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1.
王自磐 《极地研究》1994,6(1):28-37
在1989/1990年度南极夏季,对中山站附近麦氏贼鸥雏鸟的生长进行了观察和研究。本区麦氏贼鸥育雏期大约在每年12月中旬至翌年2月下旬,雏鸟的成活率较低,本年度为38.9%,从出雏到育成(首飞日),育期平均53.2天(范围52-55天)。雏鸟平均体重日增长率,第一雏鸟为27.42g/d,第二雏鸟为16.56g/d。雏鸟生长的逻辑斯蒂克曲线数学方程式为:W=1255.41+22.6034e-0.1518t(第一雏鸟)生长曲线渐近线为1255.4g,拐点为20.5d,第一雏鸟体重的最大日增率x=43.94±8.24(g)。影响本区麦氏贼鸥雏鸟生长和成活率的主要外部因子是天气(如暴风雪)同类自残以及食物等  相似文献   

2.
李亚红  王惠 《盐湖研究》1996,4(3):48-51
测定了三元体系RECl3(RE=Dy,Yb)-HOAc-H2O(30℃)的平衡态的溶度数据并绘制了相应的溶度图。在两个体系中分别得到了DyCl3.6H2O和YbCl3.6H2O两种固相。依据HOAc和DyCl3.6H2O和YbCl3.6H2O有盐析作用这一结论得到了一种制备DyCl3.6H2O和YbCl3.6H2O的HCl-HOAc法。同时, 在分析测定酸的重百分浓度时,利用“差减法”得到了H的准  相似文献   

3.
2005—2017 年拉萨小时降水变化特征   总被引:1,自引:0,他引:1       下载免费PDF全文
利用拉萨站 2005—2017 年汛期(5~9 月)逐时地面观测资料,分析了拉萨逐年小时降水(降 水量、降水频次和降水强度)的变化特征,结合谐波分析方法讨论了小时降水的日循环信号,最后 对比了不同时长和等级的小时降水出现频次及其对总降水的贡献。结果表明:(1)拉萨逐年汛期 小时降水以“单峰型”结构为主,峰值出现在夜间。(2)拉萨汛期小时降水变化为全日周期,其中盛 夏(7~8 月)期间的日循环信号最强。(3)拉萨汛期降水按持续时间可分为:短历时(1~3 h)、中历 时(4~6 h)和长历时(>6 h)3 种类型,其中短(长)历时降水出现频次最多(少),但其贡献率最小 (大),短历时降水的日峰值出现在下午到前半夜,而中历时和长历时降水的日峰值出现在后半 夜。(4)各等级小时降水中小雨(3>r≥1)和中雨(r≥3)对降水总量的贡献率明显大于微雨(1>r≥ 0.1),随着降水等级的上升,夜雨概率增大。  相似文献   

4.
《地理教学》2008,(12):3-3
气象部门统计显示,今年夏季(6至8月),北京市平原地区的平均降水量为443.1毫米,比近十年平均值(319.1毫米)偏多近4成,较去年同期(284.4毫米)偏多5成多,是1999年以来夏季降水最多的一年。北京今夏降水主要集中在城区西部、西北部的昌平及东北部的密云、平谷和顺义,大部分地区降水量在350—550毫米之间。北京频繁降水对水库蓄水极为有利。卫星监测表明,8月下旬,密云水库、  相似文献   

5.
郑博华  陈胜  王勇 《干旱区地理》2020,43(1):108-116
利用2010—2017年1~12月新疆喀什地区10个气象站逐小时降水资料,分析统计喀什地区近8 a降雨雪(以下统称降水)日变化特征。结果表明:(1) 喀什地区全年降水量和降水频次日变化存在明显的波动,总体上呈现“正弦波”一峰一谷特征,降水量峰值出现在03:00(北京时,下同),谷值出现在18:00;降水频次峰值出现在04:00,谷值出现在18:00;两者峰谷值出现时间接近。(2) 2010—2017年喀什地区全年降水量和降水频次呈明显的增加趋势;而降水强度年际变化趋于平缓,无明显变化。(3) 降水强度日变化趋势与降水量、降水频次并不存在一致性。(4) 喀什地区全年降水主要以短时段降水为主,其中,持续1 h降水次数为最大值,但降水量和贡献率最大值却同出现在2 h和6 h持续降水中。全年降水主要以后半夜和上午开始的降水过程为主导,且仍主要为短时段降水。  相似文献   

