Search

Human-induced biodiversity change impairs ecosystem functions crucial to human well-being. However, the consequences of this change for ecosystem multifunctionality are poorly understood beyond effects of plant species loss, particularly in regions with high biodiversity across trophic levels. Here we adopt a multitrophic perspective to analyze how biodiversity affects multifunctionality in biodiverse subtropical forests. We consider 22 independent measurements of nine ecosystem functions central to energy and nutrient flow across trophic levels. We find that individual functions and multifunctionality are more strongly affected by the diversity of heterotrophs promoting decomposition and nutrient cycling, and by plant functional-trait diversity and composition, than by tree species richness. Moreover, cascading effects of higher trophic-level diversity on functions originating from lower trophic-level processes highlight that multitrophic biodiversity is key to understanding drivers of multifunctionality. A broader perspective on biodiversity-multifunctionality relationships is crucial for sustainable ecosystem management in light of non-random species loss and intensified biotic disturbances under future environmental change. Biodiversity change can impact ecosystem functioning, though this is primarily studied at lower trophic levels. Here, Schuldt et al. find that biodiversity components other than tree species richness are particularly important, and higher trophic level diversity plays a role in multifunctionality. [ABSTRACT FROM AUTHOR]

Knowledge of plant functional traits and trait-environment interactions is important for characterizing species strategies and understanding ecological processes. However, comprehensive field data on both above- and belowground traits, together with their environmental variables are scarce. Biome-scale studies are particularly lacking. Here we present two large-scale data sets that include functional traits of leaves and fine roots and their corresponding soil and climatic variables in China's grasslands. Leaf, fine root, and soil samples were collected in three biogeographic regions: temperate grassland on the Inner Mongolia Plateau, alpine grassland on the Tibetan Plateau, and mountain grassland in the Xinjiang mountain areas. Field data were collected over two periods. The first data set collected between 2003 and 2004 includes 13 foliar traits (leaf mass per area, LMA; photosynthetic nitrogen use efficiency, PNUE; water use efficiency, WUE; stomatal conductance for water vapor, Gs; transpiration rate, TR; mass- and area-based photosynthetic capacity, Amass and Aarea; mass- and area-based carbon concentrations, Cmass and Carea; nitrogen concentrations, Nmass and Narea; and phosphorus concentrations, Pmass and Parea) for 170 species at 173 sites. The second data set collected between 2006 and 2007 includes six sets of analogous traits for both leaves and fine roots (C, N, and P concentrations; leaf thickness/root diameter; specific leaf area, SLA; specific root length, SRL; and tissue density) for 139 species at 82 sites, along with soil attributes (soil total and organic carbon, STC and SOC; total and available N, STN and SAN; total and available P, STP and SAP; pH, bulk density, and moisture). Moreover, associated information was also gathered, including geographical location (latitude, longitude, and altitude), climate (mean annual temperature, MAT; mean annual precipitation, MAP; growing season temperature, GST; growing season precipitation, GSP; potential evapotranspiration, PET; and actual evapotranspiration, AET) and site descriptions (vegetation and soil types). The data sets are unique because they integrate plant above- and belowground traits, climate, and soil factors over broad regional, elevational, and taxonomic ranges in understudied regions (e.g., the Tibetan Plateau). This is the only database on China's grassland species for unrestricted global access. These data sets will make a valuable contribution to future large-scale trait-based ecological studies. [ABSTRACT FROM AUTHOR]

Little is known about soil organic carbon (SOC) stocks in permafrost-affected soils in Greenland. Generally, occurrence and stocks of SOC in permafrost-affected soils of the Arctic were underestimated for many years. Compared to the assumed dimension of the influence of carbon dynamics on climate change this knowledge should be substantially widened. A total of 155 soil samples were used to get a better understanding about SOC stocks, depth function and spatial distribution of SOC in permafrost-affected soils in a characteristic deglaciated valley in West Greenland southeast of Kangerlussuaq. The valley is characterized by a high variability of active layer thickness and pedo-variance mainly caused by topography. The average SOC stock of the Umimmalissuaq valley is 9.9 kg m − 2 in the upper 30 cm and around 30 kg m − 2 in the first meter, which is remarkably higher than regional predictions with 6–15.9 kg m − 2 in the first 100 cm. To account for spatial heterogeneity landscape units are developed which are most useful for grouping and predicting SOC stocks. The SOC store measured 14.2 kg m − 2 in the upper 30 cm, 11.5 kg m − 2 on north-facing slopes, and 8.4 kg m − 2 on south-facing slopes. Little SOC stocks with around 6 kg m − 2 were found under abrasion fields particularly on hilltops and moraine ridges. Soils on south-facing slopes usually have very low SOC stocks in deeper soil horizons except of organic rich horizons in rarely occurring paleosols. North-facing soils and valley bottom slopes generally have high SOC stocks of around 19 kg SOC m − 2 in soil horizons with a depth of 30–100 cm. In general, the main influencing parameter on SOC stocks is the soil organic matter input from the vegetative cover. The vegetative cover is mainly a result of topographic position and aspect related to the ice margin and katabatic winds. Soil moisture and high active layer may influence SOC stocks positively. [ABSTRACT FROM AUTHOR]

