Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a...Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.展开更多
In the present article, the author looks into several influential questions that are too often given insufficient emphasis in the classroom teaching and the following conclusions are reached through the research: (1...In the present article, the author looks into several influential questions that are too often given insufficient emphasis in the classroom teaching and the following conclusions are reached through the research: (1) Classroom is a behavior setting where students of different characteristics come to bring about desirable changes. Different strategies must be used to meet their needs; (2) Teachers are not just transmitters of knowledge; they must be an educator as well as a helpful person; (3) Students should be encouraged to communicate with teachers and their peers to achieve a conducive classroom climate.展开更多
The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum(HCO), using proxies ...The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum(HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and 7.7 cal. ka BP and corresponding to the HCO, from the Qinzhou Bay in Guangxi, China, is quantitatively partitioned into three end-members according to their sources: mangrove-derived, terrigenous,and marine phytoplanktonic, using a three-end-member model depicted by organic carbon isotope(δ13Corg) and the molar ratio of total organic carbon to total nitrogen(C/N). The percentage of mangrove-derived organic matter(MOM) contribution is used as a proxy for mangrove development. Three visible drops in MOM contribution occurred at ca. 7.3, ca. 6.9, and ca. 6.2 cal. ka BP, respectively, are recognized against a relatively stable and higher MOM contribution level, indicating that three distinct mangrove forest degradations occurred in the Qinzhou Bay during the HCO. The three mangrove forest degradations approximately correspond to the time of the strengthened/weakened Asian winter/summer monsoon. This indicates that even during a period favorable for the mangrove development, such as the HCO, climatic extremes, such as cold and dry events driven by the strengthened/weakened Asian winter/summer monsoon, can trigger the degradation of mangrove forests.展开更多
Three alpine meadows were chosen from the eastern margin of the Qilian Mountain:Polygonum viviparum meadow(P),Stipa capillata grassland(S)and Rhododendron simsii shrub meadow(R);LI-8100 A soil CO2 flux auto-mon...Three alpine meadows were chosen from the eastern margin of the Qilian Mountain:Polygonum viviparum meadow(P),Stipa capillata grassland(S)and Rhododendron simsii shrub meadow(R);LI-8100 A soil CO2 flux auto-monitoring system and lab analysis were applied to analyze the soil organic carbon density,dynamics of carbon flux,and their relationship with environmental factors.The results showed that different vegetations varied greatly in soil organic carbon density:R 〉 S 〉 P,and the soil carbon density reduced with the increasing depth;soil CO2flux:S 〉 P 〉 R,and sample plot P and S showed unimodal changes.The peak values appeared at 14:00-15:00 p.m.;soil CO2 flux was negatively correlated with near-ground air humidity and carbon content,positively correlated with soil temperature and near-ground air temperature,and showed no obvious correlation with soil moisture.展开更多
Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon(SOC) storage i...Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon(SOC) storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil(0–20 cm) organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that:(1) the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.(2) SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn't show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.展开更多
Abstract New-entry employees expect to be involved rather than to be marginalized. This paper proposes a model to examine the process through which employees can be exempt from marginalization in their organization as...Abstract New-entry employees expect to be involved rather than to be marginalized. This paper proposes a model to examine the process through which employees can be exempt from marginalization in their organization as a "political arena." We argue that an employee, in order not to be marginalized, would like to perform high-quality in-role and extra-role behaviors and also develop good guanxi with his/her immediate supervisor. Moreover, the effects of employee efforts and guanxi on workplace marginalization are moderated by the organization political climate. Two studies were performed to examine the hypothesized model. The pilot study employed a sample of civil servants to develop and validate the measurement of workplace marginalization. The main study collected matched data from 343 employees, 662 of their colleagues, and 343 immediate supervisors. Results of hierarchical linear modeling analysis show that employee job performance, organizational citizenship behavior, and supervisor-subordinate guanxi are negatively related to workplace marginalization. In addition, the negative relationship between guanxi and workplace marginalization is stronger in firms with less organizational politics than those with intensive politics.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41301242,41201213)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA05050509)
文摘Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.
