Aims In this study,we examined the effects of Solidago altissima(hereafter Solidago)and two species in the genus Verbesina,Verbesina virginica and Verbesina occidentalis(hereafter Verbesina),on the structure of an old...Aims In this study,we examined the effects of Solidago altissima(hereafter Solidago)and two species in the genus Verbesina,Verbesina virginica and Verbesina occidentalis(hereafter Verbesina),on the structure of an old-field plant community and establishment by an invasive plant species,Lespedeza cuneata(hereafter Lespedeza).Methods We removed Solidago,Verbesina and both Solidago and Verbesina from 4m^(-2)plots in an intact old-field community during two growing seasons.We then quantified the effects of these removals on richness,evenness,diversity and composition of the subdominant plant community.We also measured the total aboveground biomass and the aboveground biomass of the subdominant community.To assess how these removals affected establishment by Lespedeza,we planted 20 seeds in each plot and tracked seedling emergence and survival for one growing season.Important Findings Subdominant community evenness and Shannon diversity were higher in plots from which Solidago and Verbesina were removed relative to control plots.However,there were no effects of dominant species removal on species richness or composition of the subdominant community.Total aboveground biomass was not affected by dominant species removal,suggesting that the community of subdominant species exhibited compensation.In fact,subdominant community biomass was greater when Solidago,but not Verbesina,was removed.Light availability was also greater in plots where Solidago was removed relative to control plots throughout the growing season.In addition,removal of dominant species,in particular Solidago,indirectly reduced the emergence,but not survival,of Lespedeza seedlings by directly promoting subdominant community biomass.Taken together,our results suggest that dominant old-field plant species affect subdominant community structure and indirectly promote establishment by Lespedeza.展开更多
To achieve the Paris Agreement,China pledged to become“Carbon Neutral”by the 2060s.In addition to massive decarbonization,this would require significant changes in ecosystems toward negative CO_(2)emissions.The abil...To achieve the Paris Agreement,China pledged to become“Carbon Neutral”by the 2060s.In addition to massive decarbonization,this would require significant changes in ecosystems toward negative CO_(2)emissions.The ability of coastal blue carbon ecosystems(BCEs),including mangrove,salt marsh,and seagrass meadows,to sequester large amounts of CO_(2)makes their conservation and restoration an important“nature-based solution(NbS)”for climate adaptation and mitigation.In this review,we examine how BCEs in China can contribute to climate mitigation.On the national scale,the BCEs in China store up to 118 Tg C across a total area of 1,440,377 ha,including over 75%as unvegetated tidal flats.The annual sedimental C burial of these BCEs reaches up to 2.06 Tg C year^(−1),of which most occurs in salt marshes and tidal flats.The lateral C flux of mangroves and salt marshes contributes to 1.17 Tg C year^(−1)along the Chinese coastline.Conservation and restoration of BCEs benefit climate change mitigation and provide other ecological services with a value of$32,000 ha^(−1)year^(−1).The potential practices and technologies that can be implemented in China to improve BCE C sequestration,including their constraints and feasibility,are also outlined.Future directions are suggested to improve blue carbon estimates on aerial extent,carbon stocks,sequestration,and mitigation potential.Restoring and preserving BCEs would be a cost-effective step to achieve Carbon Neutral by 2060 in China despite various barriers that should be removed.展开更多
An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet w...An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(RF)probe was employed in the study.The magnetic field was changed to set the resonance frequency of each nucleus to the fixed RF probe frequency of 33.7 MHz.Two cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were interrogated.One cell was pristine,and one was charged to a cell voltage of 4.2 V.The results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion batteries.These methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.展开更多
We explore the use of the parallel-plate resonator for the study of thin cuboid samples over a wide range of magnetic resonance frequencies.The parallel-plate resonator functions at frequencies from tens to hundreds o...We explore the use of the parallel-plate resonator for the study of thin cuboid samples over a wide range of magnetic resonance frequencies.The parallel-plate resonator functions at frequencies from tens to hundreds of MHz.Seven parallel-plate resonators are presented and discussed in a frequency range from 8 to 500 MHz.Magnetic resonance experiments were performed on both horizontal and vertical bore magnet systems with lithium and hydrogen nuclei.Parallel-plate radiofrequency(RF)probes are easy to build and easy to optimize.Experiments and simulations showed good sensitivity of the parallel-plate RF probe geometry with a small decrease in sensitivity at higher frequencies.展开更多