Looking at soils from the perspective of an environmental scientist or agronomist might neglect various dimensions of valuation that can be attributed to soils. Especially social and cultural connoted values including ecosystem services cannot always be measured in terms of scientific values or classified as soil types or soil qualities in a modern, economic way. Even though soils are a fact and have been present on the Earth's surface and used by people, at least for food production, at different times and in different cultures, the ways of dealing with soils and the valuations of soils are extremely diverse. Researchers in anthropology, archaeology, and agriculture, for example, are investigating different perspectives like soils as common good or as private property. This concerns not only different knowledge orders about soils, but also beliefs, techniques, foodways, practices, and power relations concerning soils and cereal cultivation. Based on the example of agriculture with a focus on cereal cultivation, we argue that there is still a great need for interdisciplinarity between the sciences and humanities. However, there is also a need to distinguish and explain between fundamental interdisciplinary research and application of findings in a socio‐economic context. It is necessary to understand different knowledge orders and valuations in time or space and to reevaluate today's perspectives on soils and agriculture for facing modern problems such as soil degradation, erosion, salinization, and an overall loss of soil fertility. [ABSTRACT FROM AUTHOR]

Soil erosion threatens ecosystem functioning by reducing soil organic carbon stocks or relocating nutrients. A common measure to protect soil against erosion is afforestation. There is growing evidence that mixed-species forest stands have beneficial effects on ecosystem functions (growth rates, nutrient cycling). In addition, species-rich forests tend to have higher and denser crown cover and thus might affect soil erosion. This study investigated the role of tree species richness on throughfall kinetic energy (TKE) as an important part of the soil erosion process and examined the spatial variability of TKE in mixed-species forest stands. The research was conducted within BEF-China, a large-scale forest biodiversity experiment in subtropical China. In summer 2013, 1800 TKE measurements were carried out during five rainfall events. TKE was measured using splash cups and related to tree height, crown base height, number of branches, leaf area index, stem ground diameter and crown area. Our experiment showed that TKE was not influenced by tree species richness at the plot level. This is likely due to the young age of the experimental forest where a dense and high tree canopy has not yet been developed. However, TKE was influenced by neighborhood tree species richness indicating that tree species richness only affected TKE on a small spatial scale within the direct neighborhood in young forests. TKE showed distinct spatial variability. Directly below the first branch of the tree individuals TKE was lowest (430 J/m 2 ) while it was highest in the middle of four tree individuals (556 J/m 2 ). Mean freefall kinetic energy (FKE) was 480 J/m 2 . Lower TKE below the first branch than FKE can be attributed to low rain drop velocities due to short falling heights. Higher TKE in the middle of four tree individuals than FKE can be ascribed to a larger crown area on which drops can confluence resulting in an increase of drop mass. Furthermore, TKE was positively affected by the number of influencing tree individuals with a 13% increase of TKE from one to four influencing tree individuals. However, further investigation on TKE below mature trees and dense canopies is needed to confirm our findings for later successional stages. [ABSTRACT FROM AUTHOR]

In order to obtain information about landscape activity and stability during the Late Quaternary in the Transcaucasian region, fluvial sediments of the lower Algeti River in SE-Georgia were studied by means of geomorphologic, sedimentologic and geochronologic methods. These investigations show that sediments aggraded by the Late Pleistocene braided Algeti River were strongly incised around the Pleistocene/Holocene transition, and subsequently a small-scale pattern of diachronous fluvial terraces deposited by the now meandering river developed in the new valley during the Holocene. Prior to ca. 3 cal. ka BP, active phases of river channel aggradation and overbank sedimentation about 6 cal. ka BP and 3.4–3.2 cal. ka BP can be linked with climate-driven vegetation changes, i.e. stronger fluvial dynamics with sedimentation occurred during more arid and colder periods whereas the Caucasian Holocene climate optimum between 6 and 3.4 cal. ka BP was characterized by stable geomorphologic conditions. After 3 cal. ka BP, strongly increased human impact documented by former pollen studies is reflected by the fluvial dynamics as well, i.e. an activity phase of strong overbank sedimentation 2.7–2.1 cal. ka BP occurred during a period when forests in the Lesser Caucasus were burnt down. Two subsequent activity phases with fluvial sedimentation can be linked with historic events that probably both influenced vegetation distribution of the region, i.e. a period of flourishing of Georgia during the Middle Age and a time of large-scale destruction of the country due to a Persian invasion at the end of the 18th century AD, respectively. Thus, whereas no influence of tectonic events or fluctuations of the Caspian Sea level on the fluvial dynamics could be detected, SE-Georgia shows its fragile character with respect to climate- and human driven vegetation-changes similar to other semi-arid landscapes of the Mediterranean region. [ABSTRACT FROM AUTHOR]

