Assessing the distribution and impacts of Prosopis juliflora through participatory approaches

Invasive species pose global biological and economic challenges. Over the past four decades, Prosopis taxa have emerged as a major invader of the arid and semi-arid regions of the world. Prosopis juliflora, one of the highly invasive Prosopis species, is dominantly present in the Afar region of Ethiopia and continues to spread into the surrounding areas. The objective of this study was to aid the mapping, utilization, and management of the invasive P. juliflora in Afar, by employing participatory research techniques. We assessed the introduction history, impacts, uses, and control strategies of invasive P. juliflora by interviewing 108 pastoralists and agro-pastoralists. In addition, we used Participatory Mapping (PM), Geographic Information Systems (GIS), Global Positioning System (GPS), and remote sensing technologies and approaches to map sites invaded by P. juliflora. Sketch maps were produced by men, women, pastoralist and agro-pastoralist groups. Experts aggregated, scaled and reproduced the sketch maps with support from the Afar communities. We provided GPS and GIS trainings to selected community members who assisted us in collecting the GPS locations of more than 70 key features and landmarks. The sketch maps were digitized and geo-referenced by experts using the 70 GPS records as control points. Geo-referenced community maps were superimposed on pan-sharpened Landsat 8 satellite images and presented to the communities for verification. We overlaid the verified community maps on ancillary land-cover layers, and detected the land-cover classes that were most affected by P. juliflora invasion. Despite its uses as source of fire wood, charcoal, and animal fodder, the species has adverse impacts on native species and livestock resources. Afar communities mapped P. juliflora infestations, particularly those that occurred near their villages, using high and moderate density classes. The two highly invaded land-cover categories were dense grassland, and exposed sand & soils. Participants collaborated in creating the produced maps, suggesting that participatory research approaches are another tool for early detection of invasive species and guiding fine-scale management strategies.     

REVIEWS OF GEOGRAPHIC SOFTWARE

Geographic Software Reviewed in this article: LIFE TABLES and the LESLIE MATRIX. CONDUIT MENTMAP2 . Lawrence W. Carstensen Jr . PC-MATLAB , Version 1.0. The Math Works, Inc. QUICKMAP , version 1.0. Sammamish Data Systems, Inc. SYSTAT: THE SYSTEM FOR STATISTICS , Version 2.1, Systat Inc. USA DISPLAY . Instant Tecall     

遥感图谱认知理论与计算

近年来,随着对地观测技术的迅猛发展,卫星遥感领域逐渐进入了大数据时代。针对当前遥感应用的需求和特点,开展与视觉认知相结合的高分辨率遥感认知理论与方法研究是可行且必要的。在此背景下,受地学信息图谱思想启发,本文对遥感认知领域的图谱问题进行了研究,系统地提出了遥感图谱认知理论与计算方法论,旨在规范高分辨率遥感信息提取流程,构建精细化、定量化、智能化、综合化相结合的遥感信息解译模型。整套方法体系由横向“自底向上的分层抽象”和纵向“自顶向下的知识迁移”2个方向上的认知计算组成,分别对应了“由谱聚图”、“图谱协同”和“认图知谱”3大图谱转化过程。论文对涉及的概念、基本思想、关键技术及难点问题进行了重点分析,强调综合利用大数据、逐步融入知识来实现不同层次的遥感认知,以期为数据源极大丰富条件下的遥感信息解译提供新的视角。     

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Structures in the phase space of a four dimensional symplectic map

We numerically investigate the projections of non periodic orbits in a 4-dimensional (4-D) symplectic map composed of two coupled 2-dimensional (2-D) maps. We describe in detail the structures that are produced in different planes of projection and we find how the morphology of the 4-D orbits is influenced by the features of the 2-D maps as the coupling parameter increases. We give an empirical law that describes this influence.     

