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Using multispectral landsat and sentinel-2 satellite data to investigate vegetation change at Mount St. Helens since the great volcanic eruption in 1980

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Journal of Mountain Science 2018年第9期15卷 1851-1867页

作者： Katharina TELTSCHER Fabian Ewald FASSNACHT Institute of geography and geoecology Karlsruhe Institute of Technology

Long-term analyses of vegetation succession after catastrophic events are of high interest for an improved understanding of succession dynamics. However, in many studies such analyses were restricted to plot-based measurements. Contrarily, spatially continuous observations of succession dynamics over extended areas and timeperiods are sparse. Here, we applied a change vector analysis(CVA) to investigate vegetation succession dynamics at Mount St. Helens after the great volcanic eruption in 1980 using Landsat. We additionally applied a supervised random forest classification using Sentinel-2 data to map the currently prevailing vegetation types. Change vector analysis was performed with the normalized difference vegetation index(NDVI) and the urban index(UI) for three subsequent decades after the eruption as well as for the whole observation time between 1984 and 2016. The influence of topography on the current vegetation distribution was examined by comparing altitude, slope angles and aspect values of vegetation classes derived by the random forest classification. WilcoxRank-Sum test was applied to test for significant differences between topographic properties of the vegetation classes inside and outside of the areas affected by the eruption. For the full time period, a total area of 516 km2 was identified as re-vegetated, whereas the area and magnitude of re-growing vegetation decreased during the three decades and migrated closer to the volcanic crater. Vegetation losses were mainly observed in regions unaffected by the eruption and related mostly to timber harvesting. The vegetation type classification reached a high overall accuracy of approximately 90%. 36 years after the eruption, coniferous and deciduous trees have established at formerly devastated areas dominating with a proportion of 66%, whereas shrubs are more abundant in riparian zones. Sparse vegetation dominates at regions very close to the crater. Elevation was found to have a great influence on th

关键词： Mount St. Helens Vegetation change Remote sensing Change vector analysis (CVA) Supervised classification Topography Density-plots

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Influence of tributaries on downstream bed sediment grain sizes under flysch conditions

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Journal of Mountain Science 2021年第4期18卷 847-862页

作者： SMAZAK Ivan GALLA Tomas Department of Physical geography and geoecology Faculty of ScienceUniversity of OstravaChittussiho 1071000 OstravaCzech Republic

Tributaries are one of the most important factors contributing to variability in the downstream evolution of bed sediment grain *** primary aim of this work is to evaluate the response of the bed sediment texture in the recipient channel induced by ten tributaries of the?ernáOstravice stream and find reach-scale and catchment-scale parameters that would be able to predict this *** research was based on collecting information on the grain size distributions at sites adjacent to confluence zones.A significant change in sediment texture occurred in the vicinity of five *** the other factors contributing to grain size variability(e.g.,local channel geometry,lithology,and lateral sediment sources),it was assumed that only four of them were associated with a sufficient bedload influx to alter the sediment calibre below the ***,a significant morphological effect in the form of a large confluence bar was observed in one *** tributaries had several common features:(i)they had a larger relative catchment area than that of nonsignificant tributaries;(ii)they were characterized by different bed grain sizes,with some exceptions;and(iii)they had a higher unit stream power close to the confluence in relation to that of the *** characteristics were represented by the proposed relative parameters,including the relative unit stream power and bed material texture,which allowed the best classification of significant and nonsignificant *** their simplified form,the parameters described the transport capacity and grain size distribution,which were generally considered to be primary factors responsible for a redefinition of the sediment texture in the recipient ***,it should be noted that these results are subject to some degree of uncertainty due to the relatively small sample size of only 10 tributaries.

