Effect of Covering-soil Thickness on Crop Growth on Bare Rock nd Gravel Land in an Ecological Restoration Project     

ZHANG Yang  LI Zhanbin  HAN Jichang  LI Peng  LI Juan 《资源与生态学报(英文版)》2018,9(5):484-492

To study the mechanism by which the thickness of covering soil effects crop growth in an ecological restoration project of bare rock and gravel land, the physiological characteristics of summer maize were observed during 2010-2015. This experiment was set up on exposed rock land, which had been covered by soil with six different thicknesses: 30 (C30), 40 (C40), 50 (C50), 60 (C60), 80 (C80) and 100 cm (C100). During the experiment, soil physical properties and the physiological traits and yields of crops were recorded. The results indicated several effects. 1) With the same thickness level, soil bulk density of the covering soil increased in successive planting years. There was a logarithmic relationship between soil bulk density and covering thickness. There was also a strong algorithmic relationship between covering thickness and sedimentation coefficient (R²=0.91). 2) The thickness of covering soil had a significant influence on both the height of summer maize, and soil and plant analyzer development (SPAD) values. In each treatment, the growth rates of the crops during the jointing and booting stages were higher than that in the booting to grain filling stage. After two years of land-use, the mean height of the crop in the C50 treatment was 8.16%, 3.32%, 3.31%, 9.86% and 7.55% higher than that for the C30, C40, C60, C80 and C100 treatments, respectively. The differences between treatments were significant (p < 0.05). SPAD values were highest at the heading stage. The highest value for the C50 treatment was 298.41 after two years of land-use. 3) Soil thickness significantly affected yields and the water use efficiency (WUE) of summer maize. The highest average crop yield and WUE value during the experimental period for the C50 treatment were 4614.12 kg hm^-2 and 13.57 kg hm^-2 mm, respectively. For the C50 treatment the multi-year average water use efficiency was significantly higher than that of the other treatments in 2010-2015. In conclusion, a soil thickness of 50 cm covering the bare exposed rock was adequate as a tillage layer for the crop, and all crop growth indexes in this treatment were better than for other soil thicknesses. The results provide a scientific basis for the land remediation and ecological restoration of bare rock and gravel land. At the same time, for Africa, where one-third of the land is desert, arable land resources are relatively scarce and agricultural ecology is fragile, can serve as a significant reference to improve the ecological environment, develop arable land resources and increase agricultural income.  相似文献   

黄河口及其邻近海域营养盐分布特征     

陈淑珠  顾郁翘  刘敏光  张敏秀  杨淑海  李静 《中国海洋大学学报(自然科学版)》1991,(1)

1985年5、8月中法联合调查黄河口海域的营养盐,其样品采用常规的分光光度法测定。营养盐的分布总趋势是河口附近浓度高,外海浓度低,河口与外海浓度之比达数百倍。在河口及其邻近海域营养盐的分布梯度与盐度的分布一致。在河口控制营养盐含量的主要因素是河水和海水的混合过程。在119°30′～50′E,37°25′～38°5′N,PO_4—P,SiO_3—Si出现低值区。在此范围附近恰恰浮游植物的总量比较高。对8月份的02站进行了25h的连续观测,其结果是底层营养盐与盐度有良好的负相关性,而表层的相关性较差 黄河具有很高的氮磷比值,这很可能是农业上用氮肥量增多引起的。  相似文献   

夏季东海西部表层海水中的pCO₂及海-气界面通量   总被引：10，自引：0，他引：10  

谭燕  张龙军  王凡  胡敦欣 《海洋与湖沼》2004,35(3):239-245

根据2001年夏季长江口及东海西部海域表层海水pCO  相似文献   

热带气旋的云系结构对其移动影响的数值试验   总被引：1，自引：1，他引：1  

王学忠  沙文钰  端义宏 《热带海洋学报》2003,22(3):52-60

应用上海台风研究所发展的东海热带气旋模式，根据热带云团的特点，设计了积云模型并叠加到台风中去，研究台风云系结构对其路径的影响。理想试验表明，只考虑温度场扰动，台风的移动偏向于密闭云区方向；而仅考虑湿度场扰动，台风的移动无固定的偏向。对9414号台风19940810的初始场，叠加积云模型的试验表明，预报路径较好地反映了其运动的特征。  相似文献   

Sea surface temperature variations in the southwestern South China Sea over the past 160 ka   总被引：1，自引：0，他引：1  

XIE Hongqin  JIA Guodong  PENG Ping''an  SHAO Lei 《海洋学报(英文版)》2007,26(2):49-55

Sea surface temperatures (SSTs) in the southwestern South China Sea have been reconstructed for the past 160 ka using the Uk37 paleothermometer from the core MD01-2392. The temperature differences between glacial times (MISs 6 and 2) and interglacial times (MISs 5.5 and 1) are 2.2~2.5 ℃. Younger Dryas event during the last deglaciation was documented in both the planktonic foraminiferal δ18O and SST records. After MIS 5.5, SSTs displayed a progressive cooling from 28.6 to 24.5 ℃, culminating at the LGM. During this gradual cooling period, warm events such as MISs 5.3, 5.1 and 3 were also clearly documented. By comparison of SST between the study core and Core 17954, a pattern of low or no meridional SST gradients during the interglacial periods and high meridional SST gradients during the glacial periods was exhibited. This pattern indicates the much stronger East Asian winter monsoon at the glacial than at the interglacial periods. Spectral analysis gives two prominent cycles: 41 and 23 ka, with the former more pronounced, suggesting that SSTs in the southern SCS varied in concert with high-latitude processes through the connection of East Asian winter monsoon.  相似文献   

