Temporal fragmentation analysis of a large oak forest in Morocco using landscape metrics

Forest fragmentation, characterized by the reduction of forested areas and changes in their spatial distribution, greatly affects the balance of the physical environment, biodiversity, and species richness. This study aims to assess forest fragmentation and analyze overall landscape heterogeneity using landscape metrics within the Maâmora forest, the largest oak forest in Morocco, covering an area of approximately 133,000 hectares. Landsat imagery spanning a 33-years period (1989-2022) was collected and processed to evaluate forest fragmentation throughout the research period. The results revealed a downward trend in forest land class, whereas bare land, settlements, and paved roads showed an increase in area. From 1989 to 2022, forest land decreased by 15.27% relative to its initial extent in 1989, while bare land, settlements, and paved roads increased by 14.83%, 0.18%, and 0.26%, respectively. The study area was progressively fragmented, as evidenced by increased values of Patch Number (41.29%), Patch Density (41.11%), Edge Density (25.89%), and Interspersion and Juxtaposition Index (17.45%), alongside decreased values of Largest Patch Index (43.24%), Aggregation Index (3.38%) and Effective mesh size (64.67%) at the class level. Moreover, at the landscape level, the Number of Patches, Shannon Diversity Index, and Simpson Diversity Index increased by 33.3%, 15.31%, and 18.03%, respectively, whereas the Contagion Index decreased by 15.65% during the study period. These changes are primarily driven by logging, agricultural expansion, overgrazing, and infrastructure development, which increase habitat fragmentation and reduce ecological connectivity. The findings highlight the adverse effects of land cover change and forest landscape fragmentation, providing spatially explicit information to guide restoration programs and sustainable land-use planning aimed at conserving the Maâmora oak forest.