文摘In the present article, the author looks into several influential questions that are too often given insufficient emphasis in the classroom teaching and the following conclusions are reached through the research: (1) Classroom is a behavior setting where students of different characteristics come to bring about desirable changes. Different strategies must be used to meet their needs; (2) Teachers are not just transmitters of knowledge; they must be an educator as well as a helpful person; (3) Students should be encouraged to communicate with teachers and their peers to achieve a conducive classroom climate.
基金The National Basic Research Program (973 Program) of China under contract No.2010CB951203the National Natural Science Foundation of China under contract Nos 41376075,41576061 and 41206057
文摘The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum(HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and 7.7 cal. ka BP and corresponding to the HCO, from the Qinzhou Bay in Guangxi, China, is quantitatively partitioned into three end-members according to their sources: mangrove-derived, terrigenous,and marine phytoplanktonic, using a three-end-member model depicted by organic carbon isotope(δ13Corg) and the molar ratio of total organic carbon to total nitrogen(C/N). The percentage of mangrove-derived organic matter(MOM) contribution is used as a proxy for mangrove development. Three visible drops in MOM contribution occurred at ca. 7.3, ca. 6.9, and ca. 6.2 cal. ka BP, respectively, are recognized against a relatively stable and higher MOM contribution level, indicating that three distinct mangrove forest degradations occurred in the Qinzhou Bay during the HCO. The three mangrove forest degradations approximately correspond to the time of the strengthened/weakened Asian winter/summer monsoon. This indicates that even during a period favorable for the mangrove development, such as the HCO, climatic extremes, such as cold and dry events driven by the strengthened/weakened Asian winter/summer monsoon, can trigger the degradation of mangrove forests.
基金Sponsored by Natural Science Foundation of China(31360569)Key Laboratory of Grassland Ecosystem Program(CYZS-2011007)Modern Agricultural Technical System of Gansu Agricultural University CARS-35
文摘Three alpine meadows were chosen from the eastern margin of the Qilian Mountain:Polygonum viviparum meadow(P),Stipa capillata grassland(S)and Rhododendron simsii shrub meadow(R);LI-8100 A soil CO2 flux auto-monitoring system and lab analysis were applied to analyze the soil organic carbon density,dynamics of carbon flux,and their relationship with environmental factors.The results showed that different vegetations varied greatly in soil organic carbon density:R 〉 S 〉 P,and the soil carbon density reduced with the increasing depth;soil CO2flux:S 〉 P 〉 R,and sample plot P and S showed unimodal changes.The peak values appeared at 14:00-15:00 p.m.;soil CO2 flux was negatively correlated with near-ground air humidity and carbon content,positively correlated with soil temperature and near-ground air temperature,and showed no obvious correlation with soil moisture.
基金The National Basic Research Program of China(973 Program),No.2011CB403206No.2012CB416906National Key Technology R&D Program,No.2013BAC03B04
文摘Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon(SOC) storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil(0–20 cm) organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that:(1) the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.(2) SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn't show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.
文摘Abstract New-entry employees expect to be involved rather than to be marginalized. This paper proposes a model to examine the process through which employees can be exempt from marginalization in their organization as a "political arena." We argue that an employee, in order not to be marginalized, would like to perform high-quality in-role and extra-role behaviors and also develop good guanxi with his/her immediate supervisor. Moreover, the effects of employee efforts and guanxi on workplace marginalization are moderated by the organization political climate. Two studies were performed to examine the hypothesized model. The pilot study employed a sample of civil servants to develop and validate the measurement of workplace marginalization. The main study collected matched data from 343 employees, 662 of their colleagues, and 343 immediate supervisors. Results of hierarchical linear modeling analysis show that employee job performance, organizational citizenship behavior, and supervisor-subordinate guanxi are negatively related to workplace marginalization. In addition, the negative relationship between guanxi and workplace marginalization is stronger in firms with less organizational politics than those with intensive politics.