Influence of tree mycorrhizal type, tree species identity, and diversity on forest root-associated mycobiomes.

Understanding the complex interactions between trees and fungi is crucial for forest ecosystem management, yet the influence of tree mycorrhizal types, species identity, and diversity on tree-tree interactions and their root-associated fungal communities remains poorly understood. Our study addresses this gap by investigating root-associated fungal communities of different arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) tree species pairs (TSPs) in a subtropical tree diversity experiment, spanning monospecific, two-species, and multi-species mixtures, utilizing Illumina sequencing of the ITS2 region. The study reveals that tree mycorrhizal type significantly impacts the alpha diversity of root-associated fungi in monospecific stands. Meanwhile, tree species identity's influence is modulated by overall tree diversity. Tree-related variables and spatial distance emerged as major drivers of variations in fungal community composition. Notably, in multi-species mixtures, compositional differences between root fungal communities of AM and EcM trees diminish, indicating a convergence of fungal communities irrespective of mycorrhizal type. Interestingly, dual mycorrhizal fungal communities were observed in these multi-species mixtures. This research underscores the pivotal role of mycorrhizal partnerships and the interplay of biotic and abiotic factors in shaping root fungal communities, particularly in varied tree diversity settings, and its implications for effective forest management and biodiversity conservation.

Overlooked uneven progress across sustainable development goals at the global scale: Challenges and opportunities.

Differences in progress across sustainable development goals (SDGs) are widespread globally; meanwhile, the rising call for prioritizing specific SDGs may exacerbate such gaps. Nevertheless, how these progress differences would influence global sustainable development has been long neglected. Here, we present the first quantitative assessment of SDGs' progress differences globally by adopting the SDGs progress evenness index. Our results highlight that the uneven progress across SDGs has been a hindrance to sustainable development because (1) it is strongly associated with many public health risks (e.g., air pollution), social inequalities (e.g., gender inequality, modern slavery, wealth gap), and a reduction in life expectancy; (2) it is also associated with deforestation and habitat loss in terrestrial and marine ecosystems, increasing the challenges related to biodiversity conservation; (3) most countries with low average SDGs performance show lower progress evenness, which further hinders their fulfillment of SDGs; and (4) many countries with high average SDGs performance also showcase stagnation or even retrogression in progress evenness, which is partly ascribed to the antagonism between climate actions and other goals. These findings highlight that while setting SDGs priorities may be more realistic under the constraints of multiple global stressors, caution must be exercised to avoid new problems from intensifying uneven progress across goals. Moreover, our study reveals that the urgent needs regarding SDGs of different regions seem complementary, emphasizing that regional collaborations (e.g., demand-oriented carbon trading between SDGs poorly performed and well-performed countries) may promote sustainable development achievements at the global scale.

Effect of Training on the Ability of Nurses to Provide Humanistic Care: Systematic Review and Meta-analysis.

BACKGROUND: This article describes a systematic review evaluating the effectiveness of training on the humanistic care abilities of nurses. METHOD: The literature search was conducted in electronic databases to identify studies that evaluated the effect of training on the humanistic care abilities of nurses. Study selection was based on precise eligibility criteria. After the systematic review, a meta-analysis of standardized mean differences (SMDs) between posttraining and pretraining humanistic care scale scores was performed to evaluate the effect of training. RESULTS: A total of 11 studies were included (624 nurse participants; 97% women; weighted average age = 38.4 years; 95% confidence interval (CI) [31.5, 45.4]). Training schedules varied and ranged from a full-day workshop to brief weekly sessions for up to 2 months. The training framework involved compassion and empathy communication in most of the included studies. Training improved the humanistic care scale scores of the participants (SMD = 1.171; 95% CI [0.626, 1.716]; p < .0001), whereas no significant change was seen in the scores of control subjects (SMD = 0.588; 95% CI [-0.536, 1.713]; p = .305). The effect of training was observable for up to 1 year, although few studies carried out follow-up evaluations. CONCLUSION: Training has the potential to improve the humanistic care abilities of nurses. [J Contin Educ Nurs. 2023;54(9):430-436.].

Vegetation structural shift tells environmental changes on the Tibetan Plateau over 40 years.