进入渤海的热带气旋路径特点分析     

张晓慧  卢霞  陈金龙 《海洋预报》2003,20(4):1-4

热带气旋是夏季影响渤海的灾害性天气系统之一。其影响路径主要有三类，各类路径在影响时前期中高纬500hPa高空环流形势及夏季西太平洋副热带高压特征指数有显著差异。  相似文献   

North Pacific Subtropical Mode Waters Observed in Long XBT Cross Sections along 32.5°N Line     

Kimio Hanawa  Hiroyuki Yoritaka 《Journal of Oceanography》2001,57(6):679-692

The S/V Shoyo, of the Hydrographic Department, Japan Coast Guard, has conducted high-density expendable bathythermograph (XBT) measurements along the 32.5°N line in the North Pacific every year from 1990 to 1993 as a part of the Japanese-World Ocean Circulation Experiment (WOCE). These XBT data are analyzed here, focusing on year-to-year variations of the inventory and core layer temperature (CLT) of the North Pacific subtropical mode water (NPSTMW). Large year-to-year changes are found in the NPSTMW CLTs estimated in longitudes between 140°E and 160°E. CLT values were found of 17.4°C in 1990, 17.1°C in 1991, 17.3°C in 1992 and 17.6°C in 1993. Inspection of the wintertime westerlies over the formation area and sea surface temperature distribution revealed that this change in CLT can be qualitatively attributed to the strength of atmospheric cooling in the formation area in the previous winter. Although a large year-to-year variation of NPSTMW inventory was also found, it is hard to state any relationship between CLT and atmospheric forcing. There is a possibility that different observational seasons may affect the inventory. It has also been found that the thermocline depth in 1991 was shallower in the sea area east of 180° than in 1992 and 1993. Associated with this change, the North Pacific central mode water (NPCMW), characterized by thermostad with temperatures ranging from 14°C to 11°C, appears in the sea area east of 180° in the 1992 and 1993 cross sections. The 1993 cross section, which ranged from the Japanese coast to the west coast of North America, possessed another thermostad in the surface layer, with a temperature of about 17°C in the eastern part of the cross section, off California. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

海浪预报产品数据库管理系统开发研究     

许富祥  李凤金  刘煜  戴明瑞  高志华  杨春城  李洁  韦锋余 《海洋预报》2003,20(1):44-51

本文介绍海浪预报产品数据库管理系统，包括数据库管理系统的总体设计，硬软件的配置，数据库管理系统的主要内容和解决的关键技术。该数据库管理系统的建成，提供了我国近海和西北太平洋海浪预报的系统性资料，不仅对提高海浪预报准确率提供基础资料，也给海浪中长期预测预报方法研究和区域海洋学研究带来极大帮助。  相似文献   

Long-term changes in the fish community structure from the Tsushima warm current region of the Japan/East Sea with an emphasis on the impacts of fishing and climate regime shift over the last four decades     

Yongjun Tian  Hideaki Kidokoro  Tatsuro Watanabe 《Progress in Oceanography》2006,68(2-4):217

Japanese fisheries production in the Japan/East Sea between 1958 and 2003 increased to their peak (1.76 million tons) in the late 1980s and decreased abruptly with the collapse of Japanese sardine. Catch results for 58 fisheries and various environmental time-series data sets and community indices, including mean trophic level (MTL) and Simpson’s diversity index (DI), were used to investigate the impacts of fishing and climate changes on the structure of the fish community in the Tsushima warm current (TWC) region of the Japan/East Sea. The long-term trend in fisheries production was largely dependent on the Japanese sardine that, as a single species, contributed up to 60% of the total production in the Japanese waters of the Japan/East Sea during the late 1980s. Excluding Japanese sardine, production of the small pelagic species was higher during 1960s and 1990s but lower during 1970s and 1980s. This variation pattern generally corresponds with the trend in water temperature, warmer before early 1960s and after 1990s but colder during 1970s and 1980s. The warm-water, large predatory fishes and cold water demersal species show opposite responses to the water temperature in the TWC region, indicating the significant impact of oceanic conditions on fisheries production of the Japan/East Sea. Declines in demersal fishes and invertebrates during 1970s and 1980s suggested some impact of fishing. MTL and DI show a similar variation pattern: higher during 1960s and 1990s but lower during 1970s and 1980s. In particular, the sharp decline during the 1980s resulted from the abundant sardine catches, suggesting that dominant species have a large effect on the structure of the fish community in the Japan/East Sea. Principal component analysis for 58 time-series data sets of fisheries catches suggested that the fish community varied on inter-annual to inter-decadal scales; the abrupt changes that occurred in the mid-1970s and late 1980s seemed to correspond closely with the climatic regime shifts in the North Pacific. These results strongly suggest that the structure of the fish community in the Japan/East Sea was largely affected by climatic and oceanic regime shifts rather than by fishing. There is no evidence showing “fishing down food webs” in the Japan/East Sea. However, in addition to the impacts of abrupt shifts that occurred in the late 1980s, the large predatory and demersal fishes seem to be facing stronger fishing pressure with the collapse of the Japanese sardine.  相似文献   

雷州半岛灯楼角海岸地貌演变   总被引：10，自引：0，他引：10  

王丽荣  赵焕庭  宋朝景  袁家义  于红兵 《海洋学报》2002,24(6):135-144

灯楼角岬角位于雷州半岛的西南端,地处热带北缘.过去几次开展的区域地貌和第四纪地质调查及制图,均包括本区1),2),[1～2].宋朝景曾做过涉及本区海底的地貌与浅地层调查3),又指导学生研究本段海岸地貌4).近年赵焕庭等[3]开展该区珊瑚礁研究,使用了1960年版航空照片和1964年版1:10000地形图,结合野外调查,进一步研究了本区海岸地貌的演变.  相似文献