Showing papers by "Wenxuan Han published in 2022"

Phytoplankton Species Diversity Patterns and Associated Driving Factors in China’s Jiulong River Estuary: Roles That Nutrients and Nutrient Ratios Play

Abstract: Understanding diversity patterns and associated driving factors are the critical topics in macroecology and conservation biology. Phytoplankton are highly susceptible to environmental changes in estuaries, particularly eutrophication. This study examined phytoplankton alpha and beta diversity using investigation data in May (springtime), August (summer) and November (autumn) 2009 in China’s Jiulong River estuary, where it was easily polluted because of considerable discharge from a highly dense human population and low self-purification capacity with its limited river basin area, potentially resulting in eutrophication and then influencing phytoplankton diversity. Potential influencing factors were also explored, including dissolved oxygen, salinity, nutrients, nutrient ratios, geographic and hydrologic distance, and so on. The results indicated that Shannon’s index (H’) and Pielou’s index (J) decreased from the estuary’s upper to middle and then increased from middle to lower reaches, Simpson’s (D) observed the opposite trend and species number (S) gradually increased from the estuary’s upper to lower reaches. For beta diversity, all the indices showed a gradual decrease trend from the estuary’s upper to lower reaches, where also, turnover dominated beta diversity for all seasons. It is noteworthy that the significant roles that nutrients and nutrient ratios played in shaping phytoplankton diversity patterns and the nutrient balance were characterized by excess nitrogen (N) and silicon (Si) and limited phosphorus (P), which could potentially cause diatom blooms. Findings also showed that decreasing Si concentrations can help to reduce overall pollution levels as well as the restoration of the estuary’s ecosystem better than just reducing N alone. Accordingly, this study advocates for the protection of the entire estuary system with particular emphasis on its upper reaches. Moreover, greater attention should also be paid to impacts associated with N input and nutrient ratio trade-offs to the prospective watershed management of this estuary. This study provides a practical approach to explore estuarine diversity in a comprehensive way, which can inform effective biodiversity conservation and also be applied to other marine ecosystems to better guide sustainable management and conservation practices.

Global Patterns and Drivers of Litter Decomposition Under Nitrogen Enrichment: A Meta-Analysis

Abstract: Nitrogen (N) enrichment has substantially altered patterns of terrestrial litter decomposition, with positive, neutral, and negative effects. However, the general response patterns and drivers of litter decomposition to N enrichment rates are poorly understood, and how litter decomposition has changed under the N enrichment rate, especially in different ecosystems, still requires further study. We reviewed 118 published papers dealing with litter mass remaining after N enrichment to assess the influences of various environmental and experimental factors on the relationships between N enrichment and litter decomposition in grasslands, forests, and wetland ecosystems. The results indicated that N enrichment had an insignificant effect on litter decomposition globally. However, the effects varied greatly among ecosystem types, with an increase in litter decomposition of 3.91% in grasslands and 1.82% in wetlands and a decrease of 1.23% in forests. When forests were subdivided into plantations, primary, and secondary forests, the results showed that N enrichment significantly slowed litter decomposition rate by 2.96% in plantations but had no significant influence in primary and secondary forests. However, litter decomposition was significantly influenced by the level of N addition in plantations and secondary forests, with an increase in litter mass loss at low N addition (50 kg N ha–1 year–1) and a decrease in litter mass loss at high N addition (>50 kg N ha–1 year–1). The magnitude and direction of the N effect are affected by experimental and environmental factors. Specifically, mixed N enrichment (for example, urea and glycine) exerted a stronger effect on litter decomposition compared with an N fertilizer alone. Our findings indicated the different effects of N on litter decomposition in forests and grasslands and knowledge which will greatly advance our ability to accurately evaluate and predict global C cycling under increased N deposition, which should improve future models of global biogeochemical cycling.

Determination of Leaf pH without Grinding the Sample: Is It Closer to the Reality?

Abstract: This study recommends a non-grinding measurement method of leaf pH which can reduce the destructive interference to the measured fresh-leaf pH values. To verify the accuracy of this method, we measured leaf pH with the non-grinding and grinding method and further assessed the dilution effect on leaf pH in the grinding process. Compared with the non-grinding method, the grinding method significantly increased the measured pH value; leaf pH increased with decreasing leaf–water ratio in the procedure of the grinding method, but gradually stabilized. The grinding effects of severe physical damage and thereafter oxidization of leaf samples, and the dilution effects according to the Debye–Hückel limiting law and acid-base ionization theory, may both contribute to the increased leaf pH measured with the grinding method. Thus, leaf pH measured with the non-grinding method was expected to be much closer to those of leaf sap in vivo and be more suitable to indicating the dynamic variation or instant response of leaf pH to the environmental changes. Finally, considering that non-significant difference had been proved in the measured leaf pH between dried, frozen, refrigerated, and fresh ground samples, a conversion equation was provided to facilitate mutual conversion of the results with non-grinding fresh samples (y) against those with grinding dried samples (as representative) (x): y = 1.097x − 0.722.

