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This article exposes methods and results of a remote sensing exercise based on combined classifications and spatial analysis. This work was carried out as part of the EVA programme which looked at estimating the economic and social value of marine ecosystems within West African Marine Protected Areas (MPA). The remote sensing methods utilised in this study are innovative in that they stem from non supervised combined classifications and principal component analysis. These techniques offer a reliable method for the calculation of ecosystem surfaces, as well as estimation of their health status, both elements that are compulsory to the economic valuation exercises. From an application perspective, this modelling process is particularly relevant to regions of data-poor marine ecosystem mapping where biodiversity conservation is developed or large-scale areas where access is made difficult and costly in time and financial resources. Further, these results are likely to influence the identification of priority areas for conservation measures as part of the MPA management plan.

This study seeks to analyze changes in vegetation cover in the ecoregions of Senegal over the past two decades (2000 to 2019) using a time series of 16-day MODIS NDVI images with a spatial resolution of 250m. The study method is a combination of remote sensing and statistics. The data processing followed three main steps which are: first, the Main Component Analysis (PCA) on the 2000-2019 time series followed by the unsupervised classification using the PCA result; second, the calculation of the average NDVI of the 23 16-day periods; third, the calculation of the Kendall correlation or “tau” (τ) associated with the p 0.1 significance test. The results indicate changes in the phenological rhythm of the classes corresponding to lowland crops, floodable valleys, mangroves, dense forests, and wooded and wooded savannah. Some modifications are similar to degradation, and others to a regreening Similarly, there was a time lag and a later green season. Kendall’s correlation indicated an increase in NDVI between 2000-2009 primarily in the eastern, southwest and estuarine (ZDE) ecoregions with a significant trend. During the 2010-2019 decade, a set of small areas of progress was noted. On the other hand, the negative correlations of NDVI values, which indicate a decrease in vegetative activity, are observed mainly in the northern and central-western ecoregions of the country, although with a non-significant trend.

The algerian steppe is an arid ecosystem characterized by limited natural resources, a poor soil, and low and opened vegetable formations and severe climatic conditions.This work is a contribution of studying the problem of the desertification in El Bayadh region. It is based on two methods of follow-up and understanding, a phyto-ecological diagnosis and the use of remote sensing and SIG as powerful tool of follow-up and investigation. The objective of this paper is to highlight the importance of desertification phenomena in Algeria and to analyze the principal discriminating factors in the evolution of this ecological problem and its socio-economic consequences on the traditional system balance of the pastoral organization.

This paper document the usefulness of offshore and coastal wind maps from satellite techniques. As a step before metering programs, remote sensing approaches are gaining much interest, especially for offshore analysis. As an intermediate approach, it gives first estimates of the best wind sites. In the complex coastal area of St-Lawrence gulf, strong effects of local topography characterize wind fields and the wind resource assessment is challenging. Wind fields are extracted from Synthetic Aperture Radar (SAR) scenes provided by the RADARSAT-1 satellite and from QuickSCAT scatterometer collocated wind direction. The spatial resolution of such a technique is around 400 m covering wide region until 300 by 300 km. Among interesting findings, it appears that a relative small sample of scenes can already indicates the best spots to investigate for further analysis. Accuracy of the method is evaluated at 1.5 m/s offshore and around 2 m/s close to the shore.

Monts Kouffe's region concerns here Monts Kouffe's forest reserve and its south suburb. In Benin, Monts Kouffe forest reserve undergoes anthropic pressures which are galloping population growth, a shifting cultivation, anarchy meadow and poaching, unfair forestry woods using, forested ecosystems' dysfunction and loss of biodiversity. The aim of this study is to characterize Monts Kouffe forest reserve and periphery’s dense forests islands in order to present their spatio-temporal dynamic. The adopted methodology is based on Remote Sensing, Cartography and Landscape Ecology techniques. From 1986 Landsat TM and 2006 Landsat ETM+ images for 30 m spatial resolution, these allowed the computation of spatial indexes as number of spots (dense forests islands), total area of spots, dominance, average area, spots areas’ diversity and, shape index.

