound soils (SoilAnt) and the surrounding soils (SoilCon) using pyrolysis-chromatography/mass (py-GC/MS). SOC, total nitrogen and WEOC contents of SoilAnt were significantly lower than those of SoilCon. SoilAnt samples had significant higher nitrogen containing compounds proportions in pyrolysis products of HAs as opposed to SoilCon samples. Another remarkablecharacteristic was that no polysaccharides, lignin, and phenols were identified in HAs of SoilAnt samples. It indicated that ant colonization significantly changed the molecular composition of soil organic matter.

29090. 题目: Comprehensive analysis of grazing intensity impacts soil organic carbon: A case study in typical steppe of Inner Mongolia, China
文章编号: N180625A2
期刊: Applied Soil Ecology
作者: Meng Zhang, Xiaobing Li, Hong Wang, Qi Huang
更新时间: 2018-06-25
摘要: Overgrazing is a primary cause of grassland degradation, including the loss of soil carbon, but comprehensive analysis of the mechanism by which grazing affects soil organic carbon (SOC) is limited. To investigate this mechanism, we measured the contents of total soil organic carbon (TSOC) and active SOC fractions in grazed and ungrazed soil, and we examined the influence of grazing on soil microenvironments, soil carbon input, transformation and utilization, and soil respiration. The experiment was conducted in typical steppe in Inner Mongolia, China, under light, moderate, and heavy grazing plus a no-grazing control. Grazing changed the contents and stocks of the TSOC and active SOC fractions as well as the composition of the SOC. After three years, light and moderate grazing increased TSOC content by 3.44% and 5.43%, respectively, while heavy grazing decreased it by 4.30%. The changes in active SOC fractions were not uniform under different grazing intensities. All grazing intensities increased the stocks of microbial biomass carbon (MBC) and dissolved organic carbon (DOC) compared with the control, but their magnitudes did not rise with increased grazing intensity. Moderate grazing increased the stocks of potentially mineralizable carbon (PMC) and particulate organic carbon (POC), whereas light and heavy grazing decreased them; this may indicate likely long-term changes in SOC following changes in grazing intensity. Light grazing resulted in a larger C input to soil and faster transformation, more emission, and less accumulation of SOC. Moderate grazing led to a smaller C input to soil, and its transformation, utilization and emission rates were between those associated with light grazing and heavy grazing, and there was more accumulation. Heavy grazing resulted in the smallest C input, faster transformation and utilization, less change in emission, and less accumulation. Based on these results, moderate grazing is likely the most practical grazing intensity for the sustainable utilization of this grassland ecosystem to feed livestock. However, because this was a short-term study, the results did not reach significance, and long-term studies are needed.

29091. 题目: Distribution of prokaryotic communities throughout the Chernozem profiles under different land uses for over a century
文章编号: N180625A1
期刊: Applied Soil Ecology
作者: Mikhail V. Semenov, Timofey I. Chernov, Azida K. Tkhakakhova, Alena D. Zhelezova, Ekaterina A. Ivanova, Tatyana V. Kolganova, Olga V. Kutovaya
更新时间: 2018-06-25
摘要: Land use affects physical, chemical and biological properties and processes in soil. Long-term field experiments were employed to reveal changes of soil characteristics induced by land use. Using high-throughput 16S rRNA gene amplicon sequencing and quantitative PCR, comparative analyses were conducted on prokaryotic community structure in different soil diagnostic horizons of Chernozems under forest, fallow and arable land within a long-term field experiment established by V.V. Dokuchaev in 1892. Soil organic carbon (SOC) was a more sensitive and reliable indicator of changes than microbial diversity indexes. Verrucomicrobia changed most among different prokaryotic phyla. Long-term tillage did not result in detectable changes in α-diversity of Chernozem prokaryotic communities, except for that plow pan horizon that showed a pronounced decrease in microbial diversity. The differences in prokaryotic community structure between soil horizons were more contrasting than between land uses. Analysis of β-diversity indicated that soil microbial communities at different depths formed non-overlapping clusters of A and B horizons, while microbiomes of transitional AB horizons fall in between these two clusters. The sharp decline in α-diversity in the plow pan horizon, as well as significant differences between the communities of A and B horizons indicate that the soil microbiomes are horizon-specific.

