Managing land-use effects on Northland dune lakes: lessons from the past     

Tom Stephens  Paul Augustinus  Brett Rip  Patricia Gadd  Atun Zawadski 《新西兰海洋与淡水研究杂志》2018,52(3):409-429

The Northland region of New Zealand includes numerous high-value, macrophyte-dominated dune lakes. Recent water policy reforms offer limited guidance on managing for aquatic macrophytes. In addition, dune lake histories are poorly known as regular monitoring dates to 2005 AD. Here, ca. 4000 years of lake functional behaviour is reconstructed from sedimentary archives in two Northland dune lakes (Humuhumu and Rotokawau). Results demonstrated that macrophyte dominance is sensitive to catchment erosion and hydrological drawdown. Degradation of macrophyte communities occurred in the nineteenth and twentieth centuries, earlier at Lake Humuhumu than Lake Rotokawau (post-1880 AD and post-1930 AD, respectively). In both lakes, increased erosional influx reduced macrophyte productivity, before later increases to wider trophic state (post-1970 AD). Lake-level decline is linked to increased nutrient loading at Lake Rotokawau but less so, Lake Humuhumu which is more strongly groundwater-fed. In Northland dune lakes, water-level reduction and erosional influx from land use have driven macrophyte degradation.  相似文献   

鄂尔多斯盆地宜川地区二叠纪孢粉化石组合特征          下载免费PDF全文

高存山 《山东国土资源》2018,34(11)

通过对延长油矿延223井晚古生代孢粉组合研究以及古植被的恢复,探讨了该区晚古生代孢粉植物化石组合的地层学和古气候意义。根据孢粉化石主要属种的时代分布及其在各样品中百分含量的规律性变化,自下而上建立了3个孢粉组合:Gulisporites cochlearius-Laevigatosporites minimus组合、Sinulatisporites-Florinites组合和Lueckeisporites permianus-Platysaccus radialis组合。根据对划分孢粉组合的特征分析,通过与邻区及华北地区晚古生代孢粉组合的对比,探讨了孢粉组合的时代意义。通过孢粉组合,推测了相应时期的古植被类型,并与前人在相同地质时期所建立的大植物化石带进行了对比,分析了各地质时期植被的兴起、发展、繁盛以及衰退绝灭的历史过程,研究区二叠纪植物群属于典型的华夏植物群,反映了一种温暖潮湿的热带雨林气候,二叠纪晚期随着松柏类植物所占比例的增加,气候有变干旱的趋势。  相似文献   

松辽盆地中生代沉积基准面变化研究   总被引：6，自引：0，他引：6  

张世奇  任延广 《地球科学与环境学报》2003,25(2):1-5

利用地质资料研究来恢复沉积基准面变化。首先根据沉积物的分布规律、沉积构造、古生物组合及古生态、自生矿物和波基面等特征来获得古水深,然后利用对地层做脱水压实校正获得沉积物原始厚度。对湖盆地区古水深和沉积物原始厚度累加起来就可得到沉积基准面变化曲线。沉积基准面变化曲线为在松辽盆地中进行地层对比提供了依据。  相似文献   

Change of ancient hydrology net in Northeast China Plain     

Hui QU  Yu CHU  Fenglong ZHANG  Fuli QI  Xiangkui YANG 《世界地质(英文版)》2006,9(2)

Comparing with lithofacies palaeogeography of several great plains, the authors analyzed four great plains in Quaternary diastrophism, the sedimentary facies, sedimentary environment and their evolution from the independent embryonic and river system of ancient Heilongjiang finally to the Halar highland, Songnen Plain, Sanjiang Plain, the Xingkai Lake Plain and various river systems, collected the unification outside the system of Heilongjiang River to release into the sea, south ancient Xialiao River finally piracy Dongliao River, Xialiao River had released into the sea the ancient water law vicissitude and the evolved rule.  相似文献   

Plant distribution at the mobile dune scale and its relevance to soil properties and topographic features     

Xiaoan Zuo  Halin Zhao  Xueyong Zhao  Yirui Guo  Yulin Li  Yayong Luo 《Environmental Geology》2008,54(5):1111-1120

A survey was conducted in an 11-year recovery mobile dune (RMD11) and a 20-year recovery mobile dune (RMD20), in Horqin Sandy Land, Northern China, to determine plant distribution at the mobile dune scale and its relevance to soil properties and topographic features. The results showed that (1) vegetation cover and species number increased from dune top to bottom in the restoration process of mobile dune; (2) the average value of soil organic C, total N, pH, relative height of sampling site, very fine sand content and soil water contents (40−60 and 60−80 cm) of RMD11 were less than that of RMD20, respectively, and there were significant differences (P < 0.05) between the two dunes; (3) soil resources were redistributed by shrub restoration and relative height of sampling site on dune. The distribution of sand pioneer plant, Agriophyllum squarrosum, was positively related to the relative height of sampling site and soil water content, while that of other herbaceous plants was positively related to soil nutrients in the restoration process of mobile dune. These results suggest that at mobile dune scale, plant distributions are determined by a combination of soil properties and topographic feature. Much effort should be made to preserve the interdune lowland and to improve the level of soil nutrients on mobile dune.  相似文献   

