Microbial mechanisms for improved soil phosphorus mobilization in monoculture conifer plantations by mixing with broadleaved trees.

Replanting broadleaved trees in monoculture conifer plantations has been shown to improve the ecological environment. However, not much is known about the distribution properties of soil phosphate-mobilizing bacteria (PMB) under different mixed plantings or how PMB affects biometabolism-driven phosphorus (P) bioavailability. The phoD and pqqC genes serve as molecular markers of PMB because they regulate the mobilization of organic (Po) and inorganic (Pi) P. Differences in soil bioavailable P concentration, phoD- and pqqC-harboring PMB communities, and their main regulators were analyzed using biologically-based P (BBP) and high-throughput sequencing approaches after combining coniferous trees (Pinus massoniana) and five individual broadleaved trees (Bretschneidera sinensis, Michelia maudiae, Cercidiphyllum japonicum, Manglietia conifera, and Camellia oleifera). The findings revealed that the contents of litter P, soil organic carbon (SOC), available Pi (CaCl2-P), and labile Po (Enzyme-P) were significantly higher in conifer-broadleaf mixed plantations than those in the monospecific Pinus massoniana plantations (PM), especially in the mixed stands with the introduction of Cercidiphyllum japonicum, Michelia maudiae, and Camellia oleifera. Conifer-broadleaf mixing had little effect on the abundance of phoD and pqqC genes but significantly altered species composition within the communities. Conifer-broadleaf mixing improved soil microbial habitat mainly by increasing the pH, increasing carbon source availability and nutrient content, decreasing exchangeable Fe3+ and Al3+ content, and decreasing the activation degrees of Fe and Al oxides in acidic soils. A small group of taxa (phoD: Bradyrhizobium, Tardiphaga, Nitratireductor, Mesorhizobium, Herbaspirillum, and Ralstonia; pqqC: Burkholderia, Variovorax, Bradyrhizobium, and Leptothrix) played a key role in the synthesis of P-related enzymes (e.g., alkaline phosphomonoesterase, ALP) and in lowering the levels of mineral-occluded (HCl-P) and chelated (Citrate-P) Pi. Overall, our findings highlight that mixing conifers and broadleaves could change the PMB communities that produce ALP and dissolve Pi to make P more bioavailable.

Mixing of pine and arbuscular mycorrhizal tree species changed soil organic carbon storage by affecting soil microbial characteristics.

Pure and mixed pine forests are found all over the world. The mycorrhizal type affects soil microbial activity and carbon sequestration capacity in pure forests. However, the effects of mycorrhizal type on microbial characteristics and carbon sequestration capacity in pine mixed forests remain untested. Further, making it difficult to predict carbon storage of the conversion from pure pine forests to mixed forests at larger scales. Herein, a meta-analysis showed that the contents of soil microbial biomass, mineral-associated organic carbon, and soil organic carbon in pine mixed forests with introduced arbuscular mycorrhizal tree species (PMAM) increased by 26.41 %, 58.55 %, and 27.41 %, respectively, compared to pure pine forests, whereas those of pine mixed forests without arbuscular mycorrhizal tree species (PMEcM) remained unchanged. Furthermore, the effect size of microbial biomass, mineral-associated organic carbon and organic carbon contents in subsoil of PMAM are 56.48 %, 78.49 % and 43.05 %, respectively, which are higher than those in topsoil. The improvement of carbon sinks throughout the PMAM soil profile is positively correlated with increases in microbial biomass and mineral-associated organic carbon in subsoil, according to regression analysis and structural equation modelling. In summary, these results highlight that the positive effects of introducing arbuscular mycorrhizal tree species rather than ectomycorrhizal tree species into pure pine forests on soil microbial biomass and carbon sequestration. The positive link between microbial biomass, mineral-associated organic carbon, and soil organic carbon suggests an underlying mechanism for how soil microorganisms store carbon in pine mixed forests. Nevertheless, our findings also imply that the soil carbon pool of PMAM may be vulnerable under climate change. Based on the above findings, we propose that incorporating mycorrhizal type of tree species and soil thickness into mixed forests management and biodiversity conservation.

Understanding the role of digital immersive technology in educating the students of english language: does it promote critical thinking and self-directed learning for achieving sustainability in education with the help of teamwork?

PURPOSE: Universities are constantly searching for best practices to promote sustainability when it comes to educating students of the English language. Although this area of study has recently gained the attention of scholars around the world there is still a need to explore it from various perspectives. OBJECTIVE: This study aims to comprehensively investigate the impact of digital immersive technology on the education of English language students, specifically focusing on its potential to promote critical thinking and self-directed learning for achieving sustainability in education through teamwork. The research will assess the influence of digital immersive experiences on enhancing learning outcomes, examining their role in fostering critical thinking skills and encouraging self-directed learning practices. Additionally, the study explores the collaborative aspects of digital immersive technology, evaluating its contribution to teamwork among students. METHODOLOGY: The objective was achieved by using a survey questionnaire to collect data from 304 registered students in various universities in Beijing. Data analysis was conducted by applying Mplus 7.0 software. FINDINGS: The findings revealed that the use of digital immersive technology was pivotal for achieving sustainable education both directly and indirectly to an extent. In addition, team working moderated all the respective paths except the path involving the use of digital immersive technology and critical thinking. IMPLICATIONS: These results generated implications for teachers and policymakers to promote and facilitate the use of digital technology for teaching the English language to students, encouraging them to develop critical skills and self-directed learning strategies. The study also offered guidance and deeper understanding for researchers to address the concerns linked to the use of digital technology and sustainable education particularly in their future endeavors.

