Hindu Kush Himalaya(HKH) is the largest and the most diverse mountain region in the world that provides ecosystem services to one fifth of the total world population. The forests are fragmented to different degrees du...Hindu Kush Himalaya(HKH) is the largest and the most diverse mountain region in the world that provides ecosystem services to one fifth of the total world population. The forests are fragmented to different degrees due to expansion and intensification of human land use. However, the quantitative relationship between fragmentation and demography has not been established before for HKH vis-à-vis along elevation gradient. We used the globally available tree canopy cover data derived from Landsat-TM satellite to find out the decadal forest cover change over 2000 to 2010 and their corresponding fragmentation levels. Using SRTMderived DEM, we observed high forest cover loss up to2400 m that highly corroborated with the population distribution pattern as derived from satellite observation. In general, forest cover loss was found to be higher in south-eastern part of HKH. Forest fragmentation obtained using ‘area-weighted mean radius of gyration' as indicator, was found to be very high up to 2400 m that also corroborated with high human population for the year 2000 and 2010. We observed logarithmic decrease in fragmentation change(area-weighted mean radius of gyration value),forest cover loss and population growth during 2000-2010 along the elevation gradient with very high R^2 values(i.e., 0.889, 0.895, 0.944 respectively). Our finding on the pattern of forest fragmentation and human population across the elevation gradient in HKH region will have policy level implication for different nations and would help in characterizing hotspots of change. Availability of free satellite derived data products on forest cover and DEM, griddata on demography, and utility of geospatial tools helped in quick evaluation of the forest fragmentation vis-a-vis human impact pattern along the elevation gradient in HKH.展开更多
Contrary to the countries of northern coast, the forest formations on Southern and East coast of the Mediterranean are in regression. With the combined action of the ax, fire and pasture, these ecosystems are subjecte...Contrary to the countries of northern coast, the forest formations on Southern and East coast of the Mediterranean are in regression. With the combined action of the ax, fire and pasture, these ecosystems are subjected to a pressure of permanent degradation. Indeed, the degradation of the forest ecosystems represents one of the most important causes of reduction and erosion of the biodiversity in the world. The massif of Aur6s is located in the North-East of Algeria. The analysis of the spatiotemporal dynamics of this vulnerable vegetation is not approached yet. This study proposes a focus on the analysis of the dynamics of this vegetation and to study the factors of its degradation. For that, a methodological approach of diachronic follow-up between two dates was adopted by using any kind of old information sources （archives, aerial photographs, topographic maps） and recent （Images satellite of American Landsat and data of land）. The results reveal a degradation of vegetable cover thus expressing a very thorough reduction of the formations forest replaced by herbaceous formations very sensitive and threatened by the overgrazing.展开更多
Keita region is largely dependent on agriculture and livestock as the main economic activities with about 90% of the population are actively engaged in rural activities. However, these activities are dwindling at a ra...Keita region is largely dependent on agriculture and livestock as the main economic activities with about 90% of the population are actively engaged in rural activities. However, these activities are dwindling at a rate that corresponds with increase in the ecosystem’s vulnerability. The following study focused on land use/land cover change in Keita. The study aims to better understand changes through diachronic analysis by integrating remote sensing and GIS. There was an interpretation of satellites imagery (1975, 1984, 1995 and 2001), and statistical techniques were used to provide quantitative analysis of land use/cover change information and drivers underlying in the study area. The changes are affected by simultaneous influence of successive droughts (1973-1974 and 1983-1984) that have transformed ecological balance, anthropogenic and livestock impacts, ecosystems degradation and policies. The land use temporal dynamics are undergone continual degradation of vegetation, the state of land saturation results in conflicts between farmer and herders, the drop in grazing areas, bare land expansion, the erosion of stream bed, and the decline in flooded plain.展开更多
基金International Centre for Integrated Mountain Development(ICIMOD)for research funding
文摘Hindu Kush Himalaya(HKH) is the largest and the most diverse mountain region in the world that provides ecosystem services to one fifth of the total world population. The forests are fragmented to different degrees due to expansion and intensification of human land use. However, the quantitative relationship between fragmentation and demography has not been established before for HKH vis-à-vis along elevation gradient. We used the globally available tree canopy cover data derived from Landsat-TM satellite to find out the decadal forest cover change over 2000 to 2010 and their corresponding fragmentation levels. Using SRTMderived DEM, we observed high forest cover loss up to2400 m that highly corroborated with the population distribution pattern as derived from satellite observation. In general, forest cover loss was found to be higher in south-eastern part of HKH. Forest fragmentation obtained using ‘area-weighted mean radius of gyration' as indicator, was found to be very high up to 2400 m that also corroborated with high human population for the year 2000 and 2010. We observed logarithmic decrease in fragmentation change(area-weighted mean radius of gyration value),forest cover loss and population growth during 2000-2010 along the elevation gradient with very high R^2 values(i.e., 0.889, 0.895, 0.944 respectively). Our finding on the pattern of forest fragmentation and human population across the elevation gradient in HKH region will have policy level implication for different nations and would help in characterizing hotspots of change. Availability of free satellite derived data products on forest cover and DEM, griddata on demography, and utility of geospatial tools helped in quick evaluation of the forest fragmentation vis-a-vis human impact pattern along the elevation gradient in HKH.
文摘Contrary to the countries of northern coast, the forest formations on Southern and East coast of the Mediterranean are in regression. With the combined action of the ax, fire and pasture, these ecosystems are subjected to a pressure of permanent degradation. Indeed, the degradation of the forest ecosystems represents one of the most important causes of reduction and erosion of the biodiversity in the world. The massif of Aur6s is located in the North-East of Algeria. The analysis of the spatiotemporal dynamics of this vulnerable vegetation is not approached yet. This study proposes a focus on the analysis of the dynamics of this vegetation and to study the factors of its degradation. For that, a methodological approach of diachronic follow-up between two dates was adopted by using any kind of old information sources （archives, aerial photographs, topographic maps） and recent （Images satellite of American Landsat and data of land）. The results reveal a degradation of vegetable cover thus expressing a very thorough reduction of the formations forest replaced by herbaceous formations very sensitive and threatened by the overgrazing.
文摘Keita region is largely dependent on agriculture and livestock as the main economic activities with about 90% of the population are actively engaged in rural activities. However, these activities are dwindling at a rate that corresponds with increase in the ecosystem’s vulnerability. The following study focused on land use/land cover change in Keita. The study aims to better understand changes through diachronic analysis by integrating remote sensing and GIS. There was an interpretation of satellites imagery (1975, 1984, 1995 and 2001), and statistical techniques were used to provide quantitative analysis of land use/cover change information and drivers underlying in the study area. The changes are affected by simultaneous influence of successive droughts (1973-1974 and 1983-1984) that have transformed ecological balance, anthropogenic and livestock impacts, ecosystems degradation and policies. The land use temporal dynamics are undergone continual degradation of vegetation, the state of land saturation results in conflicts between farmer and herders, the drop in grazing areas, bare land expansion, the erosion of stream bed, and the decline in flooded plain.
