On the Influence of Afforestation on Soil Erosion and Soil Carbon in a Subtropical Chinese Forest Ecosystem - Results from a tree diversity experiment

Die Wälder im subtropischen China erfuhren in den letzten Jahrzehnten große Verände-rungen durch umfassende Entwaldungen. Aufforstungen können nicht nur dazu beitra-gen, die Holzproduktion zu steigern, sondern auch Dienstleistungen von Waldökosys-temen wie z.B. Schutz gegen Bodenerosion, Verbesserung von Bodeneigenschaften oder Kohlenstoffspeicherung sicherzustellen und damit einen Beitrag zur Eindämmung des Klimawandels zu leisten. Die hügelige „Red Soil“ Region in Südchina ist auch trotz zahlreicher, langfristiger Aufforstungsprojekte nach wie vor mit hohen Bodenerosionsra-ten konfrontiert. Dies kann u.a. auf funktionelle Mängel der ausgewählten Baumarten und der für die Aufforstung geplanten Baumartendiversität zurückzuführen sein. Es ist daher von großem Interesse, wie Baumarten und Baumartenvielfalt, sowie insbesonde-re der Zusammenhang zwischen Artenvielfalt und Ökosystemfunktionen die Bodenero-sion beeinflussen. Darüber hinaus befassen sich nur wenige Studien mit der Rolle der Aufforstung für den Kohlenstoff- und Stickstoff-Haushalt, sowie deren Transport durch Bodenerosionsprozesse unter Wald. Diese Fragestellungen sind für die Bodenfrucht-barkeit und die Bewertung von Kohlenstoff- und Stickstoffflüssen vom Boden zu an-grenzenden aquatischen Ökosystemen sowie zur Atmosphäre von großer Wichtigkeit. Weiterhin ist bisher auch nur wenig über die Dynamik des organischen Kohlenstoffs im Boden in frühen Phasen der Aufforstung bekannt. Dies gilt insbesondere für subtropi-sche Waldökosysteme unter intensiver menschlicher Nutzung. Im Rahmen eines Biodiversitätsprojekts innerhalb eines subtropischen chinesischen Waldgebietes (BEF China) wurden in dieser Arbeit zunächst Punktwolkendaten von terrestrischen Laserscannern (TLS) und Splash Cups verwendet, um den räumlichen Blattflächenindex (LAI) zu analysieren und das Potenzial der Splash-Erosion im Be-standsniederschlag (TKE) vorherzusagen. Während der Regenzeiten von 2013 bis 2015 wurden Messungen der Sedimentfracht mit Erosionsmessplots durchgeführt, um zeitli-che Veränderungen der Erosionsraten und der Kohlenstoff- und Stickstoffflüsse im Bo-den zu erfassen und die Auswirkungen von Baumarten und Baumartendiversität auf diese zu untersuchen. In den Jahren 2010 und 2014 wurden 132 Bodenprofile in fünf Tiefenstufen (0-5 cm, 5-10 cm, 10-20 cm, 20-30 cm, 30-50 cm) untersucht, um die Veränderungen der Kohlenstoff-Bestände im Boden zu beurteilen. Die Ergebnisse zeigen, dass lognormale und exponentielle lineare Modelle geeignet sind, die vertikale und horizontale LAI-Verteilung ausgewählter Baumarten zu beschrei-ben. Die vertikalen Verteilungen von LAI und TKE verschiedener Baumarten waren signifikant unterschiedlich. Innerhalb des BEF China Projektes lassen sich auch nach 6 Jahren Baumwachstum noch immer starke Erosionsraten nachweisen. LAI und biologi-sche Bodenkrusten waren die beiden Haupteinflussfaktoren auf Bodenerosionsprozes-se in Baumbeständen mit unterschiedlichem Artenreichtum. Eine höherer Baumarten-diversität führte zu einer abnehmenden Bodenerosion durch positive Auswirkungen der Kronendächer und flächendeckender biologischer Bodenkrusten. Die Konzentrationen von C und N im Sedimentabtrag stiegen im Untersuchungszeitraum an, während die jährlichen Abflüsse von C und N in den beobachteten drei Jahren zusammen mit der Sedimentabgabe signifikant um 50 % zurückgingen. Die C- und N-Flüsse waren auch nach 6 Jahren Baumwachstum so hoch wie in Entwaldungsgebieten. Die junge Auffors-tung im BEF China Experiment führte zu einer Reduktion von insgesamt