RESUMO
The surface water is an important habitat for freshwater microorganisms, but there is a lack of understanding of the pattern of microbial diversity and structure in stream continuums of small subtropical forest watersheds. Therefore, this study aimed to understand the variations in microbial diversity and community structure along stream orders (1-5) in the small subtropical forest catchments of the Wuyi Mountains. Using GIS software, 20 streams were chosen and classified into 5 orders. Illumina sequencing was used to analyze the dynamics of microbial communities, along with stream orders and hydro-chemical properties of stream water were also determined. Our results indicated that the bacterial and fungal richness (ACE index) was higher in low-order (1 and 2 orders) streams than in high-order (3, 4, and 5 orders) streams, with the highest value in the order 2 streams (P < 0.05). The water temperature and dissolved oxygen were positively correlated with fungal richness (P < 0.05). The bacterial rare taxa had a significant correlation with the abundance taxa (P < 0.05). The relative abundances of Bacteroidetes, Actinobacteria, and Chytridiomycota microbial phyla were significantly different among different order streams (P < 0.05). Using the neutral community model, we found that the fungal community structure was significantly shaped by hydro-chemical properties, while the bacterial community structure was largely regulated by stochastic processes. Our findings suggest that variations in microbial community structure in subtropical headwaters are largely shaped by the water temperature and dissolved oxygen.
Assuntos
Bactérias , Microbiota , Bactérias/genética , Água Doce/microbiologia , Água/química , OxigênioRESUMO
Non-structural carbohydrates (NSCs) are labile components in forest litter that can be released quickly at the early stage of litter decomposition and accelerate the metabolic turnover of soil microorganisms, which is essential for the formation of forest soil organic matter. Therefore, understanding the NSCs response mechanisms to forest litter at different altitudes is critical for understanding nutrient cycling in the forest soil under climate change conditions. In this study, we used the net bag decomposition method to observe the dynamics of NSCs release in Chinese fir topsoil and canopy litter at four altitudes for 360 days based on the climatic zone characteristics distributed vertically along the elevation of Wuyi Mountain. The release of NSCs in Chinese fir litter rise gradually with height increases during the decomposition. The difference of the cumulative release percentage of soluble sugar between different altitudes is more significant than that of starch. The response of the NSC content in different treatment groups at four altitudes are different. The release of NSCs in the leaf canopy litter is higher than that in the leaf topsoil litter. On the contrary, the release of NSCs in the mixture of leaf and twig topsoil litter is higher than that in the mixture of leaf and twig canopy litter. Taken together, this study is of great significance for a comprehensive understanding of the effect of climate change on NSCs during the decomposition of Chinese fir litter.
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The complete mitochondrial genome (mitogenome) of Rana wuyiensis (Anura, Ranidae) was sequenced and annotated. The circular complete mitogenome was 17,779 bp in length (OL467321) and constituted of 37 genes including 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and two ribosomal RNAs (rRNAs), and a D-loop region. The result of Bayesian phylogenetic analysis indicated that R. wuyiensis exhibits a close relationship with R. johnsi. R. wuyiensis was recently discovered and therefore holds a lot of potential for future research studies. Our study added a new mitochondrial data and provided valuable reference material to the taxonomy of Rana.
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To address the difficulty of extracting the features of composite-fault signals under a low signal-to-noise ratio and complex noise conditions, a feature-extraction method based on phase-space reconstruction and maximum correlation Re'nyi entropy deconvolution is proposed. Using the Re'nyi entropy as the performance index, which allows for a favorable trade-off between sporadic noise stability and fault sensitivity, the noise-suppression and decomposition characteristics of singular-value decomposition are fully utilized and integrated into the feature extraction of composite-fault signals by the maximum correlation Re'nyi entropy deconvolution. Verification based on simulation, experimental data, and a bench test proves that the proposed method is superior to the existing methods regarding the extraction of composite-fault signal features.
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A new species of the frog genus Rana sensu lato from Wuyi Mountain, Fujian Province, China is described. Molecular phylogenetic analyses clustered the new species into the R.johnsi group and indicated that it was genetically divergent from its closely related species. The new species could be distinguished from its congeners by a combination of the following characters: body size medium, SVL 41.4-45.6 mm (42.9 ± 1.9 mm, n = 4) in adult males and 47.6-50.3 mm (n = 2) in adult females; adult male with a pair of internal subgular vocal sacs; lateroventral grooves present on tip of toes; webbing on fourth toes reaching the tip of toe; transverse skin ridges distinctly present on the dorsal surface of thigh and tibia, the number large (mean 26.5 ± 2.7, range 22-29, n = 6); breeding males possess creamy white nuptial pad with tiny velvety spines on the dorsal surface of the first finger, divided into three parts.
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Despite widespread anthropogenic nutrient enrichment, it remains unclear how nutrient enrichment influences plant-arbuscular mycorrhizal fungi (AMF) symbiosis and ecosystem multifunctionality at the global scale. Here, we conducted a meta-analysis to examine the worldwide effects of nutrient enrichment on AMF and plant diversity and ecosystem multifunctionality using data of field experiments from 136 papers. Our analyses showed that nutrient addition simultaneously decreased AMF diversity and abundance belowground and plant diversity aboveground at the global scale. The decreases in AMF diversity and abundance associated with nutrient addition were more pronounced with increasing experimental duration, mean annual temperature (MAT) and mean annual precipitation (MAP). Nutrient addition-induced changes in soil pH and available phosphorus (P) predominantly regulated the responses of AMF diversity and abundance. Furthermore, AMF diversity correlated with ecosystem multifunctionality under nutrient addition worldwide. Our findings identify the negative effects of nutrient enrichment on AMF and plant diversity and suggest that AMF diversity is closely linked with ecosystem function. This study offers an important advancement in our understanding of plant-AMF interactions and their likely responses to ongoing global change.