Identified particle elliptic flow results are presented for the Au+Au reaction at S_(NN)^(1/2)=200GeV as a function of transverse momentum and pseudorapidity.Data at pseudorapiditiesη≈0,1,and 3.4 were obtained using...Identified particle elliptic flow results are presented for the Au+Au reaction at S_(NN)^(1/2)=200GeV as a function of transverse momentum and pseudorapidity.Data at pseudorapiditiesη≈0,1,and 3.4 were obtained using the two BRAHMS spectrometers.Differential v_2(η,p_t)values for a given particle type are found to be essentially constant over the covered pseudorapidity range,in contrast to the integral v_2 values which have previously been observed to decrease at forward rapidities.A softening of the particle spectra at forward angles is found to account for at least part of the integral v_2 falloff.The data are found to be consistent with existing constituent quark scaling systematics.展开更多
Aims Biodiversity is often positively related to the capacity of an ecosystem to provide multiple functions simultaneously(i.e.multifunctionality).However,there is some controversy over whether biodiversity–multifunc...Aims Biodiversity is often positively related to the capacity of an ecosystem to provide multiple functions simultaneously(i.e.multifunctionality).However,there is some controversy over whether biodiversity–multifunctionality relationships depend on the number of functions considered.Particularly,investigators have documented contrasting findings that the effects of biodiversity on ecosystem multifunctionality do not change or increase with the number of ecosystem functions.Here,we provide some clarity on this issue by examining the statistical underpinnings of different multifunctionality metrics.Methods We used simulations and data from a variety of empirical studies conducted across spatial scales(from local to global)and biomes(temperate and alpine grasslands,forests and drylands).We revisited three methods to quantify multifunctionality including the averaging approach,summing approach and threshold-based approach.Important Findings Biodiversity–multifunctionality relationships either did not change or increased as more functions were considered.These results were best explained by the statistical underpinnings of the averaging and summing multifunctionality metrics.Specifically,by averaging the individual ecosystem functions,the biodiversity–multifunctionality relationships equal the population mean of biodiversity-single function relationships,and thus will not change with the number of functions.Likewise,by summing the individual ecosystem functions,the strength of biodiversity–multifunctionality relationships increases as the number of functions increased.We proposed a scaling standardization method by converting the averaging or summing metrics into a scaling metric,which would make comparisons among different biodiversity studies.In addition,we showed that the range-relevant standardization can be applied to the threshold-based approach by solving for the mathematical artefact of the approach(i.e.the effects of biodiversity may artificially increase with the number of functions considered).Our 展开更多
Aims Decades of empirical work have demonstrated how dominant plant species and nitrogen fertilization can influence the structure and function of plant communities.More recent studies have examined the interplay betw...Aims Decades of empirical work have demonstrated how dominant plant species and nitrogen fertilization can influence the structure and function of plant communities.More recent studies have examined the interplay between these factors,but few such studies use an explicit trait-based framework.In this study,we use an explicit trait-based approach to identify potential mechanisms for community-level responses and to test ecological niche theory.Methods We experimentally manipulated plant communities(control,−dom-inant species,−random biomass)and nitrogen(N)inputs(control,+organic N,+inorganic N)in a fully factorial design.We predicted that traits related to plants’ability to take up different forms of soil N would differ between dominant and subordinate species,resulting in interactive effects of dominant species loss and N fertilization on plant community structure and function.The study took place in a montane meadow in the Rocky Mountains,Colorado,USA.Important Findings After four years,the plant community in removal plots converged toward a species composition whose leaf and root functional traits resembled those of the previously removed dominant species.Ecosystem productivity generally increased with N addition:soil carbon efflux was~50%greater when either form of N was added,while inorganic N addition increased aboveground biomass pro-duction by~60%relative to controls.The increase in production was mediated by increased average height,leaf mass:area ratio and leaf dry matter content in plant communities to which we added inorganic N.Contrary to our predictions,there were no interactive effects of N fertilization and dominant species loss on plant com-munity structure or ecosystem function.The plant community com-position in this study exhibited resistance to soil N addition and,given the functional convergence we observed,was resilient to spe-cies loss.Together,our results indicate that the ability of species to compensate functionally for species loss confers resilience and maintains diversity in mon展开更多
