qiuxiang tian - Academia.edu (original) (raw)

Papers by qiuxiang tian

Raw data of site description and key soil properties along a topographic transect with ridge, mid... more Raw data of site description and key soil properties along a topographic transect with ridge, middle slope, lower slope and valley positions in a subtropical mountain forest of China.

Journal of Forestry Research

Fine roots play key roles in belowground C cycling in terrestrial ecosystems. Based on their dist... more Fine roots play key roles in belowground C cycling in terrestrial ecosystems. Based on their distinct functions, fine roots are either absorptive fine roots (AFRs) or transport fine roots (TFRs). However, the function-based fine root dynamics of trees and their responses to forest stand properties remain unclear. Here, we studied the dynamics of AFRs and TFRs and their responses to stand conditions and root density in a subtropical montane mixed forest based on a 2-a root window experiment. Mean (± SE) annual production, mortality, and turnover rate of AFRs were 7.87 ± 0.17 m m−2 a−1, 8.13 ± 0.20 m m−2 a−1and 2.96 ± 0.24 a−1, respectively, compared with 7.09 ± 0.17 m m−2 a−1, 4.59 ± 0.17 m m−2 a−1, and 2.01 ± 0.22 a−1, respectively, for TFRs. The production and mortality of fine roots were significantly higher in high root-density sites than in low-root density sites, whereas the turnover of fine roots was faster in the low root-density sites. Furthermore, root density had a larger ...

Science of The Total Environment

Microbial Ecology, 2022

Microorganisms inhabit the entire soil profile and play important roles in nutrient cycling and s... more Microorganisms inhabit the entire soil profile and play important roles in nutrient cycling and soil formation. Recent studies have found that soil bacterial diversity and composition differ significantly among soil layers. However, little is known about the vertical variation in soil bacterial communities and how it may change along an elevation gradient. In this study, we collected soil samples from 5 forest types along an elevation gradient in Taibai Mountain to characterize the bacterial communities and their vertical patterns and variations across soil profiles. The richness and Shannon index of soil bacterial communities decreased from surface soils to deep soils in three forest types, and were comparable among soil layers in the other two forests at the medium elevation. The composition of soil bacterial communities differed significantly between soil layers in all forest types, and was primarily affected by soil C availability. Oligotrophic members of the bacterial taxa, such as Chloroflexi, Gemmatimonadetes, Nitrospirae, and AD3, were more abundant in the deep layers. The assembly of soil bacterial communities within each soil profile was mainly governed by deterministic processes based on environmental heterogeneity. The vertical variations in soil bacterial communities differed among forest types, and the soil bacterial communities in the Betula albo-sinensis forest at the medium elevation had the lowest vertical variation. The vertical variation was negatively correlated with mean annual precipitation (MAP), weighted rock content, and weighted sand particle content in soils, among which MAP had the highest explanatory power. These results indicated that the vertical mobilization of microbes with preferential and matrix flows likely enhanced bacterial homogeneity. Overall, our results suggest that the vertical variations in soil bacterial communities differ along the elevation gradient and potentially affect soil biological processes across soil profiles.

Frontiers in Microbiology, 2021

Elevational gradients strongly affect the spatial distribution and structure of soil bacterial co... more Elevational gradients strongly affect the spatial distribution and structure of soil bacterial communities. However, our understanding of the effects and determining factors is still limited, especially in the deep soil layer. Here, we investigated the diversity and composition of soil bacterial communities in different soil layers along a 1,500-m elevational gradient in the Taibai Mountain. The variables associated with climate conditions, plant communities, and soil properties were analyzed to assess their contributions to the variations in bacterial communities. Soil bacterial richness and α-diversity showed a hump-shaped trend with elevation in both surface and deep layers. In the surface layer, pH was the main factor driving the elevational pattern in bacterial diversity, while in the deep layer, pH and soil carbon (C) availability were the two main predictors. Bacterial community composition differed significantly along the elevational gradient in all soil layers. In the surfa...

Frontiers in Soil Science, 2021

The input of dissolved organic carbon (DOC) into soil affects soil organic carbon mineralization ... more The input of dissolved organic carbon (DOC) into soil affects soil organic carbon mineralization and microbial community composition by changing carbon availability. However, up to now, there is little knowledge about the microbial groups that utilize the added DOC and how the incorporation process may vary over time. In this study, we added 13C-labeled litter-derived DOC (treatment) or pure water (control) to a forest soil from different layers to investigate the effects of DOC addition on soil microbial biomass and community composition in a 180-d laboratory incubation experiment. Soil microbial phospholipid fatty acid (PLFA) were measured to assess changes in the microbial community composition. The 13C incorporation into microbial biomass and PLFAs was analyzed to trace the microbial utilization of litter-derived DOC. Our results indicated that DOC addition increased the biomass of gram-negative bacteria, gram-positive bacteria, fungi, and actinomycetes, but the microbial commun...

