Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenh...Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.展开更多
Guar is a drought and salt tolerant summer annual legume, which could be a potential alternative crop in the semi-arid Southern High Plains. Increased use of guar gum in oil industries has increased the demand of guar...Guar is a drought and salt tolerant summer annual legume, which could be a potential alternative crop in the semi-arid Southern High Plains. Increased use of guar gum in oil industries has increased the demand of guar globally. Planting date effects on stand establishment, physiological parameters, and yield formation of guar genotypes were investigated at the New Mexico State University’s Agricultural Science Center at Clovis, NM for two seasons (2014 and 2015). Four guar genotypes (HES 1123, Kinman, Lewis, and Matador) were tested under three planting dates (June 18, July 7, and July 22 in 2014;and June 18, July 6, and July 20 in 2015). Higher temperature and rainfall were recorded under mid-June planting than early-July and late-July plantings. Guar planted under mid-June had better stand establishment as shown by the higher number of plants m<sup>-2</sup>, better physiology as revealed by higher photosynthetic rate (P<sub>n</sub>), transpiration rate (T<sub>r</sub>), leaf area index (LAI), and SPAD values than early-July and late-July plantings. Guar planted under mid-June resulted in taller plants, and therefore, produced higher plant biomass than both of the July plantings. Yield attributing characteristics including clusters plant<sup>-1</sup>, pods plant<sup>-1</sup>, seeds plant<sup>-1</sup>, seed spod<sup>-1</sup>, 1000 seed weight, and harvest index (HI) were highest under mid-June planting followed by the early-July and late-July plantings, respectively. The mid-June planting increased seed yield by 26% and 55% over early-July and late-July (1399 vs. 1111 and 903 kg·ha<sup>-1</sup>) plantings, respectively in 2014;while the same increase in 2015 was 51% and 243% (1308 vs. 868 and 381 kg·ha<sup>-1</sup>), respectively. These results indicate that delaying planting beyond mid-June is detrimental to guar productivity. However, genotypes did not show any significant variation in their performance. Overall, warmer growing conditions and more precipitation under mid-June planting caused better growth and yield formation of guar genotypes.展开更多
Objective LGM is a critical climate period in the late Quaternary and is the most recent extreme cold event. Clark et al. （2009） used 4271^14C records and 475 cosmogenic nuclide datings to define LGM be in 26.5-19....Objective LGM is a critical climate period in the late Quaternary and is the most recent extreme cold event. Clark et al. （2009） used 4271^14C records and 475 cosmogenic nuclide datings to define LGM be in 26.5-19.0 kaBP. LGM age often changes with time in different regions （Mix et al., 2001; Zhang Zhigang et al., 2015）. However, LGM has not been described to date in the Beijing region. During our field work in 2015-2017, LGM event stratigraphy was discovered from sevral boreholes in the middle and lower region of Yongding river basin, Southern Beijing plain.展开更多
基金funded by Commonweal Trade Scientific Research from the Ministry of Land and Resources of the People's Republic of China
文摘Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.
文摘Guar is a drought and salt tolerant summer annual legume, which could be a potential alternative crop in the semi-arid Southern High Plains. Increased use of guar gum in oil industries has increased the demand of guar globally. Planting date effects on stand establishment, physiological parameters, and yield formation of guar genotypes were investigated at the New Mexico State University’s Agricultural Science Center at Clovis, NM for two seasons (2014 and 2015). Four guar genotypes (HES 1123, Kinman, Lewis, and Matador) were tested under three planting dates (June 18, July 7, and July 22 in 2014;and June 18, July 6, and July 20 in 2015). Higher temperature and rainfall were recorded under mid-June planting than early-July and late-July plantings. Guar planted under mid-June had better stand establishment as shown by the higher number of plants m<sup>-2</sup>, better physiology as revealed by higher photosynthetic rate (P<sub>n</sub>), transpiration rate (T<sub>r</sub>), leaf area index (LAI), and SPAD values than early-July and late-July plantings. Guar planted under mid-June resulted in taller plants, and therefore, produced higher plant biomass than both of the July plantings. Yield attributing characteristics including clusters plant<sup>-1</sup>, pods plant<sup>-1</sup>, seeds plant<sup>-1</sup>, seed spod<sup>-1</sup>, 1000 seed weight, and harvest index (HI) were highest under mid-June planting followed by the early-July and late-July plantings, respectively. The mid-June planting increased seed yield by 26% and 55% over early-July and late-July (1399 vs. 1111 and 903 kg·ha<sup>-1</sup>) plantings, respectively in 2014;while the same increase in 2015 was 51% and 243% (1308 vs. 868 and 381 kg·ha<sup>-1</sup>), respectively. These results indicate that delaying planting beyond mid-June is detrimental to guar productivity. However, genotypes did not show any significant variation in their performance. Overall, warmer growing conditions and more precipitation under mid-June planting caused better growth and yield formation of guar genotypes.
基金financially supported by Beijing 1:50 000 Liulihe,Panggezhuang,Ancixian regional geological survey Projects of China Geological Survey(grant No.12120114007701)
文摘Objective LGM is a critical climate period in the late Quaternary and is the most recent extreme cold event. Clark et al. （2009） used 4271^14C records and 475 cosmogenic nuclide datings to define LGM be in 26.5-19.0 kaBP. LGM age often changes with time in different regions （Mix et al., 2001; Zhang Zhigang et al., 2015）. However, LGM has not been described to date in the Beijing region. During our field work in 2015-2017, LGM event stratigraphy was discovered from sevral boreholes in the middle and lower region of Yongding river basin, Southern Beijing plain.
