U.S. Department of the InteriorU.S. Geological Survey

Regreening the Sahel andFarmer Managed Natural Regeneration:

What the Satellite Imagery Shows

First Drylands WeekJune 10-17, 2011

Dakar, Senegal

Gray Tappan, U.S. Geological SurveyEarth Resources Observation and Science (EROS) Center

Sioux Falls, South Dakota USAtappan@usgs.gov

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 Controlin 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

Image Courtesy of NASA: SeaWiFs

Remote Sensing Advantages• Synoptic perspective• Unique vantage point• Extra-visual information• Historical and permanent record

SeaWIFS Image

• Meteosat

• SeaWIFS

• MODIS

• SPOT Vegetation

• NOAA-AVHRR

• Landsat

• Corona

• ASTER

• SPOT 5

• IKONOS

• Quickbird

• Historical Aerial Photography

• Recent Aerial Photography

• Aerial Videography

Remote sensing systems that provide coverage of West Africa

Approach to Mapping, Monitoring, and Modeling LULC

Satellite level Aerial level Ground level

*All data collected through time

*Levels of Data Collection

Field Data Collection: 1982 – 1984

Dicrostachysglomerata

Permanent Monitoring Sites in Senegal (Established in 1982-1983)

Field Data Collection:

• Determining vegetationstructure for mapping

• Species-level inventoriesto monitor biodiversity

• Biomass and carbonmeasurements

Revisited Ground Sites to Document Changes in Natural Resources

1983 1994

1996 1998

1983

1996

Monitoring on-farmtrees in the Peanut Basin:28-year comparison

Jan 1983Jan 1983

Feb 2011Feb 2011

Woody Species at Site 487:

1984Bombax costatumAnnona senegalensisCombretum crotonoidesCombretum geitonophyllumCombretum glutinosumCombretum micranthumCombretum nigricansCrossopterix febrifugaDanielia oliveriDetarium microcarpumGardenia erubescensHexalobus monopetalusHymenocardia acidaLannea acidaOstryoderris stuhlmanniiPiliostigma thonningiiPterocarpus erinaceusStychnos spinosaTerminalia avicennioidesTerminalia macropteraVitex madiensisXimenia americanaCordyla pinnataEntada africanaSterculia setigera

Protection of an ecosystem:(Niokolo-Koba, Senegal)

2007

1984

2007Bombax costatumAnnona senegalensisCombretum crotonoidesCombretum geitonophyllumCombretum glutinosumCombretum micranthumCombretum nigricansCrossopterix febrifugaDanielia oliveriDetarium microcarpumGardenia erubescensHexalobus monopetalusHymenocardia acidaLannea acidaOstryoderris stuhlmanniiPiliostigma thonningiiPterocarpus erinaceusStychnos spinosaTerminalia avicennioidesTerminalia macropteraVitex madiensisXimenia americanaCordyla pinnataEntada africanaSterculia setigera

Aerial Surveys with the Centre de Suivi Ecologique (CSE)

A powerful combination: Airplane, GPS and a camera

Landsat Image: Mangroves, Protected areas, and Cropland

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 inthe Kedougou and Casamance Regions

Published Vegetation Map of Senegal (1986)

Soils of Senegal

NOAA-AVHRR

Seasonal VegetationPatterns

NDVI (vegetation index or greenness)

Satellite observed greening trend

Source: Herrmann et al., 2005

Trends in NDVI 1982 – 2006 corrected for the effects of rainfall:

Tree Parkland Dominated by Faidherbia albida:Leaf-off Stage in the Rainy Season

Enlargement from a Landsat Image, October 2000:Tree parklands not visible (south of Aguié, Niger)

0 5 km

Niger Land Cover in 1975

Niger Land Cover in 2000

Southern Niger in the 1980s

Southern Niger in 1997: Early Evidence of FMNR

Preparing for flightat Tahoua, Niger

Tahoua Region, Niger in 2005: Well established FMNR

Parkland Renaissance: trees are young and growing

Agricultural Parkland east of Matamèye

Impact of trees on crop growth

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

Landscape DynamicsSouthwest of Zinder

19551955

2005200519751975

Landscape DynamicsSouthwest of Zinder

19551955

2005200519751975

Percent Tree Cover Trend in the Study Area (Mirria-Magaria-Matameye Triangle)

General Extent of Farmer-Managed Natural Regeneration

Is It Increased Rainfall?

