Fixed field experimental studies are carried out on daily variations of the undis-turbed community and soil respiration fluxes in different phenological phases of 2001―2002 in semiarid Aneurolepidium chinense steppe ...Fixed field experimental studies are carried out on daily variations of the undis-turbed community and soil respiration fluxes in different phenological phases of 2001―2002 in semiarid Aneurolepidium chinense steppe of Inner Mongolia,China using static black chamber method.Corresponding statistical analysis of the contributions of the water-heat factors(air temperature,ground temperature,surface soil water content)and ecological factors(above-ground biomass,underground biomass,litter biomass)to daily variation law of the undisturbed community and soil respiration fluxes as well as differences in daily respiration are also con-ducted.The results indicate that undisturbed community and soil respiration have apparent daily variation laws,daily variation patterns of respiration fluxes during different phenological phases are basically the same,and the variations of environmental factors only exert effect on CO_(2)emission intensities,while the effect on daily variation pattern of grassland CO_(2)emission fluxes is relatively small.The daily total respiration of the undisturbed community in different phenological phases ranges from 1.34―10.13 g·m^(-2);soil daily total respiration ranges from 0.98―5.17 g·m^(-2);both daily variations of undisturbed community and soil respiration fluxes are significantly corre-lated(p<0.05)or extremely significantly correlated(p<0.01)with air temperatures and ground surface temperatures,but the correlativity with the soil temperature at 5 and 10 cm depths is relatively weak;multiple regression analysis indicates that about 80%of the difference in daily respiration of the undisturbed community among different phenological phases is induced by the variation of the aboveground biomass,while the variations of the remaining factors can jointly explain around 20%of the daily respiration variations of the whole grassland ecosystem;about 83%of the soil daily respiration variation of the different phenological phases is caused by 0―20 cm underground biomass.Besides,surface soil water content is also an important environmental factor affecting soil daily respiration variations of the Aneurolepidium chinense steppe,but its partial correlation coefficient with soil daily respiration amount does not reach the significance level of 0.05.展开更多
Based on the static opaque chamber method,the respiration rates of soil microbial respiration,soil respiration,and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season ...Based on the static opaque chamber method,the respiration rates of soil microbial respiration,soil respiration,and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season in semiarid Leymus chinensis steppe in the Xilin River Basin of Inner Mongolia,China. Soil temperature and moisture were the main factor affecting respiration rates. Soil temperature can explain most CO2 efflux variations （R2=0.376-0.655） excluding data of low soil water conditions. Soil moisture can also effectively explain most of the variations of soil and ecosystem respiration （R2=0.314-0.583）,but it can not explain much of the variation of microbial respiration （R2=0.063）. Low soil water content （≤5%） inhibited CO2 efflux though the soil temperature was high. Rewetting the soil after a long drought resulted in substantial increases in CO2 flux at high temperature. Bi-variable models based on soil temperature at 5 cm depth and soil moisture at 0-10 cm depth can explain about 70% of the variations of CO2 effluxes. The contribution of soil respiration to ecosystem respiration averaged 59.4%,ranging from 47.3% to 72.4%; the contribution of root respiration to soil respiration averaged 20.5%,ranging from 11.7% to 51.7%. The contribution of soil to ecosystem respiration was a little overestimated and root to soil respiration little underestimated because of the increased soil water content that occurred as a result of plant removal.展开更多
Large-scale crystalline boron nanowires (BNWs) were synthesized by a simple chemical vapor deposition method on Au-coated Si substrates using two kinds of innoxious and inexpensive reactant materials as the precursor ...Large-scale crystalline boron nanowires (BNWs) were synthesized by a simple chemical vapor deposition method on Au-coated Si substrates using two kinds of innoxious and inexpensive reactant materials as the precursor at relatively low temperature (≤1000°C).The morphology and structural properties of samples were characterized by SEM,TEM,SAED,and XPS analytic instruments.The BNWs have lengths of several tens of micrometers with diameters of 80-150 nm.SAED and HRTEM analytic results testified that BNWs were single crystal core with a thin oxide sheath.By comparison of the BNW samples synthesized at difference temperatures,we conclude that BNWs have lower growth rate at 950°C,whilst the suitable growth rate can be gained at 1000°C.This result shows that BNWs can be synthesized via one step CVD process at 1000°C,and overly high growth temperature (≥1200°C) is probably unnecessary.展开更多
基金the Statc Key Basic Research Development and Planning Project(Grant No.2002CB412503)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX1-sw-01-04)the Knowl-edge Innovation Project of the Institute of Geographic Sciences and Natural Resources Research,CAS(Grant No.CXIOG-E01-03-01).