Abstract: In order to investigate the environmental impacts of the Laacher See eruption (12,900 calendar years B.P.) and the deposition of the Laacher See tephra at a large distance from the volcano, fine-resolution micromorphological, diatomological, and palynological investigations were carried out on closely spaced areas in the Reinberg basin (Vorpommern, NE Germany). The lower part of the LST originates from atmospheric input, whereas the upper part was washed-in from the surrounding basin slopes. Diatom populations expanded as a consequence of the input of silica, while simultaneously dissolution of dead diatoms decreased. The tephra provided a favourable habitat for many epilithic and epipelic diatom taxa. The diatoms show a slight acidification and an increase in specific conductivity of the water, whereas no eutrophication is indicated. These effects disappeared after lake sediments covered the tephra. The pollen diagrams from the Reinberg basin as well as many other pollen diagrams from NE Germany indicate that the vegetation reacted to rising temperatures after the cooler Gerzensee fluctuation, to a short-lived water-level rise connected with higher precipitation after the volcanic eruption, and to minor openings in the forest vegetation due to increased fire probably connected with severe thunderstorms. [Copyright &y& Elsevier]

Compared to the 1970s, the edge of the Ecology Glacier on King George Island, maritime Antarctica, is positioned more than 500 m inwards, exposing a large area of new terrain to soil-forming processes and periglacial climate for more than 40 years. To gain information on the state of soil formation and its interplay with microbial activity, three hyperskeletic Cryosols (vegetation cover of 0–80%) deglaciated after 1979 in the foreland of the Ecology Glacier and a Cambic Cryosol (vegetation cover of 100%) distal to the lateral moraine deglaciated before 1956 were investigated by combining soil chemical and microbiological methods. In the upper part of all soils, a decrease in soil pH was observed, but only the Cambic Cryosol showed a clear direction of pedogenic and weathering processes, such as initial silicate weathering indicated by a decreasing Chemical Index of Alteration with depth. Differences in the development of these initial soils could be related to different microbial community compositions and vegetation coverage, despite the short distance among them. We observed—decreasing with depth—the highest bacterial abundances and microbial diversity at vegetated sites. Multiple clusters of abundant amplicon sequence variants were found depending on the site-specific characteristics as well as a distinct shift in the microbial community structure towards more similar communities at soil depths > 10 cm. In the foreland of the Ecology Glacier, the main soil-forming processes on a decadal timescale are acidification and accumulation of soil organic carbon and nitrogen, accompanied by changes in microbial abundances, microbial community compositions, and plant coverage, whereas quantifiable silicate weathering and the formation of pedogenic oxides occur on a centennial to a millennial timescale after deglaciation. [ABSTRACT FROM AUTHOR]

We review and contrast three frameworks for analyzing human-land interactions in the Holocene: the traditional concept of favored and disfavored landscapes, the new concept of ResourceCultures from researchers at University of Tübingen, and complex adaptive systems, which is a well-established contemporary approach in interdisciplinary research. Following a theoretical integration of fundamental concepts, we analyze three paired case studies involving modern agriculture in Germany and Belize, prehistorical changes in land use in southwest Germany, and aquaculture on the Pacific and Atlantic coasts of North America. We conclude that ResourceCultures and complex adaptive systems provide different but complementary strengths, but that both move beyond the favordisfavor concept for providing a holistic, system-level approach to understanding human-land interactions. The three frameworks for understanding human responses to contemporary cultural and biophysical challenges are relevant to new thinking related to sustainability, resilience, and long-term environmental planning in the Anthropocene. [ABSTRACT FROM AUTHOR]

The soil organic carbon (SOC) pool of the Northern Hemisphere contains about half of the global SOC stored in soils. As the Arctic is exceptionally sensitive to global warming, temperature rise and prolonged summer lead to deeper thawing of permafrost‐affected soils and might contribute to increasing greenhouse gas emissions progressively. To assess the overall feedback of soil organic carbon stocks (SOCS) to global warming in permafrost‐affected regions the spatial variation in SOCS at different environmental scales is of great interest. However, sparse and unequally distributed soil data sets at various scales in such regions result in highly uncertain estimations of SOCS of the Northern Hemisphere and here particularly in Greenland. The objectives of this study are to compare and evaluate three controlling factors for SOCS distribution (vegetation, landscape, aspect) at two different scales (local, regional). The regional scale reflects the different environmental conditions between the two study areas at the coast and the ice margin. On the local scale, characteristics of each controlling factor in form of defined units (vegetation units, landscape units, aspect units) are used to describe the variation in the SOCS over short distances within each study area, where the variation in SOCS is high. On a regional scale, we investigate the variation in SOCS by comparing the same units between the study areas. The results show for both study areas that SOCS are with 8 kg m−2 in the uppermost 25 cm and 16 kg m−2 in the first 100 cm of the soil, i.e., 3 to 6 kg m−2 (37.5%) higher than existing large scale estimations of SOCS in West Greenland. Our approach allows to rank the scale‐dependent importance of the controlling factors within and between the study areas. However, vegetation and aspect better explain variations in SOCS than landscape units. Therefore, we recommend vegetation and aspect for determining the variation in SOCS in West Greenland on both scales. [ABSTRACT FROM AUTHOR]

