Degradation of High Mountain Ecosystems in Northern Europe     

JorgLoffler 《山地科学学报》2004,1(2):97-114

Data material of a long-term high mountain ecosystem research project was used to interpret the grazing impact of reindeers. In central Norway investigations were conducted to both, areas where reindeer grazing is excluded, and areas where intensive pasturing is present for a long period of time.The comparative analysis of grazing impact was based on similar environmental conditions. The results were transposed to northern Norway where dramatic overgrazing had been exceeding the carrying capacity. Using landscape ecological mappings, especially of vegetation and soils, the impact of reindeer grazing in different areas became obvious. Non-grazed lichen-dominated ecosystems of the snow-free locations functioned sensitively near the limit of organism survival. These localities were most influenced by grazing as they offer the winter forage to the reindeers. So, intensive grazing in central Norway led to landscape degradation by destruction of the vegetation and superinduced by soil erosion. Those features were comparable to the situation in northern Norway, where a broad-scale destruction of the environment combined with a depression of the altitudinal belts had occurred due to overgrazing. Functioning principles of intact high mountain systems were explained and used to interpret the environmental background for the understanding of degradation phenomena. Finally, the use of a new model calculating the carrying capacity of high mountain landscape was discussed.  相似文献   

西秦岭西段共和盆地周缘西功卡花岗闪长岩体锆石U Pb年龄、地球化学特征及其构造意义   总被引：2，自引：0，他引：2  

杨瀚文  申俊峰  魏立勇  张振  刘满年  冯博鑫  张洛宁 《现代地质》2018,32(2):316

西功卡花岗闪长岩体位于西秦岭西段的共和盆地周缘。对该岩体进行了系统的岩相学、锆石U Pb年代学和岩石地球化学研究。锆石LA ICP MS U Pb年龄为(2272±73) Ma(MSWD=20),代表岩体侵位时间。西功卡岩体具有高硅(SiO2=6986%~7094%)、富钾(K2O= 320%~408%)、富碱(K2O+Na2O=561%~703%)、弱过铝质(A/CNK=099~120)特征,属于高钾钙碱性Ⅰ型花岗岩。西功卡岩体富集K、Rb、Ba、Th、U等大离子亲石元素,亏损Nb、Ta、Ti、P等高场强元素,轻重稀土元素分馏较明显(LREE/HREE=1104~1313),具有中等Eu负异常(δEu=072~ 084)。岩石地球化学特征表明,西功卡花岗闪长岩主要由壳源物质熔融形成,结合前人研究成果,笔者认为,西功卡岩体形成于晚三叠世,与区域其他岩体年龄基本一致,均形成于后碰撞构造环境,为同一构造-岩浆事件的产物。研究表明,西秦岭造山带西段共和盆地周缘于晚三叠世进入后碰撞构造演化阶段,该认识对西秦岭造山带构造-岩浆事件演化过程提供了新的约束。  相似文献   

四川省山地类型界定与山区类型划分   总被引：6，自引：1，他引：5  

范建容  张子瑜  李立华 《地理研究》2015,34(1):65-73

山地类型的界定是科学认知山地规律的基础,对山地科学的发展有着基础性的意义。山地科学研究的出发点与落脚点,是为了促进山区区域在各方面的可持续发展,所以在山地类型界定的研究结果基础上对山区类型进行划分,是山区可持续发展的基本科学依据。采用GIS技术并结合DEM数据,对四川省的山地类型进行界定,同时对山区的类型进行划分。在山地类型界定涉及到的地形起伏度计算中,对均值变点法的应用结果进行了讨论与改进,得到地形起伏度最佳统计单元为9.92 km2。将四川省山地类型界定为丘陵、低山、中低山、中山、次高山、高山、极高山;将山区划分为纯丘陵县、半山区县、准山区县、显山区县、整山区县,并对山区发展的政策方向提出了一定的建议。  相似文献   

豫南大别山北麓姚冲钼矿床辉钼矿Re-Os同位素年龄及其地质意义     

罗正传  李永峰  李俊平  魏明君  李毅  高阳 《地质学报》2013,87(9):1359-1369

河南省新县姚冲钼矿床是大别山北麓近期新发现的外接触带斑岩型钼矿床,矿体主要赋存于花岗斑岩体(脉)外接触带的元古宇大别片麻杂岩中,主要受隐伏岩体和构造控制。成矿可分为石英-钾长石、辉钼矿-钾长石-石英、辉钼矿-石英、方解石4个阶段,有经济意义的矿化为辉钼矿-钾长石-石英、辉钼矿-石英2个阶段。本次利用电感耦合等离子体质谱仪TJA X-series ICPMS对姚冲钼矿床6件辉钼矿样品进行了Re-Os同位素年龄测定,获得Re-Os等时线年龄为136.9±1.20Ma、模式年龄加权平均为137.19±0.79Ma,准确厘定其成矿时代为早白垩世。通过对姚冲钼矿床辉钼矿Re同位素及矿石硫同位素组成特征的研究,认为姚冲钼矿床的成矿物质主要来源于下地壳,并混有少量的地幔组分。结合前人在大别山北麓的研究成果,认为大别山北麓存在140 Ma左右和127~110Ma两期钼成矿事件,这两期成矿作用的时限与东秦岭第二期和第三期成矿时限基本一致。它们是印支期后大别造山带构造体制从挤压收缩向区域性伸展转化直至岩石圈强烈伸展减薄的地球动力学响应。  相似文献   

