Landscape changes in the semi-closed Raya agricultural graben floor of northern Ethiopia

Over the last few decades, the need for landscape monitoring and assessment of changes in spatial patterns over time has grown. Landscapes sustain changes of various aspects, such as their structure, in response to continuous modifications in land cover, land management regimes and policy decisions. This study investigates changes in the landscape structure along the Raya graben bottom in northern Ethiopia from 1986 to 2017. Landsat imageries were used to analyse land cover. The spatial structure of the landscape for 3 decades was evaluated using FRAGSTATS. The number of patches increased at the class and landscape levels. At the landscape level, the patches totalled 8,147 in 1986 and increased to 886,893 in 2017. Similarly, the patch density (PD) in 1986 was 3.4 and reached 372.7 in 2017. Therefore, high landscape fragmentation occurred within the study area. The value of the Shannon diversity index is close to 1.1, and the diversity of patch types within the landscape is regular. The Shannon Evenness Index value ranges from 0.6 to 0.7. Moreover, the diversity of patches has shown an increment across the study period. Each land cover reduces in size and proximity. Those changes were caused by population size, infrastructural development and commercial agriculture. Thus, proper land use planning must be practiced to reduce fragmentation and environmental impacts in landscapes that face increasing population pressure and continuous land cover changes.