Retrieval of forest canopy height in a mountainous region with ICESat-2 ATLAS

Forest canopy height is one of the important forest parameters for accurately assessing forest biomass or carbon sequestration. ICESat-2 ATLAS provides the potential for retrieval of forest canopy height at global or regional scale, but the current canopy height product (ATL08) has coarse resolution and high uncertainty compared to airborne LiDAR-derived canopy height (hereafter ALCH) in mountainous regions, and is not ready for such applications as biomass modeling at finer scale. The objective of this research was to explore the approach to accurately retrieve canopy height from ATLAS data by incorporating an airborne-derived digital terrain model(DTM) and a data-filtering strategy. By linking ATLAS ATL03 with ATL08 products, the geospatial locations,types, and (absolute) heights of photons were obtained, and canopy heights at different lengths (from 20 to 200 m at 20-m intervals) of segments along a track were computed with the aid of airborne LiDAR DTM. Based on the relationship between the numbers of canopy photons within the segments and accuracy of ATLAS mean canopy height compared to ALCH, a filtering method for excluding a certain portion of unreliable segments was proposed.This method was further applied to different ATLAS ground tracks for retrieval of canopy heights and the results were evaluated using corresponding ALCH. The results show that the incorporation of high-precision DTM and ATLAS products can considerably improve the retrieval accuracy of forest canopy height in mountainous regions.Using the proposed filtering approach, the correlation coefficients (r) between ATLAS canopy height and corresponding ALCH were 0.61–0.91, 0.65–0.92, 0.68–0.94 for segment lengths of 20, 60, and 100 m, respectively;RMSE were 1.90–4.35, 1.55–3.63, and 1.34–3.23 m for the same segment lengths. The results indicate the necessity of using high-precision DTM and using the proposed filtering method to retrieve accurate canopy height from ICESat-2 ATLAS in mountainous regions with dense forest cover and complex terrain conditions.

Lithospheric structure in NW of Africa:Case of the Moroccan Atlas Mountains

This study presents the outcomes of the local earthquake tomography applied in the Moroccan Atlas domains. A seismic data collected by 36 seismic and a linearized inversion technics are used for determination of local velocity structure.The interpretation of tomography images results emphasizes a new and detailed lithosphere structure： a remaining subducted zone beneath the Souss Basin located from 20-to 45-km depth dipping to the North is detected and interpreted as a body that marks the border between the Moroccan Anti-Atlas and the Meseta-Atlas domains.A subduction zones is detected in the SW of the High Atlas, beneath the Hercynian Tichka massif from 10 to 50-km inclined away from Anti Atlas and in the eastern part of Anti Atlas, dipping northward from Jbel Ougnat at 15e40 km.The junction of the western and middle High Atlas is depicted by two high velocity blocks subducting from 10 to 50 km depth. The first is dipping SW beneath the High Atlas and the second is dipping SE beneath the Ouarzazate Basin.In the northern part of the southwestern High Atlas, a high velocity body dipping towards the north beneath the Essaouira Basin from 15 to 45 km depth.In northeastern part of the High Atlas in the Mougeur zone, a high velocity body is detected from 10 to 45 km depth, dipping to the Se E beneath the eastern High Atlas.The negative lithospheric anomalies found in the upper and in the lower crust are interpreted as a hot asthenospheric material upwelling from deep and gradually replacing the part of crust detached in the High Atlas. The occurrence magmatic activities in these regions testify the existence of a remaining subduction process. This paper argues the implication of these deep structures in the evolution of the Moroccan Atlas Mountain.

Ediacarian Volcanic Rocks and Basic Dikes from the Lac Ifni Sector of the Central High Atlas Mountains:Petrographic Studies and Clinopyroxene Chemical Composition

The Ediacarian volcanic series from the Lac Ifni sector are composed of a large variety of rocks from basalts and rhyolites to intermediates facies such as andesites,rhyodacites and pyroclastites.All these rocks are intruded by dolerite dikes.Secondary processes are reflected by total serpentinization of olivine within basic andesite and by albitization

Study of Atlas Cedar Growth (<i>Cedrus atlantica</i>Manetti) in El M’sid Mountains (East Algeria): Productivity and Growth According to Planting Methods

