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ABSTRACT The Sahel region in West Africa is highly vulnerable facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use. In Sahel, as in other arid environments,... more
ABSTRACT The Sahel region in West Africa is highly vulnerable facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use. In Sahel, as in other arid environments, biological soil crusts are present over a large area. The BIOCRUST project focuses on the use of BSC as an indicator of environmental quality in the context of climate change and human activities pressures and on providing useful informations for best management practices for the Sahelian environment. To this end, a characterisation of BSC is required first at a local level based on the use of Very High Resolution satellite imagery. Two detailed field campaigns were undertaken to identify key variables indicative of the presence of biological soil crusts. A Statistic analysis ascertained that vegetation cover, land use, soil types and rainfall were the most significant variables to consider. From these, a predictive model of the spatial distribution of BSC was developed, based on a logistic regression. The extraction of the variables from the satellite imagery makes it possible to run the prediction model for 2 catchment areas of about 50km2 each situated in Niger on a North South transect. With a view to apply the prediction model to the central part of the Sahel scale, the same methodology was used with Medium Resolution satellite imagery and field data collected on a North South transect in Niger and Burkina Faso. Preliminary results indicate that the model is applicable at regional scale and show the potential spatial distribution of BSCs over a large portion of the Central part of the Sahel region.
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... forest in the late 1960s and has since been cropped using shifting cultivation practi-ces ... the threshold value depending on each individual image's characteristics (or grey level distribution). ... skeleton image; Spix... more
... forest in the late 1960s and has since been cropped using shifting cultivation practi-ces ... the threshold value depending on each individual image's characteristics (or grey level distribution). ... skeleton image; Spix the actual pixel size (equivalent to image spatial resolution); and F ...
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... 1 ), or-ganic matter content and clay mineralogy (Table 1 ). Soils hereafter referred to as "loamy" include loam, clay loam, silty clay loam and silt loam; "sandy" soils include sand, loamy sand,... more
... 1 ), or-ganic matter content and clay mineralogy (Table 1 ). Soils hereafter referred to as "loamy" include loam, clay loam, silty clay loam and silt loam; "sandy" soils include sand, loamy sand, sandy loam and sandy clay loam. ...
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... use of rainfall simulators may be very helpful in obtaining data on the effects of various rainfall patterns on the stages of crust formation (Epstein and Grant, 1967; Farres, 1978; Norton, 1987). 0016-7061/91/$03.50 1991-Elsevier... more
... use of rainfall simulators may be very helpful in obtaining data on the effects of various rainfall patterns on the stages of crust formation (Epstein and Grant, 1967; Farres, 1978; Norton, 1987). 0016-7061/91/$03.50 1991-Elsevier Science Publishers BV 202 c. VALENTIN It must ...
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Biological soil crusts occur extensively in semi-arid regions. In the western part of Niger, they are associated with various types of physical soil crusts in fallows and in the “tiger bush ecosystem” (a landscape with a typical banded... more
Biological soil crusts occur extensively in semi-arid regions. In the western part of Niger, they are associated with various types of physical soil crusts in fallows and in the “tiger bush ecosystem” (a landscape with a typical banded pattern consisting of densely vegetated bands of small trees and shrubs alternating with bare soil bands). Despite their widespread occurrence, not much
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... example, where aeolian sands cover the soil uniformly, no vegetation banding occurs on the Niger plateaux (d'Herbès and Valentin, 1997). ... The occurrence of crusted surfaces in the interbands have been noted in most studies... more
... example, where aeolian sands cover the soil uniformly, no vegetation banding occurs on the Niger plateaux (d'Herbès and Valentin, 1997). ... The occurrence of crusted surfaces in the interbands have been noted in most studies (eg, Boaler and Hodge, 1962; White, 1971, Mabbut ...
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Geology, Climate Change, Arid Land Ecology, Soil Erosion, Soil organic matter, and 13 moreCatena, Soil Fertility, Soil sciences, Spatial Distribution, Arid Zone, Biomass production, Land Degradation, Semi Arid Region, Water Resource, Ecosystem Function, HUman Disturbance, Long Term Monitoring, and Vegetation Cover
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Geology, Climate Change, Environmental Change, Land Use Change, Global change, and 23 moreHigh Frequency, Impact Factor, Soil Erosion, Gully Erosion, Nitrogen, Spatial Scale, Erosion Control, Catena, Labour Productivity, Soil sciences, Reduced Tillage, Sandy soil, North America, Arid Zone, High Resolution, Research Needs, Infection prevention and control, North East, Feedback loop, Management Strategy, Vegetation Cover, Strontium Isotopes, and Crop Yield
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... 2. For each of these ten zones, the amounts of run-off (Off), run-on (On), and infiltration (In) was calculated using the model proposed by Casenave and Valentin (1992), and recently validated at similar scales in the region (Peugeot,... more
... 2. For each of these ten zones, the amounts of run-off (Off), run-on (On), and infiltration (In) was calculated using the model proposed by Casenave and Valentin (1992), and recently validated at similar scales in the region (Peugeot, 1995; d'Herbès and Valentin, 1997). ...
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Geology, Climate Change, Environmental Change, Land Use Change, Soil Erosion, and 15 moreLandscape Evolution, Gully Erosion, Land Use, Spatial Scale, Erosion Control, Catena, Soil Degradation, Experimental Study, Soil sciences, Agricultural land use change, Research Needs, Soil loss, Water Erosion, Sediment Yield, and Site Effect
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... INTERNATIONAL GEOSPHERE - BIOSPHERE PROGRAMME BOOK SERIES The Terrestrial Biosphere and Global Change Implications for natural and managed ecosystems Edited by BrianWalker, Will Steffen, Josep Canadell and John Ingram CAMBRIDGE... more
... INTERNATIONAL GEOSPHERE - BIOSPHERE PROGRAMME BOOK SERIES The Terrestrial Biosphere and Global Change Implications for natural and managed ecosystems Edited by BrianWalker, Will Steffen, Josep Canadell and John Ingram CAMBRIDGE UNIVERSITY ...
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Land management, Southeast Asia, Vietnam, Seasonality, Environmental Sciences, and 15 moreStandard Deviation, Soil Erosion, Maize, Land Use, Shifting Cultivation, Conservation Agriculture, Suspended Sediment, Land Degradation, Soil management, Management Strategy, FARMING SYSTEM, Crop Yield, Tree Improvement, Sediment Yield, and Site Effect
Systems including a long fallow period have proven to be sustainable in the tropics for they enable the transfer of the rich store of nutrients from the vegetation to the ensuing crops. These systems have been mainly studied in the forest... more
Systems including a long fallow period have proven to be sustainable in the tropics for they enable the transfer of the rich store of nutrients from the vegetation to the ensuing crops. These systems have been mainly studied in the forest zone with a peculiar focus on the maintenance of organic and chemical fertility. By contrast, the effects of the