DNA methylation is an important epigenetic modification associated with transcriptional repressio... more DNA methylation is an important epigenetic modification associated with transcriptional repression, and plays key roles in normal cell growth as well as oncogenesis. Among the three main DNA methyltransferases (DNMT1, DNMT3A, and DNMT3B), DNMT3A mediates de novo DNA methylation with partial functional redundancy with DNMT3B. However, the general effects of DNMT3A and its downstream gene regulation profile are yet to be unveiled. In the present study, we used CRISPR/Cas9 technology to successfully create DNMT3A deficient human embryonic kidney cell line HEK293, with frameshift mutations in its catalytic domain. Our results showed that the cell growth slowed down in DNMT3A knockout cells. UPLC-MS analysis of DNMT3A deficient cells showed that the genome-level DNA methylation was reduced by 21.5% and led to an impairment of cell proliferation as well as a blockage of MAPK and PI3K-Akt pathways. Whole genome RNA-seq revealed that DNMT3A knockout up-regulated expression of genes and path...

Journal of Forestry Research, 2020

In terrestrial ecosystems, deep soils (below 30 cm) are major organic carbon (C) pools. The labil... more In terrestrial ecosystems, deep soils (below 30 cm) are major organic carbon (C) pools. The labile carbon input could alter soil organic carbon (SOC) mineralization, resulting in priming effect (PE), which could be modified by nitrogen (N) availability, however, the underlying mechanism is unclear for deep soils, which complicates the prediction of deep soil C cycling in response to N deposition. A series of N applications with 13C labeled glucose was set to investigate the effect of labile C and N on deep SOC mineralization. Microbial biomass, functional community, metabolic efficiency and enzyme activities were examined for their effects on SOC mineralization and PE. During incubation, glucose addition promoted SOC mineralization, resulting in positive PE. The magnitude of PE decreased significantly with increasing N. The N-regulated PE was not dependent on extracellular enzyme activities but was positively correlated with carbon use efficiency and negatively with metabolic quotie...

Environmental Pollutants and Bioavailability, 2020

PeerJ, 2020

Background Labile carbon input could stimulate soil organic carbon (SOC) mineralization through p... more Background Labile carbon input could stimulate soil organic carbon (SOC) mineralization through priming effect, resulting in soil carbon (C) loss. Meanwhile, labile C could also be transformed by microorganisms in soil as the processes of new C sequestration and stabilization. Previous studies showed the magnitude of priming effect could be affected by soil depth and nitrogen (N). However, it remains unknown how the soil depth and N availability affect the amount and stability of the new sequestrated C, which complicates the prediction of C dynamics. Methods A 20-day incubation experiment was conducted by adding 13C labeled glucose and NH4NO3 to study the effects of soil depth and nitrogen addition on the net C sequestration. SOC was fractioned into seven fractions and grouped into three functional C pools to assess the stabilization of the new sequestrated C. Results Our results showed that glucose addition caused positive priming in both soil depths, and N addition significantly r...

Forest Science, 2019

Dissolved organic matter is important in the vertical and lateral translocation of nutrients in f... more Dissolved organic matter is important in the vertical and lateral translocation of nutrients in forest ecosystems. However, little is known about the changes in dissolved organic matter concentration and chemical components in ecosystem sources in humid mountain forests. Here, we measured the concentration and chemical components of dissolved organic matter at throughfall, stemflow, litter leachate, runoff, and soil pore water (at depths of 10 cm, 30 cm, and 60 cm) in a subtropical humid mountain forest during two growing seasons. The concentration of dissolved organic carbon and dissolved nitrogen showed a clear monthly trend. The dissolved organic carbon concentration and the proportion of hydrophobic organic acid in the surficial water were higher than those in the soil pore water, and this difference was accompanied by a decrease in the hydrophobic organic acid concentration from the surficial water to the soil pore water. We also found that dissolved organic matter properties i...

Soil Biology and Biochemistry, 2017

Journal of Plant Ecology, 2017

Scientific reports, Jan 6, 2016

Changes in soil organic carbon (SOC) stability may alter carbon release from the soil and, conseq... more Changes in soil organic carbon (SOC) stability may alter carbon release from the soil and, consequently, atmospheric CO2 concentration. The mean annual temperature (MAT) can change the soil physico-chemical characteristics and alter the quality and quantity of litter input into the soil that regulate SOC stability. However, the relationship between climate and SOC stability remains unclear. A 500-day incubation experiment was carried out on soils from an 11 °C-gradient mountainous system on Changbai Mountain in northeast China. Soil respiration during the incubation fitted well to a three-pool (labile, intermediate and stable) SOC decomposition model. A correlation analysis revealed that the MAT only influenced the labile carbon pool size and not the SOC stability. The intermediate carbon pool contributed dominantly to cumulative carbon release. The size of the intermediate pool was strongly related to the percentage of sand particle. The decomposition rate of the intermediate pool ...