The Salonga National Park (PNS) and its biological resources hold significant environmental and economic importance for the surrounding communities that rely on its resources for survival. This study aims to quantify the impact of human activities on the primary forests of the southern part of the PNS using Landsat image classification from the years 2002, 2007, 2014, and 2020, combined with landscape ecology analysis tools. The results revealed that the landscape remained predominantly covered by primary forests between 2002 and 2020, although their area consistently decreased in favor of secondary forests and agricultural zones. Specifically, the area of primary forests decreased from 12,636.82 km² in 2002 to 11,266 km² in 2020. The total loss of primary forests during this period amounted to 10.4%, with an annual deforestation rate of 0.6%. The total number of primary forest fragments also slightly decreased, from 525,142 in 2002 to 524,584 in 2020. Additionally, the results indicated that the proportion of primary forests increased as the distance from villages increased, suggesting a significant impact of village areas on forest degradation. The anthropogenic impact on the southern part of the PNS is clearly evidenced by the reduction in primary forest areas, primarily due to agricultural activities. These findings underscore the necessity for regular monitoring of human activities within the PNS and the development of an integrated management strategy to preserve this ecologically crucial area.

Between 60 and 70 % of the native flora of the islands of French Polynesia (South Pacific) are located in montane ecosystems, in the so-called “orophilous vegetation“. Due to its cooler climate, this high elevation zone is relatively protected from anthropogenic activities and from the invasion of alien species which are particularly aggressive at lower elevations. If global warming, recorded to be 0.034°C per year since 1958 in the main island of Tahiti, is persisting, air temperature will increase by 3.1°C in 2100, causing a vertical shift of vegetation and a drastic decrease of the orophilous vegetation area. Some endemic species unable to migrate higher in elevation will be doomed. According to our results, orophilous vegetation will decrease from 14,000 ha nowadays to 1,500 ha in 2100, which represents a 90 % reduction of the current area. Consequences on biodiversity will be : (i) the loss of a unique ecosystem in French Polynesia, the subalpine zone, and the extinction of, at least, six plant species restricted to this habitat and endemic to Tahiti ; (ii) the loss and fragmentation of the cloud forests, which will only be found on the highest summits, leading to an additional risk of extinction ; and (iii) the expansion of alien invasive species, having already an enormous ecological impact in Tahiti.

This article proposes a method for monitoring spatial dynamics of biodiversity which have occurred along the past 40 years ago in a farming community, Benfica, State of Pará, Brazilian Amazon. It is designed to assess "where", “when”, “why” changes have occurred, and "how much" surface is impacted. ? The goal is to help assess the impact of settlement policies on these dynamics. Data collected on both spatial disparities and rhythms of transformation should enrich knowledge on biodiversity evolution. In the current approach biodiversity is assessed by a scale of values resulting from several indicators combined. Each one contributes to estimate changes which occur during the land use change from forest to cropping. Biodiversity is then evaluated at two levels : one encountering the various forms of resources exploitation and attributing the measure of biodiversity to a landscape component (forest, fallow and crop / pasture) ; and the other, the category of actors (smallholders vs farmers), and reporting the extent of biodiversity to territory units which is preferentially operated. This monitoring process of this territory is easily replicable in time. In fact, it only depends on the availability of satellite images. This approach is on the process of validation to be used in further works dealing with similar anthropic forest regions.

The present study aims to work out a methodology based on the use of the sensors such TERRA MODIS (MODerate resolution Imaging Spectroradiometer) in the desertification following and the detection of desertification risk zones in the northern area of Algeria. To this end, some geophysical parameters (albedo "R0", vegetation index "NDVI'' and surface temperature "TS") are produced regularly and cover the period of 2000 to 2005. The combination of these parameters two per two especially R0 -TS, NDVI-TS and R0 - NDVI has allowed respectively the characterization of the hydric and vegetation state. The synthesis of the totality of results under a geographical information system GIS as well as their confrontation with others types of data have allowed to map the desertification risk following five degrees (very high, high, moderated, weak and stable). Our results show that 75 % of the risk zones are already desertify or near of desertification.

