[Objective]This study was to reveal the essence of mechanism about how the alien invasive plants spread.[Method]Species niche and material/energy flow were used as basic research indicators to analyze the intrinsic me...[Objective]This study was to reveal the essence of mechanism about how the alien invasive plants spread.[Method]Species niche and material/energy flow were used as basic research indicators to analyze the intrinsic mechanism of alien plants invasion.[Result]Most of the invasive plants have not been explicitly defined and their effective control methods not brought forward.[Conclusion]Overrun of alien invasive plants depends on whether the niche of a species could be continuously met at spatial level.Based on this we put forward corresponding control measures,proposed an assumption to establish a cylinder-network model and discussed the definition of alien invasive plants.展开更多
Using seasonally collected data(2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed,we examined the spatio-temporal patterns of fish assemblages along two longitu...Using seasonally collected data(2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed,we examined the spatio-temporal patterns of fish assemblages along two longitudinal gradients to explore the effects of a large dam on fish assemblages at the watershed scale.No significant variation was observed in either species richness or assemblage structure across seasons.Species richness significantly varied according to stream order and gradient.Dam construction appeared to decrease species richness upstream substantially,while a significant decrease between gradients only occurred within fourth-order streams.Along the gradient without the large dam,fish assemblage structures presented distinct separation between two neighboring stream orders,with the exception of fourth-order versus fifth-order streams.However,the gradient disrupted by a large dam displayed the opposite pattern in the spatial variation of fish assemblages related with stream orders.Significant between-gradient differences in fish assemblage structures were only observed within fourth-order streams.Species distributions were determined by local habitat environmental factors,including elevation,substrate,water depth,current discharge,wetted width,and conductivity.Our results suggested that dam construction might alter the longitudinal pattern in fish species richness and assemblage structure in Qingyi Stream,despite the localized nature of the ecological effect of dams.展开更多
This article addresses the magnetohydrodynamics(MHD) flow of a third grade fluid over an exponentially stretching sheet. Analysis is carried out in the presence of first order chemical reaction. Both cases of construc...This article addresses the magnetohydrodynamics(MHD) flow of a third grade fluid over an exponentially stretching sheet. Analysis is carried out in the presence of first order chemical reaction. Both cases of constructive and destructive chemical reactions are reported. Convergent solutions of the resulting differential systems are presented in series forms. Characteristics of various sundry parameters on the velocity, concentration, skin friction and local Sherwood number are analyzed and discussed.展开更多
Iron-rich groundwater flowing into wetlands is a worldwide environmental pollution phenomenon that is closely associated with the stability of wetland ecosystems. Combined with high phosphorus(P) loading from agricult...Iron-rich groundwater flowing into wetlands is a worldwide environmental pollution phenomenon that is closely associated with the stability of wetland ecosystems. Combined with high phosphorus(P) loading from agricultural runoff, the prediction of the evolution of wetland vegetation affected by compound contamination is particularly urgent. We tested the effects of anaerobic iron-rich groundwater discharge in a freshwater marsh by simulating the effect of three levels of eutrophic water on native plants(Glyceria spiculosa(Fr. Schmidt.) Rosh.). The management of wetland vegetation with 1–20 mg/L Fe input is an efficient method to promote the growth of plants, which showed an optimum response under a 0.10 mg/L P surface water environment. Iron-rich groundwater strongly affects the changes in ecological niches of some wetland plant species and the dominant species. In addition, when the P concentration in a natural body of water is too high, the governance effect of eutrophication might not be as expected. Under iron-rich groundwater conditions, the δ^(13)C values of organs were more depleted, which can partially explain the differences in δ^(13)C in the soil profile. Conversely, the carbon isotope composition of soil organic carbon is indicative of past changes in vegetation. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in eutrophic environments.展开更多
We investigate the exact nonstationary solutions of a two-component Bose-Einstein condensate whichcompose of two species having different atomic masses. We also consider the interesting behavior of the atomic velocity...We investigate the exact nonstationary solutions of a two-component Bose-Einstein condensate whichcompose of two species having different atomic masses. We also consider the interesting behavior of the atomic velocityand the flow density. It is shown that the motion of the two components can be controlled by the experimental parameters.展开更多
A new species of river loach, Schistura megalodon sp. nov., is described from the Irrawaddy basin in Yingjiang County, Dehong Autonomous Prefecture, Yuunan Province, China. The following combination of diagnostic char...A new species of river loach, Schistura megalodon sp. nov., is described from the Irrawaddy basin in Yingjiang County, Dehong Autonomous Prefecture, Yuunan Province, China. The following combination of diagnostic characters serve to distinguish it from all other congeners in the given zoogeographical region： a large processus dentiformes in the upper jaw, a short pre-anus length of 65.4%-66.3% of SL, long paired fins （pectoral： 20.8%-24.2% of SL; pelvic： 17.9%-20.6% of SL）, a wide body of 9.7%-11.3% of SL at anal fin origin, an incomplete lateral line, the absence of an orbital lobe, and a broad and distinct basicaudal bar with forward extensions.展开更多