秦皇岛昌黎黄金海岸的沙丘沉积和发育机理   总被引：7，自引：0，他引：7  

曾照爽  庄振业  祁兴芬  刘志杰 《海洋地质前沿》2003,19(7):23-27

昌黎黄金海岸长40km，分布1～1．5km宽的风成沙丘。主沙丘链高30～40m，顺岸线分布，与其斜交数列新月形横向沙丘链。沙丘以中细砂组成，分选极好，层理构造十分丰富。距今3～4ka以前，沙坝形成时就开始形成沙丘；1915年滦河新三角洲发育以来增加了风沙的输沙量，增高沙丘和扩宽了沙丘带。  相似文献   

Sedimentary Features of Shallow Ancient River Channels on the Northern Shelf of the South China Sea   总被引：1，自引：0，他引：1  

Kou Yangqi  Du Deli nd Marine Geological Investigation Party  MGMR  Guangzhou  Guangdong Jiang M inxi 《《地质学报》英文版》1995,69(1)

Quaternary buried ancient river channels are widespread in the shallow-level sediments of the northern shelf of the South China Sea. The sedimentary sequence mainly of fluvial deposits comprise an important component part of the low-stand system tract and transgressive system tract in the study region. The plannar variation and spatial association of the sedimentary features such as incised valley fillings, deltaic foreset wedges and block slides of shelf-marginal fans reflect the palaeogeographic environment during the fall of the regional sea level in the northern part of the South China Sea. Based on the high-resolution seismic reflection data and gelogical data from boreholes, the present paper makes an integrated interpretation of the Quaternary ancient river channels in the shallow sediments of the study area, studies the sedimentary features of the ancient channels such as their spatial distribution, seismic facies reflection indicators, sedimentary facies and sand -body types, and discusses thei  相似文献   

MODERNIZATION PROCESS IN HISTORICAL ASIAN CITIES AND THEIR CHARACTERISTICS: A COMPARATIVE STUDY ON SEOUL, TOKYO AND BEIJING     

Li Wenyan 《地理学报(英文版)》1995,(2)

Thspaperwaspresatedatthe"94SeoulIntemationalSyInPosiumonCityandffistory"heldonOCtober27to28,l994andthenpublishedinTheJoumaIofSeouIShndesVo.IV.Thepresentvisionhasbeenslighlyrevised.Bejing,SeoulandTokyoarecapitalsofthreeneighbouringcoUnnesinNortheastAsia,wh…  相似文献   

萨拉乌苏河流域萨拉乌苏组沙丘砂沉积特征   总被引：7，自引：1，他引：7  

欧先交  李保生  靳鹤龄  吴正  温小浩  董光荣  曾兰华  欧阳椿陶  杨艺  刘宇飞 《地理学报》2006,61(9):965-975

萨拉乌苏河流域米浪沟湾剖面萨拉乌苏组含7层古流动沙丘砂、4层古固定-半固定沙丘砂.对这些沙丘砂的沉积构造观察以及粒度、扫描电镜和常量化学元素分析结果表明：（1）这些沙丘砂具有与现代沙丘砂相似的风成沉积构造特征;（2）粒度及其参数——Mz、σ、Sk和Kg,以及主要化学组分SiO2、Al2O3和TOFE也与现代沙丘砂相近;（3）Mz-σ、SiO2-Al2O3＋TOFE散点图和概率累积曲线显示这些沙丘砂与萨拉乌苏组中的河湖相、古土壤差别明显,而与现代沙丘砂一致;（4）石英砂颗粒具有良好的磨圆以及碟形坑、新月形坑、麻坑、上翻解理薄片、硅质沉淀和硅质裂纹等表面结构特征,反映其曾受持久的风力搬运作用.沉积构造、粒度、石英砂颗粒表面结构和化学元素等多个方面具备了与现代沙丘砂类似的风成特征,证明这些沙丘砂的成因是风成的.  相似文献   

额济纳绿洲沙尘暴沉积特征     

温小浩  李保生  王为  LI Sen  OU Xianjiao  ZHENG Yanming 《地理学报(英文版)》2006,16(4):502-508

1 Introduction Oases are unique ecosystems and important residences for our ancestors in arid and semiarid regions of the world, and have deeply been imprinted by human actions, such as Jericho oasis of Jordan Valley, Jarmo oasis of the Euphrates River an…  相似文献