关键词： Tributary Bed sediments Headwater streams Flysch Carpathians

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Assessment of sediment connectivity using modelling and field-based approaches in the Slavíč River catchment(MoravskoslezskéBeskydy Mts,Czech Republic)

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Journal of Mountain Science 2024年第3期21卷 734-753页

作者： MACUROVÁ Tereza ŠKARPICH Václav Department of Physical geography and geoecology Faculty of ScienceUniversity of OstravaChittussiho 1071000 OstravaCzech Republic

Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and channels)of the catchment is *** study focused on sediment connectivity analysis in the SlavíčRiver catchment in the MoravskoslezskéBeskydy Mts in the eastern part of the Czech *** connectivity index and connectivity index target modelling were combined with an analysis of anthropogenic ***,field mapping,grain size of bed sediments and stream power analysis were used to obtain information about connectivity in the *** on the analysis and obtained results,terrain topography is the current main driving factor affecting the connectivity of sediment movement in the SlavíčRiver ***,the modelling provided valuable information about high sediment connectivity despite different recent land use conditions(highly forested area of the catchment)than those in historical times from the 16th to 19th centuries when the SlavíčRiver catchment was highly deforested and sediment connectivity was probably *** analysis of anthropogenic interventions,field mapping,grain size of bed sediments and stream power analysis revealed more deceleration of sediment movement through the catchment,decreased sediment connectivity with bed erosion,and gradual river channel process transformation in some *** mapping has identified various natural formations and human-induced changes impacting the longitudinal and lateral connectivity in the Slavíč*** instance,embankments along 48%of the river's length,both on the right and left banks,significantly hinder lateral sediment supply to the *** power index analysis indicates increased energy levels in the flowing water in the river's upper reaches(up to 404.8 W m^(-2)).This high energy is also observed in certain downstream sections(up to 337.6 W

关键词： Mountain stream Connectivity analysis Modelling Grain size analysis SlavíčRiver MoravskoslezskéBeskydy Mts

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Geomorphic evidence of ancient catastrophic flow type landslides in the mid-mountain ridges of the Western Flysch Carpathian Mountains(Czech Republic)

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International Journal of Sediment Research 2009年第1期24卷 88-98页

作者： T. PNEK J. HRADECKY K. ILHN Assoc. University of Ostrava Faculty of Science Department of Physical Geography and Geoecology Chittussiho 10 71000 Ostrava Czech Republic University of Ostrava Faculty of Science Department of Physical Geography and Geoecology Chittussiho 10 71000 Ostrava Czech Republic

Ancient flow type landslides are relatively frequent fossil forms of the relief in mid-mountain conditions of the Czech Carpathian Mountains. Sixty rather distinctive displays of debris flows,rock avalanches,and debris avalanches have been mapped in the uppermost part of the territory. Unlike contemporary sporadic and low volume debris flows,ancient(Pleistocene and Lower Holocene) accumulations are a few orders of magnitude more extensive and were of considerable geomorphologic significance in forming the steep sections of mountain valleys and slopes. This geomorphic pattern does not hold for flow type slides,the source of which is material released as a consequence of numerous deep-seated landslides. Due to deep disruption of slopes,a few high-magnitude flow type landslides(e.g.,rock avalanches),quite rare in flysch mid-mountain conditions,also occurred in the Late Holocene.

关键词： Debris flows Rock avalanches Deep-seated landslides Flysch Western Carpathian Mountains

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Sources of nitrous and nitric oxides in paddy soils: Nitrification and denitrification

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Journal of Environmental Sciences 2014年第3期26卷 581-592页

作者： Ting Lan Yong Han Marco Roelcke Rolf Nieder Zucong Cai State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Institute of geoecology Technische Universitt Braunschweig School of geography Sciences Nanjing Normal University

Rice-paddies are regarded as one of the main agricultural sources of N 2O and NO emissions. To date, however, specific N2O and NO production pathways are poorly understood in paddy soils. ^15N-tracing experiments were carded out to investigate the processes responsible for N2O and NO production in two paddy soils with substantially different soil properties. Laboratory incubation experiments were carried out under aerobic conditions at moisture contents corresponding to 60% of water holding capacity. The relative importance of nitrification and denitrification to the flux of NaO was quantified by periodically measuring and comparing the enrichments of the N2O, NH^-N and NO3-N pools. The results showed that both N2O and NO emission rates in an alkaline paddy soil with clayey texture were substantially higher than those in a neutral paddy soil with silty loamy texture. In accordance with most published results, the ammonium N pool was the main source of N2O emission across the soil profiles of the two paddy soils, being responsible for 59.7% to 97.7% of total N2O emissions. The NO3-N pool of N2O emission was relatively less important under the given aerobic conditions. The rates of N2O emission from nitrification （N2On） among different soil layers were significantly different, which could be attributed to both the differences in gross N nitrification rates and to the ratios of nitrified N emitted as NzO among soil layers. Furthermore, NO fluxes were positively correlated with the changes in gross nitrification rates and the ratios of NO/N2O in the two paddy soils were always greater than one （from 1.26 to 6.47）. We therefore deduce that, similar to N2O, nitrification was also the dominant source of NO in the tested paddy soils at water contents below 60% water holding capacity.