ca. 274 Mg Bodenkohlenstoff von 2010 bis 2014. Die Reduktion des Kohlenstoffs erfolgte haupt-sächlich im Oberboden (0-20 cm). Aufgeforstete Flächen mit höheren ursprünglichen C-Beständen zeigten höhere Verluste. Baumwachstum und Streufall als wichtiger Koh-lenstoffeintrag in den Boden konnten die Reduzierung des C-Bestands in der frühen Phase der Aufforstung nicht kompensieren.Forests in subtropical China were undergoing great changes in the last decades, mainly caused by extensive deforestation. Afforestation in turn can help not only to increase the production of timber but also to enhance forest ecosystem services such as soil erosion control, soil properties, carbon storage and thus help mitigating climate change. However, even after long-term afforestation projects the hilly red soil region in southern China is still facing serious soil erosion. This might result from structural shortcomings of the tree species chosen and tree species richness planed for afforestation. Therefore, it is urgent to answer the question how tree species and tree diversity and especially the relationship between diversity and ecosystem functioning affect soil erosion. In addition, little research addresses the role of afforestation for carbon (C) and nitrogen (N) turno-ver and transport by soil erosion under forest, which is important for soil fertility and the assessment of carbon and nitrogen fluxes from soil to adjacent aquatic ecosystems as well as to the atmosphere. Moreover, in the earlier stage of afforestation after defor-estation, soil organic carbon (SOC) dynamics are still unclear, especially in subtropical areas with intensive human impacts on forest ecosystems. Based on a biodiversity and ecosystem functioning project in China (BEF China), this dissertation firstly used point cloud data from terrestrial laser scanners (TLS) and splash cups to analyze spatial leaf area index (LAI) and to predict the potential of splash ero-sion in subtropical forests. Measurements of sediment delivery were conducted during the rainy seasons from 2013 to 2015 to detected temporal changes of soil erosion and soil carbon and nitrogen fluxes and investigate the influences of tree species and diver-sity. Finally, 132 soil profiles at five increments (0-5 cm, 5-10 cm, 10-20 cm, 20-30 cm, 30-50 cm) were sampled in 2010 and 2014 to assess changes of SOC stocks. Results showed that lognormal and exponential linear models were suitable to describe the vertical and horizontal LAI distribution of selected tree species, respectively. Vertical distributions of LAI and throughfall kinetic energy (TKE) of different tree species were significantly different. BEF China is still suffering from severe soil erosion even after 6 years of tree growth. Leaf area index (LAI) and biological soil crusts (BSCs) were the two main factors driving soil erosion within tree stands of different species richness. Higher tree species richness lead to decreasing soil erosion by positive effects on tree canopies and surface covering BSCs. Sediment C and N concentrations increased while annual soil C and N fluxes significantly decreased at a rate of 50% in the ob-served three years together with sediment delivery. Soil C and N fluxes in the study were as high as in deforestation areas even after 6 years of tree growth. Earlier affor-estation in BEF China resulted in a reduction of approximately 274 Mg SOC from 2010 to 2014 in total. The reduction of SOC is mainly from the 0-20 cm topsoil. Afforested areas with higher original SOC stock showed higher losses. Tree growth and litter fall as an important carbon input to soil could not compensate SOC stock reduction in the ear-lier stage of the afforestation