Structural information of grassland changes on the Tibetan Plateau is essential for understanding alterations in critical ecosystem functioning and their underlying drivers that may reflect environmental changes. However, such information at the regional scale is still lacking due to methodological limitations. Beyond remote sensing indicators only recognizing vegetation productivity, we utilized multivariate data fusion and deep learning to characterize formation-based plant community structure in alpine grasslands at the regional scale of the Tibetan Plateau for the first time and compared it with the earlier version of Vegetation Map of China for historical changes. Over the past 40 years, we revealed that (1) the proportion of alpine meadows in alpine grasslands increased from 50% to 69%, well-reflecting the warming and wetting trend; (2) dominances of Kobresia pygmaea and Stipa purpurea formations in alpine meadows and steppes were strengthened to 76% and 92%, respectively; (3) the climate factor mainly drove the distribution of Stipa purpurea formation, but not the recent distribution of Kobresia pygmaea formation that was likely shaped by human activities. Therefore, the underlying mechanisms of grassland changes over the past 40 years were considered to be formation dependent. Overall, the first exploration for structural information of plant community changes in this study not only provides a new perspective to understand drivers of grassland changes and their spatial heterogeneity at the regional scale of the Tibetan Plateau, but also innovates large-scale vegetation study paradigm.

Functional Potential of Soil Microbial Communities and Their Subcommunities Varies with Tree Mycorrhizal Type and Tree Diversity.

Soil microbial communities play crucial roles in the earth's biogeochemical cycles. Yet, their genomic potential for nutrient cycling in association with tree mycorrhizal type and tree-tree interactions remained unclear, especially in diverse tree communities. Here, we studied the genomic potential of soil fungi and bacteria with arbuscular (AM) and ectomycorrhizal (EcM) conspecific tree species pairs (TSPs) at three tree diversity levels in a subtropical tree diversity experiment (BEF-China). The soil fungi and bacteria of the TSPs' interaction zone were characterized by amplicon sequencing, and their subcommunities were determined using a microbial interkingdom co-occurrence network approach. Their potential genomic functions were predicted with regard to the three major nutrients carbon (C), nitrogen (N), and phosphorus (P) and their combinations. We found the microbial subcommunities that were significantly responding to different soil characteristics. The tree mycorrhizal type significantly influenced the functional composition of these co-occurring subcommunities in monospecific stands and two-tree-species mixtures but not in mixtures with more than three tree species (here multi-tree-species mixtures). Differentiation of subcommunities was driven by differentially abundant taxa producing different sets of nutrient cycling enzymes across the tree diversity levels, predominantly enzymes of the P (n = 11 and 16) cycles, followed by the N (n = 9) and C (n = 9) cycles, in monospecific stands and two-tree-species mixtures, respectively. Fungi of the Agaricomycetes, Sordariomycetes, Eurotiomycetes, and Leotiomycetes and bacteria of the Verrucomicrobia, Acidobacteria, Alphaproteobacteria, and Actinobacteria were the major differential contributors (48% to 62%) to the nutrient cycling functional abundances of soil microbial communities across tree diversity levels. Our study demonstrated the versatility and significance of microbial subcommunities in different soil nutrient cycling processes of forest ecosystems. IMPORTANCE Loss of multifunctional microbial communities can negatively affect ecosystem services, especially forest soil nutrient cycling. Therefore, exploration of the genomic potential of soil microbial communities, particularly their constituting subcommunities and taxa for nutrient cycling, is vital to get an in-depth mechanistic understanding for better management of forest soil ecosystems. This study revealed soil microbes with rich nutrient cycling potential, organized in subcommunities that are functionally resilient and abundant. Such microbial communities mainly found in multi-tree-species mixtures associated with different mycorrhizal partners can foster soil microbiome stability. A stable and functionally rich soil microbiome is involved in the cycling of nutrients, such as carbon, nitrogen, and phosphorus, and their combinations could have positive effects on ecosystem functioning, including increased forest productivity. The new findings could be highly relevant for afforestation and reforestation regimes, notably in the face of growing deforestation and global warming scenarios.

Plant Community Associates with Rare Rather than Abundant Fungal Taxa in Alpine Grassland Soils.