29092. 题目: DNA occurrence in organic matter fractions isolated from amended, agricultural soils
文章编号: N180625A0
期刊: Applied Soil Ecology
作者: Claudio Zaccone, Luciano Beneduce, Concetta Lotti, Giulia Martino, César Plaza
更新时间: 2018-06-25
摘要: The persistence of soil organic matter (SOM) constituents as a function of their recalcitrance has been recently questioned, with several papers showing the influence of the combined action of physical protection and chemical stabilization mechanisms as the main factors affecting SOM mean residence time. Using a physical fractionation method, SOM located between aggregates (FR), occluded within macro- (MA) and micro-aggregates (MI), and associated with the mineral fractions (MIN) were isolated from an agricultural soil differently amended (using compost, sewage sludge and biochar), and the occurrence of (total, bacterial and plant) DNA in these SOM pools was investigated. Following physical fractionation, total DNA (tDNA) was recovered from all SOM pools and from all treatments. Independently from the amendment, most tDNA accumulates in the FR fraction (30–70%), followed by the MIN pool (25–55%). The positive correlation between tDNA contents and C/N ratios (both tending to decrease following the order FR, MA and MI) observed for the light SOM fractions, together with the opposite pattern characterizing the heavy, MIN fraction (characterized by relatively high tDNA contents and low C/N ratios), suggests a different origin of the latter SOM pool, i.e., new molecules resulting from microbial transformations rather than highly degraded litter inputs. Therefore, tDNA may represent a promising proxy of organic matter dynamics in mineral soils. Finally, the MI fraction shows the highest number of microbial taxa and diversity, and seems to constitute a separate microbial niche in which different bacterial communities carry out their activity.

29093. 题目: Effect of water table decline on the abundances of soil mites, springtails, and nematodes in the Zoige peatland of eastern Tibetan Plateau
文章编号: N18062599
期刊: Applied Soil Ecology
作者: Xue Wei, Rui Cao, Xinwei Wu, Nico Eisenhauer, Shucun Sun
更新时间: 2018-06-25
摘要: Despite the important role of soil fauna in the decomposition of soil organic matter, the abundance response of soil fauna to environmental changes has been scarcely studied in peatlands, where soil carbon content is exceptionally high. The water table of the Zoige peatland, the largest alpine peatland worldwide, has been declining due to climate change and human drainage in recent decades, which likely induces changes in the abundance of soil fauna. In order to examine the abundance response of soil mites, springtails, and nematodes to water table decline in the Zoige peatland, we conducted an in situ field drainage experiment, consisting of low, intermediate, and ambient water table levels for four consecutive years. We measured the abundances of mites, springtails, and nematodes at five soil depths (0–5, 5–10, 10–15, 15–20, and 20–25 cm), for four times in the third and fourth year of the experiment. Results show that the effect of water table decline on the abundance of soil fauna varied among soil animal groups, soil depths, and the sampling times over the course of the experiment. While mites did not respond significantly to the experimental treatments, the abundance of springtails at soil depths of 0–5, 5–10, and 10–15 cm and that of nematodes at a depth of 15–20 cm were significantly higher in the drained treatments than in the undrained one. Moreover, water table decline increased the proportion of herbivorous nematodes in the top soil (0–5 cm) and decreased the proportion of bacterivorous nematodes at soil depths of 0–5 and 5–10 cm, while fungivorous and omnivorous-predaceous nematodes did not respond significantly. Given the demonstrated importance of soil fauna to soil carbon dynamics, the changes in the abundances of soil mites, springtails, and nematodes depicted here indicate that soil fauna should be further studied in relation to the recently reported rapid loss of soil carbon in the Zoige peatland.

29094. 题目: Effects of permafrost thaw-subsidenceon soil bacterial communities in the southern Qinghai-Tibetan Plateau
文章编号: N18062598
期刊: Applied Soil Ecology
作者: Xiaodong Wu, Lin Zhao, Guimin Liu, Haiyan Xu, Xiaolan Zhang, Yongjian Ding
更新时间: 2018-06-25
摘要: Permafrost thaws cause ground subsidence as the ground ice melts and drains away. Little is known about the effects of this permafrost thaw subsidence on bacterial communities. In this study, using Illumina sequencing methods, we investigated the structure of bacterial communities in the upper 50 cm of the soil in a typical permafrost thaw subsidence area on the southern Qinghai-Tibetan plateau. The micro topographies in the study area were classified as control, collapsing, and subsided types. Results showed that the organic carbon content in the collapsing areas was slightly lower than that in the control areas, while there was a substantial decrease in the subsided areas, with a loss of 23.6 ± 13.2% of organic carbon. The microbial carbon contents showed the highest values in collapsing areas. For all three types of soils, the most abundant microbial groups were Proteobacteria, Acidobacteria, and Bacteroidetes. The Non-metricmultidimensionalscaling (NMDS) results showed that the bacterial communities were different in the subsided areas than in the control and collapsing areas. In the control and collapsing areas, the soil bacterial communities showed a clear vertical distribution pattern with depth, which was not apparent in the subsided areas. The bacterial communities also correlated with soil variables such as carbon, moisture, nitrogen contents, and the C:N ratio. The ground subsidence can greatly change these variables. The results suggested that permafrost thaw subsidence had important effects on microbial communities via the changes of soil properties.

