Plant roots play important roles in acquisition of water and nutrients, storage, anchoring, transport, and symbiosis with soil microorganisms, thus quantitative researches on root developmental processes are essential...Plant roots play important roles in acquisition of water and nutrients, storage, anchoring, transport, and symbiosis with soil microorganisms, thus quantitative researches on root developmental processes are essential to understand root functions and root turnover in ecosystems,and at the same time such researches are the most difficult because roots are hidden underground. Therefore, how to investigate efficiently root functions and root dynamics is the core aspect in underground ecology. In this article, we reviewed some experimental methods used in root researches on root development and root system architecture, and summarized the advantages and shortages of these methods. Based on the analyses, we proposed three new ways to more understand root processes：（1） new experimental materials for root development;（2） a new observatory system comprised of multiple components, including many observatory windows installed in field, analysis software,and automatic data transport devices;（3） new techniques used to analyze quantitatively functional roots.展开更多
Root tips are the main components of absorptive fine roots,but their seasonal dynamics and relationship to environmental factors remain unclear due to the difficulties in methodology.In this study,we explored the temp...Root tips are the main components of absorptive fine roots,but their seasonal dynamics and relationship to environmental factors remain unclear due to the difficulties in methodology.In this study,we explored the temporal patterns of root-tip production and mortality in monoculture plantations of five temperate tree species at a common site in northeastern China,and identified the general environmental controls on such processes.We made monthly in-situ assessments of root tip length(RTL)production and mortality in two hardwood and three coniferous species with a minirhizotron(MR)method during the growing seasons of 2008 and 2009.Air temperature,rainfall,soil temperature and water content at 10 cm depth were determined concurrently.RTL production in all species exhibited consistent peaks in summer(June–August)in two growing seasons.RTL mortality showed substantial interannual and interspecific variability,with peaks in autumn and winter in 2008,but various patterns in 2009.RTL production positively correlated with monthly soil and air temperature across all species,and with monthly rainfall in three coniferous species.However,there was no significant correlation between RTL production and soil water content.By contrast,RTL mortality was weakly related to environmental factors,showing positive correlations with soil temperature in Korean spruce,and with rainfall in Korean pine and Korean spruce.Our findings suggest that the seasonal patterns of RTL production are convergent across the five temperate tree species due to the overlapped distribution of heat and rainfall,which can conduce roots to maximizing the acquisition of nutrient resources in the soil.展开更多
To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were ch...To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.展开更多
The addition of ectomycorrhizal fungi(ECMF),beneficial rhizosphere microorganisms,to the soil can pro-mote plant growth and resistance.Here,Populus davidi-ana×Populus bolleana tissue culture seedlings were grown ...The addition of ectomycorrhizal fungi(ECMF),beneficial rhizosphere microorganisms,to the soil can pro-mote plant growth and resistance.Here,Populus davidi-ana×Populus bolleana tissue culture seedlings were grown for 3 months in soils inoculated with one of the species,then seedlings were assessed for mycorrhizal colonization rate and growth,physiological and root traits.Suillus luteus and Populus involutus each formed ectomycorrhizal associa-tions with the seedlings.Seedling height,ground diameter,biomass,and leaf area were significantly greater after treat-ment with ECMF than in the non-inoculated controls.Treat-ment improved all physiological and root variables assessed(chlorophylls and carotenoids,cellulose,and soluble sugars and proteins;root length,surface area,projected area,mean diameter,volume,number of root tips).Seedlings inocu-lated with S.luteus outperformed those inoculated with P.involutus.展开更多
To characterize effects of plant roots on preferential flow（PF）,we measured root length density（RLD）and root biomass（RB） in Jiufeng National Forest Park,Beijing,China.Comparisons were made for RLD and RB between...To characterize effects of plant roots on preferential flow（PF）,we measured root length density（RLD）and root biomass（RB） in Jiufeng National Forest Park,Beijing,China.Comparisons were made for RLD and RB between soil preferential pathways and soil matrices.RLD and RB declined with the increasing soil depth（0–10,10–20,20–30,30–40,40–50,50–60 cm） in all experimental plots.RLD was greater in soil preferential pathways than in the surrounding soil matrix and was 69.5,75.0 and72.2 % for plant roots of diameter（d） ／1,1 ／ d ／ 3 and3 ／ d ／ 5 mm,respectively.Fine root systems had the most pivotal influence on soil preferential flow in this forest ecosystem.In all experimental plots,RB content was the sum of RB from soil preferential pathways and the soil matrix in each soil depth.With respect to 6 soil depth gradient（0–10,10–20,20–30,30–40,40–50,50–60 cm） in each plot,the number of soil depth gradient that RB content was greater in soil preferential pathways than in the soil matrix was characterized,and the proportion was68.2 % in all plots.展开更多
