Ghana’s once-thriving Upper Guinean forests are in peril, with human activity, fires, and economic pressures threatening biodiversity.
Researchers are leveraging satellite data to study degradation patterns, with alarming findings of accelerated forest loss and degradation since 2015. Conservation initiatives like the Forest Data Partnership aim to counter these trends, offering a beacon of hope for sustainable solutions.
Protected Forests Under Threat
In southwestern Ghana, patches of tropical forest are scattered among farmlands and towns. These forest fragments are what remains of the Upper Guinean forest, a biodiversity hotspot in West Africa that has been heavily impacted by human activities and frequent fires.
These primary forests are home to a rich variety of wildlife, including primates, elephants, hippopotamuses, and butterflies. Most of these forests are located within protected reserves, yet satellite data shows that even these areas have been shrinking over recent decades. False-color images from Landsat 4 and Landsat 9 satellites reveal the changes between 1989 (lower image above) and 2023 (upper image above). In these images, the dark green areas represent the forest canopies of 12 protected reserves and Bia National Park in the Bia-Goaso forest district, while the lighter green indicates the surrounding farmlands and degraded landscapes.
Tracking Forest Loss and Degradation
“This area has historically been important forest habitat for biodiversity, but elephant populations have declined precipitously because of human encroachment and habitat degradation,” said Michael Wimberly, a professor of geography and environmental sustainability at the University of Oklahoma. The photograph below, taken by Wimberly, shows intact forests in a reserve east of the Bia-Goaso region.
Accelerating Changes and Key Drivers
Wimberly and a team of researchers in the United States and Ghana used Landsat data to study forest degradation, loss, and recovery in the reserves across Ghana from 2003 to 2019. Although vegetation change was relatively slow from 2003 to 2015, it picked up significantly between 2015 and 2019. Overall, there was more forest loss and degradation than recovery, resulting in a gradual decline of tree cover.
The drivers of change here are multifaceted, noted Wimberly. In 2016, drought associated with El Niño parched forests and promoted fires across more than 12 percent of Ghana’s moist semi-deciduous and upland evergreen forests. Forest loss was especially prevalent in a reserve known as Bonsam Bepo, south of the city of Goaso.
In a reserve southeast of this image, mining operations contributed to forest loss. In the reserve north of Bia National Forest, widespread logging for timber from 2017 to 2019 led to forest degradation. In other reserves, such as Krokosua (the u-shaped reserve at the bottom of the image), the expansion of cocoa farms has consumed forest. Ghana and neighboring Côte D’Ivoire produce about two-thirds of the world’s cocoa.
Solutions and Sustainability Efforts
A 2024 United Nations report on the state of the world’s forests highlighted the Forest Data Partnership, an effort to help people in Ghana access remote sensing data to track commodities linked to deforestation and prevent forest loss. The approach is being field-tested in Ghana and at the joint NASA-USAID SERVIR program’s regional hub for West Africa to help make agricultural production and food systems more sustainable.
Wimberly and colleagues continue to monitor Ghana’s tropical forest landscapes and forest reserves using Landsat data and models to classify the health of forests. Their updated results can be explored in this interactive map.
NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey.
