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51.
Assessing participatory GIS for community-based natural resource management: claiming community forests in Cameroon 总被引:6,自引:1,他引:6
This paper critically reviews and analyses participatory GIS (PGIS) and participatory mapping applications within participatory spatial planning for community-based natural resource management in developing countries. There is an often implicit assumption that PGIS use is effective, in that it meets content needs, satisfies underlying local stakeholder interests and therefore is a tool for better governance. The analytical framework looks at participatory spatial planning performance with respect to key dimensions of governance, especially the intensity of community participation and empowerment, equity within communities and between 'governed' and 'governing', respect for indigenous knowledge, rights, ownership, legitimacy, and effectiveness. Specific development focus is given by a case study using participatory mapping and PGIS in community forest legitimization, planning and management in Tinto, Cameroon. 'Good governance' criteria are applied ex-post to the implementation procedures, the geo-information outputs, and the longer-term outcomes of the PGIS processes. Impacts of incorporating PGIS were examined in terms of the types and degrees of participation in the process; access to, and the uses made of, the geographic information; whether the information outputs met stakeholders' requirements; and the overall changes in equity and empowerment in the community. It was found that PGIS/participatory mapping processes contributed – positively, though not comprehensively – to good governance, by improving dialogue, redistributing resource access and control rights – though not always equitably – legitimizing and using local knowledge, exposing local stakeholders to geospatial analysis, and creating some actor empowerment through training. PGIS promoted empowerment by supporting community members' participation in decision-making and actions, and by enabling land use planning decisions beyond community forestry itself. 相似文献
52.
Collin Nkono Olivier Fmnias Daniel Demaiffe 《Journal of Volcanology and Geothermal Research》2009,187(1-2):13-25
This study is a part of a wider investigation to evaluate how much can be learnt by using low-cost methods such as systematic moderate-resolution remote sensing to map and quantify geological structures at the regional scale on very large volcanic provinces only partly studied in the field. Volcanic-centre and cinder-cone distribution, faults and structural lineaments are mapped combining Shuttle Radar Topography Mission (SRTM), Digital Elevation Models (DEMs) and Landsat satellite images. As an example of the method, we present the interpretation of structural data and morphological features of three contrasted areas from the Cameroon Volcanic Line (Tombel graben, Upper Benue valley, and Ngaoundéré area) for which local field studies are available for comparison. At a local scale, this remote-sensing method of mapping displays good to excellent correlations with previously published data and, by itself, it allows one to constrain the structural setting of each area. Numerical treatment of vent and cinder-cone localisation can be related to tension fractures (T direction), whereas numerical treatment of the lineaments constrains the associated fault system to a single transtensional (strike-slip + extension) Riedel type fracture network. The first results on the Cameroon Volcanic Line are promising and could be used at a larger scale on numerous volcanic provinces for which field data are not yet available. 相似文献
53.
Martin Yemefack Wietske Bijker Steven M. De Jong 《International Journal of Applied Earth Observation and Geoinformation》2006
This paper investigates statistical relationships between land use/land cover (LULC), Landsat-7 ETM+ imagery and landscape mosaic structure in southern Cameroon where the conversion of tropical rain forest to shifting cultivation leads to dynamic processes, acting on the spatial aggregation of various LULC types. A Global Positioning System (GPS) was used in the field to identify a total of 171 shifting cultivation patches representing eight LULC types in two sub-areas. Because of the lack of a cloud-free image for the date of field sampling, the ETM+ imagery was acquired 2 months after field survey, during which it was assumed that no significant changes in LULC occurred (all dry season). Per pixel correlations were developed between spectral reflectance data, vegetation indices and LULC. As an exploratory study, several statistical methods (analysis of variance, means separations (Tukey HSD), principal component analysis (PCA), geo-statistical analysis, image classification and landscape metrics) were applied on point data and sensor images for evaluating the spatial variability within the landscape. Most variables explained 30–72% of LULC variation in the whole dataset. Those variables with high information content of LULC (infrared bands 4, 5, 7 and derived indices and PC1) also showed long ranges (6 km) spatial dependence as compared to those varying only within 1 km range. The results of these statistical analyses suggested the need to group some LULC types and the application of the Maximum Likelihood Classifier (MLC) for supervised classification provided a LULC map with the highest accuracy (81%) after consolidation of perennial LULC types, such as bush fallow, forest fallow and cocoa plantations. Landscape metrics computed from this map showed a high level of patch diversity and connectivity within the landscape and provided input data that can further be used to simulate predictive maps as substitute to cloud-covered sensor imageries. Landsat-7 ETM+ imagery proved to be useful in discriminating (with about 80% accuracy) the most dynamic LULC types such cropped plots and young fallow patches (shifting every season) and the extension front of the agricultural landscape. 相似文献
54.