Effect of Loading Rate and Initial Strain on Seismic Performance of an Innovative Self-Centering SMA Brace.

In order to improve the energy dissipation capacity and to reduce the residual deformation of civil structures simultaneously, this paper puts forwards an innovative self-centering shape memory alloy (SMA) brace that is based on the design concepts of SMA's superelasticity and low friction slip. Seven self-centering SMA brace specimens were tested under cyclic loading, and the hysteresis curves, bond curves, secant stiffness, energy dissipation coefficient, equivalent damping coefficient, and the self-centering capacity ratio of these specimens were investigated, allowing us to provide an evaluation of the effects of the loading rate and initial strain on the seismic performance. The test results show that the self-centering SMA braces have an excellent energy dissipation capacity, bearing capacity, and self-centering capacity, while the steel plates remain elastic, and the SMA in the specimens that are always under tension are able to return to the initial state. The hysteresis curves of all of the specimens are idealized as a flag shape with low residual deformation, and the self-centering capacity ratio reached 89.38%. In addition, both the loading rate and the initial strain were shown to have a great influence on the seismic performance of the self-centering SMA brace. The improved numerical models combined with the Graesser model and Bouc-Wen model in MATLAB were used to simulate the seismic performance of the proposed braces with different loading rates and initial strains, and the numerical results are consistent with the test results under the same conditions, meaning that they can accurately predict the seismic performance of the self-centering SMA brace proposed here.

The complete mitochondrial genome of Sardinops sagax (Jenyns, 1842) (Clupeiformes: Clupeidae) and phylogenetic analyses of sardines.

Pacific sardine Sardinops sagax (Jenyns, 1842), a sardine species that widely distributes in Pacific, is an important commercial species in many areas. In this study, we characterized the complete mitochondrial genome of S. sagax using next generation sequencing technology. The complete mitogenome of S. sagax was 16,883 base pairs (bp) in length and comprised 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA genes (rRNA), and one control region (D-loop). Phylogenetic analysis indicated that sardine species included three clades (I, II and III) and S. sagax clustered with Sardinops melanostictus.

Effects of Small Gaps on the Relationship Among Soil Properties, Topography, and Plant Species in Subtropical Rhododendron Secondary Forest, Southwest China.

Background: The secondary forests have become the major forest type worldwide, and forest gap was also a common small disturbance in secondary forests. We aimed to analyze the effects of small gap disturbance on the plant species richness of subtropical secondary forest with natural regeneration barriers and examine the relationship between soil topography and plant species in a subtropical Rhododendron secondary forest of the Baili Rhododendron National Nature Reserve. Methods: The major plant species and soil topography gradient factors of the small gaps and closed canopy (control group) were analyzed using two-way ANOVA, multivariate permutational analysis of variance, nonmetric multi-dimensional scaling, random forest, canonical correspondence analysis, redundancy analysis, and a generalized linear model. Results: Small gaps had significant impact on the distribution of soil available potassium (AK), organic carbon to total phosphorus (C/P) ratio rather than slope position for soil pH and calcium (Ca) under closed canopy. Soil pH and AK followed by total phosphorus (TP) were the most important variables explaining the spatial distributions of soil properties in both habitats. Determining the spatial distribution of individual woody plant species were soil pH in small gaps, instead of lower altitude, TP, total potassium (TK) and sodium (Na) concentrations for both habitats. Moreover, Ericaceae and Fagaceae were strongly associated with pH in the small gaps. However, there was soil Na for the herbaceous plant in the closed canopy. The species richness of woody plant species in small gaps was affected significantly by pH, soil water content (SWC), and TK, instead of soil organic carbon (SOC), SWC and C/P ratio in both habitats. Conclusions: Small gaps were not always significantly improved the composition of soil nutrients, but provided a good microenvironment for plant growth, species richness of major woody plant differed between habitats.

Distribution of Bottom Trawling Effort in the Yellow Sea and East China Sea.

Bottom trawling is one of the most efficient fishing activities, but serious and persistent ecological issues have been observed by fishers, scientists and fishery managers. Although China has applied the Beidou fishing vessel position monitoring system (VMS) to manage trawlers since 2006, little is known regarding the impacts of trawling on the sea bottom environments. In this study, continuous VMS data of the 1403 single-rig otter trawlers registered in the Xiangshan Port, 3.9% of the total trawlers in China, were used to map the trawling effort in 2013. We used the accumulated distance (AD), accumulated power distance (APD), and trawling intensity as indexes to express the trawling efforts in the Yellow Sea (YS) and East China Sea (ECS). Our results show that all three indexes had similar patterns in the YS and ECS, and indicated a higher fishing effort of fishing grounds that were near the port. On average, the seabed was trawled 0.73 times in 2013 over the entire fishing region, and 51.38% of the total fishing grounds were with no fishing activities. Because of VMS data from only a small proportion of Chinese trawlers was calculated fishing intensity, more VMS data is required to illustrate the overall trawling effort in China seas. Our results enable fishery managers to identify the distribution of bottom trawling activities in the YS and ECS, and hence to make effective fishery policy.