An attempt has been made to systematically revise the Late Cretaceous （Turonian） bivalves of the Bagh Beds, central India. Altogether, fifteen species have been described here. The two species Nicaniella （N） trigo...An attempt has been made to systematically revise the Late Cretaceous （Turonian） bivalves of the Bagh Beds, central India. Altogether, fifteen species have been described here. The two species Nicaniella （N） trigonoides ＆ Protocardia （P） laticostata, which are earlier known from Late Cretaceous of Tiruchirapalli subbasin, southern India, have been recorded for the first time from Narmada Basin. The other species recorded are： Modiolus typicus, Neithea morrisi, Plicatula batnensis, P. numidica, P. instabilis, Lucina （L.） cf. fallax, Astarte similis, Opis corniformis, Protocardia hillana, P. madagascariense, Cytherea （Callista） lancianata, Trigonocallista spathi and Pholadomya sp.. During course of systematic revision, it has been found that many species described by earlier workers from the Late Cretaceous of Bagh Beds have been found conspecific to already known species from the Cretaceous of different parts of the globe and hence, they have been recorded here as junior synonyms. These species have immense implication in the palaeobiogeography of the region.展开更多
The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year.The Yalong River will be dramatically impacted hydrologically and eco...The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year.The Yalong River will be dramatically impacted hydrologically and ecologically because more than 60% of the runoff will be diverted.An ecohydrological model was used to evaluate the impacts of the project on river corridor and wetland in this study.Schizothorax is a typical plateau river species and was used as the indicator species for assessment of the impact of water transfer project.The model simulated the habitat area of Schizothorax in the reach between the Reba Dam and the Ganzi Hydrology Station on the Yalong River.The Reba Dam,A'an Dam and Renda Dam will be constructed in the Yalong River for enhancing the water level for water diversion into the Yellow River.The velocity,channel width,runoff,and water depth will be reduced due to the water transfer,especially during flood season.The reduction in the velocity,channel width,runoff and water depth will occur mainly in the reach near the three dams and the reduction will be reduced to a minimum level in a distance about 100 km downstream of the dams.The maximum net water loss of Kasha Lake is only 1197200 m3,only 0.3% of runoff flowing into the lake.The project cannot bring adverse effect on the lake.The habitat area of Schizothorax in the Yalong River might be reduced if the water was transferred from the Reba Dam.The habitat area of this species will be reduced more than 40%.展开更多
Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present...Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium cur- vispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a disper- sal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range展开更多
Aims The introduction of Robinia pseudoacacia(RP)has some effects on undergrowth herbaceous plants(UH),soil properties and their relationships,which may be related to the vegetation zone.However,few studies have teste...Aims The introduction of Robinia pseudoacacia(RP)has some effects on undergrowth herbaceous plants(UH),soil properties and their relationships,which may be related to the vegetation zone.However,few studies have tested effects of RP on UH and soil over a large-scale area of the Loess Plateau.Methods The study area consisted of three vegetation zones(the steppe,forest-steppe and forest zone).Two canopy plant types were selected:RP stands and adjacent native vegetation.We measured five leaf functional traits:leaf carbon content(LC),leaf nitrogen content(LN),leaf phosphorus content(LP),specific leaf area(SLA)and leaf tissue density(LTD).The functional diversity,species diversity and community-weighted mean(CWM)traits were calculated.Important Findings(i)CWM.LN,CWM.LP and CWM.SLA increased significantly,whereas CWM.LC and CWM.LTD decreased significantly in the three vegetation zones,compared with the native communities.(ii)Species diversity,functional diversity and community biomass decreased in the steppe zone,increased in the forest zone,and did not differ significantly in the forest-steppe zone.(iii)We found only soil organic carbon(P<0.05)and soil total nitrogen(P<0.05)in the forest zone decreased significantly compared with the native plots.(iv)The relationship between UH and soil properties was affected by RP and the vegetation zone.Overall,the effect of RP on UH and soil properties was associated with the vegetation zone.This result is of great significance to the planning of restoration and reconstruction of artificial forests in the Loess Plateau.展开更多
基金Supported by Joint Research Fund from National Natural Science Foundation of China(NSFC)-Yunnan Province(U0933601)Students Research Fund from Southwest Forestry University(1001)~~
文摘[Objective]This study was to reveal the essence of mechanism about how the alien invasive plants spread.[Method]Species niche and material/energy flow were used as basic research indicators to analyze the intrinsic mechanism of alien plants invasion.[Result]Most of the invasive plants have not been explicitly defined and their effective control methods not brought forward.[Conclusion]Overrun of alien invasive plants depends on whether the niche of a species could be continuously met at spatial level.Based on this we put forward corresponding control measures,proposed an assumption to establish a cylinder-network model and discussed the definition of alien invasive plants.
