ABSTRACT
Here, we characterize the temporal and spatial dynamics of forest community structure and species diversity in a subtropical evergreen broad-leaved forest in China. We found that community structure in this forest changed over a 15-year period. Specifically, renewal and death of common species was large, with the renewal of individuals mainly concentrated within a few populations, especially those of Aidia canthioides and Cryptocarya concinna. The numbers of individual deaths for common species were concentrated in the small and mid-diameter level. The spatial distribution of community species diversity fluctuated in each monitoring period, showing a more dispersed diversity after the 15-year study period, and the coefficient of variation on quadrats increased. In 2010, the death and renewal of the community and the spatial variation of species diversity were different compared to other survey years. Extreme weather may have affected species regeneration and community stability in our subtropical monsoon evergreen broad-leaved forests. Our findings suggest that strengthening the monitoring and management of the forest community will help better understand the long- and short-term causes of dynamic fluctuations of community structure and species diversity, and reveal the factors that drive changes in community structure.
ABSTRACT
The aim of this study was to explore the carbon storage potential of karst forest soils in the Lijiang River Basin, reveal the spatial pattern of soil organic carbon (SOC), investigate the contributions and pathways of each driving factor to the spatial distribution of soil organic carbon, and provide a scientific basis for assessing the carbon cycle function of karst forests in the region. We employed structural equation modeling (SEM) and correlation analysis to investigate the spatial distribution characteristics of forest soil organic carbon in different basin sections (upper, middle, and lower reaches) and soil layers at different depths of the Lijiang River. Additionally, the direct and indirect ratios of each factor were quantified. The results showed that the overall soil layer of karst forest soils in the Lijiang River Basin was shallow, and soil organic carbon was phenoconcentric. The distribution of soil organic carbon content in different watershed sections was upstream > downstream > midstream, and the distribution of readily oxidizable carbon (ROC) and dissolved organic carbon (DOC) was consistent, whereas the distribution of microbial biomass carbon (MBC) was upstream > midstream > downstream. The contribution of various biotic and abiotic factors to the spatial distribution of soil organic carbon in karst forests in the watershed was different, and their contributions were ranked in descending order as:soil physicochemical factors > soil organic carbon active fraction > sample elevation > sample species diversity, with the total effects of 1.148, 0.574, 0.284, and -0.013, respectively. Among them, the sample site elevation had only an indirect effect on soil organic carbon, and the soil organic carbon active fraction had only a direct effect on soil organic carbon. Among the driving factors, total soil nitrogen, soil oxidizable organic carbon, sample site species richness, and soil soluble organic carbon could be used as important predictors of soil organic carbon content in karst forests in the Lijiang River Basin. Therefore, it is necessary to establish an effective eco-environmental protection mechanism covering the whole Lijiang River Basin, to reduce and control the impact of anthropogenic disturbances (especially in the middle urban section of the Lijiang River Basin), and to enhance and protect the species diversity of karst forests in the basin in order to improve soil physicochemical properties, improve and enhance the content of the soil organic carbon active fraction, and enhance the soil organic carbon stocks of karst forests in the Lijiang River Basin through other effective ways, as well as to promote the enhancement of the regional forest carbon sink function.
ABSTRACT
BACKGROUND: We evaluated the safety and efficacy of fecal microbiota transplantation (FMT) for chronic functional constipation (CFC) ineffectively treated by conventional constipation medication. METHODS: Thirty-four patients with CFC underwent FMT treatment (three rounds, via gastroscopy). Clinical scales, including the Wexner constipation score as the main index of efficiency, were completed at baseline; after each treatment, and at 2 and 3 months of follow up. Secondary evaluation indices included the self-assessment of constipation symptoms, patient assessment constipation quality-of-life questionnaire, Bristol stool form scale, and Zung's self-rating depression and anxiety scales. Gastrointestinal motility, motilin, gastrin, nitric oxide (NO), and 5-hydroxytryptamine (5-HT) were assessed before and after treatment. Intestinal flora changes were assessed by 16S ribosomal ribonucleic acid (rRNA) sequencing. RESULTS: There were no serious adverse reactions. The clinical cure rate was 73.5% (25/34), clinical remission rate was 14.7% (5/34), and the inefficiency rate was 11.8% (4/34). Clinical scale data indicated that the FMT treatment was effective. Furthermore, FMT treatment promoted intestinal peristalsis, increased gastrointestinal motility, and increased serum NO and 5-HT levels. The 16S rRNA sequencing data indicated that high abundances of Bacteroides, Klebsiella, Megamonas, Erysipelotrichaceae and Epulopiscium may be the cause of constipation, and high abundances of Prevotella, Acidaminococcus and Butyricimonas may be the main factors in curing constipation. CONCLUSION: Treatment with FMT regulates the intestinal microflora and changes the abundance of CFC-associated bacterial flora to improve constipation.