M. Bouyo Houketchang S.F. Toteu E. Deloule J. Penaye W.R. Van Schmus 《Journal of African Earth Sciences》2009,54(5):144-154
U–Pb (TIMS–ID and SIMS) and Sm–Nd analyses of zircons and garnet-whole rock pairs were applied on high-pressure granulite facies metapelites and metagranodiorite from Tcholliré and Banyo regions, respectively in the Adamawa–Yadé and Western Domains of the Central-African Fold Belt (CAFB) of Cameroon. Cathodoluminescence (CL) images of zircons reveal that they are made up of ubiquitous magmatitic xenocrystic cores, surrounded and/or overprinted by light unzoned recrystallized domains. U–Pb data on cores yield ages ranging from Paleoproterozoic to Neoproterozoic, which we consider as dating inheritances. Data on overgrowths and recrystallized domains give ages ranging between 594 and 604 Ma, interpreted as the time of HP granulite-facies metamorphism in the Tcholliré and Banyo regions. This is also supported by ages derived from Sm–Nd garnet-whole rock pairs. Sediments of the Tcholliré region were deposited after ca. 620 Ma from Paleoproterozoic, Mesoproteroszoic and Neoproterozoic protoliths, while those from the Banyo region were deposited after 617.6 ± 7.1 Ma essentially from Neoproterozoic protoliths. 相似文献
55.
Stéphane Audry Henriette Ateba Bessa Jean-Pierre Bedimo Bedimo Jean-Loup Boeglin Laurie Boithias Jean-Jacques Braun Bernard Dupré Mikael Faucheux Christelle Lagane Jean-Christophe Maréchal Jules Remy Ndam-Ngoupayou Bernadette Nka Nnomo Justin Nlozoa Jean-Claude Ntonga Olivier Ribolzi Jean Riotte Emma Rochelle-Newall Laurent Ruiz 《水文研究》2021,35(5):e14138
Simultaneously acquiring time series of climate, hydrology and hydrochemical data over decades on river systems is pivotal to understand the complex interactions involving rock, soil water, air and biota in the Critical Zone, to build integrated modelling and to propose predictive scenarios. Among the Critical Zone Observatories (CZOs) implemented in the past 25 years, only a few are located in the humid Tropics despite the importance of these regions in terms of population density, fast-changing land use, biodiversity hotspots, biomass stock on continents, size of river systems, etc. Since 1994, weathering and erosion processes and fluxes have been investigated at both local (experimental watershed) and regional scales in the Nyong River Basin (Cameroon) which belongs to the Critical Zone Observatories network named Multiscale TROPIcal CatchmentS (M-TROPICS). The data shared by M-TROPICS in Cameroon are: (1) rainfall; (2) air temperature, air relative humidity, wind speed and direction, and global radiation; (3) stream and river water level; (4) pH, electrical conductivity, water temperature and suspended particulate matter (SPM) concentration; (5) major ion, alkalinity and dissolved organic carbon (DOC) concentrations. The dataset already contributed to describe the water partitioning in these tropical humid watersheds, to better understand the factors controlling chemical weathering and physical erosion in tropical ecosystems, particularly the role of organic matter. The dataset also contributed to calculate elemental weathering fluxes and saprolite production rate and to propose denudation rates on tropical cratonic landscapes. Hydrological modelling allowed quantification of the geographical water sources contributing to streamflow. DOC data were used to determine greenhouse-gas emissions and carbon budgets from African inland waters. However, long-term solute concentrations at the outlet of a small tributary of the Nyong River exhibit non-stationary behaviour over the last 26 years. The processes governing those fluctuations are not yet fully understood and might be related to changes in the hydrological regime, land-cover and land-use. The latter highlights the need for longer time-series and continued support for CZOs particularly in the humid tropics. 相似文献
56.
Dieudonné Bitom Boris Volkoff Anicet Beauvais Frédérique Seyler Paul-Désiré Ndjigui 《Comptes Rendus Geoscience》2004,336(13):1161-1170
Analysis of landscapes and soil covers from the outer to the inner part of a watershed in the South-Cameroon rainforest zone, characterized by important remnants of inherited ferricretes and stable hydrostatic base levels, indicates that the development of present landforms has not involved significant erosion by slope retreat because of the relative preservation of downslope residual ferricrete and that soil covers have vertically decayed under in situ geochemical process. To cite this article: D. Bitom et al., C. R. Geoscience 336 (2004). 相似文献
57.