Background:Inputs of above-and belowground litter into forest soils are changing at an unprecedented rate due to continuing human disturbances and climate change.Microorganisms drive the soil carbon(C)cycle,but the ro...Background:Inputs of above-and belowground litter into forest soils are changing at an unprecedented rate due to continuing human disturbances and climate change.Microorganisms drive the soil carbon(C)cycle,but the roles of above-and belowground litter in regulating the soil microbial community have not been evaluated at a global scale.Methods:Here,we conducted a meta-analysis based on 68 aboveground litter removal and root exclusion studies across forest ecosystems to quantify the roles of above-and belowground litter on soil microbial community and compare their relative importance.Results:Aboveground litter removal significantly declined soil microbial biomass by 4.9%but root exclusion inhibited it stronger,up to 11.7%.Moreover,the aboveground litter removal significantly raised fungi by 10.1%without altering bacteria,leading to a 46.7%increase in the fungi-to-bacteria(F/B)ratio.Differently,root exclusion significantly decreased the fungi by 26.2%but increased the bacteria by 5.7%,causing a 13.3%decrease in the F/B ratio.Specifically,root exclusion significantly inhibited arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and actinomycetes by 22.9%,43.8%,and 7.9%,respectively.The negative effects of aboveground litter removal on microbial biomass increased with mean annual temperature and precipitation,whereas that of root exclusion on microbial biomass did not change with climatic factors but amplified with treatment duration.More importantly,greater effects of root exclusion on microbial biomass than aboveground litter removal were consistent across diverse forest biomes(expect boreal forests)and durations.Conclusions:These data provide a global evidence that root litter inputs exert a larger control on microbial biomass than aboveground litter inputs in forest ecosystems.Our study also highlights that changes in above-and belowground litter inputs could alter soil C stability differently by shifting the microbial community structure in the opposite direction.These findings are useful for predicting microbe-mediated C processes in response to changes in forest management or climate.展开更多
Most detectors for nuclear physics experiments are detector arrays composed of numerous units.Testing each detector unit is a major part of the research work on detector arrays.To save time and simplify the research p...Most detectors for nuclear physics experiments are detector arrays composed of numerous units.Testing each detector unit is a major part of the research work on detector arrays.To save time and simplify the research process,a ROOT-based detector test system was designed for detector unit testing.The test system is a general pur-pose and expandable software system that can support most of the hardware devices in the market.Users can easily build a complete detector test system using the required hardware devices.The software is based on the ROOT framework and is operated on the Linux platform.The software of the test system consists of four parts:the controller,data acquisition(DAQ),high-voltage power supply,and online monitoring and analysis.In addition,a user-friendly graphical user interface(GUI)was designed for user convenience.Moreover,the online analysis func-tion of the software can implement automatic peak searching and spectrum fitting for different radioactive sources,and the results under different conditions can be shown automatically.The completion of the test system could greatly simplify the development process of the detector.展开更多
In this paper, we consider the eigenvalue problem of a class of fourth-order operator matrices appearing in mechan- ics, including the geometric multiplicity, algebraic index, and algebraic multiplicity of the eigenva...In this paper, we consider the eigenvalue problem of a class of fourth-order operator matrices appearing in mechan- ics, including the geometric multiplicity, algebraic index, and algebraic multiplicity of the eigenvalue, the symplectic orthogonality, and completeness of eigen and root vector systems. The obtained results are applied to the plate bending problem.展开更多
Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan ...Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan at the global scale are still limited.We compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan variations.Overall,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than angiosperms.Fine root lifespan was longer for evergreens than deciduous trees.Ectomycorrhizal(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)plants.Among different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical zone.Fine root lifespan increased with soil depth and root order.Furthermore,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker effects.Our results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental factors.These findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.展开更多
Plant stoichiometry and nutrient allocation may reflect adaptation strategies to environmental nutrient changes.Fire,as a major disturbance in forests,mediates soil nutrient availability that may influence plant nutri...Plant stoichiometry and nutrient allocation may reflect adaptation strategies to environmental nutrient changes.Fire,as a major disturbance in forests,mediates soil nutrient availability that may influence plant nutrient dynamics.However,plant–soil stoichiometric allocation strategies during different post-fire periods and the effects of soil,enzymes,and microbial biomass on plant stoichiom-etry are largely unknown.The pioneer tree species Betula platyphylla in burnt forests of northern China was the object of this study,and severely burned areas selected with dif-ferent fire years.Nearby unburned areas acted as a control.Carbon(C),nitrogen(N),and phosphorus(P)contents in leaves,branches,and fine roots and rhizosphere soil,C-,N-and P-acquiring enzyme activities were examined.Microbial biomass C,N,and P were measured,and factors influenc-ing C:N:P stoichiometry of plants during the burned area restoration were explored.Our results show that C and N contents in leaves increased with time since fire,while C and P in branches and C,N and P in fine roots decreased.Activities of C-,N-,and P-acquiring enzymes and microbial biomass N increased with time since fire.Redundancy analy-sis showed that changes in soil N-acquiring enzyme activity,microbial biomass C,and N had significant effects on plant ecological stoichiometry.These results show a significant flexibility in plant nutrient element allocation strategies and C:N:P stoichiometric characteristics.Soil extracellular enzyme activity drives the changes in stoichiometry during the process of post-fire restoration.展开更多