The importance of the rare microbial biosphere in maintaining biodiversity and ecological functions has been highlighted recently. However, the current understanding of the spatial distribution of rare microbial taxa is still limited, with only a few investigations for rare prokaryotes and virtually none for rare fungi. Here, we investigated the spatial patterns of rare and abundant fungal taxa in alpine grassland soils across 2,000 km of the Qinghai-Tibetan plateau. We found that most locally rare fungal taxa remained rare (13.07%) or were absent (82.85%) in other sites, whereas only a small proportion (4.06%) shifted between rare and abundant among sites. Although they differed in terms of diversity levels and compositions, the distance decay relationships of both the rare and the abundant fungal taxa were valid and displayed similar turnover rates. Moreover, the community assemblies of both rare and abundant fungal taxa were predominantly controlled by deterministic rather than stochastic processes. Notably, the community composition of rare rather than abundant fungal taxa associated with the plant community composition. In summary, this study advances our understanding of the biogeographic features of rare fungal taxa in alpine grasslands and highlights the concordance between plant communities and rare fungal subcommunities in soil. IMPORTANCE Our current understanding of the ecology and functions of rare microbial taxa largely relies on research conducted on prokaryotes. Despite the key ecological roles of soil fungi, little is known about the biogeographic patterns and drivers of rare and abundant fungi in soils. In this study, we investigated the spatial patterns of rare and abundant fungal taxa in Qinghai-Tibetan plateau (QTP) alpine grassland soils across 2,000 km, with a special concentration on the importance of the plant communities in shaping rare fungal taxa. We showed that rare fungal taxa generally had a biogeographic pattern that was similar to that of abundant fungal taxa in alpine grassland soils on the QTP. Furthermore, the plant community composition was strongly related to the community composition of rare taxa but not abundant taxa. In summary, this study significantly increases our biogeographic and ecological knowledge of rare fungal taxa in alpine grassland soils.

Multi-group biodiversity distributions and drivers of metacommunity organization along a glacial-fluvial-limnic pathway on the Tibetan plateau.

Extensive global glacial retreats are threatening cryosphere ecosystem functioning and the associated biota in glacier-fed water systems. Understanding multi-group biodiversity distributions and compositional variation across diverse but hydrologically linked habitats under varying glacial influences will help explain the mechanisms underlying glacial community organization and ecosystem processes. However, such data are generally lacking due to the difficulty of obtaining biodiversity information across wide taxonomic ranges. Here, we used a multi-marker environmental DNA metabarcoding approach to simultaneously investigate the spatial patterns of community compositions and assembly mechanisms of four taxonomic groups (cyanobacteria, diatoms, invertebrates, and vertebrates) along the flowpaths of a tributary of Lake Nam Co on the Tibetan Plateau-from its glacier headwaters, through its downstream river and wetlands, to its estuary. We detected 869 operational taxonomic units: 119 cyanobacterial, 395 diatom, 269 invertebrate, and 86 vertebrate. Taxonomic richnesses consistently increased from upstream to downstream, and although all groups showed community similarity distance decay patterns, the trend for vertebrates was the weakest. Cyanobacteria, diatom, and invertebrate community compositions were significantly correlated with several environmental factors, while the vertebrate community was only correlated with waterway width. Variation partitioning analysis indicated that varying extents of environmental conditions and spatial factors affected community organizations for different groups. Furthermore, stochastic processes contributed prominently to the microorganisms' community assembly (Sloan's neutral model R2 = 0.77 for cyanobacteria and 0.73 for diatoms) but were less important for macroorganisms (R2 = 0.21 for invertebrates and 0.15 for vertebrates). That trend was further substantiated by modified stochasticity ratio analyses. This study provides the first holistic picture of the diverse biotic communities residing in a series of hydrologically connected glacier-influenced habitats. Our results both uncovered the distinct mechanisms that underlie the metacommunity organizations of different glacial organisms and helped comprehensively predict the ecological impacts of the world's melting glaciers.

Unimodal productivity-biodiversity relationship along the gradient of multidimensional resources across Chinese grasslands.

Resources can affect plant productivity and biodiversity simultaneously and thus are key drivers of their relationships in addition to plant-plant interactions. However, most previous studies only focused on a single resource while neglecting the nature of resource multidimensionality. Here we integrated four essential resources for plant growth into a single metric of resource diversity (RD) to investigate its effects on the productivity-biodiversity relationship (PBR) across Chinese grasslands. Results showed that habitats differing in RD have different PBRs-positive in low-resource habitats, but neutral in medium- and high-resource ones-while collectively, a weak positive PBR was observed. However, when excluding direct effects of RD on productivity and biodiversity, the PBR in high-resource habitats became negative, which leads to a unimodal instead of a positive PBR along the RD gradient. By integrating resource effects and changing plant-plant interactions into a unified framework with the RD gradient, our work contributes to uncovering underlying mechanisms for inconsistent PBRs at large scales.

