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Search Results: 1 - 10 of 6638 matches for " northern China "
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Possible Trajectories of Agricultural Cropping Systems in China from 2011 to 2050  [PDF]
Junfang Zhao, Jianping Guo
American Journal of Climate Change (AJCC) , 2013, DOI: 10.4236/ajcc.2013.23019
Abstract:

Predicting the possible impacts of future climate change on cropping systems can provide important theoretical support for reforming cropping system and adjusting the distribution of agricultural production in the future. The study was based on the daily data of future B2 climate scenario (2011-2050) and baseline climate condition (1961-1990) from high resolution regional climate model PRECIS (~50 km grid interval). According to climatic divisions of cropping systems in China, the active accumulated temperature stably passing the daily average temperature of 0°C, the extreme minimum temperature and the termination date passing the daily average temperature of 20°C which were justified by dominance as a limitation of different cropping systems in zero-grade zone were investigated. In addition, the possible trajectories of different cropping systems in China from 2011 to 2050 were also analyzed and assessed. Under the projected future B2 climate scenario, from 2011 to 2050, the northern boundaries of double cropping area and triple cropping area would move northward markedly. The most of the present double cropping area would be replaced by the different triple cropping patterns, while current double cropping area would shift towards areas presently dominated by single cropping systems. Thus the shift of multiple cropping areas would lead to a significant decrease of single cropping area. Compared with China’s land area, the percentage cover of single cropping area and double cropping area would decrease slowly, while percentage cover of triple cropping area would gradually increase.

Novel associations between rhizobial populations and legume species within the genera Lathyrus and O xytropis grown in the temperate region of China
Sui XinHua,Han LiLi,Wang EnTao,Jiang Feng,Liu YiHai,Chen WenXin
Science China Life Sciences , 2009, DOI: 10.1007/s11427-008-0132-7
Abstract: Fifty rhizobial isolates of Lathyrus and Oxytropis collected from northern regions of China were studied in their genotypic characterization based upon analyses of ARDRA, 16S-23S IGS PCR-RFLP, TP-RAPD, MLEE, sequences of 16S rDNA gene and housekeeping genes of atpD, recA and glnII. The results demonstrated that most of the Lathyrus rhizobia belonged to Rhizobium and most of the Oxytropis rhizobia belonged to Sinorhizobium. A novel group of Rhizobium sp. I and S. meliloti were identified as the main microsymbionts respectively associated with Lathyrus and Oxytropis species in the collection area, which were new associations between rhizobia and the mentioned hosts. This study also provides new evidence for biogeography of rhizobia.
Variation of drought over northern China during 1950-2000

WANG Zhiwei,ZHAI Panmao,ZHANG Hongtao,

地理学报 , 2003,
Abstract: Based on China's monthly precipitation data of 629 stations during 1950-2000, we calculated Z indices and separated them into seven Dryness and Wetness grades. Further, a drought area index was proposed to study changes in drought severity in northern China. The results revealed that the different severity of droughts all showed expanding trends in northern China's main agricultural area. Moreover, the area coverage of droughts in different seasons and different regions displayed different trends.
Modelling scenarios of land use change in northern China in the next 50 years