Site conditions and species identity have a combined effect on fine root growth of trees in pure and mixed stands.However,mechanisms that may contribute to this effect are rarely studied,even though they are essential...Site conditions and species identity have a combined effect on fine root growth of trees in pure and mixed stands.However,mechanisms that may contribute to this effect are rarely studied,even though they are essential to assess the potential of species to cope with climate change.This study examined fine root overlap and the linkage between fine root and stem growth of European beech(Fagus sylvatica)growing in pure and mixed stands with Douglas fir(Pseudotsuga menziesii)or Norway spruce(Picea abies)at two different study sites in northwestern Germany.The study sites represented substantially different soil and climate conditions.At each site,three stands,and at each stand,three pairs of trees were studied.In the pure beech stand,the pairs consisted of two beech trees,while in the mixed stands each pair was composed of a beech tree and a conifer.Between each pair,three evenly spaced soil cores were taken monthly throughout the growing season.In the pure beech stands,microsatellite markers were used to assign the fine roots to individual trees.Changes in stem diameter of beech were quantified and then upscaled to aboveground wood productivity with automatic high-resolution circumference dendrometers.We found that fine root overlap between neighboring trees varied independently of the distance between the paired trees or the stand types(pure versus mixed stands),indicating that there was no territorial competition.Aboveground wood productivity(wood NPP)and fine root productivity(root NPP)showed similar unimodal seasonal patterns,peaking in June.However,this pattern was more distinct for root NPP,and root NPP started earlier and lasted longer than wood NPP.The influence of site conditions on the variation in wood and root NPP of beech was stronger than that of stand type.Wood NPP was,as expected,higher at the richer site than at the poorer site.In contrast,root NPP was higher at the poorer than at the richer site.We concluded that beech can respond to limited resources not only above-but also belowground and that the negative relationship between above-and belowground growth across the study sites suggests an‘optimal partitioning’of growth under stress.展开更多
Let n≥2 and let L be a second-order elliptic operator of divergence form with coefficients consisting of both an elliptic symmetric part and a BMO anti-symmetric part in ℝ^(n).In this article,we consider the weighted...Let n≥2 and let L be a second-order elliptic operator of divergence form with coefficients consisting of both an elliptic symmetric part and a BMO anti-symmetric part in ℝ^(n).In this article,we consider the weighted Kato square root problem for L.More precisely,we prove that the square root L^(1/2)satisfies the weighted L^(p)estimates||L^(1/2)(f)||L_(ω)^p(R^(n))≤C||■f||L_(ω)^p(R^(n);R^(n))for any p∈(1,∞)andω∈Ap(ℝ^(n))(the class of Muckenhoupt weights),and that||■f||L_(ω)^p(R^(n);R^(n))≤C||L^(1/2)(f)||L_(ω)^p(R^(n))for any p∈(1,2+ε)andω∈Ap(ℝ^(n))∩RH_(2+ε/p),(R^(n))(the class of reverse Hölder weights),whereε∈(0,∞)is a constant depending only on n and the operator L,and where(2+ε/p)'denotes the Hölder conjugate exponent of 2+ε/p.Moreover,for any given q∈(2,∞),we give a sufficient condition to obtain that||■f||L_(ω)^p(R^(n);R^(n))≤C||L^(1/2)(f)||L_(ω)^p(R^(n))for any p∈(1,q)andω∈A_(p)(R^(n))∩pRH_(q/p),(R^(n)).As an application,we prove that when the coefficient matrix A that appears in L satisfies the small BMO condition,the Riesz transform∇L^(−1/2)is bounded on L_(ω)^(p)(ℝ^(n))for any given p∈(1,∞)andω∈Ap(ℝ^(n)).Furthermore,applications to the weighted L^(2)-regularity problem with the Dirichlet or the Neumann boundary condition are also given.展开更多
Objective: To estimate the presence and the quantity of endotoxin of periodontally involved root surfaces after root surface debridement.Methods: Ninety single rooted teeth with severe bone resorption were selected,wh...Objective: To estimate the presence and the quantity of endotoxin of periodontally involved root surfaces after root surface debridement.Methods: Ninety single rooted teeth with severe bone resorption were selected,which were scheduled for extraction.The teeth were randomly assigned into 3 groups.The teeth in the first group were served as control and they did not receive any debridement.The teeth in the second group were scaled and root planned with Gracey curettes.The teeth in the third group were debrided with the new ultrasonic device VectorTM-system(Dürr Dental).The endotoxin concentrations before and after debridement were assessed by Limulus Amebocyte Lysat(LAL).Results: The concentration of endotoxin of periodontally involved teeth in the control group was 0.825 EU/ml.Scaling and root planning resulted in a significant reduction of the values as follows: Gracey curettes 0.240 EU/ml,VectorTM-system 0.184 EU/ml.Conclusion: Scaling and root planning leads to obvious reduction of the endotoxin on periodontally involved root surfaces and VectorTM-system is comparatively more effective than Gracey curettes.展开更多