Soil diazotrophic abundance, diversity, and community assembly mechanisms significantly differ between glacier riparian wetlands and their adjacent alpine meadows.

Global warming can trigger dramatic glacier area shrinkage and change the flux of glacial runoff, leading to the expansion and subsequent retreat of riparian wetlands. This elicits the interconversion of riparian wetlands and their adjacent ecosystems (e.g., alpine meadows), probably significantly impacting ecosystem nitrogen input by changing soil diazotrophic communities. However, the soil diazotrophic community differences between glacial riparian wetlands and their adjacent ecosystems remain largely unexplored. Here, soils were collected from riparian wetlands and their adjacent alpine meadows at six locations from glacier foreland to lake mouth along a typical Tibetan glacial river in the Namtso watershed. The abundance and diversity of soil diazotrophs were determined by real-time PCR and amplicon sequencing based on nifH gene. The soil diazotrophic community assembly mechanisms were analyzed via iCAMP, a recently developed null model-based method. The results showed that compared with the riparian wetlands, the abundance and diversity of the diazotrophs in the alpine meadow soils significantly decreased. The soil diazotrophic community profiles also significantly differed between the riparian wetlands and alpine meadows. For example, compared with the alpine meadows, the relative abundance of chemoheterotrophic and sulfate-respiration diazotrophs was significantly higher in the riparian wetland soils. In contrast, the diazotrophs related to ureolysis, photoautotrophy, and denitrification were significantly enriched in the alpine meadow soils. The iCAMP analysis showed that the assembly of soil diazotrophic community was mainly controlled by drift and dispersal limitation. Compared with the riparian wetlands, the assembly of the alpine meadow soil diazotrophic community was more affected by dispersal limitation and homogeneous selection. These findings suggest that the conversion of riparian wetlands and alpine meadows can significantly alter soil diazotrophic community and probably the ecosystem nitrogen input mechanisms, highlighting the enormous effects of climate change on alpine ecosystems.

Joint control of seasonal timing and plant function types on drought responses of soil respiration in a semiarid grassland.

Globally, droughts are the most widespread climate factor impacting carbon (C) cycling. However, as the second-largest terrestrial C flux, the responses of soil respiration (Rs) to extreme droughts co-regulated by seasonal timing and PFT (plant functional type) are still not well understood. Here, a manipulative extreme-duration drought experiment (consecutive 30 days without rainfall) was designed to address the importance of drought timing (early-, mid-, or late growing season) for Rs and its components (heterotrophic respiration (Rh) and autotrophic respiration (Ra)) under three PFT treatments (two graminoids, two shrubs, and their combination). The results suggested that regardless of PFT, the mid-drought had the greatest negative effects while early-drought overall had little effect on Rh and its dominated Rs. However, PFT treatments had significant effects on Rh and Rs in response to the late drought, which was PFT-dependence: reduction in shrubs and combination but not in graminoids. Path analysis suggested that the decrease in Rs and Rh under droughts was through low soil water content induced reduction in MBC and GPP. These findings demonstrate that responses of Rs to droughts depend on seasonal timing and communities. Future droughts with different seasonal timing and induced shifts in plant structure would bring large uncertainty in predicting C dynamics under climate changes.

Characteristics of nitrogen deposition research within grassland ecosystems globally and its insight from grassland microbial community changes in China.