The Atlas cedar (Cedrus atlantica) is one of the more valuable reforestation species in the Mediterranean areas. But this species suffers from rainfall limitation and climate changes, particularly in its originated area, North Africa. Therefore, any knowledge about the plantation practices to improve the tree water availability and the reforestation success has great importance. The current study has been undertaken in this view, i.e. to compare the growth of cedar plots located in El M’Sid Mountains, Souk Ahras department (700 km east of Algiers), according to different planting methods. The radial growth and the productivity have been measured on a cedar plot with a total surface of 165 ha. 150 ha has been planted in 1970 on hillside ditches, and 15 ha of which the majority is planted in a simple hole and some bouquets on terraces, both are originated from a complementary reforestation achieved during 1980. The results show that most of the trees planted in 1970 reach a height ranging between 10 and 17 m and a diameter between 23 and 44 cm. Even some trees were 20 m high with diameter of 65 cm. The productivity fluctuates between 3 and 8 m3/ha/year, values close to the one of natural native plots. Trees planted in 1980 reach a height ranging between 5. 5 to 7 m, and diameter between 11.5 to 23 cm. The radial growth improves that the hillside ditches help the roots anchoring and trees growth during the first season after plantation. These results indicate that the cedar tree can be used with success in areas outside the natural cedar forest presence, and that appropriate planting techniques can compensate in part the lower rainfall occurring in these chosen regeneration areas.

Annual and seasonal changes of the air temperature with altitude in the Upper Dades valley, High Atlas, Morocco

The purpose of this study is to determine the size of air temperature changes with altitude in the mountains of the arid zone, on the example of the Upper Dades valley(High Atlas, Morocco). The air temperature change with altitude was determined on the basis of 5 years data from three meteorological stations. The analysis was carried out on an annual and seasonal basis. The annual and daily variations of thermal gradients between pairs of stations were also determined. It was found that the average thermal gradient in the Upper Dades valley was-1.02℃ per 100 m. The highest values of the thermal gradient occur in winter and the lowest in summer. In winter,the thermal gradient was characterized by the greatest variability. Minima of the daily variation of air temperature gradients were observed in early morning hours and maxima around midday. In the lower part of the valley, air temperature inversion frequently developed between 10 AM and 3 PM UTC.The obtained results show high thermal gradients in the mountains of the arid zone, with their annual amplitude increasing in the lower parts of the valley.The instantaneous values of the gradients were significantly modified by the supply of latent heat and the occurrence of dust storms. It has been shown that the advection factor plays an important role in shaping large gradient values. The study contains novel results of thermal gradient measurements in high mountains of arid zone.

Divergence of tree-ring-based drought reconstruction between the individual sampling site and the Monsoon Asia Drought Atlas: an example from Guancen Mountain

To evaluate the applicability of the Standardized Precipitation-Evapotranspiration Index （SPEI） and the self-calibrated Palmer Drought Severity Index （scPDSI） to paleoclimate reconstructions in the east Asian summer monsoon region, we used a 194-year tree-ring width chronology from Guancen Mountain, Shanxi Province, China, to investigate its correlation with SPEI and scPDSI, respectively. The results indicated scPDSI as a robust drought index that could be reconstructed from tree-ring width on Guancen Mountain other hydroclimate-related Significant correlations with series illustrated that our reconstruction captured common variations of hydroclimate in the surrounding areas. Additionally, our reconstruction showed significant correlation with nearby grid points of the Monsoon Asia Drought Atlas （MADA）. However, while unprecedented drying trend existed during the past several decades in MADA, it was not represented in our reconstruction or in instrumental scPDSI/Dai-PDSI. This may imply that MADA overestimated drought severity during the past several decades in our study area; this overestimation was probably caused by an insufficient spatiotemporal distribution of the tree-ring network used by MADA. Therefore, more drought reconstructions based on individual sampling sites in eastern Asia are necessary to gain a thorough understanding of the Asian Monsoon climate variability.