文摘Aims In this study,we examined the effects of Solidago altissima(hereafter Solidago)and two species in the genus Verbesina,Verbesina virginica and Verbesina occidentalis(hereafter Verbesina),on the structure of an old-field plant community and establishment by an invasive plant species,Lespedeza cuneata(hereafter Lespedeza).Methods We removed Solidago,Verbesina and both Solidago and Verbesina from 4m^(-2)plots in an intact old-field community during two growing seasons.We then quantified the effects of these removals on richness,evenness,diversity and composition of the subdominant plant community.We also measured the total aboveground biomass and the aboveground biomass of the subdominant community.To assess how these removals affected establishment by Lespedeza,we planted 20 seeds in each plot and tracked seedling emergence and survival for one growing season.Important Findings Subdominant community evenness and Shannon diversity were higher in plots from which Solidago and Verbesina were removed relative to control plots.However,there were no effects of dominant species removal on species richness or composition of the subdominant community.Total aboveground biomass was not affected by dominant species removal,suggesting that the community of subdominant species exhibited compensation.In fact,subdominant community biomass was greater when Solidago,but not Verbesina,was removed.Light availability was also greater in plots where Solidago was removed relative to control plots throughout the growing season.In addition,removal of dominant species,in particular Solidago,indirectly reduced the emergence,but not survival,of Lespedeza seedlings by directly promoting subdominant community biomass.Taken together,our results suggest that dominant old-field plant species affect subdominant community structure and indirectly promote establishment by Lespedeza.
基金CAS Project for Young Scientists in Basic Research(YSBR-037)ANSO collaborative research(ANSO-CR-KP-2022-11)+4 种基金National Natural Science Foundation of China(U2106209,42141003,42141016,and 32171594)Guangdong Basic and Applied Basic Research Foundation(2021B1515020011 and 2021B1212110004)CAS Youth Innovation Promotion Association(2021347)National Forestry and Grassland Administration Youth Talent Support Program(2020BJ003)R&D program of Guangdong Provincial Department of Science and Technology(2018B030324003).
文摘To achieve the Paris Agreement,China pledged to become“Carbon Neutral”by the 2060s.In addition to massive decarbonization,this would require significant changes in ecosystems toward negative CO_(2)emissions.The ability of coastal blue carbon ecosystems(BCEs),including mangrove,salt marsh,and seagrass meadows,to sequester large amounts of CO_(2)makes their conservation and restoration an important“nature-based solution(NbS)”for climate adaptation and mitigation.In this review,we examine how BCEs in China can contribute to climate mitigation.On the national scale,the BCEs in China store up to 118 Tg C across a total area of 1,440,377 ha,including over 75%as unvegetated tidal flats.The annual sedimental C burial of these BCEs reaches up to 2.06 Tg C year^(−1),of which most occurs in salt marshes and tidal flats.The lateral C flux of mangroves and salt marshes contributes to 1.17 Tg C year^(−1)along the Chinese coastline.Conservation and restoration of BCEs benefit climate change mitigation and provide other ecological services with a value of$32,000 ha^(−1)year^(−1).The potential practices and technologies that can be implemented in China to improve BCE C sequestration,including their constraints and feasibility,are also outlined.Future directions are suggested to improve blue carbon estimates on aerial extent,carbon stocks,sequestration,and mitigation potential.Restoring and preserving BCEs would be a cost-effective step to achieve Carbon Neutral by 2060 in China despite various barriers that should be removed.
基金BJB thanks the Canada Chairs program for a Research Chair in MRI of Materials[950e230894]an NSERC Discovery Grant[2015-6122]GRG thanks NSERC for a Discovery Grant[RGPIN-2017-06095].
文摘An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(RF)probe was employed in the study.The magnetic field was changed to set the resonance frequency of each nucleus to the fixed RF probe frequency of 33.7 MHz.Two cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were interrogated.One cell was pristine,and one was charged to a cell voltage of 4.2 V.The results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion batteries.These methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.
基金the Canada Chairs program for a Research Chair in MRI of Materials[950-230894]an NSERC Discovery Grant[2015-6122].GRG thanks NSERC for a Discovery Grant[RGPIN-2017-06095].