Nutrient cycling in alpine grasslands is susceptible to climate change and anthropogenic activities, which can affect soil phosphorus (P) availability. Despite the crucial role of soil P availability in maintaining stability and productivity of grassland ecosystems, limited research has been conducted on the effects of nitrogen (N) addition and winter grazing on P transformation on the Qinghai-Tibet Plateau. In an 8-year experiment, we applied four different N addition rates (0, 25, 50, and 100 kg urea ha−1 year−1) in combination with winter grazing to investigate the effects of N addition and winter grazing on the soil P fractions. The results reveal that increasing the N addition gradually reduced the resin-Pi and NaOH-Pi contents in the soil by increasing the plant P uptake and promoting the release of carboxylates in the rhizosheath, regardless of grazing. Winter grazing decreased the NaHCO 3 -Pi and NaOH-Pi contents compared with the no-grazing treatment by increasing the P uptake of the plants. In contrast, neither grazing nor N addition affected the HCl conc. -P or residual-P content. In the no-grazing plots, the soil NaHCO 3 -Po content exhibited a gradual increase in response to N addition, whereas N addition had no discernible effect on the NaOH-Po content. In the grazing plots, the NaHCO 3 - and NaOH-Po contents gradually decreased with N addition, which was associated with the increased acid phosphatase activity in the rhizosheath and the export of forage. Thus, we conclude that N addition promotes the dissolution of NaOH-Pi to more available inorganic P forms. Under winter grazing conditions only, the transformation of P from inorganic to organic forms gradually decreased with increasing N additions. • N addition promotes the dissolution of NaOH-Pi to more available inorganic P forms. • Winter grazing reduces the P transformation from inorganic to organic forms. • N addition only decreases the organic P accumulation in the presence of grazing. [ABSTRACT FROM AUTHOR]

As limited resources, soils are the largest terrestrial sinks of organic carbon. In this respect, 3D modelling of soil organic carbon (SOC) offers substantial improvements in the understanding and assessment of the spatial distribution of SOC stocks. Previous three-dimensional SOC modelling approaches usually averaged each depth increment for multi-layer two-dimensional predictions. Therefore, these models are limited in their vertical resolution and thus in the interpretability of the soil as a volume as well as in the accuracy of the SOC stock predictions. So far, only few approaches used spatially modelled depth functions for SOC predictions. This study implemented and evaluated an approach that compared polynomial, logarithmic and exponential depth functions using non-linear machine learning techniques, i.e. multivariate adaptive regression splines, random forests and support vector machines to quantify SOC stocks spatially and depth-related in the context of biodiversity and ecosystem functioning research. The legacy datasets used for modelling include profile data for SOC and bulk density (BD), sampled at five depth increments (0-5, 5-10, 10-20, 20-30, 30-50 cm). The samples were taken in an experimental forest in the Chinese subtropics as part of the biodiversity and ecosystem functioning (BEF) China experiment. Here we compared the depth functions by means of the results of the different machine learning approaches obtained based on multi-layer 2D models as well as 3D models. The main findings were (i) that 3rd degree polynomials provided the best results for SOC and BD (R2 = 0.99 and R2 = 0.98; RMSE = 0.36% and 0.07 g cm-3). However, they did not adequately describe the general asymptotic trend of SOC and BD. In this respect the exponential (SOC: R2 = 0.94; RMSE = 0.56%) and logarithmic (BD: R2 = 84; RMSE = 0.21 g cm-3) functions provided more reliable estimates. (ii) random forests with the exponential function for SOC correlated better with the corresponding 2.5D predictions (R2: 0.96 to 0.75), compared to the 3rd degree polynomials (R2: 0.89 to 0.15) which support vector machines fitted best. We recommend not to use polynomial functions with sparsely sampled profiles, as they have many turning points and tend to overfit the data on a given profile. This may limit the spatial prediction capacities. Instead, less adaptive functions with a higher degree of generalisation such as exponential and logarithmic functions should be used to spatially map sparse vertical soil profile datasets. We conclude that spatial prediction of SOC using exponential depth functions, in conjunction with random forests is well suited for 3D SOC stock modelling, and provides much finer vertical resolutions compared to 2.5D approaches. [ABSTRACT FROM AUTHOR]