Aftershock risk assessment and the decision to open traffic on bridges     

S. Alessandri  R. Giannini  F. Paolacci 《地震工程与结构动力学》2013,42(15):2255-2275

Critical issues in emergency management after a seismic event are assessing the functionality of the main infrastructures (hospitals, road network, etc.) and deciding on their usability just after the mainshock. The use of a pure analytical tool to assess the aftershock risk of a structure can be contrasted with the limited time available to make a decision about the usability of a structure. For this reason, this paper presents a method for evaluating post‐earthquake bridge practicability based on a rational combination of information derived from numerical analyses and in situ inspections. In particular, we propose an effective tool to speed up the decision‐making process involved in evaluating the seismic risk of mainshock‐damaged bridges in the context of aftershocks. The risk is calculated by combining the aftershock hazard using the Omori law and the fragility curves of the structure, which are calculated using the regression analysis of a sample of results obtained with data randomly generated by the Latin Hypercube Sampling technique and updated based on the results of in situ inspection. Different decision criteria regarding the practicability of bridges are discussed, and a new criterion is proposed. This tool was applied to an old highway RC viaduct. There are two main findings, including the high sensitivity to Bayesian updating (especially when the damage predicted by numerical analysis does not match the real damage) and the criteria used to decide when re‐open bridges to traffic. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Evaluating the utility of the EUMETSAT HSAF snow recognition product over mountainous areas of eastern Turkey     

Serdar Surer 《水文科学杂志》2013,58(8):1684-1694

Abstract

Monitoring snow parameters (e.g. snow-cover area, snow water equivalent) is challenging work. Because of its natural physical properties, snow strongly affects the evolution of weather on a daily basis and climate on a longer time scale. In this paper, the snow recognition product generated from the MSG-SEVIRI images within the framework of the Hydrological Satellite Facility (HSAF) Project of EUMETSAT is presented. Validation of the snow recognition product H10 was done for the snow season (from 1 January to 31 March) of the water year 2009. The MOD10A1 and MOD10C2 snow products were also used in the validation studies. Ground truth of the products was obtained by using 1890 snow depth observations from 20 meteorological stations, which are mainly located in mountainous areas and are distributed across the eastern part of Turkey. The possibility of 37% cloud cover reduction was obtained by merging 15-min observations from MSG-SEVIRI as opposed to using only one daily observation from MODIS. The coarse spatial resolution of the H10 product gave higher commission errors compared to the MOD10A1 product. Snow depletion curves obtained from the HSAF snow recognition product were compared with those derived from the MODIS 8-day snow cover product. The preliminary results show that the HSAF snow recognition product, taking advantage of using high temporal frequency measurement with spectral information required for snow mapping, significantly improves the mapping of regional snow-cover extent over mountainous areas.

Citation Surer, S. and Akyurek, Z., 2012. Evaluating the utility of the EUMETSAT HSAF snow recognition product over mountainous areas of eastern Turkey. Hydrological Sciences Journal, 57 (8), 1–11.  相似文献   

低丘缓坡荒滩等未利用地开发利用宜建适宜性评价--以山东青州市为例     

白杨  孟艳丽  唐伟 《山东地质》2014,(9):103-105

以青州市为例,对低丘缓坡荒滩等未利用地开发利用宜建进行适宜性评价,选取自然、社会、生态等因素的指标作为参评因子,确定标准值及权重,得出4种评价结果：最适宜建设、适宜建设、基本适宜和不适宜。  相似文献   

基于生成对抗网络的建筑物损毁检测EI北大核心CSCD     

葛小三  陈曦  赵文智  李瑞祥 《测绘学报》2022,51(2):238-247

建筑物作为自然灾害中最受影响的承灾体之一,其损毁信息的准确提取对灾后应急救援具有十分重要的意义。本文借鉴多模态的思想,提出了一种自动检测损毁建筑物的recursive-generative adversarial networks(RS-GAN)方法,将损毁建筑物检测分为灾前建筑物识别和灾后损毁建筑物检测两个任务,且分别在两个GAN分支中完成。RS-GAN加入联合损失函数将两个GAN分支进行连接,充分利用两个任务之间的潜在互利性提升检测效果。RS-GAN利用第1条GAN分支识别建筑物灾前形状与位置,并将识别结果作为第2条GAN分支的输入进行损毁建筑物检测任务,从而使检测结果具有更清晰的轮廓。该方法为端到端模型,在不需要过多的人工干预情形下,实现了损毁建筑物的自动检测。为了验证RS-GAN模型的效果,在圣罗莎和密苏里两个数据集上进行了测试。试验结果表明,RS-GAN方法拥有更好的检测性能,在圣罗莎数据集上的总体精度和平均精度分别达到了0.90和0.86。  相似文献   

“山水林田湖草沙生命共同体”理念下的科尔沁沙地生态治理     

刘志民  余海滨 《中国沙漠》2022,42(1):34-40

“山水林田湖草沙生命共同体”理念为沙地生态环境治理指明了新方向,但是在沙区开展什么研究却是新课题。本文基于生态建设面临的挑战,从山水林田湖草沙一体化治理的角度,探析了科尔沁沙地生态治理的研究方向及应重点关注的问题。  相似文献   

天山山区近50年面雨量分布及变化特征     

赵玲 《沙漠与绿洲气象(新疆气象)》2013,7(2):20-24

天山山区范围大,地形复杂,但测站稀少,而且分布很不均匀。为了尽可能的反映天山山区气候要素分布特征,利用1961~2009年天山山区44个气象站和10个水文站的观测资料,结合数字高程模型（DEM）1km?km网格数据,采用了自然正交分解（EOF）、多元回归分析、最大熵谱值分析等方法,对天山山区面雨量进行了计算,建立了区域面雨量时间序列,研究其时空分布特征及变化规律。天山山区的降水基本上呈现北多南少,西多东少的特征,年平均面雨量1093.2?08m3,1987年发生突变。冬季降水在年际变化和年代际变化特征上都呈现出明显的增加趋势。  相似文献