HE Chunyang,LI Jinggang,SHI Peijun,CHEN Jin,PAN Yaozhong,LI Xiaobing,

地理学报 , 2005,
Abstract: Modelling scenarios of land use change and their impacts in typical regions are helpful to investigate the mechanism between land use and ecological systems and process the land use allocation under the ecological security. A system dynamics (SD) model with the aim to modelling scenarios of land use change and assessing ecological impact in northern China in the next 50 years is developed here. The accuracy assessment with the historic data from 1990 to 2001 indicated the SD model is robust. After the different "what-if" scenarios controlled by GDP, population, market, and technology advancement were built, the different scenarios of land use change in northern China from 2000 to 2050 were simulated with their ecological impact assessed. The result suggested that such factors as GDP, population, market and technology have a strong relationship with land use structural change in northern China. It also indicated that such measures as strict controlling of population increase, importing some food to keep the supply-demand balance in the region, and improving agricultural technology will be the guarantee of regional sustainable development with fast economic growth and the obvious land use structural improvement at the same time.
Variation of terrestrial ecosystem recorded by stable carbon isotopes of fossils in northern China during the Quaternary
Tao Deng,Junshe Dong,Yang Wang
Chinese Science Bulletin , 2002, DOI: 10.1360/02tb9015
Abstract: Stable carbon isotopes of C3 and C4 plants have completely distinct δ13C values respectively. Carbonate in tooth enamel of herbivorous mammals is significantly and regularly enriched in 13C compared to source carbon. As a result, we can reconstruct distributions of C3 and C4 plants in geological history based on carbon isotopes of mammalian tooth enamel. Carbon isotopes of 70 mammalian tooth enamel samples from 11 Quaternary localities in northern China are analyzed. This analysis indicates that C3 plants were dominant in the terrestrial ecosystem of northern China during the Quaternary, which is completely different from Pakistan with relatively close latitudes where C4 plants were absolutely dominant. The great difference was caused by the uplift of the Tibetan Plateau. A simulation implied that a marked temperature decrease would happen in the north side of the Tibetan Plateau, but a temperature increase in the south side. The warming condition caused the transition from C3 to C4 plants in Pakistan situated in the south side of this plateau. In the north side, on the contrary, the cooling condition restrained the distribution of C4 plants. As a result, C3 plants have been dominant in northern China until now.
Impact of land surface degradation in northern China and southern Mongolia on regional climate
Jingyong Zhang,Wenjie Dong,Congbin Fu
Chinese Science Bulletin , 2005, DOI: 10.1360/04wd0054
Abstract: Clear evidence provided by the singular value decomposition (SVD) analysis to the normalized difference vegetation index (NDVI) and precipitation data identifies that there exists a sensitive region of vegetation-climate interaction located in the transitional zone over northern China and its surrounding areas, where the vegetation cover change has the most significant influence on summer precipitation over China. Comparison of reanalysis data with station data provides a good method to assess the impacts of land use change on surface temperature, and the most obvious contribution of land use change may be to lead to notable warming over northern China in the interdecadal time scale. Based on the new statistical results, a high-resolution regional integrated environmental model system (RIEMS) is employed to investigate the effects of land surface degradation over the transitional zone and its surrounding areas (northern China and southern Mongolia) on the regional climate. Land degradation results in the decreases in precipitation over northern and southern China, and the increase in between, and increased and decreased temperature over vegetation change areas and the adjacent area to the south, respectively. Not only would it change the surface climate, but also bring the significant influence on the atmospheric circulation. Both the surface climate and circulation changes generally agree to the observed interdecadal anomalies over the last five decades. These integrated statistical and simulated results imply that land surface degradation over the transitional zone in northern China and its surrounding areas could be one of the main causes responsible for the climate anomalies over China, especially the drought over northern China.
Lithospheric thermal-rheological structures of the continental margin in the northern South China Sea
Xiaobin Shi,Di Zhou,Yixiang Zhang
Chinese Science Bulletin , 2000, DOI: 10.1007/BF03183537
