Under the dry weather conditions in the typical steppe region of Inner Mongolia, the diurnal change curve of photosynthetic rate of Aneurolepidium chinense community is a curve of 'double peaks' with midday de...Under the dry weather conditions in the typical steppe region of Inner Mongolia, the diurnal change curve of photosynthetic rate of Aneurolepidium chinense community is a curve of 'double peaks' with midday depression. The photosynthetic rate in the morning is height than in the afternoon, which is related to the water condition at that time. The decrease range of community photosynthetic rate at noon is closely correlated with the low air relative humidity and soil moisture, the photosynthetic rate decreases less under better water condition.The instantaneous photosynthetic rate and diurnal net photosynthesis declined in dry condition, but they rised after irrigation or nitrogen-fertilization. Thus irrigation and fertilization is a effective way to improve grasslands and to raise grassland productivity.展开更多
In the study,the reasonable sampling of the grey Aneurolepidium chinense of green grassland,the grey-green A.chinense of green grassland,the grey A.chinense of Wulimu and the grey-green A.chinense of Wulimu were analy...In the study,the reasonable sampling of the grey Aneurolepidium chinense of green grassland,the grey-green A.chinense of green grassland,the grey A.chinense of Wulimu and the grey-green A.chinense of Wulimu were analyzed by ISSR.Eight primers with clear and diverse products were screened out from 20 primers and 47 DNA fragments were amplified from 39 individuals.The average number of DNA fragments produced by each primer was 5.9,and polymorphic bands were 41 and the polymorphic rate was 87.23%,which could r...展开更多
Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a ...Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effiuxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance （CV） being over 94%, even high to 131%. The annual sums of soil CO2 effiux of the Aneurolepidium chinense steppe varied between 356.4 gC m^-2 yr^-1 and 408.8 gC m^-2 yr^-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m^-2 yr^-1 to 148.6 g Cm^-2 yr^-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation （r = 0.58 - 0.85, p 〈 0.05 or p 〈 0.01） with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content （especially that of the 10-20 cm layer） has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.展开更多
文摘Under the dry weather conditions in the typical steppe region of Inner Mongolia, the diurnal change curve of photosynthetic rate of Aneurolepidium chinense community is a curve of 'double peaks' with midday depression. The photosynthetic rate in the morning is height than in the afternoon, which is related to the water condition at that time. The decrease range of community photosynthetic rate at noon is closely correlated with the low air relative humidity and soil moisture, the photosynthetic rate decreases less under better water condition.The instantaneous photosynthetic rate and diurnal net photosynthesis declined in dry condition, but they rised after irrigation or nitrogen-fertilization. Thus irrigation and fertilization is a effective way to improve grasslands and to raise grassland productivity.
文摘In the study,the reasonable sampling of the grey Aneurolepidium chinense of green grassland,the grey-green A.chinense of green grassland,the grey A.chinense of Wulimu and the grey-green A.chinense of Wulimu were analyzed by ISSR.Eight primers with clear and diverse products were screened out from 20 primers and 47 DNA fragments were amplified from 39 individuals.The average number of DNA fragments produced by each primer was 5.9,and polymorphic bands were 41 and the polymorphic rate was 87.23%,which could r...
基金This work was jointly supported by the Knowledge Innovation Program of the Chinese Academy of Sciences （Grant No. KZCX1-SW-01-04） the National Natural Science Foundation of China （Grant No. 40501072） the project on the Carbon Cycle and Driving Mechanisms in the Chinese Terrestrial Ecosystem （Grant No. 2002CB412503）.
文摘Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effiuxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance （CV） being over 94%, even high to 131%. The annual sums of soil CO2 effiux of the Aneurolepidium chinense steppe varied between 356.4 gC m^-2 yr^-1 and 408.8 gC m^-2 yr^-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m^-2 yr^-1 to 148.6 g Cm^-2 yr^-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation （r = 0.58 - 0.85, p 〈 0.05 or p 〈 0.01） with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content （especially that of the 10-20 cm layer） has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.