6.
多源遥感降水产品在气象站点稀少或分布不均地区的干旱监测方面,发挥着至关重要的作用,比如地处中国西北的干旱区。选择5套典型遥感降水产品(PERSIANN、CHIRPS、CMORPH、TMPA和MSWEP),基于标准化降水蒸散指数(SPEI),评估了降水产品在3种时间尺度的气象干旱性能;通过游程理论识别干旱事件,阐释了遥感降水产品捕获干旱事件的能力。研究表明:(1)在西北干旱区,5套遥感降水产品均能较好地捕捉多年平均降水量的空间分布格局,但却难以准确地捕捉降水的变化趋势。(2)在捕获SPEI性能方面,MSWEP最优,其次为TMPA、PERSIANN和CHIRPS,CMORPH表现最差。1个月尺度(SPEI1)是遥感降水产品识别气象干旱的最佳时间尺度。(3)在刻画干旱事件的特性方面,CHIRPS对干旱事件数量的识别能力最佳,PERSIANN最差;MSWEP和TMPA表征干旱严重性最好,CHIRPS较差;除CMORPH外,其余4套产品均能较好地捕获干旱事件的强度和极值。综上所述,虽然5套遥感降水产品整体上可较好地捕获西北干旱区的干旱特征,但由于受降水产品反演算法、地形复杂性以及地面验证站点疏密...  相似文献   

7.
PsychologicalchangesoffifteenChineseAntarcticResearchExpeditionmembersXueZuohong(薛祚)(DepartmentofPsychology.PekingUndersity,B...  相似文献   

8.
利用 1960—2017 年水文、气象资料,采用相关分析、Mann-Kendall 和小波分析等方法,研究 了祁连山中部气候和径流量变化特征。结果表明:(1)近 60 a 来祁连山中部气温、降水和径流量总 体呈现出气温上升、降水增加、径流量增大的趋势。年平均气温以 0.39 ℃·(10 a)-1 的幅度上升,四 季气温升高趋势明显,年平均最低气温和冬季气温的升温幅度最高。降水增加了约 19.2%,降水的 增加主要归因于夏季降水的增多。(2)平均气温在 1993 年出现突变,气温突变时间早于西北其他 地区。气温和降水的主周期分别为 8 a 和 30 a,在径流量周期响应中,短周期(8 a)与平均气温振荡 非常一致,长周期(30 a)与年降水变化较为一致。(3)分析表明,降水和气温都是影响径流量变化 的主要因素,建立的径流量预测模型纳什效率系数为 0.68,能很好的分析和预测径流量,降水和气 温变化分别使径流量增加了 21.1%和 10.9%,降水对径流量的影响作用更大。  相似文献   

9.
兰州大气颗粒物和水溶性离子及其降水中元素组成的关系   总被引:8,自引:0,他引:8  
张锐  晁开 《中国沙漠》1995,15(4):357-361
本文论述了兰州市区不同季节大气颗粒物污染状况,它的水溶性复合离子浓度分布,同期降水中阴、阳离子组成以及它们之间的关系。研究结果表明;该地区大气颗粒物污染较为严重。它的水溶物和同期降水化学组成复杂,与Ca ̄(2+)离子浓度之和在二者的总离子中分别占59.2%和57.8%。并呈“硫酸-钙”型污染特征。受人为污染的影响颗粒物水溶性离子浓度冬季较高。受沙尘影响春季降水中的Ca ̄(2+)离子浓度高于其它季节。  相似文献   

10.
李兴防 《地理教学》2011,(23):43-47,42
综合题:本大题分必做题(第27题~第29题)和选做题(第30题),共计60分。 27.图15为北非简图,图16为甲、乙两地气温和降水统计图。读图回答问题。(14分) (1)甲、乙两地气温和降水的差异是。试从气压带、风带的移动规律分析产生上述差异的原因(6分)  相似文献   

