Distribution and controlling factors of phytoplankton assemblages in a semi-enclosed bay during spring and summer

The phytoplankton assemblages' patterns and their correlation to environmental factors were studied in Bohai Bay during spring and summer. Two zones, the northern (NWA) and southern (SWA) water area, were identified by cluster analysis based on their physical and chemical properties. Principal component analysis (PCA) showed that more phytoplankton species was found in the SWA with low nutrient concentration, while high phytoplankton abundance occurred in the NWA with high nutrient concentration. The seasonal variability in phytoplankton can be explained by water temperature, nutrient, and hydrodynamic conditions (includes mixing during spring and stratification during summer). Results of redundancy analysis (RDA) showed that silicate (SiO(4)) and soluble reactive phosphorus (SRP) were the most important environmental factors influencing the phytoplankton distribution during spring and summer, respectively. Hydrodynamics condition plays a key role in controlling variation of the environmental factors, which determined phytoplankton distribution in Bohai Bay.     

豫西前寒武纪汝阳群遗迹化石

本文研究的遗迹化石：Ｒｕｙａｎｇｉｃｈｎｕｓ ｌｏｙｕｅｎｓｉｓ ｉｃｈｎｏｇｅｎ，ｅｔ ｉｃｈｎｏｓｐ．ｎｏｖ．，Ｔｏｒｒｏｗａｎｇｅａ ｒｏｓｅｉ ｗｅｂｂｙ，Ｃｈａｎｇｃｈｅｎｇｉａ ｉｃｈｎｏｓｐ．，Ｓｑｕａｍｏｄｉｃｔ ｙｏｎ（？）ｉｃｈｎｏｓｐ．等发现于河南西部鲁山县和汝阳县的汝阳群云梦山组和北大尖组。根据同位素年龄值，微古植物和叠层石资料，产遗迹化石的汝阳群应相当于中元古代，可以和蓟     

Effects of grazing and climate change on species diversity in sandy grassland, Inner Mongolia, China

To understand the effects of animal grazing activities and climate change on sandy grassland vegetation in northern China, a field grazing and protected enclosure experiment was conducted from 1992 through 2006 in Horqin Sand Land, Inner Mongolia. The results showed that (1) the grazing was primary responsible for changes of the vegetation richness and diversity in the grazing grassland and that changing climate was the main reason for changes in the species richness and diversity in the grassland protected from grazing; (2) light and moderate grazing can promote restoration of the richness and the diversity in the degraded grassland, and heavy grazing could result in a decrease of the richness and diversity; (3) heavy grazing can result in significant decrease of the perennial diversity, and moderate and light grazing promotes increase of the perennial diversity; the grazing, whether heavy or moderate and light grazing, was beneficial to increase of the annual diversity; (4) heavy grazing was not beneficial to diversity of Graminean and Chenopodiaceae, and moderate and light grazing was favorable the diversity of Compositae and Chenopodiaceae; (5) the warm-humid climate was favorable to increase of the richness and the diversity, and the warm-drought climate could result in decease of the richness and the diversity; (6) increased precipitation was favorable to perennial diversity and the diversity of Graminean, Leguminosae, and Compositae, and decreased precipitation had few effects on the annual diversity and Chenopodiaceae diversity.     

Cultivated land change in the Belt and Road Initiative region

The Belt and Road Initiative (BRI)–a development strategy proposed by China – provides unprecedented opportunities for multi-dimensional communication and cooperation across Asia, Africa and Europe. In this study, we analyse the spatio-temporal changes in cultivated land in the BRI countries (64 in total) to better understand the land use status of China along with its periphery for targeting specific collaboration. We apply FAO statistics and GlobeLand30 (the world’s finest land cover data at a 30-m resolution), and develop three indicator groups (namely quantity, conversion, and utilization degree) for the analysis. The results show that cultivated land area in the BRI region increased 3.73×10⁴ km² between 2000 and 2010. The increased cultivated land was mainly found in Central and Eastern Europe and Southeast Asia, while the decreased cultivated land was mostly concentrated in China. Russia ranks first with an increase of 1.59×10⁴ km² cultivated land area, followed by Hungary (0.66×10⁴ km²) and India (0.57×104 km2). China decreased 1.95×10⁴ km² cultivated land area, followed by Bangladesh (–0.22×10⁴ km²) and Thailand (–0.22×10⁴ km²). Cultivated land was mainly transferred to/from forest, grassland, artificial surfaces and bare land, and transfer types in different regions have different characteristics: while large amount of cultivated land in China was converted to artificial surfaces, considerable forest was converted to cultivated land in Southeast Asia. The increase of multi-cropping index dominated the region except the Central and Eastern Europe, while the increase of fragmentation index was prevailing in the region except for a few South Asian countries. Our results indicate that the negative consequence of cultivated land loss in China might be underestimated by the domestic- focused studies, as none of its close neighbours experienced such obvious cultivated land losses. Nevertheless, the increased cultivated land area in Southeast Asia and the extensive cultivated land use in Ukraine and Russia imply that the regional food production would be greatly improved if China’ “Go Out policy” would help those countries to intensify their cultivated land use.     