《Comptes Rendus Geoscience》2018,350(3):130-140
The geology of the Abiete–Toko gold district in South Cameroon is investigated using a combination of Landsat 7 ETM+/SRTM image processing techniques, conventional geologic field mapping and geostatistical analysis. The satellite images were treated using Principal Component Analysis and Sobel filters to separate the background noise from lithotectonic structures which were matched with field data. The results show that this area has been affected by a polyphase deformation represented by S1 foliation, Sc1 schistosity, L1 lineation, S2 foliation, F2 folds, and F3 shear zones and faults. A detailed analysis of all the structures led to the identification of two major networks of dextral and sinistral shear zones oriented WNW–ESE and NE–SW, respectively. These results may serve in mining prospection, especially in the search for tectonically controlled primary mineralization and so may significantly guide the exploration of primary gold mineralization in the Abiete–Toko area subjected to years of artisanal gold mining. 相似文献
58.
《Chemie der Erde / Geochemistry》2014,74(4):557-570
The Matomb region constitutes an important deposit of detrital rutile. The rutile grains are essentially coarse (> 3 mm), tabular and elongated, due to the short sorting of highly weathered detritus. This study reports the major, trace, and rare-earth element distribution in the bulk and rutile concentrated fractions. The bulk sediments contain minor TiO2 concentrations (1–2 wt%), high SiO2 contents (∼77–95 wt%) and variable contents in Al2O3, Fe2O3, Zr, Y, Ba, Nb, Cr, V, and Zn. The total REE content is low to moderate (86–372 ppm) marked by high LREE-enrichment (LREE/HREE ∼5–25.72) and negative Eu anomalies (Eu/Eu* ∼0.51–0.69). The chemical index of alteration (CIA) shows that the source rocks are highly weathered, characteristic of humid tropical zone with the development of ferrallitic soils. In the concentrated fractions, TiO2 abundances exceed 94 wt%. Trace elements with high contents include V, Nb, Cr, Sn, and W. These data associated with several binary diagrams show that rutile is the main carrier of Ti, V, Nb, Cr, Sn, and W in the alluvia. The REE content is very low (1–9 ppm) in spite of the LREE-abundance (LREE/HREE ∼4–40). The rutile concentrated fractions exhibit anomalies in Ce (Ce/Ce* ∼0.58 to 0.83; ∼1.41–2.50) and Eu (Eu/Eu* ∼0.42; 1.20–1.64). The high (La/Sm)N, (La/Yb)N and (Gd/Yb)N ratios indicate high REE fractionation. 相似文献
59.
Jean-Paul Vicat André Pouclet Yves Bellion Jean-Claude Doumnang 《Comptes Rendus Geoscience》2002,334(12):885-891
Remnants of rhyolite lava-dome and of alkaline microgranite extrusions emerge, as inselbergs, in the alluvial plain, south of Lake Chad. The peralkaline, arfvedsonite- and acmite-bearing rhyolites are determined as pantellerites. They can be related to a tectonomagmatic stage, dated of the Late Cretaceous, of the western central Africa rift system. They may constitute the NNE extension of a N50° to 30° elongated succession of small alkaline complexes, from the Gulf of Guinea to the North-Cameroon, which initiated the magmatic activity of the Cameroon Line. To cite this article: J.-P. Vicat et al., C. R. Geoscience 334 (2002) 885–891. 相似文献
60.
Sadrack Felix Toteu Rose Yongue Fouateu Joseph Penaye Jacqueline Tchakounte Aubin Ciriaque Seme Mouangue William Randall Van Schmus Etienne Deloule Henrik Stendal 《Journal of African Earth Sciences》2006,44(4-5):479
TIMS-ID and SIMS U–Pb dating on zircons from metaplutonic rocks involved in the Pan-African nappe of southern Cameroon allow definition of three groups of subduction-related intrusions: group-I intrusions represented by the Masins metagabbro in the Lomie region yielded 666 ± 26 Ma; group-II intrusions represented by the Mamb metasyenogabbro and the Yaoundé pyriclasite yielded ca. 620 Ma and are broadly coeval with the deposition of the Yaoundé metasediments; group-III intrusions represented by the Elon augen metagranite and the Ngaa Mbappe metamonzodiorite yielded ca. 600 Ma. The onset of the nappe tectonics occurred under high-grade conditions in the range 616 to 610 Ma and continued around 600 Ma with the emplacement of the shallowest nappes. Finally, the construction of southern Cameroon proceeded by a multi-stage evolution characterized by a long-lived development of magmatic arcs associated with rapid opening and closure of sedimentary marginal basins in relation to a northward subduction. 相似文献