The Upper Guinean forests once covered more than 103 million acres from southern Guinea into Sierra Leone, through Liberia and southern C๔te d'Ivoire, into Ghana and western Togo. Rapid population growth and expansion of agriculture has fueled deforestation of more than 80 percent of the original forest cover, according to doctoral student Francis Dwomoh of the Geographic Information Science Center of Excellence at South Dakota State University.
Dwomoh has received a NASA Earth and Space Science Fellowship to support his research on deforestation in West Africa. Using satellite imagery, Dwomoh will examine the effect of human encroachment, climate change and fire on the Upper Guinean forests during the last 40 years and look at how fires may impact the remaining forest fragments.
The Ghana native, who began his doctoral work in 2012, is the 10th Geographic Information Science Center of Excellence doctoral student to receive this award. The one-year, $30,000 fellowship may be renewed for up to two additional years. His research adviser is senior scientist and professor of natural resource management Michael Wimberly.
Protecting diversity hotspot
The forests are home to 2,800 plant species and a diverse range of birds, reptiles, amphibians and mammals, with some only found in this region, making it what Dwomoh called a "biodiversity hotspot."
His study will focus on the remaining forest sections which are concentrated in Sierra Leone, Liberia, C๔te d'Ivoire and Ghana. Most of the fragments are confined to protected areas, including forest preserves, under government control.
Dwomoh will use Landsat imagery to track deforestation and information from NASA tropical rainfall and fire data to analyze the impact of fires on the region. Field work will also be done in Ghana.
The results will help government agencies and conservation groups determine how best to conserve these tropical forest remnants. "It will also provide a better understanding of the risks posed to tropical forests worldwide as climatic and population pressures increase," Wimberly said.
Changing landscape, climate
An estimated 70 percent of the world's cocoa supply is produced in West Africa. Farmers use slash and burn techniques to clear the land to plant cocoa trees and raise staples such as the banana-like plantain and cassava, a tuber that is the third-largest source of carbohydrates in the tropics.
Climatically, the Upper Guinean forests experience the highest temperatures and the longest dry season among tropical ecosystems worldwide, Dwomoh explained. Since the 1970s, temperatures have increased and precipitation has declined. "That's not good for agriculture either," he added.
Historically, the area experiences two rainy seasons -- the primary one from April to July when the major crops are grown, then a short dry period in August and a minor one from September to November. But, Dwomoh said, those distinctions are fading with climate change.
That increases the vulnerability of the forest fragments and leads to more frequent and intense fires, according to Dwomoh, who worked as a research scientist for the Forestry Research Institute of Ghana for eight years. His research will help ascertain whether these forest fragments may reach a tipping point at which they cannot recover from forest fires. Already some sections have been reduced to grassland littered with shrubs, he noted.
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