As global change continues to intensify, the mode and rate of nitrogen input from the atmosphere to grassland ecosystems had changed dramatically. Firstly, we conducted a systematic analysis of the literature on the topic of nitrogen deposition impacts over the past 30 years using a bibliometric analysis. A systematic review of the global research status, publication patterns, research hotspots and important literature. We found a large number of publications in the Chinese region, and mainly focuses on the field of microorganisms. Secondly, we used a meta-analysis to focus on microbial changes using the Chinese grassland ecosystem as an example. The results show that the research on nitrogen deposition in grassland ecosystems shows an exponential development trend, and the authors and research institutions of the publications are mainly concentrated in China, North America, and Western Europe. The keyword clustering results showed 11 important themes labeled climate change, elevated CO2, species richness and diversity, etc. in these studies. The burst keyword analysis indicated that temperature sensitivity, microbial communities, etc. are the key research directions. The results of the meta-analysis found that nitrogen addition decreased soil microbial diversity, and different ecosystems may respond differently. Treatment time, nitrogen addition rate, external environmental conditions, and pH had major effects on microbial alpha diversity and biomass. The loss of microbial diversity and the reduction of biomass with nitrogen fertilizer addition will alter ecosystem functioning, with dramatic impacts on global climate change. The results of the study will help researchers to further understand the subject and have a deep understanding of research hotspots, which are of great value to future scientific research.

Livelihood resilience in pastoral communities: Methodological and field insights from Qinghai-Tibetan Plateau.

Livelihood resilience is crucial for both people and the environment, especially in remote and harsh ecosystems, such as the Qinghai Tibetan Plateau (QTP). This research aimed to fill the gap of assessing herders' livelihood resilience using more inclusive method. Using survey data from 758 pastoralists, complemented with focus group discussions and transect walks in the Three River Headwater Region (TRHR) on the QTP, we first developed a livelihood resilience evaluation index comprising dimensions of buffer capacity, self-organization and learning capacity. The method of entropy-TOPSIS was then applied to assess the livelihood resilience of local herders, and the spatial patterns were analyzed by spatial autocorrelation method. The results showed the overall level of pastoral livelihood resilience resulted weak, with an east to west spatial gradient toward lower livelihood resilience. Self-organization was the most important dimensions of livelihood resilience, with social cohesion being a dominant factor. Buffer capacity resulted the less important, but the natural capital was significantly higher than the other four livelihood capitals. Furthermore, the northeastern region was a hotspot, while the northwestern region was a cold spot of livelihood resilience. While pastoral populations in the TRHR had high self-organization abilities and potentially high learning capacities, the overall low buffer capacity and livelihood capital limited the improvement of their livelihood resilience. The key findings provide support for enabling policies and integrated strategies to enhance social-ecological resilience. Study may help as paradigm shift reference for the livelihood resilience of pastoral communities in high-altitude areas globally.

Study of Subfascial Endoscopic Perforator Surgery Combined with Endovenous Laser Treatment in the Treatment of Great Saphenous Varicose Veins.

Great saphenous varicose vein (GSVV) is a venous reflux disease of the lower extremity. In order to explore the clinical effect of subfascial endoscopic perforator surgery (SEPS) with endovenous laser treatment (EVLT) in the treatment of GSVV, 80 patients who underwent unilateral saphenous varicose surgery are analyzed. The operation results show that the patients who used SEPS + EVLT have less operation time and mean blood loss, shorter postoperative active time and hospitalization stay, better curative effect, and higher notch aesthetics (P < 0.05). SEPS combined with EVLT has a remarkable curative effect in the treatment of saphenous varicose veins of lower extremity, which can significantly shorten the hospitalization time of patients and improve the coagulation index and stress index.

Tree mycorrhizal type and tree diversity shape the forest soil microbiota.

There is limited knowledge on how the association of trees with different mycorrhizal types shapes soil microbial communities in the context of changing tree diversity levels. We used arbuscular (AM) and ectomycorrhizal (EcM) tree species as con- and heterospecific tree species pairs (TSPs), which were established in plots of three tree diversity levels including monocultures, two-species mixtures and multi-tree species mixtures in a tree diversity experiment in subtropical China. We found that the tree mycorrhizal type had a significant effect on fungal but not bacterial alpha diversity. Furthermore, only EcM but not AM TSPs fungal alpha diversity increased with tree diversity, and the differences between AM and EcM TSPs disappeared in multi-species mixtures. Tree mycorrhizal type, tree diversity and their interaction had significant effects on fungal community composition. Neither fungi nor bacteria showed any significant compositional variation in TSPs located in multi-species mixtures. Accordingly, the most influential taxa driving the tree mycorrhizal differences at low tree diversity were not significant in multi-tree species mixtures. Collectively, our results indicate that tree mycorrhizal type is an important factor determining the diversity and community composition of soil microbes, and higher tree diversity levels promote convergence of the soil microbial communities. SIGNIFICANCE STATEMENT: More than 90% of terrestrial plants have symbiotic associations with mycorrhizal fungi which could influence the coexisting microbiota. Systematic understanding of the individual and interactive effects of tree mycorrhizal type and tree species diversity on the soil microbiota is crucial for the mechanistic comprehension of the role of microbes in forest soil ecological processes. Our tree species pair (TSP) concept coupled with random sampling within and across the plots, allowed us the unbiased assessment of tree mycorrhizal type and tree diversity effects on the tree-tree interaction zone soil microbiota. Unlike in monocultures and two-species mixtures, we identified species-rich and converging fungal and bacterial communities in multi-tree species mixtures. Consequently, we recommend planting species-rich mixtures of EcM and AM trees, for afforestation and reforestation regimes. Specifically, our findings highlight the significance of tree mycorrhizal type in studying 'tree diversity - microbial diversity - ecosystem function' relationships.