A well-based knowledge about the former distribution of Chernozems and Phaeozems is necessary to (i) better understand the factors influencing formation and degradation of these highly fertile soils, and (ii) better explain prehistoric settlement patterns that were also determined by natural factors such as soil fertility. During this archaeopedological study carried out in Central Germany we applied sedimentological and micromorphological methods to compare soils and pedosediments from the recent Chernozem/Phaeozem region with black-coloured pedosediments buried in early Neolithic structures of the recent Luvisol area directly to the east. Relocated clay coatings and significantly lower magnetic enhancement compared to Chernozem/Phaeozem-derived material were found in most black-coloured pedosediments in the Luvisol area. This demonstrates that despite their location next to an extensive Chernozem/Phaeozem area these sediments do not originate from Chernozems or Phaeozems. Instead, their dark colour must either originate from anthropogenic input similar to black-coloured Anthrosols ("Dark Earth"), or must stem from Ah-material of former Luvisols. Consequently, may be apart from a small relatively dry and carbonate-rich Luvisol region northwest of Leipzig there was obviously no significantly larger distribution of Neolithic Chernozems and Phaeozems in this region during the past. Consequently, the regional early Neolithic settlers of the Linear Pottery Culture settled intensively also in areas outside the distribution of Chernozems and Phaeozems, and the activities of these settlers did not lead to the formation of such soils. Thus, fertile soils were obviously only one factor among probably others to explain the regional Neolithic settlement pattern. Significantly lower carbonate contents were found for the parent material of the black-coloured pedosediments in the Luvisol region compared with the parent material of Chernzems and Phaeozems. This demonstrates that the decisive factor to explain the recent and former spatial distribution of Chernozems and Phaeozems in this relatively dry area is the carbonate dynamics. Anthropogenic activity since the early Neolithic period obviously helped to preserve the naturally formed Chernozems and Phaeozems by re-carbonatization processes, but humans were not the main soil forming factor in early settled regions. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if the Early Eocene paleosols on King George Island, Maritime Antarctica, have acquired their reddish color during the paleopedogenesis, by burial diagenesis and/or by heating of a covering lava flow. We used micromorphology, diffuse reflectance spectroscopy, X-ray diffraction, and mineral magnetic properties to identify the iron oxides in these paleosols. These are weakly/moderately developed paleosols formed on a basaltic tephra under a cool humid paleoclimate, therefore, prone to ferrihydrite and goethite rather than hematite formation. However, the iron oxide assembly was dominated by maghemite and hematite. Nevertheless, the large grain size and high crystallinity of hematites suggested they are rather diagenetic than pedogenic. The clustering, content, and distribution of hematites (finely dispersed on the groundmass; coating/replacing primary minerals and as mottles and/or nodules) rather than their crystal size were responsible for the color differences. These properties were likely the result of past pedogenesis processes (forming originally ferrihydrite) linked with paleodrainage conditions. Heating by the covering lava flow affected the magnetic properties of two profiles but without affecting their color. Taken together, all these results suggest that the burial reddening took place by dehydration and transformation of ferrihydrite to hematite. Our findings highlight the importance of detailed mineralogical analysis to identify iron oxides present in reddish paleosols because identification based solely on morphology (e.g. yellowish color, gradual horizon transitions) can lead to misinterpretation of paleoenvironmental conditions. [ABSTRACT FROM AUTHOR]

Based on field observations, remote sensing, and modeling, recent studies have reported inconsistent changes in soil organic carbon (SOC) stocks in grasslands of the Tibetan Plateau over the past few decades. However, direct evidence about the changes in SOC stocks in the plateau's grasslands coming from in situ, site-by-site, repeated surveys is rare. In this study, we carried out a repeated soil sampling to assess the changes in SOC stocks in the alpine grasslands across the Tibetan Plateau. Across all 41 sites in the alpine grasslands, SOC stocks exhibited a significant increase from 2002 to 2011 at an overall rate of 4.66 g C m − 2 yr − 1 . Mesic and low-temperature-limited alpine meadows showed an average carbon gain of 25.8 g C m − 2 yr − 1 , whereas the relatively dry alpine steppes exhibited a slight carbon loss of 11.9 g C m − 2 yr − 1 . Spatially, the changes in SOC stocks were significantly related to the original SOC stocks across alpine steppes, and soils with low carbon tended to gain carbon. Moreover, the changes in SOC stocks were also associated with March–April precipitation in alpine meadows, and with mean annual precipitation (MAP) in alpine steppes, with drier sites generally gaining carbon. Overall, the alpine grasslands of the Tibetan Plateau significantly accumulated SOC over this 10-year period, but many more site surveys are needed to comprehensively access the changes in SOC stocks across alpine grasslands on the plateau; and management strategies enhancing the ability of C sequestration should differ between alpine meadows and steppes due to their contrasting climate conditions. [ABSTRACT FROM AUTHOR]

Based on a W–E transect through the northern loess regions of Austria, palaeoenvironmental studies were carried out in three loess–palaeosol sequences (Gunderding, Krems-Wachtberg and Stillfried B locus typicus) to complement available results in the context of a multi-methodological approach. On the base of previously published datings, our study concentrates on the MIS 3/2 transition. The results of detailed micromorphological investigations prove that palaeopedogenesis, frost processes, and sedimentation rates differ in their spatial occurrence in the loess belt of Austria. All three sequences are in line with the general trend of a reduced intensity of pedogenic and cryogenic features from western to (south-)eastern Europe, which can be explained by lower Atlantic moisture influence towards the east. Interstadial cambic horizons are well developed in the MIS 3 sequence of western Austria, whereas the eastern loess profiles only show weak pedogenesis. In all studied sequences frost processes were active during the upper MIS 3 and MIS 2. The studied MIS 2 records are characterised by tundra soils with reductaquic horizons, which is a clear sign for prolonged phases of permafrost. On the spatial scale, the sedimentation rate increases in the eastern loess regions and particularly the Krems-Wachtberg sequence in the centre of the transect experienced an exceptionally high sedimentation rate and can thus be seen as one of the most important high resolution records for the MIS 3/2 transition in European loess regions. [ABSTRACT FROM AUTHOR]