文摘Fixed field experimental studies are carried out on daily variations of the undis-turbed community and soil respiration fluxes in different phenological phases of 2001―2002 in semiarid Aneurolepidium chinense steppe of Inner Mongolia,China using static black chamber method.Corresponding statistical analysis of the contributions of the water-heat factors(air temperature,ground temperature,surface soil water content)and ecological factors(above-ground biomass,underground biomass,litter biomass)to daily variation law of the undisturbed community and soil respiration fluxes as well as differences in daily respiration are also con-ducted.The results indicate that undisturbed community and soil respiration have apparent daily variation laws,daily variation patterns of respiration fluxes during different phenological phases are basically the same,and the variations of environmental factors only exert effect on CO_(2)emission intensities,while the effect on daily variation pattern of grassland CO_(2)emission fluxes is relatively small.The daily total respiration of the undisturbed community in different phenological phases ranges from 1.34―10.13 g·m^(-2);soil daily total respiration ranges from 0.98―5.17 g·m^(-2);both daily variations of undisturbed community and soil respiration fluxes are significantly corre-lated(p<0.05)or extremely significantly correlated(p<0.01)with air temperatures and ground surface temperatures,but the correlativity with the soil temperature at 5 and 10 cm depths is relatively weak;multiple regression analysis indicates that about 80%of the difference in daily respiration of the undisturbed community among different phenological phases is induced by the variation of the aboveground biomass,while the variations of the remaining factors can jointly explain around 20%of the daily respiration variations of the whole grassland ecosystem;about 83%of the soil daily respiration variation of the different phenological phases is caused by 0―20 cm underground biomass.Besides,surface soil water content is also an important environmental factor affecting soil daily respiration variations of the Aneurolepidium chinense steppe,but its partial correlation coefficient with soil daily respiration amount does not reach the significance level of 0.05.
基金Foundation： National Natural Science Foundation of China, No.41071138 National Key Technologies R＆D Program during the 1 lth Five-year Plan of China, No.2006BAJ 10B04 Independent Innovation Project of Institute of Geographic Sciences and Natural Resources Research, CAS, No.200905009
文摘Based on the static opaque chamber method,the respiration rates of soil microbial respiration,soil respiration,and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season in semiarid Leymus chinensis steppe in the Xilin River Basin of Inner Mongolia,China. Soil temperature and moisture were the main factor affecting respiration rates. Soil temperature can explain most CO2 efflux variations （R2=0.376-0.655） excluding data of low soil water conditions. Soil moisture can also effectively explain most of the variations of soil and ecosystem respiration （R2=0.314-0.583）,but it can not explain much of the variation of microbial respiration （R2=0.063）. Low soil water content （≤5%） inhibited CO2 efflux though the soil temperature was high. Rewetting the soil after a long drought resulted in substantial increases in CO2 flux at high temperature. Bi-variable models based on soil temperature at 5 cm depth and soil moisture at 0-10 cm depth can explain about 70% of the variations of CO2 effluxes. The contribution of soil respiration to ecosystem respiration averaged 59.4%,ranging from 47.3% to 72.4%; the contribution of root respiration to soil respiration averaged 20.5%,ranging from 11.7% to 51.7%. The contribution of soil to ecosystem respiration was a little overestimated and root to soil respiration little underestimated because of the increased soil water content that occurred as a result of plant removal.
基金supported by the Innovation Team Foundation of Educational Department of Liaoning Province,China (Grant No. 2007T088)the Construction Capital for Key Laboratory of Liaoning Province (Grant No. 2009403014)+1 种基金the Doctoral Scientific Research Starting Foundation of Liaoning province (Grant No. 20081081)the National Natural Science Foundation of China (Grant No. 10804040)
文摘Large-scale crystalline boron nanowires (BNWs) were synthesized by a simple chemical vapor deposition method on Au-coated Si substrates using two kinds of innoxious and inexpensive reactant materials as the precursor at relatively low temperature (≤1000°C).The morphology and structural properties of samples were characterized by SEM,TEM,SAED,and XPS analytic instruments.The BNWs have lengths of several tens of micrometers with diameters of 80-150 nm.SAED and HRTEM analytic results testified that BNWs were single crystal core with a thin oxide sheath.By comparison of the BNW samples synthesized at difference temperatures,we conclude that BNWs have lower growth rate at 950°C,whilst the suitable growth rate can be gained at 1000°C.This result shows that BNWs can be synthesized via one step CVD process at 1000°C,and overly high growth temperature (≥1200°C) is probably unnecessary.