文摘We explore the use of the parallel-plate resonator for the study of thin cuboid samples over a wide range of magnetic resonance frequencies.The parallel-plate resonator functions at frequencies from tens to hundreds of MHz.Seven parallel-plate resonators are presented and discussed in a frequency range from 8 to 500 MHz.Magnetic resonance experiments were performed on both horizontal and vertical bore magnet systems with lithium and hydrogen nuclei.Parallel-plate radiofrequency(RF)probes are easy to build and easy to optimize.Experiments and simulations showed good sensitivity of the parallel-plate RF probe geometry with a small decrease in sensitivity at higher frequencies.
基金Supported by the Office of Nuclear Physics of the U.S.Department of Energy under contract DE-FG03-96ER40981
文摘Identified particle elliptic flow results are presented for the Au+Au reaction at S_(NN)^(1/2)=200GeV as a function of transverse momentum and pseudorapidity.Data at pseudorapiditiesη≈0,1,and 3.4 were obtained using the two BRAHMS spectrometers.Differential v_2(η,p_t)values for a given particle type are found to be essentially constant over the covered pseudorapidity range,in contrast to the integral v_2 values which have previously been observed to decrease at forward rapidities.A softening of the particle spectra at forward angles is found to account for at least part of the integral v_2 falloff.The data are found to be consistent with existing constituent quark scaling systematics.
基金supported by the National Natural Science Foundation of China(31600428)to X.J.a Semper Ardens grant from Carlsberg Foundation to N.J.S.F.T.M.the global drylands dataset were supported by the European Research Council(ERC Grant Agreements 242658[BIOCOM]and 647038[BIODESERT]).
文摘Aims Biodiversity is often positively related to the capacity of an ecosystem to provide multiple functions simultaneously(i.e.multifunctionality).However,there is some controversy over whether biodiversity–multifunctionality relationships depend on the number of functions considered.Particularly,investigators have documented contrasting findings that the effects of biodiversity on ecosystem multifunctionality do not change or increase with the number of ecosystem functions.Here,we provide some clarity on this issue by examining the statistical underpinnings of different multifunctionality metrics.Methods We used simulations and data from a variety of empirical studies conducted across spatial scales(from local to global)and biomes(temperate and alpine grasslands,forests and drylands).We revisited three methods to quantify multifunctionality including the averaging approach,summing approach and threshold-based approach.Important Findings Biodiversity–multifunctionality relationships either did not change or increased as more functions were considered.These results were best explained by the statistical underpinnings of the averaging and summing multifunctionality metrics.Specifically,by averaging the individual ecosystem functions,the biodiversity–multifunctionality relationships equal the population mean of biodiversity-single function relationships,and thus will not change with the number of functions.Likewise,by summing the individual ecosystem functions,the strength of biodiversity–multifunctionality relationships increases as the number of functions increased.We proposed a scaling standardization method by converting the averaging or summing metrics into a scaling metric,which would make comparisons among different biodiversity studies.In addition,we showed that the range-relevant standardization can be applied to the threshold-based approach by solving for the mathematical artefact of the approach(i.e.the effects of biodiversity may artificially increase with the number of functions considered).Our
文摘Aims Decades of empirical work have demonstrated how dominant plant species and nitrogen fertilization can influence the structure and function of plant communities.More recent studies have examined the interplay between these factors,but few such studies use an explicit trait-based framework.In this study,we use an explicit trait-based approach to identify potential mechanisms for community-level responses and to test ecological niche theory.Methods We experimentally manipulated plant communities(control,−dom-inant species,−random biomass)and nitrogen(N)inputs(control,+organic N,+inorganic N)in a fully factorial design.We predicted that traits related to plants’ability to take up different forms of soil N would differ between dominant and subordinate species,resulting in interactive effects of dominant species loss and N fertilization on plant community structure and function.The study took place in a montane meadow in the Rocky Mountains,Colorado,USA.Important Findings After four years,the plant community in removal plots converged toward a species composition whose leaf and root functional traits resembled those of the previously removed dominant species.Ecosystem productivity generally increased with N addition:soil carbon efflux was~50%greater when either form of N was added,while inorganic N addition increased aboveground biomass pro-duction by~60%relative to controls.The increase in production was mediated by increased average height,leaf mass:area ratio and leaf dry matter content in plant communities to which we added inorganic N.Contrary to our predictions,there were no interactive effects of N fertilization and dominant species loss on plant com-munity structure or ecosystem function.The plant community com-position in this study exhibited resistance to soil N addition and,given the functional convergence we observed,was resilient to spe-cies loss.Together,our results indicate that the ability of species to compensate functionally for species loss confers resilience and maintains diversity in mon