A quantitative bifurcation analysis of Hénon-like 2D maps

We numerically study the bifurcations of two nonlinear maps, with the same linear part, which depend on a parameter namely the Hénon quadratic map and the so called beam-beam map. Many families of periodic orbits which bifurcate from the central family, are studied. Each family undergoes a sequence of period doubling bifurcations in the quadratic map, But the behavior of the beam-beam map is completely different. Inverse bifurcations occur in both maps. But some families of the same type which bifurcate inversely in the quadratic map do not bifurcate inversely in the beam-beam map, even though both maps have common linear part.     

Frequency analysis of a dynamical system

Frequency analysis is a new method for analyzing the stability of orbits in a conservative dynamical system. It was first devised in order to study the stability of the solar system (Laskar, Icarus, 88, 1990). It is a powerful method for analyzing weakly chaotic motion in hamiltonian systems or symplectic maps. For regular motions, it yields an analytical representation of the solutions. In cases of 2 degrees of freedom system with monotonous torsion, precise numerical criterions for the destruction of KAM tori can be found. For a 4D symplectic map, plotting the frequency map in the frequency plane provides a clear representation of the global dynamics and describes the actual Arnold web of the system.     

内力线定性描绘应力场方法及其在地质构造研究中的应用

为了简化地质构造力学分析,本文探讨了用内力线来描绘应力场的方法,仿照用磁力线描绘磁场的做法,约定以从外力作用点,支承点等处发出的一族主应力迹线为代表内力传递路径的“内力线”,根据弹性理论绘制了部分简单应力场的内力线图,阐述了以简单应力场内力线图为基础绘制复杂应力场内力线图并对之进行分析的方法,同时,文中还对这一方法在山字型构造体系和断裂等板内构造应力场分析,隐伏或未知构及地质的推测,地震预报等方面的应用做了尝试。     

THEORY AND PRACTICE FOR COMPILING THE ATLAS OF NATURAL DISASTERS IN CHINA

CompilinganatlasofnaturaldisastersinChinaisabasistoresearchintoregionaldisasterssystems,torevealthetemPOralandspatialpatternofnaturaldisasters,aswellastoestablishcountermeasuresopinstnamraldisasters.TaldngtheuAtlasOfNaturalDisastersinChina"**asanexample,thisarticleinquiresintotheoreticalandpracticalproblemsaboutcompilinganatlasofregionalnaturaldisasters.ThebasictheoryofcompilinganatlasOfregionaldisastershasbeenfOundedonthecombinati0nofthesciencesofdisasters,cart0graphyandregiotalmhy.Theref…     

Seismicity and seismic hazard mapping of northern Algeria: Map of Maximum Calculated Intensities (MCI)

An earthquake catalogue covering the period1716–2000, comprising 2430 events, has beencompiled for the region lying between3°W-9°E and 31°N-38°N. It results fromraw data of IGN, ISC, USGS and Algeriansources, enabling an input consisting oforigin time H, geographical coordinates(longitude and latitude) and at least one of thefollowing parameters: surface wavemagnitude Ms, body wave magnitude Mb,epicentral intensities Io. Empiricalrelations permit transformations of Mb andMs into Io. The output consists in H,, , Ms, Mb, Io, and focal depth h whichis fixed to 10 km. The number ofevents falls to 1458 characterised by Ms 3.3 and Mb 3.6, or Io III. The fixed depth is suggested by thebest documented Algerian macroseismic mapsthat also lead to an empirical intensityattenuation law. A first application ofthis catalogue allows the drawing up of anupdated Seismicity and a MaximalCalculated Intensities (MCI) Maps ofAlgeria. The MCI map is obtained by usingthe empirical attenuation law: theintensities inferred by the whole eventsconstituting the catalogue are computed atnodes of a 5×5-km grid covering the area ofstudy. The corresponding maximum value isassigned to each node. The MCI map producedthat way gives precise spatial informationin comparison with Maximum ObservedIntensities (MOI) maps obtained in previousmacroseismic studies. This document may beuseful in mapping the seismic hazard inNorthern Algeria, without attachingprobabilities to ground-motionparameters.