关键词： ^15N tracing model N2O NO NO/N2O nitrification denitrification

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A Short Review: Limnological and Paleolimnological Researches in Mongolia Carried out by Joint Russian-Mongolian Expeditions

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Journal of Mountain Science 2005年第1期2卷 86-90页

作者： Dmitrii V.Sevastyanov Nadezhda I.Dorofeyk dept.geography & geoecology Saint-Petersburg State University 10Liniya33St.-Petersburg199178RussiaInstitute of Evolution & EcologyRussian Academy of Sciences Piatnitskaya 47Stroenie3Moscow109017Russia.

Mongolia-extensive inside-continental country,with an area of more than 1,500,000 km2. There are some mountain areas - Hangai and Hantai in the North, and Mongolian Altai in the West, and Gobi Altai - in the Center of... 详细信息

关键词：湖泊学古湖沼学外蒙古俄罗斯阿尔泰山脉

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Decreasing nutrient concentrations in soils and trees with increasing elevation across a treelineecotone in Rolwaling Himal, Nepal

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Journal of Mountain Science 2017年第5期14卷 843-858页

作者： Simon DROLLINGER Michael MULLER Timo KOBL Niels SCHWAB Jurgen BOHNER Udo SCHICKHOFF Thomas SCHOLTEN geoecology Department of Geography and Regional Research University of Vienna Vienna Austria Soil Science and Geomorphology Department of Geosciences Uniuersity of Tubingen Tubingen Germany CEN Center for Earth System Research and Sustainability Institute of Geography University of Hamburg Hamburg Germany

At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.

关键词： Foliar nutrients Himalaya Nitrogen Nutrient cycling Podzol Treeline

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Reshaping the urban hierarchy:patterns of information diffusion on social media

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Geo-Spatial Information Science 2019年第3期22卷 149-165页

作者： Jiue-An Yang Ming-Hsiang Tsou Krzysztof Janowicz Keith C.Clarke Piotr Jankowski Calit2/Qualcomm Institute University of California San DiegoLa JollaCAUSA Department of geography San Diego State UniversitySan DiegoCAUSA Department of geography University of CaliforniaSanta BarbaraCAUSA dInstitute of geoecology and Geoinformation Adam Mickiewicz UniversityPoznańPoland

The spatial diffusion of information is a process governed by the flow of interpersonal *** emergence of the Internet and especially social media platforms has reshaped this process and previous research has studied how online social networks contribute to the diffusion of *** such processes can help devise methods to maximize or control the reach of information or even identify upcoming events and social *** activities in cyberspace are still confined to physical locations and this geographic connection tends to be *** this research,we focus on geographic regions instead of individuals and study how the underlying hierarchical structure of regions relates to their response to the *** examined the top 30 populated cities and metropolitan areas in the *** retrieved Twitter data related to two selected topics from these regions,the 2015 Nepal Earthquake and the#JesuisCharlie hashtag in response to the Paris attacks on the Charlie Hebdo *** analyzed the similarity among regions of their response using multiple statistical methods and three urban *** results indicate that the diffusion of information is impacted by the hierarchy of urban regions and that the Twitter responses act more similar when the populated regions are positioned at the same level in the urban hierarchy.