11.
河西防护林体系的持续高效发展   总被引:4,自引:1,他引:3  
赫卓峰 《中国沙漠》1995,15(3):288-292
祁连山水源涵养林和河西走廊防风固沙林的持续高效发展,必须通过社会林业和优化林业内部结构来实现。  相似文献   

12.
 2006年开始在库布齐沙漠选择4种藓类植物进行人工培养促进结皮层形成实验,发现人工结皮层中藓类成活率、盖度与土壤基质、降雨量、小生境和藓类植物的生长和繁殖特性密切相关。双色真藓(Bryum dichotomum)成活率和盖度最高,密度与盖度相关,可形成大面积藓类结皮层。单位面积内土生对齿藓(Didymodon vinealis)密度最大,对结皮层的稳定具有重要作用。在培养初期藓类植物生长和繁殖速度较快的原因是消耗繁殖体内营养的结果,以后稳定在一个水平上不会出现生长的高峰期。本项研究为人工培养藓类植物促进结皮层的形成提供了实验依据,并为深入探讨生物结皮层的形成和维持机制提供基础科学资料。  相似文献   

13.
The field trial was established to investigate the effects of planting condition(soil water content,soil buried depth,rhizome length)and time on the survival rate and growth of Phragmites australis rhizomes.The results indicated that survival rate and growth of Phragmites australis were affected by soil water content and rhizome length significantly,but not by soil buried depth.The survival rate of Phragmites australis in moist condition was higher than those in natural and flooding conditions.Rhizomes length did not affect survival rate,height and shoot number,but influenced biomass and buds number,which were higher with 15 cm length than those with 30 cm length.Based on the suitable soil water content(moisture)and rhizome length(15 cm),the survival rate of Phragmites australis was the highest when they were planted in May(91%)comparing to June and July.The number of shoots and buds were the highest in June,which had more suitable temperature and light for Phragmites australis to grow.Therefore,the optimizing transplanting condition of Phragmites australis was that rhizomes of 15 cm with some buds were planted in May with moisture(soil water content).  相似文献   

14.
砂旋复花的防风固沙作用   总被引:4,自引:0,他引:4  
韩广 《中国沙漠》1995,15(3):273-277
砂旋复花是一种沙生先锋多年生草本植物,营养繁殖能力极强,能很好地适应恶劣的流沙环境。研究结果表明,砂旋复花群聚的防风固沙作用非常突出,作为一种优良固抄植物,值得在北方沙区大力推广。  相似文献   

15.
TAN Fang-Lin 《湿地科学》2007,5(2):105-110
Spartina is a kind of very important and invasive grass. In its native range, it is very important for erosion control, fish, wildlife, and estuary reclamation. Therefore, it was introduced to many countries. Since 1963, it was introduced to China. Up to now, it was intentionally or accidentally planted nearly all estuaries in the east coast of China and the area was estimated over 0.1×106 hm2. As other introduced plants, Spartina grows very vigorously in China, and this caused many environmental and economical problems. So, it is an emergency to develop a Spartina control strategy of China. In the paper, the history of Spartina introduction in China was reviewed, and several methods which were probably feasible for China to control Spartina were introduced, including physical/mechanical (such as mowing, digging, and dredging), chemical, and biological methods. Before taking any measurments to control Spartina, 2 things should be done. The first was to develop a plan and make an inventory; the second was to select a feasible method according to local climatic, economic, social, and ecological conditions. It was suggested that it would be very important to assess the possible effect of control methods on the environment in order to prevent from causing other environmental problems.  相似文献   