秦岭东段洛河流域土地利用变化的地形梯度效应研究

明晰典型地势起伏区土地利用变化与地形因素的关系,对国土空间布局及区域协调发展具有重要现实意义。基于秦岭东段洛河流域多期土地利用数据及DEM数据,运用土地利用图谱法、标准差椭圆分析法和地形位分析法,揭示自2000年以来当地土地利用变化的时空分异特征,并探讨在不同土地利用变化下的地形梯度效应。研究结果表明:(1)20年间,土地利用变化多围绕耕地、草地和建设用地进行,且表现出显著的类型异质性及阶段差异性特点。(2)以耕地和林地为主的稳定型图谱面积占比达到88.17%,前期变化型和后期变化型分别为7.44%和3.51%,耕地被建设占用更偏向于无序化发展。(3)中低及其以上地形梯度的耕地逐渐趋向于低地形梯度区发展,林地的地形分布指数呈“S”型上升态势,草地则表现出中间高两边低的正态分布规律。(4)各图谱的地形分布指数随地形位增加表现出不同的趋势性规律,土地利用变化呈明显地形梯度效应。研究认为当地国土管理工作应重点关注反复变化型图谱和持续变化型图谱,并注意科学缓解和引导耕地水土流失及坡耕地开发利用问题。

天山北坡绿洲乡村聚落空间基因解析及影响机制研究

空间基因蕴含着聚落与环境互动形成的空间信息,在空间特色传承上有着重要作用。由于新疆天山北坡地区聚落在独特的自然环境中形成了互动演化的聚落空间形态,因此以其为研究对象,通过卫星影像图和三维数据采集其中的12个典型聚落样本,在从自然环境、空间片段形态、聚落形态、路网形态和拓扑连接五方面提取空间基因的基础上,构建聚落空间基因图谱,运用因子分析与聚类分析方法,对聚落进行分类,阐释其背后蕴含的环境-空间互动影响模式,并提出保护与改造建议,以期为不同地区乡村聚落空间基因研究提供借鉴,为聚落类型划分、乡村特色保护与发展提供研究思路。

Image Style of the Tianping Mountain Landscape in the Ming Dynasty

Starting from the Tianping Mountain theme painting in Suzhou in the Ming Dynasty, we explore how did the painters and literati in this period shape the image of the Tianping Mountain through their works, thereby reflecting their understanding on many landscapes on the Tianping Mountain. By exploring a series of paintings and poems, we try to analyze the characteristics and cultural connotation of landscape paintings of the Tianping Mountain in the Ming Dynasty, which is conducive to improving position of the Tianping Mountain natural and humanistic landscape in Suzhou.

安徽岳西县四望山初秋部分开花植物的花粉形态

为了获得更多的现代花粉形态特征数据与图谱,采集了安徽岳西县四望山初秋部分开花植物的花粉,一是用Erdtman醋酸酐分解法处理,再用甘油胶和石蜡制成永久装片,在光学显微镜下观察、测量花粉的形态特征数据和拍照;二是将花粉粘在粘有金属箔纸的铜台上,在扫描电镜下观察、拍照.获得了四望山初秋开花的16科23属20种1亚种2变种植物花粉的大小、形状、萌发孔结构和外壁结构等形态特征数据以及光镜和电镜下的花粉图谱.

桐柏大别山区土地利用时空变化图谱分析

运用地学信息图谱理论方法,基于地理信息系统时空分析模型,以桐柏大别山区20 a土地利用3期(1987、1997、2007)空间数据为基础,通过建立桐柏大别山区土地利用变化图谱和涨落势图谱,分析该区域土地利用变化的时空特征,预测未来土地利用变化的趋势。结果表明:1)1987—2007年,研究区土地利用发生了很大变化,耕地面积持续性减少,林地和建设用地面积持续性增加,草地和未利用地面积先增加后减少,水域面积先减少后增加;2)空间格局上,耕地与林地相互转化遍布整个研究区域,耕地和林地转为建设用地主要分布在各县市周边地区,水域转为耕地和林地主要位于水域与其他用地交接地带;3)涨落势图谱中,林地涨势最明显,增加了5 904.06 km2,占新增图谱单元61.31%,主要来源于耕地和水域转出,耕地落势最明显,减少了6 394.71 km2,占萎缩图谱单元66.41%,主要转为林地和建设用地;4)未来10年,桐柏大别山区土地利用类型仍将以耕地、林地为主。

太行山猕猴寰椎和枢椎的初步研究

对成年太行山猕猴寰椎和枢椎变量进行了测量 ;以肱骨最大长为参照 ,对其变量进行了异速生长分析。结果表明 :寰椎全宽及枢椎椎孔横径接近等速生长 ,其余变量均为负异速生长。

