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Regreening the Sahel and Farmer Managed Natural Regeneration: What the Satellite Imagery Shows First Drylands Week June 10-17, 2011 Dakar, Senegal Gray Tappan, U.S. Geological Survey Earth Resources Observation and Science (EROS) Center Sioux Falls, South Dakota USA tappan@usgs.gov.
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Regreening the Sahel andFarmer Managed Natural Regeneration:What the Satellite Imagery ShowsFirst Drylands WeekJune 10-17, 2011 Dakar, SenegalGray Tappan, U.S. Geological SurveyEarth Resources Observation and Science (EROS) CenterSioux Falls, South Dakota USAtappan@usgs.gov U.S. Department of the Interior U.S. Geological Survey
The U.S. Geological Survey’s Earth Resources Observation and Science (EROS) Center’s vision is to be the world’s leading source of land information for exploring our changing planet.
Many thanks for funding and support: U.S. Agency for International Development CILSS (Permanent Interstate Committee for Drought Control in the Sahel) African Regreening Initiative Centre de Suivi Ecologique, Senegal Institut des Sciences de l’Environnement (ISE/UCAD), Senegal
Challenges in Monitoring Agro-Environmental Transformations • Farmers don’t tell you when they’ve made land improvements • Biophysical changes occur on a vast geographic scale • Distinguishing climate versus anthropogenic factors is complicated • Visual evidence of benefits often not apparent in less than 3-4 years; • Significant biophysical changes may take a decade or more • Time-series mapping of land cover is technically challenging
Remote Sensing: A Definition • Remote sensing is the science and art of acquiring information about the Earth’s surface without being in physical contact with it. Image Courtesy of NASA: SeaWiFs
Remote Sensing Advantages • Synoptic perspective • Unique vantage point • Extra-visual information • Historical and permanent record Image Courtesy of NASA: SeaWiFs
Remote sensing systems that provide coverage of West Africa • Meteosat • SeaWIFS • MODIS • SPOT Vegetation • NOAA-AVHRR • Landsat • Corona • ASTER • SPOT 5 • IKONOS • Quickbird • Historical Aerial Photography • Recent Aerial Photography • Aerial Videography SeaWIFS Image
Approach to Mapping, Monitoring, and Modeling LULC *Levels of Data Collection • Satellite level • Aerial level • Ground level *All data collected through time
Field Data Collection: 1982 – 1984 Dicrostachys glomerata
Permanent Monitoring Sites in Senegal (Established in 1982-1983)
Field Data Collection: • Determining vegetation • structure for mapping • Species-level inventories • to monitor biodiversity • Biomass and carbon • measurements
Revisited Ground Sites to Document Changes in Natural Resources 1994 1983 1983 1996 1996 1998
Jan 1983 Monitoring on-farm trees in the Peanut Basin: 28-year comparison Feb 2011
1984 Protection of an ecosystem: (Niokolo-Koba, Senegal) Woody Species at Site 487: 1984 Bombax costatum Annona senegalensis Combretum crotonoides Combretum geitonophyllum Combretum glutinosum Combretum micranthum Combretum nigricans Crossopterix febrifuga Danielia oliveri Detarium microcarpum Gardenia erubescens Hexalobus monopetalus Hymenocardia acida Lannea acida Ostryoderris stuhlmannii Piliostigma thonningii Pterocarpus erinaceus Stychnos spinosa Terminalia avicennioides Terminalia macroptera Vitex madiensis Ximenia americana Cordyla pinnata Entada africana Sterculia setigera 2007 Bombax costatum Annona senegalensis Combretum crotonoides Combretum geitonophyllum Combretum glutinosum Combretum micranthum Combretum nigricans Crossopterix febrifuga Danielia oliveri Detarium microcarpum Gardenia erubescens Hexalobus monopetalus Hymenocardia acida Lannea acida Ostryoderris stuhlmannii Piliostigma thonningii Pterocarpus erinaceus Stychnos spinosa Terminalia avicennioides Terminalia macroptera Vitex madiensis Ximenia americana Cordyla pinnata Entada africana Sterculia setigera 2007
Mapping and Monitoring: The Senegal Experience • Mapped the Land Resources of Senegal (1982 - 1985) • Monitored land cover trends with CSE through four decades (completed in 1999) • Built on results for quantifying carbon stocks in soils and vegetation (completed in 2003) • Currently assessing and mapping land resources in • the Kedougou and Casamance Regions
Seasonal Vegetation Patterns NOAA-AVHRR NDVI (vegetation index or greenness)
Satellite observed greening trend Trends in NDVI 1982 – 2006 corrected for the effects of rainfall: Source: Herrmann et al., 2005
Tree Parkland Dominated by Faidherbia albida: Leaf-off Stage in the Rainy Season
Enlargement from a Landsat Image, October 2000: Tree parklands notvisible (south of Aguié, Niger) 0 5 km
Preparing for flight at Tahoua, Niger
Impact of a single F. albida tree on crop growth (radius of high productivity: 5 m around a small tree)
Quickbird Image of Medium Density Tree Parkland East of Maradi, Oct. 2005
1955 Landscape Dynamics Southwest of Zinder 2005 1975
1955 Landscape Dynamics Southwest of Zinder 1975 2005
Percent Tree Cover Trend in the Study Area (Mirria-Magaria-Matameye Triangle)
More People – More Trees Population
Location of 12 Terroirs Used for Comparing Tree Density Across the Niger-Nigeria Border Niger • Tahoua Terroirs • Zinder • Maradi ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Nigeria ■ ■ 0 200 km
Terroir in Niger 19 km North of the Niger-Nigeria Border Source: Google Earth, 2005 Source: Google Earth, 2005