The Persistence of Logging Roads in Forest Reserves in Ghana

Abstract:

Increased forest logging is a growing concern in tropical forests because it can lead to forest degradation and eventually result in deforestation. Not only is the direct removal of trees a concern, but also the roads created for logging can disrupt the local ecosystem through forest fragmentation, soil erosion, and nutrient loss. Logging has been occurring within the forest reserves in Ghana for many decades, but the extent of logging roads and their environmental impacts have not been studied. The main objective of this study was to determine if the density of logging roads increased or decreased within ten different forest reserves in Ghana from 2010-2019, and assess whether logging roads were persistent or changed from year to year.

Data for the study came from very high resolution RapidEye, (visible, near-infrared, and red-edge bands at 5 m resolution), and PlanetScope, visible and (near-infrared bands at 3 m resolution) satellite images from 2010-2019. Because of the frequent revisit time of these satellite constellations (six days for RapidEye and daily for PlanetScope) we were able to obtain cloud-free dry-season imagery for nearly every year. The roads that were visible from the satellite images were digitized, and a map of roads was created for each year. The change in density was determined for each forest reserve over the ten-year period.

We identified two major road types. There were a number of main roads that were persistent and visible for the entire study period. Also, there were smaller, temporary roads that were often offshoots from the main roads. These temporary roads appeared and disappeared within the ten-year time frame. It was expected that the total road density would increase in each reserve during the study period because road creation was occurring at a faster rate than road disappearance. The results from this study will help to advance research about the different causes and ecological impacts of forest degradation. Information on the density of roads and their changes over time can also help to influence future forest management techniques. Knowing where roads are located and how long they persist is necessary for assessing risk of future degradation and developing forest conservation plans.