SHIMA SEIKI leads the world's flat knitting industry with a rich history of technological innovation.Having invented the world's first Digital Stitch Control System and seam-free WHOLEGARMENT knitting,they are...SHIMA SEIKI leads the world's flat knitting industry with a rich history of technological innovation.Having invented the world's first Digital Stitch Control System and seam-free WHOLEGARMENT knitting,they are also known as an industry pioneer.Now,with original hardware,software and research in new materials,SHIMA SEIKI enters the field of technical textiles.展开更多
Two-year-old Scots pine (Pinus sylvstris var.mongolica) seedlings were treated with Pt mycorrhiza powder, ABT root-growing powder, HRC water-absorbing agent and high-yield powder, and planted on the sandy land in Bali...Two-year-old Scots pine (Pinus sylvstris var.mongolica) seedlings were treated with Pt mycorrhiza powder, ABT root-growing powder, HRC water-absorbing agent and high-yield powder, and planted on the sandy land in Balinyouqi, Inner Mongolia (180°12′13″E and 43°13′05″N). The effect and function of these biological agents on survival rate of seedlings were tested and analyzed by measuring the fine root growth and gross root growth. The results showed that the survival rates of the seedlings treated with Pt3, ABT, and HRC biological agents increased by 29.3%, 23.6%, and 16%, respectively. The regression analysis revealed that the length of fine roots (<2 mm) was positively correlated with seedling survival rate, which means that the Pt3 powder, ABT foot-growing powder and HRC water-absorbing powder increased the survival rates of the seedlings by promoting the growth of fine roots. Keywords Biological agents - Pinus sylvstris var.mongolica - Sandy soil - Roots - Survival rate CLC number S723.1 - S791.253 Document code A Foundation item: This article was supported by the National Natural Science Foundation of China (No. 39970627).Biography: TANG Feng-de (1967-), male, Ph. Doctor in Institute of Applied Ecology. Chinese Academy of Sciences, Shenyang 110016, P. R. China.Responsible editor: Zhu Hong展开更多
The impacts of elevated atmospheric CO2 concentrations (500 靘olmol-1and 700 靘olmol-1) on total soil respiration and the contribution of root respiration of Pinus koraiensis seedlings were investigated from May to Oc...The impacts of elevated atmospheric CO2 concentrations (500 靘olmol-1and 700 靘olmol-1) on total soil respiration and the contribution of root respiration of Pinus koraiensis seedlings were investigated from May to October in 2003 at the Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, Jilin Province, China. After four growing seasons in top-open chambers exposed to elevated CO2, the total soil respiration and roots respiration of Pinus koraiensis seedlings were measured by a LI-6400-09 soil CO2 flux chamber. Three PVC cylinders in each chamber were inserted about 30 cm into the soil in-stantaneously to terminate the supply of current photosynthates from the tree canopy to roots for separating the root respiration from total soil respiration. Soil respirations both inside and outside of the cylinders were measured on June 16, August 20 and October 8, respectively. The results indicated that: there was a marked diurnal change in air temperature and soil temperature at depth of 5 cm on June 16, the maximum of soil temperature at depth of 5 cm lagged behind that of air temperature, no differences in temperature between treatments were found (P>0.05). The total soil respiration and soil respiration with roots severed showed strong diurnal and seasonal patterns. There was marked difference in total soil respiration and soil respiration with roots severed between treatments (P<0.01); Mean total soil respiration and contribution of root under different treatments were 3.26, 4.78 and 1.47 靘olm 2s-1, 11.5%, 43.1% and 27.9% on June 16, August 20 and October 8, respectively.展开更多
On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged sta...On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (?<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree. Keywords Root diameter classes - Variance analysis - Root extinction coefficient - Vertical distribution characters - Site conditions - Loess Plateau CLC number S792.27.01 Document code A Foundation Item: This research was supported by National Natural Science Foundation of China (30371150 and 40371075).Biography: LI Peng (1974-) male, post: Ph. D. in Northwest Scientific & Technological University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, P. R. China. Tel: 029-82312651.Responsible editor: Chai Ruihal展开更多
基金supported by the project of public benefits in China(No.201503221)the open fund in the Institute of Root Biology,Yangtze University
文摘Plant roots play important roles in acquisition of water and nutrients, storage, anchoring, transport, and symbiosis with soil microorganisms, thus quantitative researches on root developmental processes are essential to understand root functions and root turnover in ecosystems,and at the same time such researches are the most difficult because roots are hidden underground. Therefore, how to investigate efficiently root functions and root dynamics is the core aspect in underground ecology. In this article, we reviewed some experimental methods used in root researches on root development and root system architecture, and summarized the advantages and shortages of these methods. Based on the analyses, we proposed three new ways to more understand root processes：（1） new experimental materials for root development;（2） a new observatory system comprised of multiple components, including many observatory windows installed in field, analysis software,and automatic data transport devices;（3） new techniques used to analyze quantitatively functional roots.