Southern Brazil, which has a good natural potential due to its sub-tropical climate and its favorable topography, is mainly dedicated to breeding and cultivating soybean, rice and corn. Like others in Brazil, this region is involved in the production of agricultural products for domestic and international markets. It is thus subject to the intensification of practices whose impacts on the environment are well known. The study investigates the watershed of Ibicuí (46.800 km²), located in the southwest of the state of Rio Grande do Sul. Thanks to interpretation of MODIS images, we have identified land uses and its transformations during the first decade of the twenty-first century. The cards we have been able to achieve are analyzed and confronted with surveys of agriculture stakeholders (local agriculture organizations, farmers…), carried out between 2007 and 2010. The analysis of three specific areas allows determining agricultures’s impacts and pressure on the environment : the sector of Rosario do Sul is undergoing a decline of livestock and a rise of eucalyptus plantations, while Alegrete area is dedicated to rice crops and São Francisco de Assis area is undergoing the erosion of its sandy soils and the return of the meadow. The paper examines how the environment is integrated through water uses management, through the development of innovating cultural practices like direct seeded soil systems and through environmental protection such as the laws of 2002 and 2006 on Permanent Protection Areas (APP).

This study encapsulates the evolution of the occupation and land use in the region of the Lake of Guiers. It also contributes to the characterization of the main spatial entities of the zone between 1973 and 2010. Satellite based mapping techniques have been used and complemented by field verifications, During the period under review, we have witnessed an increase in stretches of water by 14,9 %, aquatic vegetation by 17,5 %, industrial and private agricultural holdings respectively by 207,5 and 5508,8 % and a decrease of shrub-steppe and grassy-steppe of 69,9 and 64,3 %. Modifications in land occupation have become apparent mainly through the substitution of shrub steppe by grassy-steppe between 1973 and 1988 (before the construction of the dams in Diama and Manantali on River Senegal) and the extension of managed agricultural land and aquatic vegetation between 1988 and 2010 (after the construction of dams). Land use in 2010 is marked by the development of irrigated agriculture by 42 % on the zone under review. The important extension of irrigated agricultural land is the source of numerous conflicts over land. In this regard, it is important to update the development of the region as a whole through the frame of national policies of land-use planning and participative local development.

This study is included in a larger scientific project to analyse land cover changes in the region Ile-de-France. Proving a contrasting change between inner and outer suburbs, the actual tendency is towards the growth of urban areas to the detriment of rural areas. The five “villes nouvelles” (Cergy-Pontoise, Évry, Marne-la-Vallée, Sénart, Saint-Quentin-en-Yvelines), result of a strong urban policy since the 60’s, created to equilibrate the regional development, are characterized by specific urban profiles and spatial organizations, compared to others cities where urban sprawl has followed the main trend of urbanization, after the Second World War (multiple dwellings construction and then individual housing). From an urban planning point of view, a comparison between the new city of Évry and the city of Longjumeau, outer suburb’s city, characterized by rural areas disappearance in favour of individual housing, is proposed. This case study is based on computation of spatial metrics allowing a characterization of urban landscapes (irregularity and fragmented shapes, compactness or density of urban areas). This analyse reveals different urban landscapes between these territories, at the town scale and at the district scale. The urban policies, since 45 years, are expressed through specific urban landscapes in new cities. Indeed, Évry presents an urban landscape more fragmented and complex than Longjumeau, even if some areas are exceptions, like the irregularity of individual housing’s area in Longjumeau.