Abstract: Weathering indices (WI) and pedogenic oxides ratios (POR) were used to describe patterns of weathering intensities and pedogenesis along climatic gradients, mainly affected by varying influences of the Asian and Indian Monsoon. These climate settings induce particular soil moisture (SM) conditions, in turn closely related to permafrost state, substrate, and topography. Nine sites including a total of 30 soil profiles were examined along an eastern and a western transect across the central-eastern Qinghai–Tibet Plateau. Additionally, differences between four soil groups were analysed. According to our knowledge, the presented study is the first attempt of a comprehensive application of different WI and POR to substrates of currently permafrost-affected soils. It provides an evaluation of various tools in terms of chemically describing and differentiating the related processes to distinct environmental settings in low-weathering regions. We found that weathering trends along the climatic gradients could be clearly outlined by WI, whereas POR rather account for small scale variations, describing significant differences of pedogenesis between continuous and discontinuous permafrost conditions. Pyrophosphate soluble iron (Fep) proved to be useful for differentiating permafrost and ground water influenced soils, showing a strong correlation to total organic carbon (r=0.89). The chemical index of alteration (CIA) is the most suitable WI, whereas Ca-free CPA is more easily biased by salinity variations of topsoils at sites with negative water balance, thus pretending lower weathering intensities. Regression analyses for WI and POR with main independent variables underline the specific characteristics: climatic parameters best explain WI, while SM is dominant for POR. The ratio (Fed-Feo)/Fet proved as the most appropriate POR with 64% explained variation by a multiple linear regression model, implying significantly lower iron release with higher SM and pH values. Variation of Fep can be explained by 63% with soil acidity being most important, followed by SM. Importantly, the presented research provides tools for investigating past and future stability or respective degradation processes of permafrost ecosystems on the Tibetan Plateau and may be applicable to other permafrost-affected environments. [Copyright &y& Elsevier]

In this study, we assessed the abundance and diversity of bacterial communities by 16S rRNA gene-based qPCR and T-RFLP across different soil depths of three sites located on the Tibetan Plateau which are affected by discontinuous permafrost or characterized as seasonally frozen ground. Our data indicates that bacterial community structure was significantly influenced by soil depth mainly at the site affected by seasonal freezing and thawing. In contrast at sites affected by permafrost, diversity pattern of bacterial communities in the top soil and deeper soil layers changed to a far lower extend. This might be related to the fact that the investigated sites were not waterlogged at the permafrost layer, thus no processes that shifts towards bacterial communities, which require anoxic environments, could be expected. Overall, at all sites, labile and stable C as well as N pools act as main drivers for bacterial communities. [ABSTRACT FROM AUTHOR]

We analyzed the influence of above- and belowground factors on the soil microbial community in a Chinese subtropical forest, one of the most diverse biomes in the northern hemisphere. Soil samples were taken at different depths from four replicate comparative study plots in each of three forest age classes (young 10-40 years, medium 40-80 years, old ≥80 years). Microbial biomass and community structure were then determined using phospholipid fatty acid (PLFA) analysis, and basal respiration and microbial biomass carbon (C) were determined by substrate-induced respiration. These data were then related to plant community and soil variables using non-metric multidimensional scaling analysis and post-hoc permutational correlations. We found that microbial lipid composition and abundance were not related to forest age class. Instead, microbial lipid composition and abundance were related to factors reflecting primary production, i.e., percent litter cover, percent dead wood cover, and percent tree layer cover. Specifically, the relative abundance (mol fraction) of indicators for arbuscular mycorrhizal fungi, Gram-positive and Gram-negative bacteria were positively significantly correlated with percent litter cover. We also found that the biomass of all microbial groups and total PLFA were negatively significantly related to percent deadwood cover. In addition, $$ {\text{pH}}_{{{\text{H}}_{ 2} {\text{O}}}} $$ was the only soil parameter that was correlated significantly to microbial biomass. Our results indicate that overarching ecological factors such as plant productivity and soil pH are important factors influencing the soil microbial community, both in terms of biomass and of community composition in this subtropical ecosystem. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Our aim was to address the potential effect of the geographical range size of species on the relationships between plant traits, soil and climate in Chinese grasslands. Previous analyses tended to examine plant-environment relationships across many species while ignoring that species with different range sizes may respond differently to the environment. Here we hypothesized that leaf traits of narrow-ranging species would be more strongly correlated with soil and climatic variables than those of wide-ranging species. Location Chinese grasslands. Methods Data on leaf traits, including nitrogen and phosphorus concentrations, carbon/nitrogen ratio, nitrogen/phosphorus ratio and specific leaf area, as well as species range sizes for 208 species distributed across 178 sites in Chinese grasslands were collected. Soil and climate information for each study site was also gathered. The effects of range size on leaf traits were tested using one-way ANOVA. Correlations between leaf traits, soil and climate were calculated for all species pooled together and for species partitioned into range size quartiles, from the first (narrowest- ranging 25%) to the fourth (widest-ranging 25%). Results Narrow-ranging species tended to occur at high altitude with lower temperature but higher soil nutrient concentrations compared with wide-ranging species. No direct link between leaf traits and species range sizes was detected. However, patterns of leaf-soil nutrient relationships changed significantly across levels of range size. Narrow-ranging species tended to be more sensitive to variation in soil nutrient availability than wide-ranging species, resulting in a shift from a positive leaf-soil nutrient relationship for narrow-ranging plants to no relationship for wide-ranging plants. Species responses to climatic variables were unrelated to their range sizes. Main conclusions The close relationship between leaf and soil nutrients indicates a specialization of narrow-ranging species to particular habitats whereas wide-ranging species may be able to better withstand changes in environment such as soil fertility over a large area. [ABSTRACT FROM AUTHOR]

