Fine root distribution pattern of different aged Leucaena leucocephala trees in debris flow source area in Jiangjia Gully,China     

Ling-hui Guo  Dao-jie Wang  Xiang-min Sun  Dong Chen  Xiao-yan Chen 《山地科学学报》2014,11(4):941-949

Fine root is critical to restrain soil erosion and its distribution pattern is of great influence on the restraining effects. This study studied the fine root biomass(Br) distribution of different aged Leucaena leucocephala(5, 10, 15 years) in debris flow source area in Jiangjia Gully by digging downward to the bottom at different distances to stem in three directions on slope. The results showed the Br increased dramatically by 143% from 5 years to 10 years and then rose slowly by 38% from 10 years to 15 years. The Br of 5 years was significantly asymmetric between uphill and alonghill directions, but there was little difference among directions for other ages, and a concentration trend appeared to exist in downhill and alonghill directions. Moreover, fine root(D≤1 mm) was significantly heavier than that of fine root(1mmD≤2 mm), playing a leading role in the vertical distribution of the whole fine root, with a logarithmic or an exponential function. The results presented may shed light on fine root distribution pattern and evaluation of its effect on slope stability in debris flow source area.  相似文献   

莱芜市土地登记系统的设计与实现          下载免费PDF全文

李媛  邵华 《山东国土资源》2014,30(10)

针对现有土地登记发证业务的特点和作业方式,提出了莱芜市土地登记系统的设计思路和原则,依托莱芜市三维国土一张图管地平台开发设计了土地登记系统。总体上实现了土地登记办公的整个业务流程,为政府管理部门办理日常业务提供了新模式。  相似文献   

Linking Tarim Basin sea retreat (west China) and Asian aridification in the late Eocene   总被引：1，自引：0，他引：1  

R. Bosboom  G. Dupont‐Nivet  A. Grothe  H. Brinkhuis  G. Villa  O. Mandic  M. Stoica  W. Huang  W. Yang  Z. Guo  W. Krijgsman 《Basin Research》2014,26(5):621-640

The Tarim Basin in western China formed the easternmost margin of a shallow epicontinental sea that extended across Eurasia and was well connected to the western Tethys during the Paleogene. Climate modelling studies suggest that the westward retreat of this sea from Central Asia may have been as important as the Tibetan Plateau uplift in forcing aridification and monsoon intensification in the Asian continental interior due to the redistribution of the land‐sea thermal contrast. However, testing of this hypothesis is hindered by poor constraints on the timing and precise palaeogeographic dynamics of the retreat. Here, we present an improved integrated bio‐ and magnetostratigraphic chronological framework of the previously studied marine to continental transition in the southwest Tarim Basin along the Pamir and West Kunlun Shan, allowing us to better constrain its timing, cause and palaeoenvironmental impact. The sea retreat is assigned a latest Lutetian–earliest Bartonian age (ca. 41 Ma; correlation of the last marine sediments to calcareous nannofossil Zone CP14 and correlation of the first continental red beds to the base of magnetochron C18r). Higher up in the continental deposits, a major hiatus includes the Eocene–Oligocene transition (ca. 34 Ma). This suggests the Tarim Basin was hydrologically connected to the Tethyan marine Realm until at least the earliest Oligocene and had not yet been closed by uplift of the Pamir–Kunlun orogenic system. The westward sea retreat at ca. 41 Ma and the disconformity at the Eocene–Oligocene transition are both time‐equivalent with reported Asian aridification steps, suggesting that, consistent with climate modelling results, the sea acted as an important moisture source for the Asian continental interior.  相似文献   

孑遗植物四合木(Tetraena mongolica)异地保护条件下的气候生物学特征与光合效率     

智颖飙  杨持  李红丽  张荷亮  华宇鹏  赵凯  路战远  红鸽  旺扎拉  王强 《中国沙漠》2014,34(1):88-97

为了廓清异地保护条件下孑遗濒危植物四合木(Tetraena mongolica)的气候生物学特征、光合生理生态适应性及生境适宜性,应用1971—2011年的地面气象资料进行了不同试验区的气候生物图解与分析,测定了四合木及其伴生种白刺(Nitraria tangutorum)的叶片气体交换参数及光合效率。结果表明:①四合木自然分布区(内蒙古乌海地区)与异地保护区的气候生物学特征存在明显分异;②当年种植的四合木实生苗的生长量大小依次为:乌海四合木核心区实生苗鄂尔多斯实生苗阿拉善实生苗;③自然条件下,5个处理的净光合速率(Pn)依次为阿拉善移植的四合木成株(24.05±1.68μmol·m-2·s-1)乌海客土栽培的四合木(19.97±1.05μmol·m-2·s-1)乌海栽培的四合木实生苗(18.96±1.04μmol·m-2·s-1)鄂尔多斯栽培的四合木实生苗(16.64±0.92μmol·m-2·s-1)阿拉善栽培的四合木实生苗(16.48±0.13μmol·m-2·s-1);异地保护试验区栽培的四合木实生苗的Pn没有明显差异(p≥0.05),即原生境条件下栽培的四合木实生苗的Pn较高。同时,异地保护栽培四合木实生苗中,鄂尔多斯栽培的四合木实生苗的Pn阿拉善栽培的四合木实生苗。从四合木光合作用特征中的Pn、蒸腾速率、气孔导度和胞间CO2浓度、气候生物学特征和生长量等综合研究结果可以推断,从原生境区东移的实生苗迁地保护,使四合木具有更高的生理生态适宜性和环境适应性。  相似文献   

