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Scientists monitor forests, grasslands in West Africa

pastoralist in Senegal
Livestock-owning communities, known as pastoralists, herd cattle, goats and sheep, following seasonal migration routes in northern Senegal.

Two senior scientists at the Geospatial Sciences Center of Excellence will develop tools to help monitor and manage natural resources in West Africa using NASA satellite-based Earth imaging data.

Professor Michael Wimberly will utilize Landsat images to track the changes in forest reserves, while professor Niall Hanan will use Moderate Resolution Imaging Spectroradiometer, or MODIS, images to evaluate grazing lands. Both researchers are faculty in the Department of Natural Resource Management.

Their work is supported by SERVIR, a joint venture between NASA and the U.S. Agency for International Development to improve environmental decision-making in developing nations. Hanan and Wimberly are part of the applied science team for the newest center in Niamey, the capital city of Niger—SERVIR West Africa.

“SERVIR is designed to increase the uptake and utilization of NASA technology,” Hanan explained. “In addition to serving as advisers, we also do our own research and bring our own specific ideas and products to the hub.”

West Africa is composed of 18 countries covering an area two-thirds the size of the United States.  Though the hub will serve the entire region, critical regional issues, such as food security, water resources and land use change, in Burkina Faso, Ghana, Niger and Senegal have been designated as the first priorities.

Examining forests in Ghana

 Wimberly and professor Mark Cochrane, a wildfire expert, will examine forest reserves and fragments in southern Ghana through a three-year, $628,713 SERVIR grant. These researchers have built similar models to monitor forests in temperate regions and in the Amazon. One postdoctoral researcher will also work on the project.

Michael Wimberly
Michael Wimberly

The forested regions of West Africa are among the most climatically marginal tropical forests, Wimberly noted. “They are barely wet enough to be tropical forests and pressure from land-use effects and dense human populations are very intense in this region.”

The forest reserves are a relic of colonialism, when the British set aside forested areas as a resource for timber production. “Because of their potential for wood production, they haven’t been completely obliterated or converted into farmland,” he said. However, fire, overharvesting and illegal logging have degraded some of these reserves.

“We’re taking advantage of the long-term archive of Landsat imagery and using newer techniques to tease out subtle changes,” Wimberly said. Through this approach, the researchers will be able to identify intact forests as well as hotspots where degradation is occurring. That information will help government agencies decide how to manage these areas.

Assessing vegetation in grasslands

“The idea is to be able to predict, anticipate and plan,” said Hanan, who will use 15 to 20 years of MODIS data to map woody resources—trees and shrubs—and forage on the West African savannas through a three-year, $580,000 grant. One postdoctoral researcher will work on the project.

Niall Hanan
Niall Hanan

These grasslands are home to livestock-owning communities, known as pastoralists, who herd cattle, goats and sheep, following seasonal migration routes. Their animals are an important source of protein not only for their own communities, but for agricultural communities across the region.

Hanan has worked in Senegal, Niger and Mali for more than 30 years. In a recent National Science Foundation project, he used satellite imagery to show how a semiarid region with grasslands and scattered trees known as the Sahel has recovered from droughts in the 1970s and 80s.

A nongovernmental organization working in Mali could get information from the hub on the long-term changes in woody resources in their region and use that information to develop sustainable wood harvest and alternative energy strategies, Hanan explained.

At the end of the training and capacity-building project, Wimberly said, “we will transfer the methods and knowledge to partner organizations in Ghana and other West African countries.”

Hanan said, “The intent is that national and regional governments and nongovernmental agencies will use this data to impact the livelihoods and welfare of communities across the area.”