基金supported by the National Natural Science Foundation of China(32071749)。
文摘Root tips are the main components of absorptive fine roots,but their seasonal dynamics and relationship to environmental factors remain unclear due to the difficulties in methodology.In this study,we explored the temporal patterns of root-tip production and mortality in monoculture plantations of five temperate tree species at a common site in northeastern China,and identified the general environmental controls on such processes.We made monthly in-situ assessments of root tip length(RTL)production and mortality in two hardwood and three coniferous species with a minirhizotron(MR)method during the growing seasons of 2008 and 2009.Air temperature,rainfall,soil temperature and water content at 10 cm depth were determined concurrently.RTL production in all species exhibited consistent peaks in summer(June–August)in two growing seasons.RTL mortality showed substantial interannual and interspecific variability,with peaks in autumn and winter in 2008,but various patterns in 2009.RTL production positively correlated with monthly soil and air temperature across all species,and with monthly rainfall in three coniferous species.However,there was no significant correlation between RTL production and soil water content.By contrast,RTL mortality was weakly related to environmental factors,showing positive correlations with soil temperature in Korean spruce,and with rainfall in Korean pine and Korean spruce.Our findings suggest that the seasonal patterns of RTL production are convergent across the five temperate tree species due to the overlapped distribution of heat and rainfall,which can conduce roots to maximizing the acquisition of nutrient resources in the soil.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(U2006215)the National Natural Science Foundation of China(31770761)+2 种基金the Shandong Key Laboratory of Coastal Environmental Processes,YICCAS(2019SDHADKFJJ16)the Natural Science Foundation of Shangdong Province(ZR2020QD003)Taishan Scholars Program of Shandong Province,China(TSQN201909152)。
文摘To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.
基金part of the Liaoning Provincial Department of Education project LJKZ0684supported by the National Natural Science Foundation of China (31800542)
文摘The addition of ectomycorrhizal fungi(ECMF),beneficial rhizosphere microorganisms,to the soil can pro-mote plant growth and resistance.Here,Populus davidi-ana×Populus bolleana tissue culture seedlings were grown for 3 months in soils inoculated with one of the species,then seedlings were assessed for mycorrhizal colonization rate and growth,physiological and root traits.Suillus luteus and Populus involutus each formed ectomycorrhizal associa-tions with the seedlings.Seedling height,ground diameter,biomass,and leaf area were significantly greater after treat-ment with ECMF than in the non-inoculated controls.Treat-ment improved all physiological and root variables assessed(chlorophylls and carotenoids,cellulose,and soluble sugars and proteins;root length,surface area,projected area,mean diameter,volume,number of root tips).Seedlings inocu-lated with S.luteus outperformed those inoculated with P.involutus.
基金supported by a grant from the Natural Science Foundation of China(41271044)
文摘To characterize effects of plant roots on preferential flow（PF）,we measured root length density（RLD）and root biomass（RB） in Jiufeng National Forest Park,Beijing,China.Comparisons were made for RLD and RB between soil preferential pathways and soil matrices.RLD and RB declined with the increasing soil depth（0–10,10–20,20–30,30–40,40–50,50–60 cm） in all experimental plots.RLD was greater in soil preferential pathways than in the surrounding soil matrix and was 69.5,75.0 and72.2 % for plant roots of diameter（d） ／1,1 ／ d ／ 3 and3 ／ d ／ 5 mm,respectively.Fine root systems had the most pivotal influence on soil preferential flow in this forest ecosystem.In all experimental plots,RB content was the sum of RB from soil preferential pathways and the soil matrix in each soil depth.With respect to 6 soil depth gradient（0–10,10–20,20–30,30–40,40–50,50–60 cm） in each plot,the number of soil depth gradient that RB content was greater in soil preferential pathways than in the soil matrix was characterized,and the proportion was68.2 % in all plots.
基金supported by the National Natural Science Foundation of China(31830015,31901302).