Question: Knowledge of the interaction between understorey herb and overstorey tree layer diversity is mostly restricted to temperate forests. How do tree layer diversity and environmental variables affect herb layer attributes in subtropical forests and do these relationships change in the course of succession? Do abundance and diversity of woody saplings within the herb layer shift during succession? Location: Subtropical broad-leaved forests in southeast China (29°8′18″-29°17′29″N, 118°2′14″118°11′12″E). Methods: A full inventory of the herb layer including all plants below 1-m height was done in 27 plots (10 × 10 m) from five successional stages (<20, <40, <60, <80 and ≥80 yr). We quantified the contribution of different life forms (herbaceous, woody and climber species) to herb layer diversity and productivity and analysed effects of environmental variables and tree layer diversity on these attributes. Results: Herb layer composition followed a successional gradient, as revealed by non-metric multidimensional scaling (NMDS), but diversity was not correlated to the successional gradient. There was no correlation of diversity across layers. Herb layer productivity was neither affected by tree layer diversity nor by herb layer diversity. Although abundance of woody species in the herb layer decreased significantly during succession, woody species contributed extraordinarily to herb layer species diversity in all successional stages. All environmental factors considered had little impact on herb layer attributes. Conclusions: The subtropical forest investigated displays an immense richness of woody species in the herb layer while herbaceous species are less prominent. Species composition of the herb layer shows a clear successional pattern, however, the presence or absence of certain species appears to be random. [ABSTRACT FROM AUTHOR]

Soil properties and terrain attributes are of great interest to explain and model plant productivity and community assembly (hereafter P&CA). Many studies only sample surface soils, and may therefore miss important variation of deeper soil levels. We aimed to identify a critical soil depth in which the relationships between soil properties and P&CA were strongest due to an ideal interplay among soil properties and terrain attributes. On 27 plots in a subtropical Chinese forest varying in tree and herb layer species richness and tree productivity, 29 soil properties in six depth columns and four terrain attributes were analyzed. Soil properties varied with soil depth as did their interrelationships. Non-linearity of soil properties led to critical soil depths in which different P&CA characteristics were explained best (using coefficients of determination). The strongest relationship of soil properties and terrain attributes to most of P&CA characteristics (adj. R2 ~ 0.7) was encountered using a soil column of 0–16 cm. Thus, depending on the biological signal one is interested in, soil depth sampling has to be adapted. Considering P&CA in subtropical broad-leaved secondary forests, we recommend sampling one bulk sample of a column from 0 cm down to a critical soil depth of 16 cm. [ABSTRACT FROM AUTHOR]

Chernozems/Phaeozems are important agricultural resources and have been intensively used for millennia. However, their origin and age are still controversial. In Europe, the westernmost widespread Chernozem/Phaeozem area is located in Central Germany. In contrast to other German regions with anthropogenic Chernozems/Phaeozems, their natural origin is suggested in connection with intensive bioturbation. Yet, radiocarbon is unsuitable for decoding Chernozem/Phaeozem formation so this hypothesis remains untested, whereas single-grain luminescence dating allows to discriminate between different soil sub-processes and formation phases. We applied single-grain feldspar luminescence to a Central German Chernozem that was buried during the Bronze Age and subsequently protected from pedogenic processes. For the first time, we could directly determine timing and rate of Chernozem/Phaeozem formation in Central Europe by dating bioturbation as the dominant soil forming process. Accordingly, Chernozem/Phaeozem formation started at the latest in the Early Holocene prior to Neolithic settlement indicating a natural origin of Central German Chernozems/Phaeozems, and Chernozem/Phaeozem formation ceased around 6-5 ka when the regional climate became more humid. Our effective soil reworking rates show that earthworm bioturbation in Chernozems/Phaeozems is more intense than ant-dominated bioturbation, but significantly less intense than bioturbation by lugworms or ploughing. The latter effect allows to identify prehistoric ploughing in paleosols., (© 2023. The Author(s).)

Soil bacteria play a fundamental role in pedogenesis. However, knowledge about both the impact of climate and slope aspects on microbial communities and the consequences of these items in pedogenesis is lacking. Therefore, soil-bacterial communities from four sites and two different aspects along the climate gradient of the Chilean Coastal Cordillera were investigated. Using a combination of microbiological and physicochemical methods, soils that developed in arid, semi-arid, mediterranean, and humid climates were analyzed. Proteobacteria , Acidobacteria , Chloroflexi , Verrucomicrobia , and Planctomycetes were found to increase in abundance from arid to humid climates, while Actinobacteria and Gemmatimonadetes decreased along the transect. Bacterial-community structure varied with climate and aspect and was influenced by pH, bulk density, plant-available phosphorus, clay, and total organic-matter content. Higher bacterial specialization was found in arid and humid climates and on the south-facing slope and was likely promoted by stable microclimatic conditions. The presence of specialists was associated with ecosystem-functional traits, which shifted from pioneers that accumulated organic matter in arid climates to organic decomposers in humid climates. These findings provide new perspectives on how climate and slope aspects influence the composition and functional capabilities of bacteria, with most of these capabilities being involved in pedogenetic processes.