关键词： Information diffusion urban hierarchy spatiotemporal analysis social media

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Benefits and ecological restoration implications of hanging grass fences in Mongolian desert steppe

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Journal of Arid Land 2024年第11期16卷 1541-1561页

作者： MIAO Jiamin LI Shengyu XU Xinwen LIU Guojun WANG Haifeng FAN Jinglong Khaulanbek AKHMADI Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China National Engineering Technology Research Center for Desert-Oasis Ecological Construction Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Institute of geography and geoecology Mongolian Academy of SciencesUlaanbaatar 15170Mongolia

Tumbleweeds participate in a common seasonal biological process in temperate grasslands,creating hanging grass fences during the grass-withering season that result in distinct ecological *** this study,we addressed the urgent need to understand and restore the degraded desert steppe in Central Mongolia,particularly considering the observed vegetation edge effects around hanging grass *** field surveys conducted in 2019 and 2021 in the severely degraded desert steppe of Central Mongolia,we assessed vegetation parameters and soil physical and chemical properties influenced by hanging grass fences and identified the key environmental factors affecting vegetation *** results indicate that the edge effects of hanging grass fences led to changes in species distributions,resulting in significant differences in species composition between the desert steppe's interior and edge *** parameters and soil physical and chemical properties exhibited nonlinear responses to the edge effects of hanging grass fences,with changes in vegetation coverage,aboveground biomass,and soil sand content peaking at 26.5,16.5,and 6.5 m on the leeward side of hanging grass fences,*** the absence of sand dune formation,the accumulation of soil organic carbon and available potassium were identified as crucial factors driving species composition and increasing vegetation *** in species composition and plant density were primarily influenced by soil sand content,electrical conductivity,and sand accumulation *** findings suggest that hanging grass fences have the potential to alter vegetation habitats,promote vegetation growth,and control soil erosion in the degraded desert steppe of Central ***,in the degraded desert steppe,the restoration potential of hanging grass fences during the enclosure process should be fully considered.

关键词： hanging grass fences edge effects vegetation recovery enclosure treatment degraded desert steppe Central Mongolia

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草地灌溉对土壤性质和植物物种组成的影响

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Journal of Plant Ecology 2023年第2期16卷 174-188页

作者： Rebekka Gerlach Constanze Buhk Jens Schirmel Hermann F.Jungkunst iES Landau Institute of Environmental SciencesGeoecology and Physical Geography/Ecosystem AnalysisUniversity of Koblenz-LandauLandauGermany

草地是欧洲范围内生物物种最为丰富的动植物栖息地之一;为了对大面积的草地开展有效的保护,必须要采取具有针对性和可持续性的管理措施。虽然如今大都已被弃用,但传统上的灌溉却有可能是一种具有可持续性的管理策略。然而,对于一般的湿... 详细信息

草地是欧洲范围内生物物种最为丰富的动植物栖息地之一;为了对大面积的草地开展有效的保护,必须要采取具有针对性和可持续性的管理措施。虽然如今大都已被弃用,但传统上的灌溉却有可能是一种具有可持续性的管理策略。然而,对于一般的湿润性生态区域,人们还不太了解灌溉、土壤特性以及植物物种这3者之间的相互影响。我们旨在将传统的草地灌溉对植物群落的影响从传统的低施肥量效应中分离出来,从而获得植物生态学方面的新知识。我们的考察对象是植物的组成和多样性以及它们与土壤特性(有机态碳、总氮、持水性/保水力、中型土壤动物活力)和土壤养分(无机态氮、磷、钾、镁、硼)指标之间的潜在联系。在田间研究中,我们对过去长期灌溉的13块草地以及未经灌溉的13块草地(其中17块草地经过施肥,9块未经施肥)进行了比较。分析这些草地在一整年时间内的植物多样性和物种组成情况以及土壤养分和土壤特性指标,并且假设不同年份之间的差异不大。研究结果发现,灌溉和施肥使土壤特性和土壤养分发生了改变,但它们对植物物种多样性并无影响,只影响植物的物种组成。淤积土具有更细的粒度,因而拥有更高的保水力和养分储量。因此,需要获取水分和养分资源的禾本科植物在经过灌溉的草地上占据优势。本研究的结果表明,对于中欧地区大量的已开发草地,灌溉不仅能保护其生物多样性,而且还有可能使其植物具有不同的植物功能性状。

关键词：草场洪水灌溉施肥土壤养分植物多样性物种组成土壤模式

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