Evenness is important in assessing progress towards sustainable development goals.

Sustainable development goals (SDGs) emphasize a holistic achievement instead of cherry-picking a few. However, no assessment has quantitatively considered the evenness among all 17 goals. Here, we propose a systematic method, which first integrates both the evenness and the overall status of all goals, to distinguish the ideal development pathways from the uneven ones and then revisit the development trajectory in China from 2000 to 2015. Our results suggest that, despite the remarkable progress, a bottleneck has occurred in China since 2013 due to the stagnant developments in some SDGs. However, many far-reaching policies in China have been targeting these deficiencies since then, providing a perspective on how a country approaches sustainable development by promoting evenness among all SDGs. Our results also indicate that regions with the slowest progress are the developed provinces, owing to the persistent uneven status of all goals. Our study demonstrates the importance of adopting evenness in assessing and guiding sustainable development.

Spectroscopic fingerprints to track the fate of aquatic organic matter along an alpine headstream on the Tibetan Plateau.

The fragile aquatic ecosystem on the Tibetan Plateau is severely threatened by human activities and climate change. Dissolved organic matter (DOM) is a vital indicator of surface water quality; however, its comprehensive molecular analysis is challenged due to its low concentration (total organic carbon less than 0.5 mg/L) in alpine areas. This study proposes the fluorescence excitation-emission matrix (FEEM) to fingerprint DOM in a typical headstream in the Namco basin, one of the largest lake regions in Tibet. We found that the FEEM can sensitively detect low-concentration pollution traces and the variation of DOM along the flow from the ice sheet, through the wetland, eventually to the estuary of the lake. The fluorescence intensity indices for biodegradable carbon (fT/C) and humification (HIXem) responded drastically along the flow. Fluorescence regional integrals (FRIs) clearly reflected the overall increase of protein-like substances and decrease of humus-like substances along the flow, whereas this tendency was reversed when passing through the wetland. The FRIs-derived secondary parameters (HPP, HMP, WLP and SSP) further sensed likely variations in hydrophobicity, humification degree, excited-state fluorophore energy and Stokes shift. Parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy (2DCOS) of the FEEM signals witnessed the trade-off among tyrosine-like organics (C1 peak), tryptophan-like byproducts (C2 peak) and humus-like remains (C3 peak) along the flow. The C1 component can be traced back to the vicinity of the ice sheet exit, presumably due to human and animal activities. The wetland can absorb or convert part of the C1 component into C2 or C3 products, demonstrating the function of regulating water quality and buffering environmental impacts. The spectroscopic indicators evaluated in this study may provide tools for diagnosing early traces of water pollution and ecological instability in alpine areas.

Tree diversity and soil chemical properties drive the linkages between soil microbial community and ecosystem functioning.

Microbial respiration is critical for soil carbon balance and ecosystem functioning. Previous studies suggest that plant diversity influences soil microbial communities and their respiration. Yet, the linkages between tree diversity, microbial biomass, microbial diversity, and microbial functioning have rarely been explored. In this study, we measured two microbial functions (microbial physiological potential, and microbial respiration), together with microbial biomass, microbial taxonomic and functional profiles, and soil chemical properties in a tree diversity experiment in South China, to disentangle how tree diversity affects microbial respiration through the modifications of the microbial community. Our analyses show a significant positive effect of tree diversity on microbial biomass (+25% from monocultures to 24-species plots), bacterial diversity (+12%), and physiological potential (+12%). In addition, microbial biomass and physiological potential, but not microbial diversity, were identified as the key drivers of microbial respiration. Although soil chemical properties strongly modulated soil microbial community, tree diversity increased soil microbial respiration by increasing microbial biomass rather than changing microbial taxonomic or functional diversity. Overall, our findings suggest a prevalence of microbial biomass over diversity in controlling soil carbon dynamics.