文摘Background:Inputs of above-and belowground litter into forest soils are changing at an unprecedented rate due to continuing human disturbances and climate change.Microorganisms drive the soil carbon(C)cycle,but the roles of above-and belowground litter in regulating the soil microbial community have not been evaluated at a global scale.Methods:Here,we conducted a meta-analysis based on 68 aboveground litter removal and root exclusion studies across forest ecosystems to quantify the roles of above-and belowground litter on soil microbial community and compare their relative importance.Results:Aboveground litter removal significantly declined soil microbial biomass by 4.9%but root exclusion inhibited it stronger,up to 11.7%.Moreover,the aboveground litter removal significantly raised fungi by 10.1%without altering bacteria,leading to a 46.7%increase in the fungi-to-bacteria(F/B)ratio.Differently,root exclusion significantly decreased the fungi by 26.2%but increased the bacteria by 5.7%,causing a 13.3%decrease in the F/B ratio.Specifically,root exclusion significantly inhibited arbuscular mycorrhizal fungi,ectomycorrhizal fungi,and actinomycetes by 22.9%,43.8%,and 7.9%,respectively.The negative effects of aboveground litter removal on microbial biomass increased with mean annual temperature and precipitation,whereas that of root exclusion on microbial biomass did not change with climatic factors but amplified with treatment duration.More importantly,greater effects of root exclusion on microbial biomass than aboveground litter removal were consistent across diverse forest biomes(expect boreal forests)and durations.Conclusions:These data provide a global evidence that root litter inputs exert a larger control on microbial biomass than aboveground litter inputs in forest ecosystems.Our study also highlights that changes in above-and belowground litter inputs could alter soil C stability differently by shifting the microbial community structure in the opposite direction.These findings are useful for predicting microbe-mediated C processes in response to changes in forest management or climate.
基金This work was supported by the National Natural Science Foundation of China(No.U1732142).
文摘Most detectors for nuclear physics experiments are detector arrays composed of numerous units.Testing each detector unit is a major part of the research work on detector arrays.To save time and simplify the research process,a ROOT-based detector test system was designed for detector unit testing.The test system is a general pur-pose and expandable software system that can support most of the hardware devices in the market.Users can easily build a complete detector test system using the required hardware devices.The software is based on the ROOT framework and is operated on the Linux platform.The software of the test system consists of four parts:the controller,data acquisition(DAQ),high-voltage power supply,and online monitoring and analysis.In addition,a user-friendly graphical user interface(GUI)was designed for user convenience.Moreover,the online analysis func-tion of the software can implement automatic peak searching and spectrum fitting for different radioactive sources,and the results under different conditions can be shown automatically.The completion of the test system could greatly simplify the development process of the detector.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11061019 and 10962004)the Chunhui Program of Ministry of Education of China (Grant No. Z2009-1-01010)+1 种基金the Natural Science Foundation of Inner Mongolia, China(Grant Nos. 2010MS0110 and 2009BS0101)the Cultivation of Innovative Talent of ‘211 Project’ of Inner Mongolia University
文摘In this paper, we consider the eigenvalue problem of a class of fourth-order operator matrices appearing in mechan- ics, including the geometric multiplicity, algebraic index, and algebraic multiplicity of the eigenvalue, the symplectic orthogonality, and completeness of eigen and root vector systems. The obtained results are applied to the plate bending problem.
基金provided by the National Key R&D Program of China(2023YFD2200904)the Scientific Research Project of Anhui Province(2022AH050873)+1 种基金the State Key Laboratory of Subtropical Silviculture(SKLSS-KF2023-08)the Anhui Provincial Science and Technology Special Project(202204c06020014)。
文摘Understanding the drivers of variations in fine root lifespan is key to informing nutrient cycling and productivity in terrestrial ecosystems.However,the general patterns and determinants of forest fine root lifespan at the global scale are still limited.We compiled a dataset of 421 fine root lifespan observations from 76 tree species globally to assess phylogenetic signals among species,explored relationships between fine root lifespan and biotic and abiotic factors,and quantified the relative importance of phylogeny,root system structure and functions,climatic and edaphic factors in driving global fine root lifespan variations.Overall,fine root lifespan showed a clear phylogenetic signal,with gymnosperms having a longer fine root lifespan than angiosperms.Fine root lifespan was longer for evergreens than deciduous trees.Ectomycorrhizal(ECM)plants had an extended fine root lifespan than arbuscular mycorrhizal(AM)plants.Among different climatic zones,fine root lifespan was the longest in the boreal zone,while it did not vary between the temperate and tropical zone.Fine root lifespan increased with soil depth and root order.Furthermore,the analysis of relative importance indicated that phylogeny was the strongest driver influencing the variation in forest fine root lifespan,followed by soil clay content,root order,mean annual temperature,and soil depth,while other environmental factors and root traits exerted weaker effects.Our results suggest that the global pattern of fine root lifespan in forests is shaped by the interplay of phylogeny,root traits and environmental factors.These findings necessitate accurate representations of tree evolutionary history in earth system models to predict fine root longevity and its responses to global changes.
基金supported by National Natural Science Foundation of China(No.32071777)the Fundamental Research Funds for the Central Universities(2572021BA04).