Deconvoluting the relative contributions made by specific biotic and abiotic drivers to soil fungal community compositions facilitates predictions about the functional responses of ecosystems to environmental changes, such as losses of plant diversity, but it is hindered by the complex interactions involved. Experimental assembly of tree species allows separation of the respective effects of plant community composition (biotic components) and soil properties (abiotic components), enabling much greater statistical power than can be achieved in observational studies. We therefore analyzed these contributions by assessing, via pyrotag sequencing of the internal transcribed spacer (ITS2) rDNA region, fungal communities in young subtropical forest plots included in a large experiment on the effects of tree species richness. Spatial variables and soil properties were the main drivers of soil fungal alpha and beta-diversity, implying strong early-stage environmental filtering and dispersal limitation. Tree related variables, such as tree community composition, significantly affected arbuscular mycorrhizal and pathogen fungal community structure, while differences in tree host species and host abundance affected ectomycorrhizal fungal community composition. At this early stage of the experiment, only a limited amount of carbon inputs (rhizodeposits and leaf litter) was being provided to the ecosystem due to the size of the tree saplings, and persisting legacy effects were observed. We thus expect to find increasing tree related effects on fungal community composition as forest development proceeds.

Biodiversity experiments have shown that species loss reduces ecosystem functioning in grassland. To test whether this result can be extrapolated to forests, the main contributors to terrestrial primary productivity, requires large-scale experiments. We manipulated tree species richness by planting more than 150,000 trees in plots with 1 to 16 species. Simulating multiple extinction scenarios, we found that richness strongly increased stand-level productivity. After 8 years, 16-species mixtures had accumulated over twice the amount of carbon found in average monocultures and similar amounts as those of two commercial monocultures. Species richness effects were strongly associated with functional and phylogenetic diversity. A shrub addition treatment reduced tree productivity, but this reduction was smaller at high shrub species richness. Our results encourage multispecies afforestation strategies to restore biodiversity and mitigate climate change., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Forest ecosystems are an integral component of the global carbon cycle as they take up and release large amounts of C over short time periods (C flux) or accumulate it over longer time periods (C stock). However, there remains uncertainty about whether and in which direction C fluxes and in particular C stocks may differ between forests of high versus low species richness. Based on a comprehensive dataset derived from field-based measurements, we tested the effect of species richness (3-20 tree species) and stand age (22-116 years) on six compartments of above- and below-ground C stocks and four components of C fluxes in subtropical forests in southeast China. Across forest stands, total C stock was 149 ± 12 Mg ha -1 with richness explaining 28.5% and age explaining 29.4% of variation in this measure. Species-rich stands had higher C stocks and fluxes than stands with low richness; and, in addition, old stands had higher C stocks than young ones. Overall, for each additional tree species, the total C stock increased by 6.4%. Our results provide comprehensive evidence for diversity-mediated above- and below-ground C sequestration in species-rich subtropical forests in southeast China. Therefore, afforestation policies in this region and elsewhere should consider a change from the current focus on monocultures to multi-species plantations to increase C fixation and thus slow increasing atmospheric CO 2 concentrations and global warming., (© 2018 The Author(s).)

Background: "Himalayan P waves," are reported in congenital heart disease and cardiomyopathies., Methods: We report a family with hypertrophic cardiomyopathy, Himalayan P waves, extensive focal right atrial wall thickening and left ventricular hypertrabeculation/noncompaction (LVHT)., Results: The father received a pacemaker and underwent heart transplantation because of hypertrophic cardiomyopathy. His daughters showed Himalayan P waves and right atrial wall thickening. LVHT was diagnosed in sister A at age 23 years and developed in sister B between 42 and 46 years. In sister A the heart rate continuously declined. She refused implantation of a pacemaker and died with 49 years. Sister B, suffers from bradycardia., Conclusions: Himalayan P waves are due to focal right atrial wall thickening, may be familially and associated with LVHT., (© 2014 Wiley Periodicals, Inc.)

Aims: This study compared the efficacy and safety of intravenous flecainide and ibutilide for immediate cardioversion of atrial fibrillation (AF)., Methods and Results: We conducted a prospective, randomised trial, including 207 patients with AF of recent onset (< or = 48 h). Flecainide was given over 20 min at a dose of 2 mg/kg body weight (maximum 200 mg), ibutilide was infused at a dose of 1 mg (or 0.01 mg/kg if less than 60 kg) over 10 min, followed by a 10 min observation period and an identical second dose if AF did not convert to sinus rhythm (SR). Treatment was considered successful if SR occurred within 90 min of starting medication. The conversion rates were 56.4% in patients given flecainide and 50.0% in patients given ibutilide (P=0.34). Multivariate analysis revealed that a lower age for women independently increased the probability of conversion. None of the other variables, including left atrial size, left ventricular systolic function, presence of left ventricular hypertrophy, plasma levels of potassium or magnesium at baseline, or concomitant use of digoxin, beta-blocker, diltiazem or verapamil were predictors of conversion. The frequency of adverse events was comparable in the two treatment groups., Conclusions: There was no significant difference in the cardioversion efficacy or in the risk of adverse events between flecainide and ibutilide in patients with AF of recent onset. In patients without contraindications to both medications, the physician's choice has to be governed by other factors.