The composition of antibiotic resistance genes is not affected by grazing but is determined by microorganisms in grassland soils.

Grazing is expected to exert a substantial influence on antibiotic resistance genes (ARGs) in grassland ecosystems. However, the precise effects of grazing on the composition of ARGs in grassland soils remain unclear. This is especially the case for grassland soils subject to long-term grazing. Here, we investigated ARGs and bacterial community composition in soils subject to long-term historic grazing (13-39 years) and corresponding ungrazed samples. Using a combination of shotgun metagenomics, amplicon analyses and associated soil physicochemical data, we provide novel insights regarding the structure of ARGs in grassland soils. Interestingly, our analysis revealed that long-term historic grazing had no impacts on the composition of ARGs in grassland soils. An average of 378 ARGs, conferring resistance to 14 major categories of antibiotics (80%), were identified in both grazing and ungrazed sites. Actinobacteria, Proteobacteria and Acidobacteria were the most prevalent predicted hosts in these soils and were also shown to harbour genetic capacity for multiple-resistant ARGs. Our results suggested that positive effects of bacterial community composition on ARGs could potentially be controlled by affecting MGEs. Soil properties had direct effects on the composition of ARGs through affecting the frequency of horizontal gene transfer among bacteria. Twelve novel ARGs were found in S. grandis steppe grasslands, indicating that different vegetation types might induce shifts in soil ARGs. Collectively, these findings suggest that soil properties, plants and microorganisms play critical roles in shaping ARG patterns in grasslands. Together, these data establish a solid baseline for understanding environmental antibiotic resistance in grasslands.

Promoting resilience of large international collaborative research programs in times of global crisis.

The recent coronavirus disease (COVID-19) is impacting the research community worldwide with unforeseen long-term consequences for research, doctoral training, and international collaboration. It is already clear that the immediate effects of the crisis resulting from disrupted research stays and reduced career development opportunities are being most detrimental to early-career researchers. Based on a Sino-German international research training group dedicated to doctoral training and biodiversity-ecosystem functioning research, we show how resilience of large collaborative research programs can be promoted in times of global crisis. We outline possible adaptations in the areas of funding, research, teaching and learning, supervision and mentoring, and international collaboration helping to reduce detrimental impact for early-career researchers and to permanently strengthen the performance of large collaborative research groups in the postpandemic era.

Relationship between fluorescence excitation-emission matrix properties and the relative degree of DOM hydrophobicity in wastewater treatment effluents.

Excitation-emission matrix (EEM) fluorescence spectroscopy is a powerful tool for the characterization of dissolved organic matter (DOM) in wastewater systems. It is of particular value if its utility could be extended by connecting the spectral features to hydrophobicity, one of the fundamental physicochemical properties of DOM. In this study, we employed a DAX-8 resin column to fractionate the hydrophobic/philic components of DOM and determine the relative degree of hydrophobicity by adjusting the critical retention factor (k'cr, the ratio of treated water sample volume to column volume). A higher k'cr would result in a higher hydrophobicity of the column effluent. At different k'cr values (5, 10, 25, 50, 100, and 200), the EEM characteristics of the obtained DOM components were inspected, including overall properties (average fluorescence per total organic carbon and UV absorbance), regional properties (fluorescence regional integration (FRI) and its secondary parameters), and energy-related properties (energy level of the excited states, Stokes shift for relaxation of the excited states, and fluorescence lifetime). In case studies of a wastewater membrane bioreactor and an oxidation ditch, plenty of the EEM properties varied significantly with logk'cr (r > 0.9, p < 0.05). The average fluorescence per UV absorbance (reflecting quantum yield), fluorescence proportion at Stokes shift ≥ 1.1 µm-1, and some secondary FRI parameters presented the best linear fitting with logk'cr, suggesting a smooth variation of the π-conjugated structures with the relative degree of DOM hydrophobicity. This may help to further understand the relationship between EEM fingerprints and DOM hydrophobicity.