Dynamic changes in fractional amplitude of low-frequency fluctuations in patients with chronic insomnia

Abstract: Background Previous neuroimaging studies have mostly focused on changes in static functional connectivity in patients with chronic insomnia (CI). Features of dynamic brain activity in patients with CI have rarely been described in detail. The present study investigated changes in dynamic intrinsic brain activity in patients with CI by dynamic fractional amplitude of low-frequency fluctuation (dfALFF) analysis. Materials and methods A total of 30 patients with CI and 27 healthy controls (HCs) were enrolled. We compared dfALFF between these two groups, and examined the correlation between changes in dfALFF and clinical symptoms of CI. Multivariate pattern analysis was performed to differentiate patients with CI from HCs. Results Compared with HC subjects, patients with CI showed significantly increased dfALFF in the left insula, right superior temporal gyrus, left parahippocampal gyrus, right amygdala, and bilateral posterior lobes of the cerebellum. Moreover, dfALFF values in the left insula and left parahippocampal gyrus showed a positive correlation with Pittsburgh Sleep Quality Index scores. A logistic regression model was constructed that had 96.7% sensitivity, 80.0% specificity, and 83.0% overall accuracy for distinguishing patients with CI from HCs. Conclusion Dynamic local brain activity showed increased instability in patients with CI. The variability in dfALFF in the limbic system and brain areas related to sleep/wakefulness was associated with insomnia symptoms. These findings may provide insight into the neuropathologic basis of CI.

Correction of leaf nutrient resorption efficiency on the mass basis

Abstract: Nutrient resorption is a crucial mechanism for plant nutrient conservation, but most previous studies didn’t consider the leaf-mass loss during senescence for lack of measured data, leading to an underestimation of nutrient resorption efficiency (NuRE), or had to calculate NuRE of various species based on the average mass loss at plant-functional-group level in the literature, which affected its accuracy. We here measured the leaf-mass loss to correct NuRE with the species-specific mass loss correction factor (MLCF), so as to foster a more accurate calculation of the nutrient fluxes within and between plants and the soil. Green leaves and senesced leaves were collected from 35 dominant woody plants in northern China. Mass of green and senesced leaves were measured to calculate the MLCF at species level. The MLCF was reported for each of the 35 dominant woody plants in northern China. These species averagely lost 17% of the green-leaf mass during leaf senescence, but varied greatly from 1.3%~36.8% mass loss across the 35 species, or 11.7%~19.6% loss across the functional types. Accordingly, the MLCF varied from 0.632~0.987 across the 35 species with an average value 0.832. The NuRE corrected with MLCF was remarkably increased on the whole (e.g., both the average nitrogen and phosphorus NuRE became about 9% higher, or more accurate), compared with the uncorrected ones, especially in the case of low resorption efficiencies. Our field data provides reliable references for the MLCF of plants in related regions at both species and functional-type levels, and is expected to promote more accurate calculations of NuRE.

Interactive effects of plant density and nitrogen availability on the biomass production and leaf stoichiometry of Arabidopsis thaliana

Abstract: Plant density and nitrogen (N) availability influence plant survival and nutrient use strategies, but the interaction between these two factors for plant growth and the balance of elements remains poorly addressed. Here we conducted experimental manipulations using Arabidopsis thaliana, with the combination of four levels of plant density and four levels of N addition, and then examined the corresponding changes in plant biomass production (indicated by total plant biomass and biomass partitioning) and nutrient use strategies (indicated by leaf N and phosphorus (P) stoichiometry). The biomass-density relationship was regulated by N availability, with a negative pattern in low N availability but an asymptotic constant final yield pattern at high N availability. Excessive N addition reduced plant growth at low plant density, but this effect was alleviated by increasing plant density. The root to shoot biomass ratio increased with plant density at low N availability, but decreased at high N availability. N availability was more important than plant density in regulating leaf N and P stoichiometry, with the increasing leaf N concentration and decreasing leaf P concentration under increasing N addition, resulting in a negative scaling relationship between these two elemental concentrations. Our results show that N availability and plant density interactively regulate plant biomass production and leaf stoichiometry of A. thaliana, and highlight that the interactive effects of these two factors should be considered when predicting plant growth behavior under intraspecific competitive environments in the context of nutrient changes.

Diet therapy in patients with rare diseases: A scoping review.

Abstract: OBJECTIVE This scoping review presents existing research evidence regarding diet therapy in patients with rare diseases. METHODS Using the five-stage scoping review framework proposed by Arksey, O'Malley, and Levac, we searched the published literature in PubMed, Web of Science, Royal Society of Chemistry, China National Knowledge Infrastructure, VIP Database, and Wan Fang Database from January 2010 to November 2022. We selected diet therapy studies on 121 rare diseases, as categorized by the National Health Commission of China in 2018. Charts for research analysis were developed and used to categorize the data. RESULTS We ultimately included 34 diet therapy studies from 19 countries and territories for 10 rare diseases and three rare disease groups. Rare disease diet therapy studies have mainly focused on inborn errors of metabolism (92.3%) and are common in Western countries. Most studies focused on diet therapy methods for rare diseases (44%). Additionally, 29% of studies included diet therapy management, 15% included guidelines for diet therapy, and 12% included the impact of diet therapy on patients. CONCLUSIONS Current diet therapies for rare diseases lack specificity and present with limited characteristics. Therefore, it is necessary to expand the scope and depth of future research and explore evidence-based recommendations and new diet therapies focused on patient needs and family support, to provide a reference for improving the efficacy and safety of diet therapies for rare diseases. This article is protected by copyright. All rights reserved.