基金Foundation items： This study was financially supported by the National Basic Research Program of China （2009CB119200） and the Natural Science Foundation of China （31071900, 31172120）
文摘Using seasonally collected data(2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed,we examined the spatio-temporal patterns of fish assemblages along two longitudinal gradients to explore the effects of a large dam on fish assemblages at the watershed scale.No significant variation was observed in either species richness or assemblage structure across seasons.Species richness significantly varied according to stream order and gradient.Dam construction appeared to decrease species richness upstream substantially,while a significant decrease between gradients only occurred within fourth-order streams.Along the gradient without the large dam,fish assemblage structures presented distinct separation between two neighboring stream orders,with the exception of fourth-order versus fifth-order streams.However,the gradient disrupted by a large dam displayed the opposite pattern in the spatial variation of fish assemblages related with stream orders.Significant between-gradient differences in fish assemblage structures were only observed within fourth-order streams.Species distributions were determined by local habitat environmental factors,including elevation,substrate,water depth,current discharge,wetted width,and conductivity.Our results suggested that dam construction might alter the longitudinal pattern in fish species richness and assemblage structure in Qingyi Stream,despite the localized nature of the ecological effect of dams.
文摘This article addresses the magnetohydrodynamics(MHD) flow of a third grade fluid over an exponentially stretching sheet. Analysis is carried out in the presence of first order chemical reaction. Both cases of constructive and destructive chemical reactions are reported. Convergent solutions of the resulting differential systems are presented in series forms. Characteristics of various sundry parameters on the velocity, concentration, skin friction and local Sherwood number are analyzed and discussed.
基金Under the auspices of National Key Research and Development Program of China(No.2016YFA0602303,2016YFC0500408)National Key Research and Development Program of China(2016YFC0500408)+2 种基金National Natural Science Foundation of China(No.41771120,41271107,41471079)Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.IGA-135-05)the CPSF-CAS Joint Foundation for Excellent Postdoctoral Fellows(No.20150010)
文摘Iron-rich groundwater flowing into wetlands is a worldwide environmental pollution phenomenon that is closely associated with the stability of wetland ecosystems. Combined with high phosphorus(P) loading from agricultural runoff, the prediction of the evolution of wetland vegetation affected by compound contamination is particularly urgent. We tested the effects of anaerobic iron-rich groundwater discharge in a freshwater marsh by simulating the effect of three levels of eutrophic water on native plants(Glyceria spiculosa(Fr. Schmidt.) Rosh.). The management of wetland vegetation with 1–20 mg/L Fe input is an efficient method to promote the growth of plants, which showed an optimum response under a 0.10 mg/L P surface water environment. Iron-rich groundwater strongly affects the changes in ecological niches of some wetland plant species and the dominant species. In addition, when the P concentration in a natural body of water is too high, the governance effect of eutrophication might not be as expected. Under iron-rich groundwater conditions, the δ^(13)C values of organs were more depleted, which can partially explain the differences in δ^(13)C in the soil profile. Conversely, the carbon isotope composition of soil organic carbon is indicative of past changes in vegetation. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in eutrophic environments.
基金Supported by National Natural Science Foundation of China under Grant Nos. 10775049 and 10375022
文摘We investigate the exact nonstationary solutions of a two-component Bose-Einstein condensate whichcompose of two species having different atomic masses. We also consider the interesting behavior of the atomic velocityand the flow density. It is shown that the motion of the two components can be controlled by the experimental parameters.