文摘Plant stoichiometry and nutrient allocation may reflect adaptation strategies to environmental nutrient changes.Fire,as a major disturbance in forests,mediates soil nutrient availability that may influence plant nutrient dynamics.However,plant–soil stoichiometric allocation strategies during different post-fire periods and the effects of soil,enzymes,and microbial biomass on plant stoichiom-etry are largely unknown.The pioneer tree species Betula platyphylla in burnt forests of northern China was the object of this study,and severely burned areas selected with dif-ferent fire years.Nearby unburned areas acted as a control.Carbon(C),nitrogen(N),and phosphorus(P)contents in leaves,branches,and fine roots and rhizosphere soil,C-,N-and P-acquiring enzyme activities were examined.Microbial biomass C,N,and P were measured,and factors influenc-ing C:N:P stoichiometry of plants during the burned area restoration were explored.Our results show that C and N contents in leaves increased with time since fire,while C and P in branches and C,N and P in fine roots decreased.Activities of C-,N-,and P-acquiring enzymes and microbial biomass N increased with time since fire.Redundancy analy-sis showed that changes in soil N-acquiring enzyme activity,microbial biomass C,and N had significant effects on plant ecological stoichiometry.These results show a significant flexibility in plant nutrient element allocation strategies and C:N:P stoichiometric characteristics.Soil extracellular enzyme activity drives the changes in stoichiometry during the process of post-fire restoration.
基金part of the Research Training Group 2300,funded by the German research funding organization (Deutsche Forschungsgemeinschaft-DFG) Grand id:316045089
文摘Site conditions and species identity have a combined effect on fine root growth of trees in pure and mixed stands.However,mechanisms that may contribute to this effect are rarely studied,even though they are essential to assess the potential of species to cope with climate change.This study examined fine root overlap and the linkage between fine root and stem growth of European beech(Fagus sylvatica)growing in pure and mixed stands with Douglas fir(Pseudotsuga menziesii)or Norway spruce(Picea abies)at two different study sites in northwestern Germany.The study sites represented substantially different soil and climate conditions.At each site,three stands,and at each stand,three pairs of trees were studied.In the pure beech stand,the pairs consisted of two beech trees,while in the mixed stands each pair was composed of a beech tree and a conifer.Between each pair,three evenly spaced soil cores were taken monthly throughout the growing season.In the pure beech stands,microsatellite markers were used to assign the fine roots to individual trees.Changes in stem diameter of beech were quantified and then upscaled to aboveground wood productivity with automatic high-resolution circumference dendrometers.We found that fine root overlap between neighboring trees varied independently of the distance between the paired trees or the stand types(pure versus mixed stands),indicating that there was no territorial competition.Aboveground wood productivity(wood NPP)and fine root productivity(root NPP)showed similar unimodal seasonal patterns,peaking in June.However,this pattern was more distinct for root NPP,and root NPP started earlier and lasted longer than wood NPP.The influence of site conditions on the variation in wood and root NPP of beech was stronger than that of stand type.Wood NPP was,as expected,higher at the richer site than at the poorer site.In contrast,root NPP was higher at the poorer than at the richer site.We concluded that beech can respond to limited resources not only above-but also belowground and that the negative relationship between above-and belowground growth across the study sites suggests an‘optimal partitioning’of growth under stress.
基金supported by the Key Project of Gansu Provincial National Science Foundation(23JRRA1022)the National Natural Science Foundation of China(12071431)+1 种基金the Fundamental Research Funds for the Central Universities(lzujbky-2021-ey18)the Innovative Groups of Basic Research in Gansu Province(22JR5RA391).
文摘Let n≥2 and let L be a second-order elliptic operator of divergence form with coefficients consisting of both an elliptic symmetric part and a BMO anti-symmetric part in ℝ^(n).In this article,we consider the weighted Kato square root problem for L.More precisely,we prove that the square root L^(1/2)satisfies the weighted L^(p)estimates||L^(1/2)(f)||L_(ω)^p(R^(n))≤C||■f||L_(ω)^p(R^(n);R^(n))for any p∈(1,∞)andω∈Ap(ℝ^(n))(the class of Muckenhoupt weights),and that||■f||L_(ω)^p(R^(n);R^(n))≤C||L^(1/2)(f)||L_(ω)^p(R^(n))for any p∈(1,2+ε)andω∈Ap(ℝ^(n))∩RH_(2+ε/p),(R^(n))(the class of reverse Hölder weights),whereε∈(0,∞)is a constant depending only on n and the operator L,and where(2+ε/p)'denotes the Hölder conjugate exponent of 2+ε/p.Moreover,for any given q∈(2,∞),we give a sufficient condition to obtain that||■f||L_(ω)^p(R^(n);R^(n))≤C||L^(1/2)(f)||L_(ω)^p(R^(n))for any p∈(1,q)andω∈A_(p)(R^(n))∩pRH_(q/p),(R^(n)).As an application,we prove that when the coefficient matrix A that appears in L satisfies the small BMO condition,the Riesz transform∇L^(−1/2)is bounded on L_(ω)^(p)(ℝ^(n))for any given p∈(1,∞)andω∈Ap(ℝ^(n)).Furthermore,applications to the weighted L^(2)-regularity problem with the Dirichlet or the Neumann boundary condition are also given.