16.
生态恢复过程中土壤有机碳的变化   总被引:1,自引:0,他引:1  
对长汀河田严重侵蚀地采取植灌促林生态恢复措施后生态系统的土壤有机碳、可溶性有机碳和微生物生物量碳进行了研究,并以未采取生态恢复措施的严重侵蚀退化形成的光板地与村旁受保护的风水林为对照。研究结果表明:采用生态恢复措施以后,土壤有机碳含、贮量分别达到49.03g/kg和54.14t/hm^2,分别是光板地的10.43和4.06倍;土壤DOC含、贮量分别达到1.40g/kg和0.67t/hm^2,分别是光板地的10.00倍和6.50倍;土壤MBC含、贮量分别达到2.60g/kg和1.27t/hm^2,分别是光板地的6.34倍和4.23倍。  相似文献   

17.
Vegetation restoration is one of the most common and effective ways to combat desertification and prevent adjacent areas from sand encroachment in many of the desertified regions of the world. However, vegetation restoration in desertified regions is very difficult because of low rainfall, the mobile ground surface, and cost. An effective, low-cost method of afforestation is urgently required. To determine such a method, a 10-year study was carried out in the Jilantai Salt Lake area. Five different afforestation areas were established: a ‘comparison area,’ a ‘land enclosure area,’ a ‘land enclosure + irrigation area,’ a ‘leveled-afforestation area’ (the dune areas were leveled and then planted with seedlings with added irrigation), and a ‘protected afforestation area’ (the dune areas were planted with seedlings, and the surviving natural vegetation was protected as much as possible). Vegetation-related parameters (survival rate, height, trunk diameter, coverage, canopy size, and density) and environment-related factors (relative humidity, wind velocity, and amount of sand encroachment) were measured by standard methods. Results show that the protected afforestation method had the following advantages: (1) the survival rate was higher for seedlings planted in the protected afforestation area than in the leveled afforestation area; (2) vigor (height, trunk diameter, coverage, and canopy size) was better in seedlings planted in the protected afforestation area than in the leveled afforestation area, especially in the beginning period of revegetation; (3) coverage (of individual species, of all planted vegetation, and of all vegetation) was larger in the protected afforestation area than in the leveled afforestation area; (4) density of naturally germinated plant species was higher in the protected afforestation area than in the other areas, showing that the protected afforestation method provided a suitable growing environment not only for planted species but also for naturally growing species; (5) in the protected vegetation area, relative humidity of air increased and wind velocity was greatly reduced; (6) after the establishment of vegetation by the protected afforestation method, sand encroachment into the salt lake area was significantly reduced. These results suggest that protected afforestation is an effective method of vegetation rehabilitation that has the potential not only to be applied to arid lands in China but also to desertified areas throughout the world; (7) cost-effective calculation shows that the leveled afforestation area costs much more than other areas.  相似文献   

18.
差不嘎蒿在科尔沁沙地草场植被中的作用   总被引:6,自引:1,他引:5  
差不嘎蒿是科尔沁沙地草场退化过程中的一个重要缓冲种。在草场退化过程中能够迅速占领退出植物种遗留下来的空间, 生物量由81.6g/m2增加到285g/m2; 但从半固定沙丘草场到半流动沙丘草场, 其生物量减少到了190g/m2, 占总生物量的77.2%。差不嘎蒿在半流动沙丘草场中的繁殖力最高, 当年生幼苗数和果实生物量分别为59株/m2和17.6g/m2。差不嘎蒿以无性繁殖为主, 但是, 在流动沙丘草场则以种子繁殖为主。  相似文献   

19.
人工措施对川中丘陵区防护林建设的影响   总被引:2,自引:2,他引:0  
人工措施对防护林建设初期的影响,主要表现在保存率,林木生长,林分结构等方面,而这些都与防护林效益密切相关,为此,提出了营建和管理防护林中应注意的问题。  相似文献   

20.
云南哀牢山的梯田景观   总被引:4,自引:1,他引:4  
陆玉麒 《热带地理》1994,14(2):180-185
云南哀牢山区哈尼族人创造的独具特色的热带山区梯田景观,在与自然环境的协调过程中,巧妙地解决了农耕中的关键要素水分与肥料,创造了较高的粮生产水平,并以聚落分布的适中高度,均衡建构中介,最终内化为一种独特的文化形态,自然与人文在此所形成的高度协调关系,无疑具有重要的理直学研究意义。  相似文献   

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