Population

More People – More Trees

Location of 12 Terroirs Used for ComparingTree Density Across the Niger-Nigeria Border

Niger

• Zinder• Maradi

• Tahoua

0 200 km

■■

■■

■■

■■ ■

■■

■Nigeria

Terroirs

Terroir in Niger 19 km North of the Niger-Nigeria Border

Source: Google Earth, 2005Source: Google Earth, 2005

Terroir in Niger 8.5 km North of the Niger-Nigeria Border

Source: Google Earth, 2005

Terroir in Nigeria 1.5 km south of the Niger-Nigeria Border

Source: Google Earth, 2005

Terroir in Nigeria 38 km south of the Niger-Nigeria Border

Source: Google Earth, 2005

Comparative Overview of Terroirs on Opposite Sides of the Niger-Nigeria Border

Source: Google Earth, 2005

Niger

Nigeria

What is the overallextent and densityof FMNR in southern Niger?

Quickbird imagesouth of Zinder

Extent and Density of Tree Cover Across Southern Niger

Maerua crassifolia

Benefits of On-Farm Trees… a Win-Win Strategy• Firewood production • Fodder for animals• Increase biodiversity• Habitat for millions of migrating birds• Fruit production• Traditional medicine• Increased soil fertility• Decreased soil erosion• Reduced wind speed• Increased crop yields• Increased water infiltration• Decrease in temperature• Increase in rainall• Inexpensive and easy to adopt• Increase in biomass and carbon• Contribute to mitigating climate change

Senegal land cover in 1975

Senegal land cover in 2000

Mature Faidherbia albida Parkland: N. of Khombole, Peanut Basin, Senegal

Mature Faidherbia albida Parkland: 32 T Carbon / haPeanut Basin, Senegal

Tree Parkland Dominated by Faidherbia albida:Leaf-off Stage in the Rainy Season (N. of Khombole)

Permanent Monitoring Sites in Senegal (Established in 1982-1983)

1983 1994

1996 1998

1983

2003

Monitoring on-farm trees in Senegal

Peanut Basin, 20-year comparison

Site 31

Monitoring on-farmtrees in the Peanut Basin:28-year comparison

Jan 1983Jan 1983

Feb 2011Feb 2011

Monitoring on-farm trees in the Peanut Basin

Feb 1998Feb 1998

Jan 2011Jan 2011

Monitoring on-farmtrees in the Peanut Basin:15-year comparison

Nov 1995Nov 1995

Jan 2011Jan 2011

Soil Susceptibility to Wind Erosion

Very low tree density in the Saloum

May 1983May 1983

Mar 2010Mar 2010

Monitoring on-farm trees in Senegal: 27-year comparison

Site 581: Dépt. de Kaffrine

Dec 2004Dec 2004

Jan 1994Jan 1994

Monitoring on-farm trees in the Saloum, Senegal

Senegal’s Agricultural Parkland Region and Potential Directions of Expansion to other Agricultural Regions

Agriculture areasRepresented in yellow

Main parkland areaOutlined in green

Faidherbia albida trees in rice fields, Basse Casamance, Senegal

Final Remarks Time-series remote sensing imagery played a key role in characterizing the extent and magnitude of agro-environmental transformations

High resolution imagery provides a practical way to monitor FMNR

Time-series images helped convince people that a positive landscape changes were happening at a grand scale

Remote sensing provides a baseline from which tomonitor the spread, uptake and impacts of FMNR