《山地城市影像地图集》的影像分幅裁切比较研究

介绍了影像地图集具有的特点及图集生产流程中影响成图周期的环节。重点比较研究影像地图集生产中常用的几种影像分幅裁切方法。基于ArcObjects的二次开发影像分幅裁切模块实现《重庆市主城区影像地图集》裁切,取得了较好的效果,提高了作业生产效率。

《山地城市影像地图集》的影像分幅裁切比较分析

介绍了影像地图集具有的特点及图集生产流程中影响成图周期的环节。重点比较研究影像地图集生产中常用的几种影像分幅裁切方法。特别介绍了基于ArcObjects的二次开发影像分幅裁切模块,该模块实现《重庆市主城区影像地图集》裁切,取得了较好的效果,提高了作业生产效率。

山丘区中小流域洪水频率图编制构想和成果展望

中小流域洪水频率分析研究是开展洪水风险分析和管理的重要依据。提出了山丘区中小流域洪水频率图编制思路,综合考虑气候和下垫面条件对产汇流过程的影响,划分调整水文分区;对有流量资料的站点,结合历史实测和调查洪水资料,进行单站和区域洪水频率分析;同时结合暴雨频率分析成果,基于高精度地形地貌数据,以分布式水文模型为主,进行山丘区中小流域洪水频率分析,形成中小流域(山区沟道、中小河流)不同频率的洪水频率数据库和洪水频率图,以期为洪水灾害风险评估、早期应对提供基础支撑,促进提高洪水灾害防御水平。

世界海拔8000m以上雪山研究

实地科考,广博查询,长期探索,坚韧追求,人类首次、全面解开世界海拔8 000m以上雪山之迷:海拔8 000m级雪山地有17处(其中3处山地为新发现),面积共11.95414km2,海拔8 000m以上独立山峰39座.世界海拔8 000m级山地和山峰地貌形态、相互关系,己在即将出版的"世界八千米雪山地图集"中得到表示.该图集比例尺1∶100000,等高距40m,幅面550mm×790mm.该图集由序言、7幅地图和后记组成,是世界第一部关于海拔8 000m级雪山地图集.

浅析城市地图集对山地城市特色的挖掘和表达

以《重庆市地图册》的设计为例,介绍了图集在山地城市特色挖掘和表达方面的思考与实践;主要从地图集结构和内容设计、地图集表示方法设计、地图集整饰设计等方面对重庆城市特色进行了表达,可为今后山地城市地图集的个性化、特色化编制提供借鉴和参考。

山地城市地图集的设计

山地城市多元化、立体化的城市形态影响其城市地图集的设计,为研究山地城市地图集的设计方法,本文以山地城市地图集——《重庆城市地图集》的设计为例,分析山地城市地图集设计中的难点,并从内容结构设计、符号设计、色彩和整饰设计等方面阐述山地城市地图集的设计要点。总体来说,《重庆城市地图集》充分反映了重庆山地城市的特色,并采用分片矩形分幅的方式,解决了山地城市地图的分幅难点,具有一定的继承性、创新性和实用性,可为相关山地城市地图集的编制提供参考。

庐山综合地理实习教学地图集的设计

针对国内未有庐山地理实习地图集的现状,该文着重探讨了庐山地理实习地图集的内容设计、图集数据建库及编制流程、图集编制方法及关键技术,初步编制了纸质版的传统图集、PC端的电子图集、手机端的电子图集。该图集在反映庐山各自然现象和人文环境特征基础上,融入实习元素,内容翔实、形式多样,是迄今为止国内第一套综合地理实习教学地图集。

基于地质信息图谱的山区油气管道自动选线方法

目前,山区油气管道路由大多通过传统人工选线方式确定,线路质量严重依赖选线人员的经验与技术水平,选线结果往往不够科学、合理。为此,提出一种基于地质信息图谱的山区油气管道选线方法,其通过地形地貌、地质风险、高后果区、敏感区4个方面构建区域地质信息图谱,基于管道路由成本,通过因子成本量化,构建用于选线的成本栅格图谱,最终通过最优路径算法分析得出最优路径。将该方法应用于中国西南山区某管道,通过对比计算路由与现有路由发现:采用基于地质信息图谱的山区管道选线方法得到的路由能够有效避开地形复杂、地质环境条件差的地区及高后果区与环境敏感区,且综合考虑了距离成本,弥补了人工选线综合因子考虑的问题,可为线路设计人员提供参考与借鉴。