文摘A new species of river loach, Schistura megalodon sp. nov., is described from the Irrawaddy basin in Yingjiang County, Dehong Autonomous Prefecture, Yuunan Province, China. The following combination of diagnostic characters serve to distinguish it from all other congeners in the given zoogeographical region： a large processus dentiformes in the upper jaw, a short pre-anus length of 65.4%-66.3% of SL, long paired fins （pectoral： 20.8%-24.2% of SL; pelvic： 17.9%-20.6% of SL）, a wide body of 9.7%-11.3% of SL at anal fin origin, an incomplete lateral line, the absence of an orbital lobe, and a broad and distinct basicaudal bar with forward extensions.
文摘An attempt has been made to systematically revise the Late Cretaceous （Turonian） bivalves of the Bagh Beds, central India. Altogether, fifteen species have been described here. The two species Nicaniella （N） trigonoides ＆ Protocardia （P） laticostata, which are earlier known from Late Cretaceous of Tiruchirapalli subbasin, southern India, have been recorded for the first time from Narmada Basin. The other species recorded are： Modiolus typicus, Neithea morrisi, Plicatula batnensis, P. numidica, P. instabilis, Lucina （L.） cf. fallax, Astarte similis, Opis corniformis, Protocardia hillana, P. madagascariense, Cytherea （Callista） lancianata, Trigonocallista spathi and Pholadomya sp.. During course of systematic revision, it has been found that many species described by earlier workers from the Late Cretaceous of Bagh Beds have been found conspecific to already known species from the Cretaceous of different parts of the globe and hence, they have been recorded here as junior synonyms. These species have immense implication in the palaeobiogeography of the region.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51027006,51109224)the National Key Basic Research Program of China ("973" Program) (Grant No. 2010CB951102)the National Key Project of Scientific and Technical Supporting Program (Grant No. 2006BAB04A08)
文摘The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year.The Yalong River will be dramatically impacted hydrologically and ecologically because more than 60% of the runoff will be diverted.An ecohydrological model was used to evaluate the impacts of the project on river corridor and wetland in this study.Schizothorax is a typical plateau river species and was used as the indicator species for assessment of the impact of water transfer project.The model simulated the habitat area of Schizothorax in the reach between the Reba Dam and the Ganzi Hydrology Station on the Yalong River.The Reba Dam,A'an Dam and Renda Dam will be constructed in the Yalong River for enhancing the water level for water diversion into the Yellow River.The velocity,channel width,runoff,and water depth will be reduced due to the water transfer,especially during flood season.The reduction in the velocity,channel width,runoff and water depth will occur mainly in the reach near the three dams and the reduction will be reduced to a minimum level in a distance about 100 km downstream of the dams.The maximum net water loss of Kasha Lake is only 1197200 m3,only 0.3% of runoff flowing into the lake.The project cannot bring adverse effect on the lake.The habitat area of Schizothorax in the Yalong River might be reduced if the water was transferred from the Reba Dam.The habitat area of this species will be reduced more than 40%.
文摘Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium cur- vispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a disper- sal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range
基金This study was supported by the National Natural Science Foundation of China(41671289,41601586).
文摘Aims The introduction of Robinia pseudoacacia(RP)has some effects on undergrowth herbaceous plants(UH),soil properties and their relationships,which may be related to the vegetation zone.However,few studies have tested effects of RP on UH and soil over a large-scale area of the Loess Plateau.Methods The study area consisted of three vegetation zones(the steppe,forest-steppe and forest zone).Two canopy plant types were selected:RP stands and adjacent native vegetation.We measured five leaf functional traits:leaf carbon content(LC),leaf nitrogen content(LN),leaf phosphorus content(LP),specific leaf area(SLA)and leaf tissue density(LTD).The functional diversity,species diversity and community-weighted mean(CWM)traits were calculated.Important Findings(i)CWM.LN,CWM.LP and CWM.SLA increased significantly,whereas CWM.LC and CWM.LTD decreased significantly in the three vegetation zones,compared with the native communities.(ii)Species diversity,functional diversity and community biomass decreased in the steppe zone,increased in the forest zone,and did not differ significantly in the forest-steppe zone.(iii)We found only soil organic carbon(P<0.05)and soil total nitrogen(P<0.05)in the forest zone decreased significantly compared with the native plots.(iv)The relationship between UH and soil properties was affected by RP and the vegetation zone.Overall,the effect of RP on UH and soil properties was associated with the vegetation zone.This result is of great significance to the planning of restoration and reconstruction of artificial forests in the Loess Plateau.