Abstract: Thermal structures of three deep seismic profiles in the continental margin in the northern South China Sea are calculated, their “thermal” lithospheric thicknesses are evaluated based on the basalt dry solidus, and their rheological structures are evaluated with linear frictional failure criterion and power-law creep equation. “Thermal” lithosphere is about 90 km in thickness in shelf area, and thins toward the slope, lowers to 60–65 km in the lower slope, ocean crust and Xisha Trough. In the mid-west of the studied area, the lithospheric rheological structure in shelf area and Xisha Islands is of four layers: brittle, ductile, brittle and ductile. Because of uprising of heat mantle and thinning of crust and lithosphere in Xisha Trough, the bottom of the upper brittle layer is only buried at 16 km. In the eastern area, the bottom of the upper brittle layer in the north is buried at 20 km or so, while in lower slope and ocean crust, the rheological structure is of two layers of brittle and ductile, and crust and uppermost mantle form one whole brittle layer whose bottom is buried at 30–32 km. Analyses show that the characteristics of rheological structure accord with the seismic result observed. The character of rheological stratification implies that before the extension of the continent margin, there likely was a ductile layer in mid-lower crust. The influence of the existence of ductile layer to the evolution of the continent margin and the different extensions of ductile layer and brittle layer should not be overlooked. Its thickness, depth and extent in influencing continent margin’s extension and evolution should be well evaluated in building a dynamic model for the area.
Some evidence of drying trend over northern China from 1951 to 2004
Zhuguo Ma,Congbin Fu
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-2159-0
Abstract: The surface wetness index, Palmer drought sererity index and the retrieval of soil moisture over China were calculated using monthly precipitation and monthly mean surface air temperature. Based on the contrast analysis of the variation of the above three indices and precipitation, the dry/wet spatio-temporal pattern of northern China in the last 54 years was revealed, and the evidence of drying trend over northern China was analyzed, especially. The results show the following four facts: (1) The drying trend is the main characteristic of the eastern part of Northwest China and the central part of North China since the 1980s and it was enhanced in the last 15 years mainly due to the precipitation decrease and the temperature increase; (2) during the last 54 years, there was only one dry/wet shift at the interdecadal scale occurring in the eastern part of Northwest China and the central part of North China in the late 1970s, which was related to 1977/1978 global abrupt change, whereas there were three shifts in Northeast China, one was in the mid 1990s and the other two were in 1965 and 1983, respectively; (3) Unlike the variation trend of other subregions of northern China, the western part of Northwest China is currently located in a relatively wetting period, which is weakened due to the temperature increase; (4) The extreme drought frequency is obviously increasing in the eastern part of Northwest China, the central part of North China and Northeast China since the 1980s, which is closely related to the precipitation decrease and temperature increase in these subregions.
Characteristics of hydrocarbon accumulation and exploration potential of the northern South China Sea deepwater basins
WeiLin Zhu,Kai Zhong,YouChuan Li,Qiang Xu,DianYong Fang
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4940-y
Abstract: Although the huge potential of the northern South China Sea deepwater basins has been proven by a series of discoveries that followed the exploration breakthrough of well LW 3-1-1, recent drilling and other studies have demonstrated the uniqueness and complicated nature of hydrocarbon accumulations of the deepwater basins there. Based on a review of previous work and the latest exploration activities and studies, the purpose of this paper is to discuss the critical controls for hydrocarbon accumulations in the deepwater basins of the northern South China Sea. A terrestrial-marine transitional coal-bearing source rock is proposed to be the primary source rock for the deepwater basins. A marine source rock, which was first identified as contributing to hydrocarbon generation in this region, probably plays a significant role in the deep- and ultra-deep water basins south to the Pearl River Mouth and Qingdongnan basins. The shelf margin delta depositional systems in the Baiyun Sag, sourced from the Pearl River, are currently primary exploration targets in the deepwater part of the Pearl River Mouth Basin, whereas the western Red River deltaic-submarine fan depositional systems, initially proven by drilling, are the possible major exploration reservoirs in the Qingdongnan deepwater areas. Current deepwater exploration targets at the large-sized structural traps and deep and ultra-deep areas in the south of the Pearl River Mouth and Qingdongnan basins will be the future exploration focus. Deepwater exploration activities and relevant fundamental studies, supporting and promoting each other, are of great importance to the national energy supply of China, the basic regional studies of the South China Sea, advancements in technology, and development of related deepwater industries, and will safeguard national sovereignty and territorial integrity.
Isotopic characteristics of the postorogenic granites in orogenic belt of northern China and their implications in crustal growth
Fuyuan Wu,Borming Jahn,Qiang Lin
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883724
Abstract: The orogenic belt of northern China is characterized by widely developed postorogenic I fractionated and A-type granites in the Phanerozoic. The isotopic data display relatively high εNd(t) and206Pb/204Pb values and lowI St ratio. The low TDM model ages (<100 Ma) suggest that the Neo-Proterozoic-Phanerozoic is one of the main stages in the continental growth.
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