Towards a methodical framework for comprehensively assessing forest multifunctionality

Funded by Deutsche Forschungsgemeinschaft. Grant Number: DFG FOR 891/1-3 National Natural Science Foundation of China. Grant Numbers: 30710103907, 30930005, 31170457, 31210103910 Swiss National Science Foundation (SNSF) Sino-German Centre for Research Promotion in Beijing. Grant Number: GZ 986Peer reviewedPublisher PD

Genetic Ablation of PLA2G6 in Mice Leads to Cerebellar Atrophy Characterized by Purkinje Cell Loss and Glial Cell Activation

Infantile neuroaxonal dystrophy (INAD) is a progressive, autosomal recessive neurodegenerative disease characterized by axonal dystrophy, abnormal iron deposition and cerebellar atrophy. This disease was recently mapped to PLA2G6, which encodes group VI Ca2+-independent phospholipase A2 (iPLA2 or iPLA2β). Here we show that genetic ablation of PLA2G6 in mice (iPLA2β-/-) leads to the development of cerebellar atrophy by the age of 13 months. Atrophied cerebella exhibited significant loss of Purkinje cells, as well as reactive astrogliosis, the activation of microglial cells, and the pronounced up-regulation of the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Moreover, glial cell activation and the elevation in TNF-α and IL-1β expression occurred before apparent cerebellar atrophy. Our findings indicate that the absence of PLA2G6 causes neuroinflammation and Purkinje cell loss and ultimately leads to cerebellar atrophy. Our study suggests that iPLA2β-/- mice are a valuable model for cerebellar atrophy in INAD and that early anti-inflammatory therapy may help slow the progression of cerebellar atrophy in this deadly neurodegenerative disease

Developmental partitioning of SYK and ZAP70 prevents autoimmunity and cancer

Even though SYK and ZAP70 kinases share high sequence homology and serve analogous functions, their expression in B and T cells is strictly segregated throughout evolution. Here, we identified aberrant ZAP70 expression as a common feature in a broad range of B cell malignancies. We validated SYK as the kinase that sets the thresholds for negative selection of autoreactive and premalignant clones. When aberrantly expressed in B cells, ZAP70 competes with SYK at the BCR signalosome and redirects SYK from negative selection to tonic PI3K signaling, thereby promoting B cell survival. In genetic mouse models for B-ALL and B-CLL, conditional expression of Zap70 accelerated disease onset, while genetic deletion impaired malignant transformation. Inducible activation of Zap70 during B cell development compromised negative selection of autoreactive B cells, resulting in pervasive autoantibody production. Strict segregation of the two kinases is critical for normal B cell selection and represents a central safeguard against the development of autoimmune disease and B cell malignancies.acceptedVersionPeer reviewe

Toward a methodical framework for comprehensively assessing forest multifunctionality

Biodiversity-ecosystem functioning (BEF) research has extended its scope from communities that are short-lived or reshape their structure annually to structurally complex forest ecosystems. The establishment of tree diversity experiments poses specific methodological challenges for assessing the multiple functions provided by forest ecosystems. In particular, methodological inconsistencies and nonstandardized protocols impede the analysis of multifunctionality within, and comparability across the increasing number of tree diversity experiments. By providing an overview on key methods currently applied in one of the largest forest biodiversity experiments, we show how methods differing in scale and simplicity can be combined to retrieve consistent data allowing novel insights into forest ecosystem functioning. Furthermore, we discuss and develop recommendations for the integration and transferability of diverse methodical approaches to present and future forest biodiversity experiments. We identified four principles that should guide basic decisions concerning method selection for tree diversity experiments and forest BEF research: (1) method selection should be directed toward maximizing data density to increase the number of measured variables in each plot. (2) Methods should cover all relevant scales of the experiment to consider scale dependencies of biodiversity effects. (3) The same variable should be evaluated with the same method across space and time for adequate larger-scale and longer-time data analysis and to reduce errors due to changing measurement protocols. (4) Standardized, practical and rapid methods for assessing biodiversity and ecosystem functions should be promoted to increase comparability among forest BEF experiments. We demonstrate that currently available methods provide us with a sophisticated toolbox to improve a synergistic understanding of forest multifunctionality. However, these methods require further adjustment to the specific requirements of structurally complex and long-lived forest ecosystems. By applying methods connecting relevant scales, trophic levels, and above? and belowground ecosystem compartments, knowledge gain from large tree diversity experiments can be optimized

Exogenous antibiotic resistance gene contributes to intestinal inflammation by modulating the gut microbiome and inflammatory cytokine responses in mouse