The forest ecosystems of the Democratic Republic of Congo are prone to deforestation, highlighting fragmented and anthropized landscapes. The INERA Kiyaka forest station is not spared. This regression of plant cover is dependent on human activity. The cartographic and quantitative analysis by remote sensing of the dynamics of land use was carried out in order to highlight the essential factor of the deforestation of the vegetation cover between human pressure and climatic parameters. The classification by object with the supervised approach of Sentinel 2Landsat and Spot images made it possible to characterize land cover in three periods (2000, 2010 and 2020). We have selected six classes of land cover according to the realities on the ground: mature secondary forest, young secondary forest, savannah, agricultural and anthropogenic zone, water and palm grove. The analysis of the fragmentation of the landscape was done by comparing the results of the classification of satellite images of the years under study. The cartographic and quantitative analysis reveals a regressive dynamic of the forest formations (secondary forest) and the palm grove in favor of the savannah, agricultural and anthropic zone. The high percentages of regression are observed between 2010 and 2020. This study reveals that since 2000, the forest cover of the Kiyaka forest station has undergone a transformation of its landscape due to human activities supported by population growth.

The Babagulu forest region here concerns the Babagulu Forest Reserve (BFR) and its periphery. In the Democratic Republic of Congo, the forest region of Babagulu is under anthropogenic pressure, notably due to its proximity to the city of Kisangani. These anthropic pressures remain little documented and their impacts on this forest landscape remain poorly understood. The purpose of this study is to regularly monitor the anthropization of the landscape of the RFB. The methodological approach adopted is based on techniques of remote sensing, cartography and landscape ecology. The Landsat TM (1984, 1986, 1990, 1994 and 2010), ETM + (2001 and 2005) and OLI (2015 and 2018) satellite images, all of 30m spatial resolution, were used to map the land cover in three classes (primary forest, fallow land/degraded forest and rural complex). The calculation of ten spatial indices made it possible to characterize the composition and configuration of the landscape between 1984 and 2018. These spatial indices include the number of spots, the average spot size, the perimeter density, the aggregation index, largest fragment index, landscape shape index, mean Euclidean distance to nearest neighbor and fractal dimension, variation and absolute, fractal dimension and contagion index. The results show a significant regression of the primary forest for the benefit of the anthropic classes (rural complexes and fallow land and degraded forests) outside (R²= 0.98; p

A pioneering area of Ivorian cocoa and coffee plantation agriculture, the watersheds of Aghien and Mé were quickly subjected to intense deforestation. The phytogeographic landscape has been constantly changing since the country's independence in 1960. These landscape changes are linked to the pecuniary interests of different perennial crops over the years (coffee, cocoa, rubber, palm oil and sweet banana). The study of the evolution of the vegetation cover of the watersheds of Aghien and Mé from 1982 to 2013 aims to take stock of the spatio-temporal transformations of the landscape units of these two basins. To carry out this study, were used jointly remote sensing, statistical tests of trend and rupture and field surveys. Daily images of index of vegetation NDVI (Normalized Difference Vegetation Index) of NOAA (National Oceanic and atmospheric administration) were compiled. Thus, descriptive statistical analyzes and stationarity tests were carried out on the basis of the pixel values of these images. The results of these tests produced in the cartographic form have been investigated in the field. The results of the study indicate, at the temporal level, a major break between 1993 and 1997. In addition, three levels of spatial discrimination are clearly distinguishable : the increasingly urbanized area of the Aghien basin ; the northeast of the Mé basin, area of high production of perennial crops (cocoa, hevea, coffee, oil palm, etc.) and the rest of the basin characterized by a mosaic food crop-export crop.

This article proposes a methodology to interpret old aerial photography applied to the geohistorical study of torrential landscapes. Indeed, as a primary source, images are historical proxies which foremost advantages are to locate and spatialise forms of changes. The aim of these researches is to produce a cartographical following of landscapes dynamics, through this type of archive. To achieve such a purpose, we choose a landscape sensitive to changes (torrential fan), considering landscape entities which equilibrium conditions responds to the socio-environmental context of a torrential northern alpine valley. In this exploratory aim of diachronic reconstruction, the photo-interpretative technics and remote sensing were associated. In this article, we explain the potentialities of an object-oriented approach using as an example a time series of areal missions taken by the National Geographic Institute of France (IGN-F©). The results of this method give a spatial and normalised comprehension over the fifty last years.

Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua Kouté Sagbé and north-Agban Attié and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB.

This study appreciates the dynamic of land cover in a faraway or middle future. It is based on a combinatory approach that integrates spatial remote sensing, geographic information system and cellular automata techniques. Landsat TM of 1986, ETM of 2000 and NigeriaSat1 of 2006 images were used for the extraction of land cover information. These information were processed and converted to ASCII format in ArcGIS and then recuperated in SPACELLE cellular automata application model, where predictions of land cover were made towards 2025 and 2034, under defined conditions. The change detection reveals a progressive trend of farm and fallow lands, shrub and woody savannah between 1986 and 2006. Dense forest and gallery forest presented a regressive trend in the four landscape units selected. The socio-economic scenario reveals that vegetation formations will almost disappear at the profit of farm and fallow lands and settlements in 2016, 2025, trend that will be consolidated in 2034. The ecological scenario has turned to an environmental stability scenario that translated into a relative dynamic of land cover units. It preserves the resources because their degree of degradation will be low.

The forest-savannah mosaics are an ecological and heterogenous formation, where landscape structure and composition vary substantially. This study investigates the spatial organization of human activities at the scale of village terroirs of the North Batéké Chiefdom, Democratic Republic of Congo. How are human activities organized on the periphery of the villages? Is there local variability in the spatiality of these activities and what factors account for such variability? Finally, what are the consequences on the landscape, particularly in terms of deforestation? These questions were addressed by crossing data from georeferenced field surveys and socio-economic surveys, all of which were triangulated with analyses from geomatics (GIS and remote sensing). A theoretical model of the village terroir was produced for all villages, consisting of a concentric organization of activities on the periphery of villages, based on the maximum distances walked for each activity. A variation in these distances was observed, notably concerning agriculture, because of demography, availability of woodlands, the presence of community forests and the intensity of economic agriculture. This inter-village variability made it possible to highlight a village typology directly linked to the landscape composition of the terroirs, and thus to highlight different socio-ecological situations within a small area. This has made it possible to identify certain deforestation hotspots, and, conversely, areas where there is little degradation of forest cover. Ultimately, this study aims to support local policies in terms of development and conservation by enabling them to act in an integrated approach at the village level. By relying on the concept of village terroir, this research highlights the relevance of carrying out local, or even micro-local, studies in order to gain a better understanding of the complexity of human-environment relations, which are directly visible on the landscape.

This study aims to analyze the performance of spectral classifications and object oriented classification, for mapping of the urban area of Cocody and Attécoubé. To achieve our aim, a satellite image at very high spatial resolution (VHSR) was used. For this work, these two methods of classifications were successively applied to three test sites, namely a well-built area, an area with poor housing and an undeveloped area. The results of two treatments are compared to analyze performances. It appears from these treatments that object-oriented classification is better suited than the spectral approach for mapping sites built because it improves the mapping accuracy of 4,58%. At sites with poor housing, the two classifications show almost similar comprehensive details. Thus, the spectral classification provides an improvement of 0,73% compared to the object-oriented approach. On undeveloped land, the spectral classification is best shown with an overall improvement of 8.22% compared to the object-oriented approach. In short, the object-oriented classification seems appropriate for the extraction of units of well-structured sites. When the level of organization of the site decreases, the performance of the object oriented classification fall in favour of the spectral classification.urbanization, spectral classification, object-oriented classification, remote sensing, Côte d’Ivoire

This study of the urban vegetation of Toliara, city located in a semi-arid area in the Southwest of Madagascar, helps understand specific vegetation issues by exploring its typology and various functions, as well as its changes since the French colonial period. It also helps define those issues that are specific to a Southern city, first in a colonial context, then in a non-colonial one. The methodology is based on an in-situ field analysis (2016) combined with aerial (1949) and satellite remote sensing (2015).