文摘Objective: To estimate the presence and the quantity of endotoxin of periodontally involved root surfaces after root surface debridement.Methods: Ninety single rooted teeth with severe bone resorption were selected,which were scheduled for extraction.The teeth were randomly assigned into 3 groups.The teeth in the first group were served as control and they did not receive any debridement.The teeth in the second group were scaled and root planned with Gracey curettes.The teeth in the third group were debrided with the new ultrasonic device VectorTM-system(Dürr Dental).The endotoxin concentrations before and after debridement were assessed by Limulus Amebocyte Lysat(LAL).Results: The concentration of endotoxin of periodontally involved teeth in the control group was 0.825 EU/ml.Scaling and root planning resulted in a significant reduction of the values as follows: Gracey curettes 0.240 EU/ml,VectorTM-system 0.184 EU/ml.Conclusion: Scaling and root planning leads to obvious reduction of the endotoxin on periodontally involved root surfaces and VectorTM-system is comparatively more effective than Gracey curettes.
文摘SHIMA SEIKI leads the world's flat knitting industry with a rich history of technological innovation.Having invented the world's first Digital Stitch Control System and seam-free WHOLEGARMENT knitting,they are also known as an industry pioneer.Now,with original hardware,software and research in new materials,SHIMA SEIKI enters the field of technical textiles.
基金This article was supported by the National Natural Science Foundation of China (No. 39970627)
文摘Two-year-old Scots pine (Pinus sylvstris var.mongolica) seedlings were treated with Pt mycorrhiza powder, ABT root-growing powder, HRC water-absorbing agent and high-yield powder, and planted on the sandy land in Balinyouqi, Inner Mongolia (180°12′13″E and 43°13′05″N). The effect and function of these biological agents on survival rate of seedlings were tested and analyzed by measuring the fine root growth and gross root growth. The results showed that the survival rates of the seedlings treated with Pt3, ABT, and HRC biological agents increased by 29.3%, 23.6%, and 16%, respectively. The regression analysis revealed that the length of fine roots (<2 mm) was positively correlated with seedling survival rate, which means that the Pt3 powder, ABT foot-growing powder and HRC water-absorbing powder increased the survival rates of the seedlings by promoting the growth of fine roots. Keywords Biological agents - Pinus sylvstris var.mongolica - Sandy soil - Roots - Survival rate CLC number S723.1 - S791.253 Document code A Foundation item: This article was supported by the National Natural Science Foundation of China (No. 39970627).Biography: TANG Feng-de (1967-), male, Ph. Doctor in Institute of Applied Ecology. Chinese Academy of Sciences, Shenyang 110016, P. R. China.Responsible editor: Zhu Hong
文摘The impacts of elevated atmospheric CO2 concentrations (500 靘olmol-1and 700 靘olmol-1) on total soil respiration and the contribution of root respiration of Pinus koraiensis seedlings were investigated from May to October in 2003 at the Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, Jilin Province, China. After four growing seasons in top-open chambers exposed to elevated CO2, the total soil respiration and roots respiration of Pinus koraiensis seedlings were measured by a LI-6400-09 soil CO2 flux chamber. Three PVC cylinders in each chamber were inserted about 30 cm into the soil in-stantaneously to terminate the supply of current photosynthates from the tree canopy to roots for separating the root respiration from total soil respiration. Soil respirations both inside and outside of the cylinders were measured on June 16, August 20 and October 8, respectively. The results indicated that: there was a marked diurnal change in air temperature and soil temperature at depth of 5 cm on June 16, the maximum of soil temperature at depth of 5 cm lagged behind that of air temperature, no differences in temperature between treatments were found (P>0.05). The total soil respiration and soil respiration with roots severed showed strong diurnal and seasonal patterns. There was marked difference in total soil respiration and soil respiration with roots severed between treatments (P<0.01); Mean total soil respiration and contribution of root under different treatments were 3.26, 4.78 and 1.47 靘olm 2s-1, 11.5%, 43.1% and 27.9% on June 16, August 20 and October 8, respectively.
基金This research was supported by National Natural Science Foundation of China (30371150 and 40371075).
文摘On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (?<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree. Keywords Root diameter classes - Variance analysis - Root extinction coefficient - Vertical distribution characters - Site conditions - Loess Plateau CLC number S792.27.01 Document code A Foundation Item: This research was supported by National Natural Science Foundation of China (30371150 and 40371075).Biography: LI Peng (1974-) male, post: Ph. D. in Northwest Scientific & Technological University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, P. R. China. Tel: 029-82312651.Responsible editor: Chai Ruihal