29095. 题目: Incorporation of rice straw carbon into dissolved organic matter and microbial biomass along a 100-year paddy soil chronosequence
文章编号: N18062597
期刊: Applied Soil Ecology
作者: Xiaofen Chen, Ming Liu, Yakov Kuzyakov, Weitao Li, Jia Liu, Chunyu Jiang, Meng Wu, Zhongpei Li
更新时间: 2018-06-25
摘要: Dissolved organic matter (DOM) and microbial biomass (MB) are small but reactive pools of soil organic matter (SOM). The incorporation of carbon (C) from rice residue into DOM and MB in paddy soils under aerobic condition when rice straw remains in the field is poorly understood. A one-year incubation experiment was conducted, in which 13C-labelled rice straw was added to a cultivation chronosequence of paddy soils ranging from 0 to 100 years. Rice straw was rapidly decomposed during the first 30 days, after which 73% of the added straw C, on average, was retained in the soil and 46% of the straw C remained in the soil after one year. Throughouttheentireincubation period, 0.2–0.9% of the added straw C was incorporated into DOM, and 2–5% was recovered in MB. The paddy cultivation age strongly affected the straw contribution to the organic C pools. In barren land (0 year), 32–60% of the DOM was derived from straw C, while 13–30% of the DOM was derived from straw C in 5–100-year paddy soils. On average, straw C contributed to 88% of the MB in barren land, 50% in 5-year soil, and 13% in 100-year soil. Consequently, over the duration of paddy cultivation, the contribution of rice straw C to the MB decreased, while the contribution of SOM increased. Our study has indicated that DOM in paddy soils mainly originates from SOM rather than from added plant residues but that plant residues are an important C source for microorganisms.

29096. 题目: Intertidal zonation affects diversity and functional potentials of bacteria in surface sediments: A case study of the Golden Bay mangrove, China
文章编号: N18062596
期刊: Applied Soil Ecology
作者: Ping Zhu, Yaping Wang, Tiantian Shi, Xiaoli Zhang, Guoqiang Huang, Jun Gong
更新时间: 2018-06-25
摘要: The combined effects of intertidal zonation and mangrove vegetation on benthic bacterial communities and ecological functions were studied. MiSeq sequencing of the 16S rRNA gene and PICRUSt predictive functional profiles were used to investigate the diversity, community structure and potential metabolic functions of benthic bacteria in surface sediments of a mangrove ecosystem. Compared with the lower intertidal zone, bacterial alpha diversity and richness were significantly higher in the upper intertidal zone and highly associated with sediment organic matter. The upper zone was occupied by higher proportions of heterotrophic bacteria involved in the degradation of organic compounds. These included Desulfobacterales, Anaerolineae and Acidobacteria, while the proportion of Rhodobacterales and Xenococcaceae was greatly increased in the lower zone. No significant difference of either alpha diversity or community composition was found between rhizosphere and bulk sediments, except that higher relative proportions of Rhizobiales and Actinobacteria occurred in rhizosphere sediments. The shift in bacterial community structure was mainly driven by changes in sediment Pb and NH4 + concentrations. Among the major carbon, nitrogen and sulfur cycling processes examined, higher potentials of cellulose and hemicellulose degradation, dissimilatory sulfate reduction, and nitrate or nitrite reduction occurred in the upper intertidal zone. Assimilatory sulfate reduction and sulfur oxidation potentials were higher in the root-associated sediments than in the bulk sediments. This study indicated that intertidal zonation was more important than root effects in modulating benthic bacterial diversity and functional potentials in a mangrove ecosystem.

29097. 题目: Organic fertilization shapes the biodiversity of fungal communities associated with potato dry rot
文章编号: N18062595
期刊: Applied Soil Ecology
作者: Katarzyna Gleń-Karolczyk, El?bieta Bolig?owa, Jacek Antonkiewicz
更新时间: 2018-06-25
摘要: Intensive farming based on synthetic pesticides and mineral fertilizers has led to a loss of soil biodiversity, which contributes to the suppression of plant pathogens. The key role in the restoration of biodiversity and soil aggregate stability is fulfilled by organic fertilization. Potato reacts well to this type of fertilization. On the other hand, its tubers, during both the vegetative and storage periods, are exposed to a series of infections caused by soil fungi. Of particular economic importance is dry rot, a storage disease with a complex etiology. This study presents an evaluation of the impact of different organic fertilization forms (manure, white mustard intercrop, barley stubble, barley straw and a combination of barley straw and white mustard intercrop) on losses caused by dry rot. For the first time, their role in the formation of: counts, species composition and belonging to frequency and trophic groups of fungi communities colonizing dry-rotting tubers has been specified. Furthermore, a pioneering element of this research is its evaluation of fungi community biodiversity and its influence on the development of dry rot. The main discoveries are as follows: (i) 24 fungi species (14 pathogenic, 6 saprotrophic, 4 antagonistic), which are the cause of dry rot; (ii) dry rot development is mainly determined by the share of saprotrophic fungi, where their increase reduces the percentage of infected tubers; (iii) manure and white mustard favors tuber colonization by saprotrophic and antagonistic fungi and increases biodiversity of the fungi, which results in improved healthiness; (iv) straw and a lack of fertilization increase the frequency of pathogens and reduce biodiversity, resulting in a stronger development of dry rot. In sustainable agriculture management systems, disease risk can be minimized through introduction of organic matter to soil.