ABSTRACTDysregulation of the gut microbiota by environmental factors is associated with a variety of autoimmune and immune-mediated diseases. In addition, naturally-occurring extracellular antibiotic resistance genes (eARGs) might directly enter the gut via the food chain. However, following gut microbiota exposure to eARGs, the ecological processes shaping the microbiota community assembly, as well as the interplay between the microbiota composition, metabolic function, and the immune responses, are not well understood. Increasing focus on the One Health approach has led to an urgent need to investigate the direct health damage caused by eARGs. Herein, we reveal the significant influence of eARGs on microbiota communities, strongly driven by stochastic processes. How eARGs-stimulate variations in the composition and metabolomic function of the gut microbiota led to cytokine responses in mice of different age and sex were investigated. The results revealed that cytokines were significantly associated with immunomodulatory microbes, metabolites, and ARGs biomarkers. Cytokine production was associated with specific metabolic pathways (arachidonic acid and tryptophan metabolic pathways), as confirmed by ex vivo cytokine responses and recovery experiments in vivo. Furthermore, the gut microbial profile could be applied to accurately predict the degree of intestinal inflammation ascribed to the eARGs (area under the curve = 0.9616). The present study provided a comprehensive understanding of the influence of an eARGs on immune responses and intestinal barrier damage, shedding light on the interplay between eARGs, microbial, metabolites, and the gut antibiotic resistome in modulating the human immune system

Characterization of Two Neutralizing Antibodies against Rift Valley Fever Virus Gn Protein

The Rift Valley fever virus (RVFV) is an arthropod-borne virus that can not only cause severe disease in domestic animals but also in humans. However, the licensed vaccines or available therapeutics for humans do not exist. Here, we report two Gn-specific neutralizing antibodies (NAbs), isolated from a rhesus monkey immunized with recombinant human adenoviruses type 4 expressing Rift Valley fever virus Gn and Gc protein (rHAdV4-GnGcopt). The two NAbs were both able to protect host cells from RVFV infection. The interactions between NAbs and Gn were then characterized to demonstrate that these two NAbs might preclude RVFV glycoprotein rearrangement, hindering the exposure of fusion loops in Gc to endosomal membranes after the virus invades the host cell. The target region for the two NAbs is located in the Gn domain III, implying that Gn is a desired target for developing vaccines and neutralizing antibodies against RVFV

On the combined effect of soil fertility and topography on tree growth in subtropical forest ecosystems—a study from SE China

Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning (BEF) experiment in subtropical SE China. Methods Geomorphometric terrain analyses were carried out at a spatial resolution of 5×5 m. Soil samples of different depth increments and data on tree height were collected from a total of 566 plots (667 m2 each). The soils were analyzed for carbon (soil organic carbon [SOC]), nitrogen, acidity, cation exchange capacity (CEC), exchangeable cations and base saturation as soil fertility attributes. All plots were classified into geomorphological units. Analyses of variance and linear regressions were applied to all terrain, soil fertility and tree growth attributes. Important Findings In general, young and shallow soils and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment. This explains the concurrently increasing CEC and SOC stocks downslope, in hollows and in valleys. However, colluvial, carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways. The results showed that soil fertility is mainly influenced by topography. Monte–Carlo flow accumulation (MCCA), curvature, slope and aspect significantly affected soil fertility. Furthermore, soil fertility was affected by the different geomorphological positions on the experimental sites with ridge and spur positions showing lower exchangeable base cation contents, especially potassium (K), due to leaching. This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50cm depth. Few soil fertility attributes affect tree height after 1–2 years of growth, among which C stocks proved to be most important while pHKCl and CEC only played minor roles. Nevertheless, soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1–2 years growth. Hence, our study showed that forest nutrition is coupled to a recycling of litter nutrients, and does not only depend on subsequent supply of nutrients from the mineral soil. Besides soil fertility, topography affected tree height. We found that especially MCCA as indicator of water availability affected tree growth at small-scale, as well as aspect. Overall, our synthesis on the interrelation between fertility, topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions. In this respect, small-scale soil–plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility. In addition, it shows that terrain attributes should be accounted for in ecological research