“2007.4.1”四川盆地强寒潮天气过程分析

利用T2131°×1°和欧洲中心实时资料,对2007年4月1～3日四川盆地区域性寒潮天气过程的环流背景及影响系统进行了分析,结果表明:500hPa乌拉尔山到贝加尔湖以东为宽广深厚的低压带,地面上巴湖附近为冷高压,此冷高压在500hPa脊前西北气流的引导下东移南压,是造成此次寒潮大风天气的主要原因;而且低空急流也对降温有一定的作用。     

利用重复地震P波走时差观测地壳介质的微动态

基于研究区域地震震相到时资料及地震波数据,给出了两个局部地区地壳介质微动态变化的实例。一个是汶川8.0级地震起始破裂区域,即A区;另一个是三岔口地区,即B区,该区域为活动断裂交汇部位,未发生过大地震,但近年来中小地震频繁。分析A区后发现,在汶川8.0级地震前,部分台站观测的地壳介质微动态出现了中短期异常,震源区正东及北东方向波速升高,反映出地壳介质受到显著挤压而处于硬化阶段;震源区西南方向的波速则比较稳定。分析B区后发现,可能受到汶川8.0级地震的影响,部分台站给出的计算结果在地震前后发生了变化,显示出不同方位地壳介质承压状态的差异。     

深水碳酸盐岩沉积体系与储层发育控制因素 ——以中东H油田白垩系Khasib组为例

深水碳酸盐岩是有利的油气储集岩,中东地区上白垩统Khasib组缓坡型深水碳酸盐岩是重要的产油层系.伊拉克H油田Khasib组储层非均质性较强,储层发育特征及控制因素、油气分布规律不清,制约了选区评价及勘探部署.在区域地质调研的基础上,基于岩心、薄片和测井资料,对H油田Khasib组岩相、沉积微相和沉积模式、储层发育控制...     

江西南部鸡笼嶂组研究的新进展

分析了江西南部鸡笼嶂组划分的现状及存在的问题,提出了龙南盆地和石马剖面的“鸡笼嶂组”属中侏罗世－晚侏罗世早期余田群上部菖蒲组的一部分;菖蒲盆地的“鸡笼嶂组”属早白垩世晚期－晚白垩世早期版石群优胜组。鉴于安远、河岭、蔡坊、岩背等盆地的鸡笼嶂组属晚侏罗世,为火山喷发期的产物,而且整合于鸡笼嶂组之下的上丁组为火山初始期的产物,建议将赣南地区晚侏罗世火山活动形成的上丁组和鸡笼嶂组统称为莲花寨群。指出安远莲     

Farmers’ response to agricultural drought in paddy field of southern China: a case study of temporal dimensions of resilience

Seasonal water scarcity in southern China has been an issue of concern for many years. The increased frequency of low precipitation in the growing season of rice created a flurry of discussions in the academic and policy arenas. These events severely disrupted the supply of irrigation water for agriculture in paddy field areas and posed a substantial threat to farmers’ livelihoods. Within a broader context of accessing farmers’ resilience to agricultural drought, this paper focuses on the response mechanisms and adaptive strategies adopted by farming households in three types of areas (Plain, Hill, Mountain) in Dingcheng, Hunan Province. With the increasing drought frequency and the pressure from the demand for livelihood improvement, farmers’ response mechanisms have evolved, expanding from short-term adjustments to long-term adaptations, and switching focus from securing reliable water sources to improving irrigation efficiency and diversifying both on- and off- farm productions. The three types of geographic units have different resilience profiles and have developed diverse patterns of adaptive processes that update the conceptual model of Disaster Resilience of “Loss-Response” of Location. It presents a temporal dimension to the study of resilience, which is largely missing from the current literature and provides insights into how to enhance farmers’ response capacities in the face of agricultural drought in southern China.     

塔克拉玛干荒漠-绿洲过渡带尘卷风活动特征——以肖塘为例

利用1992—2011年塔克拉玛干沙漠北缘荒漠-绿洲过渡带肖塘气象站的观测资料,分析了该地区尘卷风的年、月变化规律及其与气象因子的关系。结果表明:(1) 1992—2011年尘卷风发生日数总体呈波动递减趋势;尘卷风主要发生在3—9月,占全年总日数的90.9%,其中4—7月占全年总日数的70%左右。(2)尘卷风月发生日数随月平均地表与1.5 m高处温差的增大而线性增加(r=0.875,P<0.01)。(3)尘卷风月发生日数随着月平均风速的增大而幂函数增加(r=0.89,P<0.01)。(4)尘卷风月发生日数随月平均相对湿度的增大而线性减少(r=-0.869,P<0.01)。