29098. 题目: Plant cover and management practices as drivers of soil quality
文章编号: N18062594
期刊: Applied Soil Ecology
作者: S.C. Panico, V. Memoli, F. Esposito, G. Maisto, A. De Marco
更新时间: 2018-06-25
摘要: Human activities intensively modify soil properties and quality according to land-use and management practices. In Mediterranean areas, pollution and fires may directly alter some soil abiotic properties as well as the steady-state condition of soil microbiota. The aim of this study was to evaluate if the chemical and biological characteristics of two kinds of soil, Arenosols and Andosols, of a natural reserve and an urban park respectively, were affected by the same or different plant covers (trees and grasses). At each site, five sub-samples of surface soils (0–10 cm) were collected under maquis (trees) and gap of grasses. The soils were analyzed for physico-chemical parameters (organic matter and water contents, pH, C, N, Cr, Cu, Ni and Pb concentrations) and biological parameters (microbial and fungal biomass, respiration, metabolic quotient and coefficient of endogenous mineralization). The soil quality was evaluated through an integrated index, calculated taken into account all the investigated parameters. The results highlighted that soils under trees inside the urban park, with the highest amount of organic matter, showed higher microbial biomass and activity as compared to soils under grasses. The high concentration of Cu and Pb in these latter soils inhibited the microbial biomass and activity that were not exclusively affected by litter quality. Soil quality would seem to be strongly affected by the pedogenetic derivation and the management practices more than plant covers.

29099. 题目: Reduced efficiency of tropical flies (Diptera) in the decomposition of snail cadavers following molluscicide poisoning
文章编号: N18062593
期刊: Applied Soil Ecology
作者: Finbarr G. Horgan, Carmencita C. Bernal, Socrates Letana, Alberto I. Naredo, Daniel Ramp, Maria Liberty P. Almazan
更新时间: 2018-06-25
摘要: Decomposition is a key ecosystem service that reduces non-living organic matter, returning nutrients to the soil. In this study, we examine the responses by fly (Diptera) communities to molluscicide-poisoned apple snail (Pomacea canaliculata) cadavers in a tropical rice production landscape. Fewer molluscicide-poisoned cadavers were colonised by decomposer flies (niclosamide = 61% of cadavers with fly larvae; methaldehyde = 53%; Camellia sp. seed extract [saponin] = 50%) compared to control (freezer-killed) cadavers (81%). Metaldehyde, niclosamide and saponin reduced the abundance (average 51% reduction), biomass-density (average 63% reduction) and species richness (average 38% reduction) of flies emerging from the snail cadavers. The decay of control cadavers was generally faster (57% more tissue removed over 3 days) than molluscicide-treated cadavers. We suggest that poisoned carcasses potentially affect ecological communities across a range of trophic levels.

29100. 题目: The effect of earthworm and arbuscular mycorrhizal fungi on availability and chemical distribution of Zn, Fe and Mn in a calcareous soil
文章编号: N18062592
期刊: Applied Soil Ecology
作者: H. Dehghanian, A. Halajnia, A. Lakzian, A.R. Astaraei
更新时间: 2018-06-25
摘要: Micronutrient deficiencies most frequently occur in calcareous soils. In sustainable soil management enhanced soil biological activity has been proposed as a method for improving soil fertility. Therefore, the objective of this study was to evaluate the effect of earthworm and arbuscular mycorrhizal fungi (AMF) on fractionation and availability of Zn, Fe and Mn in a calcareous soil under maize cultivation. For this purpose a greenhouse experiment was conducted with four treatments including control, earthworm addition (E), AMF inoculation (AMF) and both earthworms addition and AMF inoculation (E + AMF). The results showed that the biological treatments (E, AMF and E + AMF) significantly increased Zn, Fe and Mn uptake by maize. Although the presence of earthworms in E + AMF treatment had no significant effect on mycorrhizal colonization but decreased the concentration of Zn and Mn in shoot compared to AMF treatment. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased in all biological treatments. The highest amount of DOC and MBC were found in treatments containing earthworms (E and E + AMF) and E + AMF treatment respectively. The biological treatments significantly decreased bound to Fe-MnO fraction of studied elements compared to control. Due to the slight changes in other fractions, it seems that biological treatments increased the uptake of Zn, Mn and Fe by maize probably with impact on bound to Fe-MnO fractions.