2001-2010年中国区域旅游效率评估     

鲁小波  郭迪 《地域研究与开发》2014,(5)

选择旅游酒店数、旅行社数、旅游酒店从业人员数和旅行社从业人员数为旅游投入因素,旅游总收入为产出变量,运用数据包络分析方法中的 C2 R 模型分析2001-2010年中国区域旅游效率及其空间格局和变化趋势。中国四大区域的平均旅游效率由高至低依次为东部地区、东北地区、中部地区和西部地区。在31个中国大陆省级行政区中,天津在2001-2010年期间每年都为旅游效率最高的省份。从时间的角度,中国区域旅游效率经历了一个波浪式变化过程,2003年和2008年是2个明显的波谷。2001-2005年四大区域旅游效率的变化过程基本一致。2005-2010年四大区域旅游效率变化各不相同,东部地区呈逐步下降趋势,中部地区先增长、2010年开始下降,西部地区为起伏不定,东北地区为持续增长。  相似文献   

环渤海地区中心城市金融竞争力评价及辐射研究     

林晓  韩增林  郭建科  赵林 《地域研究与开发》2014,(6)

以环渤海地区中心城市为研究区域,通过建立城市金融竞争力评价指标体系,运用突变级数法、主成分分析法、层次分析法对环渤海地区中心城市金融竞争力进行综合评价,并通过威尔逊模型揭示了中心城市的辐射范围。环渤海地区中心城市金融发展不平衡,北京的城市金融竞争力遥遥领先于其他城市;环渤海地区并未形成一个紧密联系的金融辐射网络,金融一体化还不成熟,仍有金融盲区的存在;各中心城市在发挥自身优势的同时应打破地区间行政壁垒,优势互补,协同发展,带动环渤海地区金融发展。  相似文献   

河西走廊春季降水的空间异常分布及年代际变化     

刘洪兰  张强  王胜  郭俊琴  杨寰 《中国沙漠》2014,34(5):1386-1392

利用河西走廊19个气象站建站至2012年3—5月降水量资料,分析了河西走廊春季降水的基本气候特征;通过EOF、REOF、小波分析等方法,对河西走廊春季降水的时空特性进行了研究,用Mann-Kendall检验法检验河西走廊春季降水序列是否存在突变现象。结果表明,河西走廊春季降水空间分布极不均匀,其空间分布特征是东南部为多雨区,西北部为少雨区。河西走廊春季降水在第一空间尺度上为全区一致,在第二空间尺度上可分为2个自然气候区,在第三空间尺度上可分为5个自然气候区。从年代际变化来看,21世纪初10年是近半个世纪来降水最多的10年,20世纪70年代是降水最少的10年;河西走廊春季降水的年际变化十分显著,降水最多的年份是最少年份的6倍多。1961—2012年间河西走廊春季降水发生了明显的突变:1985年出现了一次趋于增多的突变。3年的短周期和19年的长周期是其主要周期。  相似文献   

基于GPS反射信号的岸基海冰探测的研究   总被引：1，自引：0，他引：1       下载免费PDF全文

张云郭建京  洪中华韩彦岭 《极地研究》2014,26(2):262-267

本文论述了全球导航卫星系统反射信号测量（GNSS-R）在海冰介电常数和海冰密集程度方面的潜在的研究价值,对欧洲空间局在格林兰岛迪斯科海岸采集的海冰数据进行分析,处理了两种反射信号的幅度的量化关系,同时跟踪多颗GNSS卫星并且保证了数据处理时间的连续性和有效性。根据双极化反射信号的幅度极化比和模拟海冰表面复介电常数得出结论, 幅度极化比和海冰表面的介电常数变化有联系。  相似文献   

State of the art and practice of pavement anti-icing and de-icing techniques     

WenBing Yu  Xin Yi  Ming Guo  Lin Chen 《寒旱区科学》2014,6(1):0014-0021

Pavement snow and icing are worldwide problems, but effective countermeasures are just beginning to be developed in China. The two most common snow and ice removal methods are mechanical clearance and chemical melting, and the advantages and disadvantages of each approach are discussed here, including environmental and structural damage caused by corrosive snow melting agents. New developments in chemical melting agents and mechanical equipment are discussed, and an overview of alternative thermal melting systems is presented, including the use of geothermy and non-geothermal heating systems utilizing solar energy, electricity, conductive pavement materials, and infrared/microwave applications. Strategic recommendations are made for continued enhancement of public safety in snow and ice conditions.  相似文献   

探测大气温湿廓线的35通道微波辐射计设计原理与特点     

卢建平  黄建平  郭学良  于子平  雷连发  张北斗 《气象科技》2014,42(2):193-197

总结了自主研制的MWP967KV型地基35通道微波辐射计系统设计原理和主要特点。系统将K、V双频段宽带天线及接收机、宽带调谐本振、温湿压计以及电源模块紧凑集成为一台整机设备。对各传感器的测量输出实时进行一体化综合处理,采用BP神经网络实时反演大气温度、湿度廓线和汽、水总量。廓线的垂直覆盖范围为地表至顶空10km,共划分为58层。辐射计样机于2012年秋冬季节在北京地区开展了为期2个月的观测试验,利用这段时期内的69个探空资料样本对辐射计2个层次的实时观测输出都进行了对比检验,计算了水汽、氧气通道亮温和反演所得大气温湿廓线的平均偏差、均方差以及相关性。结果表明该系统能够满足实时气象监测的需求,达到国际先进水平。  相似文献